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Sample records for reactively sputtered zno

  1. Transparent conducting indium doped ZnO films by dc reactive S-gun magnetron sputtering.

    PubMed

    Ye, Z Z; Tang, J F

    1989-07-15

    Transparent conducting ZnO films have been prepared by modified S-gun reactive dc magnetron sputtering using an indium doped Zn target. Films with a resistivity of 1.08 x 10(-3) Omega cm and average transmittance of over 80% in the visible region were obtained. The influence of indium content at the surface of Zn target on the resistivity and transmittance of ZnO films was investigated. Optical properties of ZnO films in the 0.2-2.5-microm range were modeled by the Drude theory of free electrons. The reflectance of ZnO films in the 2.5-26.0-microm region was calculated. PMID:20555606

  2. Enhanced deposition of ZnO films by Li doping using radio frequency reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Chen, Liang-xian; Liu, Sheng; Li, Cheng-ming; Wang, Yi-chao; Liu, Jin-long; Wei, Jun-jun

    2015-10-01

    Radio frequency (RF) reactive magnetron sputtering was utilized to deposit Li-doped and undoped zinc oxide (ZnO) films on silicon wafers. Various Ar/O2 gas ratios by volume and sputtering powers were selected for each deposition process. The results demonstrate that the enhanced ZnO films are obtained via Li doping. The average deposition rate for doped ZnO films is twice more than that of the undoped films. Both atomic force microscopy and scanning electron microscopy studies indicate that Li doping significantly contributes to the higher degree of crystallinity of wurtzite-ZnO. X-ray diffraction analysis demonstrates that Li doping promotes the (002) preferential orientation in Li-doped ZnO films. However, an increase in the ZnO lattice constant, broadening of the (002) peak and a decrease in the peak integral area are observed in some Li-doped samples, especially as the form of Li2O. This implies that doping with Li expands the crystal structure and thus induces the additional strain in the crystal lattice. The oriented-growth Li-doped ZnO will make significant applications in future surface acoustic wave devices.

  3. Structural and optical characterization of high-quality ZnO thin films deposited by reactive RF magnetron sputtering

    SciTech Connect

    Zhang, X.L.; Hui, K.N.; Hui, K.S.; Singh, Jai

    2013-03-15

    Highlights: ► High-quality ZnO thin films were deposited at room temperature. ► Effect of O{sub 2} flow and RF sputtering voltages on properties of ZnO films were studied. ► O{sub 2}/Ar ratios played a key role in controlling optical properties of ZnO films. ► Photoluminescence intensity of the ZnO films strongly depended on O{sub 2}/Ar ratios. ► Crystallite size, stress and strain strongly depended on O{sub 2}/Ar ratios. - Abstract: ZnO thin films were deposited onto quartz substrates by radio frequency (RF) reactive magnetron sputtering using a Zn target. The structural and optical properties of the ZnO thin films were investigated comprehensively by X-ray diffraction (XRD), ultraviolet–visible and photoluminescence (PL) measurements. The effects of the oxygen content of the total oxygen–argon mixture and sputtering voltage in the sputtering process on the structural and optical properties of the ZnO films were studied systemically. The microstructural parameters, such as the lattice constant, crystallite size, stress and strain, were also calculated and correlated with the structural and optical properties of the ZnO films. In addition, the results showed that the crystalline quality of ZnO thin films improved with increasing O{sub 2}/Ar gas flow ratio from 2:8 to 8:2. XRD and PL spectroscopy revealed 800 V to be the most appropriate sputtering voltage for ZnO thin film growth. High-quality ZnO films with a good crystalline structure, tunable optical band gap as well as high transmittance could be fabricated easily by RF reactive magnetron sputtering, paving the way to obtaining cost-effective ZnO thin films transparent conducting oxides for optoelectronics applications.

  4. High rate reactive magnetron sputter deposition of Al-doped ZnO with unipolar pulsing and impedance control system

    SciTech Connect

    Nishi, Yasutaka; Hirohata, Kento; Tsukamoto, Naoki; Sato, Yasushi; Oka, Nobuto; Shigesato, Yuzo

    2010-07-15

    Al-doped ZnO (AZO) films were deposited on quartz glass substrates, unheated and heated to 200 deg. C, using reactive sputtering with a special feedback system of discharge impedance combined with midfrequency pulsing. A planar Zn-Al alloy target was connected to the switching unit, which was operated in a unipolar pulse mode. The oxidation of the target surface was precisely controlled by a feedback system for the entire O{sub 2} flow ratio including ''the transition region''. The deposition rate was about 10-20 times higher than that for films deposited by conventional sputtering using an oxide target. A deposition rate of AZO films of 390 nm/min with a resistivity of 3.8x10{sup -4} {Omega} cm and a transmittance in the visible region of 85% was obtained when the films were deposited on glass substrates heated to 200 deg. C with a discharge power of 4 kW.

  5. Preparation of DC reactive magnetron sputtered ZnO thin film towards photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Prabhu, M.; Sivanantham, A.; Kannan, P. Karthick; Vishnukanthan, V.; Mayandi, J.

    2013-06-01

    Zinc oxide thin films deposited on glass and p-type silicon (100) substrates by DC reactive magnetron sputtering are reported here. The XRD investigations confirmed that the thin films deposited by this technique have hexagonal wurtzite structure. AFM results present the surface morphology and roughness of the deposited thin films. From the optical absorption spectrum, the band gap of the thin film is found to be ˜ 3.2 eV. The photoluminescence spectrum of the sample has an UV emission peak centered at 407 nm with broad visible emission in the range of 500-580 nm.

  6. Violet and blue-green luminescence from Ti-doped ZnO films deposited by RF reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Chen, Haixia; Ding, Jijun; Ma, Shuyi

    2011-02-01

    Pure and Ti-doped zinc oxide (TZO) films are deposited using radio frequency (RF) reactive magnetron sputtering at different RF powers. Micro-structural and optical properties in doped ZnO films are systematically investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electronic microscopy (SEM), and a fluorescence spectrophotometer. The results indicate that ZnO films show stronger preferred orientation toward the c-axis and smoother surface roughness after Ti doping. As for TZO films, the full width at half maxima (FWHM) of (002) diffraction peaks decreased first and then increased, reaching a minimum of about 0.92° at 150 W, while the residual compressive stress of the TZO film prepared at 150 W became the largest. The photoluminescent (PL) spectra measured at room temperature reveal a violet, a blue and two green emissions. Intense violet and blue-green luminescence is obtained for the sample deposited at higher RF power. The origin of these emissions is discussed.

  7. Microstructures and optical properties of Cu-doped ZnO films prepared by radio frequency reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ma, Ligang; Ma, Shuyi; Chen, Haixia; Ai, Xiaoqian; Huang, Xinli

    2011-09-01

    Pure and Cu-doped ZnO (ZnO:Cu) thin films were deposited on glass substrates using radio frequency (RF) reactive magnetron sputtering. The effect of substrate temperature on the crystallization behavior and optical properties of the ZnO:Cu films have been studied. The crystal structures, surface morphology and optical properties of the films were systematically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and a fluorescence spectrophotometer, respectively. The results indicated that ZnO films showed a stronger preferred orientation toward the c-axis and a more uniform grain size after Cu-doping. As for ZnO:Cu films, the full width at half maxima (FWHM) of (0 0 2) diffraction peaks decreased first and then increased, reaching a minimum of about 0.42° at 350 °C and the compressive stress of ZnO:Cu decreased gradually with the increase of substrate temperature. The photoluminescence (PL) spectra measured at room temperature revealed two blue and two green emissions. Intense blue-green luminescence was obtained from the sample deposited at higher substrate temperature. Finally, we discussed the influence of annealing temperature on the structural and optical properties of ZnO:Cu films. The quality of ZnO:Cu film was markedly improved and the intensity of blue peak (∼485 nm) and green peak (∼527 nm) increased noticeably after annealing. The origin of these emissions was discussed.

  8. Enhancement Of Free Exciton Peak Intensity In Reactively Sputtered ZnO Thin Films On (0001) Al2O3

    SciTech Connect

    Tuezemen, S.; Guer, Emre; Yildirim, T.; Xiong, G.; Williams, R. T.

    2007-04-23

    Wide bandgap materials such as GaN with its direct bandgap structure have been developed rapidly for applications in short wavelength light emission. ZnO, II-VI oxide semiconductor, is also promising for various technological applications, especially for optoelectronic light emitting devices in the visible and ultraviolet (UV) range of the electromagnetic spectrum. Above-band-edge absorption spectra of reactively sputtered Zn- and O-rich samples exhibit free exciton (FX) and neutral acceptor bound exciton (A deg. X) features. It is shown that the residual acceptors which bind excitons with an energy of 75 meV reside about 312 meV above the valence band, according to effective mass theory. An intra-bandgap absorption feature peaking at 2.5 eV shows correlation with the characteristically narrow A-free exciton peak intensity. Relevant annealing processes are presented as a function of time and temperature dependently for both Zn- and O- rich thin films. Enhancement of the free exciton peak intensity is observed without disturbing the residual shallow acceptor profile which is necessary for at least background p-type conductivity.

  9. c-axis inclined ZnO films for shear-wave transducers deposited by reactive sputtering using an additional blind

    SciTech Connect

    Link, M.; Schreiter, M.; Weber, J.; Gabl, R.; Pitzer, D.; Primig, R.; Wersing, W.; Assouar, M.B.; Elmazria, O.

    2006-03-15

    This article reports on the growth and characterization of polycrystalline ZnO films having c axis inclined up to 16 deg. with respect to the substrate normal. These films allow the excitation of shear and longitudinal waves with comparable electromechanical coupling constants and are of significant interest for thin film bulk acoustic resonators (FBARs). The films are deposited on silicon substrates covered by Al{sub 2}O{sub 3} and SiO{sub 2} buffer layers under low pressure using a modified reactive dc-pulsed magnetron sputtering system. A blind has been positioned between target and substrate, allowing oblique particle incidence without tilting the wafer. The study of structural properties of the deposited ZnO films by x-ray diffraction and scanning electron microscopy has permitted to show the presence of the inclined structure. Electromechanical coupling constants K up to 13% have been extracted for shear-mode excitation using highly overmoded FBARs.

  10. Thermoelectric properties optimization of Al-doped ZnO thin films prepared by reactive sputtering Zn-Al alloy target

    NASA Astrophysics Data System (ADS)

    Fan, Ping; Li, Ying-zhen; Zheng, Zhuang-hao; Lin, Qing-yun; Luo, Jing-ting; Liang, Guang-xing; Zhang, Miao-qin; Chen, Min-cong

    2013-11-01

    Al-doped ZnO (AZO) has practical applications in the industry for thermoelectric generation, owing to its nontoxicity, low-cost and stability at high temperatures. In this study, AZO thin films with high quality were deposited on BK7 glass substrates at room-temperature by direct current reactive magnetron sputtering using Zn-Al alloy target. The deposited thin films were annealed at various temperatures ranging from 623 K to 823 K with a space of 50 K. It is found that the absolute value of Seebeck coefficient of AZO thin film annealed at 723 K increases stably with increasing of measuring temperature and reaches a value of ∼60 μV/K at 575 K. After that, Al-doping content was varied to further optimize the thermoelectric properties of AZO thin films. The power factor of AZO thin films with Al content of 3 wt% increased with increase of measuring temperature and the maximum power factor of 1.54 × 10-4 W m-1K-2 was obtained at 550 K with the maximum absolute values of Seebeck coefficient of 99 μV/K, which is promising for high temperature thermoelectric application.

  11. Modeling target erosion during reactive sputtering

    NASA Astrophysics Data System (ADS)

    Strijckmans, K.; Depla, D.

    2015-03-01

    The influence of the reactive sputter conditions on the racetrack and the sputter profile for an Al/O2 DC reactive sputter system is studied by modeling. The role of redeposition, i.e. the deposition of sputtered material back on the target, is therefore taken into account. The used model RSD2013 is capable of simulating the effect of redeposition on the target condition in a spatial resolved way. Comparison between including and excluding redeposition in the RSD2013 model shows that the in-depth oxidation profile of the target differs. Modeling shows that it is important to distinguish between the formed racetrack, i.e. the erosion depth profile, and the sputter profile. The latter defines the distribution of the sputtered atoms in the vacuum chamber. As the target condition defines the sputter yield, it does determine the racetrack and the sputter profile of the planar circular target. Both the shape of the racetrack and the sputter profile change as function of the redeposition fraction as well as function of the oxygen flow change. Clear asymmetries and narrowing are observed for the racetrack shape. Similar effects are noticed for the sputter profile but to a different extent. Based on this study, the often heard misconception that the racetrack shape defines the distribution of the sputtered atoms during reactive sputtering is proven to be wrong.

  12. Conductive ZnO:Zn Composites for High-Rate Sputtering Deposition of ZnO Thin Films

    NASA Astrophysics Data System (ADS)

    Zhou, Li Qin; Dubey, Mukul; Simões, Raul; Fan, Qi Hua; Neto, Victor

    2015-02-01

    We report an electrically conductive composite prepared by sintering ZnO and metallic Zn powders. Microstructure analysis combined with electrical conductivity studies indicated that when the proportion of metallic Zn reached a threshold (˜20 wt.%), a metal matrix was formed in accordance with percolation theory. This composite has potential as a sputtering target for deposition of high-quality ZnO. Use of the ZnO:Zn composite completely eliminates target poisoning effects in reactive sputtering of the metal, and enables deposition of thin ZnO films at rates much higher than those obtained by sputtering of pure ZnO ceramic targets. The optical transmittance of the ZnO films prepared by use of this composite is comparable with that of films produced by radio frequency sputtering of pure ZnO ceramic targets. The sputtering characteristics of the conductive ZnO:Zn composite target are reported, and possible mechanisms of the high rate of deposition are also discussed.

  13. Preparation Of Transparent Conducting Zinc Oxide Films By RF Reactive Sputtering

    NASA Astrophysics Data System (ADS)

    Vasanelli, L.; Valentini, A.; Losacco, A.

    1986-09-01

    Transparent conducting zinc oxide films have been prepared by reactive sputtering in an Ar/H2 mixture. The optical and electrical properties of the films are presented and discussed. The effects of some post-deposition thermal treatment have been also investigated. ZnO/CdTe heterojunctions have .been prepared by sputtering ZnO films on CdTe single crystals. The photovoltaic conversion efficiencies of the obtained solar cells was 6.8%.

  14. On reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.

    2016-01-01

    High power impulse magnetron sputtering (HiPIMS) is an ionized physical vapor deposition (IPVD) technique that is particularly promising for reactive sputtering applications. However, there are few issues that have to be resolved before the full potential of this technique can be realized. Here we give an overview of the key experimental findings for the reactive HiPIMS discharge. An increase in the discharge current is commonly observed with increased partial pressure of the reactive gas or decreased repetition pulse frequency. There are somewhat conflicting claims regarding the hysteresis effect in the reactive HiPIMS discharge as some report reduction or elimination of the hysteresis effect while others claim a feedback control is essential. The ion energy distribution of the metal ion and the atomic ion of the reactive gas are similar and extend to very high energies while the ion energy distribution of the working gas and the molecular ion of the reactive gas are similar and are much less energetic.

  15. Pressure Effect in ZnO Films Using Off-Axis Sputtering Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, C.-H.; Lehoczky, S. L.; Peters, P.; George, M. A.

    1999-01-01

    ZnO films are deposited on (0001) sapphire, (001) Si and quartz substrates using the off-axis reactive magnetron sputtering deposition. Based on film thickness measurements, three transport regions of sputtered particles are observed when films are deposited in the pressure regions of 5 mtorr - 150 mtorr. X-ray diffraction, scanning probes microscopy, and electrical measurements are also used to characterize these films. The full width at half maximum of theta rocking curves for epitaxial films is less than 0.5 deg. In textured films, it rises to several degrees. The epitaxial films deposited at high pressure reveal a flat surface with some hexagonal facets. The density of hexagonal facets decreases when the growth pressure is reduced. The resistivity of these epitaxial films also depends on the growth pressures. A relationship between the pressure effects and film properties are discussed.

  16. Reactive sputter deposition of boron nitride

    SciTech Connect

    Jankowski, A.F.; Hayes, J.P.; McKernan, M.A.; Makowiecki, D.M.

    1995-10-01

    The preparation of fully dense, boron targets for use in planar magnetron sources has lead to the synthesis of Boron Nitride (BN) films by reactive rf sputtering. The deposition parameters of gas pressure, flow and composition are varied along with substrate temperature and applied bias. The films are characterized for composition using Auger electron spectroscopy, for chemical bonding using Raman spectroscopy and for crystalline structure using transmission electron microscopy. The deposition conditions are established which lead to the growth of crystalline BN phases. In particular, the growth of an adherent cubic BN coating requires 400--500 C substrate heating and an applied {minus}300 V dc bias.

  17. Structural transformations in reactively sputtered alumina films

    SciTech Connect

    Nayar, P. Khanna, A.

    2014-04-24

    Thin films of amorphous alumina of thickness ∼350 nm were prepared on silicon wafer by DC cathode reactive sputtering. The effects of thermal annealing on the structural properties were investigated at annealing temperatures of 600°C, 800°C, 1100°C and 1220°C. X-ray diffraction showed that crystallization starts at 800°C and produces δ and θ alumina phases, the latter phase grows with heat treatment and the film was predominantly δ-phase with small amount of a-phase after annealing at 1220°C. AFM studies found that the surface of thin films smoothened upon crystallization.

  18. Reactive sputter deposition of metal oxide nanolaminates

    NASA Astrophysics Data System (ADS)

    Rubin Aita, Carolyn

    2008-07-01

    We discuss the reactive sputter deposition of metal oxide nanolaminates on unheated substrates using four archetypical examples: ZrO2 Al2O3, HfO2 Al2O3, ZrO2 Y2O3, and ZrO2 TiO2. The pseudobinary bulk phase diagrams corresponding to these nanolaminates represent three types of interfaces. I. Complete immiscibility (ZrO2 Al2O3 and HfO2 Al2O3). II. Complete miscibility (ZrO2 Y2O3). III. Limited miscibility without a common end-member lattice (ZrO2 TiO2). We found that, although reactive sputter deposition is a far-from-equilibrium process, thermodynamic considerations strongly influence both phase formation within layers and at interfaces. We show that pseudobinary phase diagrams can be used to predict interfacial cation mixing in the nanolaminates. However, size effects must be considered to predict specific structures. In the absence of pseudoepitaxy, size effects play a significant role in determining the nanocrystalline phases that form within a layer (e.g. tetragonal ZrO2, tetragonal HfO2, and orthorhombic HfO2) and at interfaces (e.g. monoclinic (Zr,Ti)O2). These phases are not bulk standard temperature and pressure phases. Their formation is understood in terms of self-assembly into the lowest energy structure in individual critical nuclei.

  19. Room temperature sputtering of inclined c-axis ZnO for shear mode solidly mounted resonators

    NASA Astrophysics Data System (ADS)

    Rughoobur, G.; DeMiguel-Ramos, M.; Mirea, T.; Clement, M.; Olivares, J.; Díaz-Durán, B.; Sangrador, J.; Miele, I.; Milne, W. I.; Iborra, E.; Flewitt, A. J.

    2016-01-01

    ZnO films with a c-axis significantly inclined away from the surface normal were grown by a remote plasma sputtering technique at room temperature. The films were used to make solidly mounted resonators (SMRs) operating in shear mode at a resonant frequency of 1.35 GHz. Control of the ZnO microstructure was achieved using a polycrystalline AlN seed layer which can be added on top of a sputtered acoustic mirror to give a complete SMR device. The ZnO was reactively sputtered in an atmosphere of argon and oxygen from a zinc target. The c-axis of the ZnO was estimated to be at an angle of ˜45° to the surface normal. SMRs were measured to have quality factors (Q) of up to 140 and effective electromechanical coupling coefficients of up to 2.2% in air. Although an inclined c-axis can be achieved with direct growth onto the acoustic mirror, it is shown that the AlN seed layer provides higher coupling coefficients and narrower inclination angular distribution. The responses of the devices in liquids of different viscosities (acetone, water, and AZ5214E photoresist) were measured. The shear mode Q decreased by 45% in acetone, 72% in water, and 92% in AZ5214E.

  20. Effect of Oxidation Condition on Growth of N: ZnO Prepared by Oxidizing Sputtering Zn-N Film

    NASA Astrophysics Data System (ADS)

    Qin, Xuesi; Li, Guojian; Xiao, Lin; Chen, Guozhen; Wang, Kai; Wang, Qiang

    2016-06-01

    Nitrogen-doped zinc oxide (N: ZnO) films have been prepared by oxidizing reactive RF magnetron-sputtering zinc nitride (Zn-N) films. The effect of oxidation temperature and oxidation time on the growth, transmittance, and electrical properties of the film has been explored. The results show that both long oxidation time and high oxidation temperature can obtain the film with a good transmittance (over 80 % for visible and infrared light) and a high carrier concentration. The N: ZnO film exhibits a special growth model with the oxidation time and is first to form a N: ZnO particle on the surface, then to become a N: ZnO layer, and followed by the inside Zn-N segregating to the surface to oxidize N: ZnO. The surface particle oxidized more adequately than the inside. However, the X-ray photoemission spectroscopy results show that the lower N concentration results in the lower N substitution in the O lattice (No). This leads to the formation of n-type N: ZnO and the decrease of carrier concentration. Thus, this method can be used to tune the microstructure, optical transmittance, and electrical properties of the N: ZnO film.

  1. Effect of Oxidation Condition on Growth of N: ZnO Prepared by Oxidizing Sputtering Zn-N Film.

    PubMed

    Qin, Xuesi; Li, Guojian; Xiao, Lin; Chen, Guozhen; Wang, Kai; Wang, Qiang

    2016-12-01

    Nitrogen-doped zinc oxide (N: ZnO) films have been prepared by oxidizing reactive RF magnetron-sputtering zinc nitride (Zn-N) films. The effect of oxidation temperature and oxidation time on the growth, transmittance, and electrical properties of the film has been explored. The results show that both long oxidation time and high oxidation temperature can obtain the film with a good transmittance (over 80 % for visible and infrared light) and a high carrier concentration. The N: ZnO film exhibits a special growth model with the oxidation time and is first to form a N: ZnO particle on the surface, then to become a N: ZnO layer, and followed by the inside Zn-N segregating to the surface to oxidize N: ZnO. The surface particle oxidized more adequately than the inside. However, the X-ray photoemission spectroscopy results show that the lower N concentration results in the lower N substitution in the O lattice (No). This leads to the formation of n-type N: ZnO and the decrease of carrier concentration. Thus, this method can be used to tune the microstructure, optical transmittance, and electrical properties of the N: ZnO film. PMID:27251324

  2. Reactively sputtered Ru-Si-O films

    NASA Astrophysics Data System (ADS)

    Gasser, S. M.; Kolawa, E.; Nicolet, M.-A.

    1999-08-01

    Films of Ru-Si-O were synthesized by reactively sputtering a Ru1Si1 target in an Ar/O2 gas mixture. They were characterized in terms of their composition by 2.0 MeV 4He++ backscattering spectrometry, their atomic density by thickness measurements combined with backscattering data, their microstructure by x-ray diffraction and transmission electron microscopy, and their electrical resistivity by four-point-probe measurements. The compositions indicate preferential sputtering with ruthenium enrichment of the films, and a saturation level of oxygen is determined at 67 at. % corresponding to the formation of SiO2 and RuO2. X-ray diffraction spectra reveal an amorphous structure for oxygen-saturated and nanocrystals for unsaturated as-deposited films. The crystallization temperature clearly increases with the oxygen concentration of the films, from 500 °C for oxygen-free films to 1000 °C for oxygen-saturated films, when annealed in vacuum for 30 min. Transmission electron micrographs of as-deposited oxygen-saturated films show few nanocrystals of 1-2 nm in diameter in an otherwise amorphous matrix. The atomic density is roughly 8×1022 atom/cm3 for all compositions. The resistivity of the ternary alloys scales with the terminal phases in the ternary phase diagram and reaches a maximum value when the Ru-SiO2 tie line is crossed near 50 at. % oxygen. The films are stable in vacuum up to thermal stressing at 800 °C for 5 h, and their decomposition starts near 1000 °C.

  3. AFM characterization of nonwoven material functionalized by ZnO sputter coating

    SciTech Connect

    Deng Bingyao; Yan Xiong; Wei Qufu Gao Weidong

    2007-10-15

    Sputter coatings provide new approaches to the surface functionalization of textile materials. In this study, polyethylene terephthalate (PET) nonwoven material was used as a substrate for creating functional nanostructures on the fiber surfaces. A magnetron sputter coating was used to deposit functional zinc oxide (ZnO) nanostructures onto the nonwoven substrate. The evolution of the surface morphology of the fibers in the nonwoven web was examined using atomic force microscopy (AFM). The AFM observations revealed a significant difference in the morphology of the fibers before and after the sputter coating. The AFM images also indicated the effect of the sputtering conditions on the surface morphology of the fibers. The increase in the sputtering time led to the growth of the ZnO grains on the fiber surfaces. The higher pressure in the sputtering chamber could cause the formation of larger grains on the fiber surfaces. The higher power used also generated larger grains on the fiber surfaces.

  4. Structural properties of Cu2O epitaxial films grown on c-axis single crystal ZnO by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gan, J.; Gorantla, S.; Riise, H. N.; Fjellvâg, Ø. S.; Diplas, S.; Løvvik, O. M.; Svensson, B. G.; Monakhov, E. V.; Gunnæs, A. E.

    2016-04-01

    Epitaxial Cu2O films grown by reactive and ceramic radio frequency magnetron sputtering on single crystalline ZnO (0001) substrates are investigated. The films are grown on both O- and Zn-polar surface of the ZnO substrates. The Cu2O films exhibit a columnar growth manner apart from a ˜5 nm thick CuO interfacial layer. In comparison to the reactively sputtered Cu2O, the ceramic-sputtered films are less strained and appear to contain nanovoids. Irrespective of polarity, the Cu2O grown by reactive sputtering is observed to have (111)Cu2O||(0001)ZnO epitaxial relationship, but in the case of ceramic sputtering the films are found to show additional (110)Cu2O reflections when grown on O-polar surface. The observed CuO interfacial layer can be detrimental for the performance of Cu2O/ZnO heterojunction solar cells reported in the literature.

  5. The target heating influence on the reactive magnetron sputtering process

    NASA Astrophysics Data System (ADS)

    Bondarenko, A.; Kolomiytsev, A.; Shapovalov, V.

    2016-07-01

    A physicochemical model for the reactive magnetron sputtering of a “hot” target is described in this paper. The system consisting of eight algebraic equations was solved for a tantalum target sputtered in an O2 environment. It was established that the hysteresis effect disappears with the increase of the ion current density.

  6. Synthesis, characterization, and hydrogen gas sensing properties of AuNs-catalyzed ZnO sputtered thin films

    NASA Astrophysics Data System (ADS)

    Drmosh, Q. A.; Yamani, Z. H.

    2016-07-01

    Hydrogen present in concentration up to 4 vol.% forms an explosive mixture with air. Its propensity to escape in the event of leak, could lead to quick build-up and formation of an explosive mixture with air in confined spaces, such as an automobile. This necessitates its detection at very low concentration. Zinc oxide (ZnO) is a well-known wide band gap (∼3.37 eV) semiconducting oxide that has been widely used for gas sensing applications. This work reports on the fabrication, characterization and gas sensing performance of nanogold decorated ZnO thin films made by DC reactive sputtering. The sensor films were fabricated by depositing a very thin layer of gold on the sputtered ZnO thin film. The as deposited Au@ZnO films were converted into highly crystalline ZnO film covered with gold nanostructures (AuNs@ZnO) by mild heat treatment. The structural and morphological as well as the compositional homogeneity of the as-deposited and heat-treated ZnO, Au@ZnO and AuNs@ZnO thin films were ascertained. The gas sensing behavior of the AuNs@ZnO thin films towards hydrogen as a function of temperature at different H2 concentrations was investigated and compared with that of pure and heat-treated ZnO films. The effect of the presence of gold nanoparticles on imparting improvement (in terms of higher response signal, high reproducibility and complete reversibility) was established; the optimal operating temperature was about 400 °C. A plausible mechanism for the observed enhancement in the sensing behavior of AuNs@ZnO films towards H2 is proposed.

  7. REACTIVE SPUTTER DEPOSITION OF CHROMIUM NITRIDE COATINGS

    EPA Science Inventory

    The effect of substrate temperature and sputtering gas compositon on the structure and properties of chromium-chromium nitride films deposited on C-1040 steel using r.f. magnetron sputter deposition was investigated. X-ray diffraction analysis was used to determine the structure ...

  8. Morphology and Structure of ZnO Films Synthesized by Off-Axis Sputtering Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, C.-H.; Lehoczky, S. L.

    1999-01-01

    ZnO is a wide-band-gap oxide material that has many applications. A new potential application of ZnO material is for light emitting devices since its structure and electrical properties are similar to that of the GaN material (a blue laser candidate). It also is a good substrate for fabricating GaN-based devices. Off-axis sputtering technique has revealed great potential in synthesizing excellent oxide materials because the negative ion bombardment is greatly reduced when adatoms condense on substrates. The surface of films grown by off-axis sputtering will be much smoother than that produced in a regular sputtering configuration. A growth mechanism is studied by investigating the morphology and structure of ZnO films under different growth conditions and orientations. ZnO films are deposited on (0001) sapphire and quartz substrates by off- axis sputtering deposition at various oxygen/argon mixture ratios and pressures and at different temperatures. All films reveal highly textured structures on quartz substrates and epitaxial growth on sapphire substrates. Two off-axis configurations, vertical and horizontal orientations are conducted to study the process of film growth, surface morphology, and film structure. X-ray diffraction, scanning probe microscopy, and electrical measurements are used to characterize these films. Detailed results will be discussed in the presentation. Keywords: ZnO, Photonic material, Off-axis sputtering, Growth mechanism

  9. Comparison on electrically pumped random laser actions of hydrothermal and sputtered ZnO films

    SciTech Connect

    Wang, Canxing; Jiang, Haotian; Li, Yunpeng; Ma, Xiangyang; Yang, Deren

    2013-10-07

    Random lasing (RL) in polycrystalline ZnO films is an intriguing research subject. Here, we have comparatively investigated electrically pumped RL behaviors of two metal-insulator-semiconductor structured devices using the hydrothermal and sputtered ZnO films as the semiconductor components, i.e., the light-emitting layers, respectively. It is demonstrated that the device using the hydrothermal ZnO film exhibits smaller threshold current and larger output optical power of the electrically pumped RL. The morphological characterization shows that the hydrothermal ZnO film is somewhat porous and is much rougher than the sputtered one, suggesting that in the former stronger multiple light scattering can occur. Moreover, the photoluminescence characterization indicates that there are fewer defects in the hydrothermal ZnO film than in the sputtered one, which means that the photons can pick up larger optical gain through stimulated emission in the hydrothermal ZnO film. Therefore, it is believed that the stronger multiple light scattering and larger optical gain contribute to the improved performance of the electrically pumped RL from the device using the hydrothermal ZnO film.

  10. Lateral variation of target poisoning during reactive magnetron sputtering

    SciTech Connect

    Guettler, D.; Groetzschel, R.; Moeller, W.

    2007-06-25

    The reactive gas incorporation into a Ti sputter target has been investigated using laterally resolving ion beam analysis during dc magnetron deposition of TiN in an Ar/N{sub 2} atmosphere. At sufficiently low reactive gas flow, the nitrogen incorporation exhibits a pronounced lateral variation, with a lower areal density in the target racetrack compared to the target center and edge. The findings are reproduced by model calculations. In the racetrack, the balance of reactive gas injection and sputter erosion is shifted toward erosion. The injection of nitrogen is dominated by combined molecular adsorption and recoil implantation versus direct ion implantation.

  11. Lateral variation of target poisoning during reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Güttler, D.; Grötzschel, R.; Möller, W.

    2007-06-01

    The reactive gas incorporation into a Ti sputter target has been investigated using laterally resolving ion beam analysis during dc magnetron deposition of TiN in an Ar /N2 atmosphere. At sufficiently low reactive gas flow, the nitrogen incorporation exhibits a pronounced lateral variation, with a lower areal density in the target racetrack compared to the target center and edge. The findings are reproduced by model calculations. In the racetrack, the balance of reactive gas injection and sputter erosion is shifted toward erosion. The injection of nitrogen is dominated by combined molecular adsorption and recoil implantation versus direct ion implantation.

  12. Synthesis and annealing study of RF sputtered ZnO thin film

    NASA Astrophysics Data System (ADS)

    Singh, Shushant Kumar; Sharma, Himanshu; Singhal, R.; Kumar, V. V. Siva; Avasthi, D. K.

    2016-05-01

    In this paper, we have investigated the annealing effect on optical and structural properties of ZnO thin films, synthesized by RF magnetron sputtering. ZnO thin films were deposited on glass and silicon substrates simultaneously at a substrate temperature of 300 °C using Argon gas in sputtering chamber. Thickness of as deposited ZnO thin film was found to be ~155 nm, calculated by Rutherford backscattering spectroscopy (RBS). These films were annealed at 400 °C and 500 °C temperature in the continuous flow of oxygen gas for 1 hour in tube furnace. X-ray diffraction analysis confirmed the formation of hexagonal wurtzite structure of ZnO thin film along the c-axis (002) orientation. Transmittance of thin films was increased with increasing the annealing temperature estimated by UV-visible transmission spectroscopy. Quality and texture of the thin films were improved with annealing temperature, estimated by Raman spectroscopy.

  13. Zn(O, S) layers for chalcoyprite solar cells sputtered from a single target

    NASA Astrophysics Data System (ADS)

    Grimm, A.; Kieven, D.; Lauermann, I.; Lux-Steiner, M. Ch.; Hergert, F.; Schwieger, R.; Klenk, R.

    2012-09-01

    A simplified Cu(In, Ga)(S, Se)2/Zn(O, S)/ZnO:Al stack for chalcopyrite thin-film solar cells is proposed. In this stack the Zn(O, S) layer combines the roles of the traditional CdS buffer and undoped ZnO layers. It will be shown that Zn(O, S) films can be sputtered in argon atmosphere from a single mixed target without substrate heating. The photovoltaic performance of the simplified stack matches that of the conventional approach. Replacing the ZnO target with a ZnO/ZnS target may therefore be sufficient to omit the CdS buffer layer and avoid the associated complexity, safety and recycling issues, and to lower production cost.

  14. Deposition of reactively ion beam sputtered silicon nitride coatings

    NASA Technical Reports Server (NTRS)

    Grill, A.

    1982-01-01

    An ion beam source was used to deposit silicon nitride films by reactively sputtering a silicon target with beams of Ar + N2 mixtures. The nitrogen fraction in the sputtering gas was 0.05 to 0.80 at a total pressure of 6 to 2 millionth torr. The ion beam current was 50 mA at 500 V. The composition of the deposited films was investigated by auger electron spectroscopy and the rate of deposition was determined by interferometry. A relatively low rate of deposition of about 2 nm. one-tenth min. was found. AES spectra of films obtained with nitrogen fractions higher than 0.50 were consistent with a silicon to nitrogen ratio corresponding to Si3N4. However the AES spectra also indicated that the sputtered silicon nitride films were contaminated with oxygen and carbon and contained significant amounts of iron, nickel, and chromium, most probably sputtered from the holder of the substrate and target.

  15. Rotating cylindrical magnetron sputtering: Simulation of the reactive process

    SciTech Connect

    Depla, D.; Mahieu, S.; Van Aeken, K.; Leroy, W. P.; Haemers, J.; De Gryse, R.; Li, X. Y.; Bogaerts, A.

    2010-06-15

    A rotating cylindrical magnetron consists of a cylindrical tube, functioning as the cathode, which rotates around a stationary magnet assembly. In stationary mode, the cylindrical magnetron behaves similar to a planar magnetron with respect to the influence of reactive gas addition to the plasma. However, the transition from metallic mode to poisoned mode and vice versa depends on the rotation speed. An existing model has been modified to simulate the influence of target rotation on the well known hysteresis behavior during reactive magnetron sputtering. The model shows that the existing poisoning mechanisms, i.e., chemisorption, direct reactive ion implantation and knock on implantation, are insufficient to describe the poisoning behavior of the rotating target. A better description of the process is only possible by including the deposition of sputtered material on the target.

  16. Elementary surface processes during reactive magnetron sputtering of chromium

    SciTech Connect

    Monje, Sascha; Corbella, Carles Keudell, Achim von

    2015-10-07

    The elementary surface processes occurring on chromium targets exposed to reactive plasmas have been mimicked in beam experiments by using quantified fluxes of Ar ions (400–800 eV) and oxygen atoms and molecules. For this, quartz crystal microbalances were previously coated with Cr thin films by means of high-power pulsed magnetron sputtering. The measured growth and etching rates were fitted by flux balance equations, which provided sputter yields of around 0.05 for the compound phase and a sticking coefficient of O{sub 2} of 0.38 on the bare Cr surface. Further fitted parameters were the oxygen implantation efficiency and the density of oxidation sites at the surface. The increase in site density with a factor 4 at early phases of reactive sputtering is identified as a relevant mechanism of Cr oxidation. This ion-enhanced oxygen uptake can be attributed to Cr surface roughening and knock-on implantation of oxygen atoms deeper into the target. This work, besides providing fundamental data to control oxidation state of Cr targets, shows that the extended Berg's model constitutes a robust set of rate equations suitable to describe reactive magnetron sputtering of metals.

  17. Sputter deposition of Al-doped ZnO films with various incident angles

    SciTech Connect

    Sato, Yasushi; Yanagisawa, Kei; Oka, Nobuto; Nakamura, Shin-ichi; Shigesato, Yuzo

    2009-09-15

    Al-doped ZnO (AZO) films were sputter deposited on glass substrates heated at 200 degree sign C under incident angles of sputtered particles at 0 degree sign (incidence normal to substrate), 20 deg., 40 deg., 60 deg., and 80 deg. In the case of normal incidence, x-ray diffraction pole figures show a strong [001] preferred orientation normal to the film surface. In contrast, in the case wherein the incident angles were higher than 60 degree sign , the [001] orientation inclined by 25 deg. - 35 deg. toward the direction of sputtered particles. Transmission electron microscopy revealed that the tilt angle of the [001] orientation increased with increasing angle of the incident sputtered particles, whereas the columnar structure did not show any sign of inclination with respect to the substrate plane.

  18. Local structure investigation of Co doped ZnO thin films prepared by RF sputtering technique

    NASA Astrophysics Data System (ADS)

    Yadav, A. K.; Haque, S. Maidul; Shukla, D.; Phase, D. M.; Jha, S. N.; Bhattacharyya, D.

    2016-05-01

    Co doped ZnO thin films have been prepared using rf magnetron sputtering technique with varying Co doping concentration. GIXRD has been used to probe long range order and Zn, Co and Oxygen K-edge XAFS measurements have been used for investigating local structure around Zn and Co atoms. GIXRD results show wurzite structure of the samples while XANES and EXAFS results at Zn and Co K edge show that Co is going at Zn site in ZnO matrix and no other phase is present. These results are further confirmed by O K edge and Co L2,3 edge XANES measurements.

  19. Highly conducting ZnSe films by reactive magnetron sputtering

    NASA Technical Reports Server (NTRS)

    Nouhi, A.; Stirn, R. J.

    1986-01-01

    This paper presents the results of an effort to deposit high-conductivity ZnSe on glass and conducting SnO2-coated glass substrates by reactive magnetron sputter deposition, using pure metal sputter targets of Zn and dopants such as In, Ga, and Al. Clear yellow ZnSe films were successfully obtained. By using substrate temperatures as low as 150 C, cosputtered dopants, and sputter parameters and H2Se injection rates which maximize the Zn-to-Se ratio in the films, ZnSe bulk resistivities have been lowered by up to seven orders of magnitude, reaching values as low as 20 ohm cm. The most effective dopant to data has been In, cosputtered with Zn in amounts leading to In atomic concentrations as high as 1.4 percent. Atomic-absorption measurements show an average 49.9/48.9 ratio of Zn to Se.

  20. Orientation Effects in ZnO Films Using Off-Axis Sputtering Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehoczky, S.; George, M. A.

    1999-01-01

    ZnO is a wide-band-gap oxide material and has been used in numerous applications. It is also a good substrate for fabricating GaN-based (a blue laser candidate) devices. Off-axis sputtering technique is one of the best techniques in synthesizing oxide materials because negative ion bombardment and particle kinetic energy is greatly reduced when adatoms condense on substrates. Since the sputtered material from the target arrive on the substrate surface at a 90 deg. configuration, which differs from the normal sputtering geometry, it is expected that the film uniformity and composition distributions will be affected. However, the details of these properties and mechanisms have not been well studied. ZnO films are synthesized on (0001) sapphire and quartz substrates by off-axis sputtering deposition in various oxygen/argon mixture ratios and pressures at different temperatures. Substrates and sputtering sources are placed at three different orientations that are orthogonal to each other. The normal direction of a substrate is parallel to the gravity vector and the other is perpendicular to it. Film thickness profiles at different growth orientations are determined using a profimeter. All films grown at high temperatures have highly textured structures on quartz substrates and epitaxially grow on sapphire substrates. Because of this process, the film surface is very smooth. X-ray diffraction, scanning probe microscopy, and Fourier transfer infrared spectroscopy, and electrical measurements will be used to characterize these films. Detailed results will be discussed in the presentation.

  1. Near band edge emission characteristics of sputtered nano-crystalline ZnO films

    NASA Astrophysics Data System (ADS)

    Kunj, Saurabh; Sreenivas, K.

    2016-05-01

    Sputtered zinc oxide (ZnO) thin films deposited on unheated glass substrate under different sputtering gas mixtures (Ar+O2) have been investigated using X-ray diffraction and photo luminescence spectroscopy. Earlier reported studies on ZnO films prepared by different techniques exhibit either a sharp/broad near band edge (NBE) emission peak depending on the crystalline quality of the film. In the present study zinc oxide films, grown on unheated substrates, are seen to possess a preferred (002) orientation with a microstructure consisting of clustered nano-sized crystallites. The splitting in the near band edge emission (NBE) into three characteristic peaks is attributed to quantum confinement effect, and is observed specifically under an excitation of 270 nm. Deep level emission (DLE) in the range 400 to 700 nm is not observed indicating absence of deep level radiative defects.

  2. Highly textured and transparent RF sputtered Eu2O3 doped ZnO films.

    PubMed

    Sreedharan, Remadevi Sreeja; Ganesan, Vedachalaiyer; Sudarsanakumar, Chellappan Pillai; Bhavsar, Kaushalkumar; Prabhu, Radhakrishna; Mahadevan Pillai, Vellara Pappukutty Pillai

    2015-01-01

    Background : Zinc oxide (ZnO) is a wide, direct band gap II-VI oxide semiconductor. ZnO has large exciton binding energy at room temperature, and it is a good host material for obtaining visible and infrared emission of various rare-earth ions. Methods : Europium oxide (Eu2O3) doped ZnO films are prepared on quartz substrate using radio frequency (RF) magnetron sputtering with doping concentrations 0, 0.5, 1, 3 and 5 wt%. The films are annealed in air at a temperature of 773 K for 2 hours. The annealed films are characterized using X-ray diffraction (XRD), micro-Raman spectroscopy, atomic force microscopy, ultraviolet (UV)-visible spectroscopy and photoluminescence (PL) spectroscopy. Results : XRD patterns show that the films are highly c-axis oriented exhibiting hexagonalwurtzite structure of ZnO. Particle size calculations using Debye-Scherrer formula show that average crystalline size is in the range 15-22 nm showing the nanostructured nature of the films. The observation of low- and high-frequency E2 modes in the Raman spectra supports the hexagonal wurtzite structure of ZnO in the films. The surface morphology of the Eu2O3 doped films presents dense distribution of grains. The films show good transparency in the visible region. The band gaps of the films are evaluated using Tauc plot model. Optical constants such as refractive index, dielectric constant, loss factor, and so on are calculated using the transmittance data. The PL spectra show both UV and visible emissions. Conclusion : Highly textured, transparent, luminescent Eu2O3 doped ZnO films have been synthesized using RF magnetron sputtering. The good optical and structural properties and intense luminescence in the ultraviolet and visible regions from the films suggest their suitability for optoelectronic applications. PMID:25765728

  3. Highly textured and transparent RF sputtered Eu2O3 doped ZnO films

    PubMed Central

    Sreedharan, Remadevi Sreeja; Ganesan, Vedachalaiyer; Sudarsanakumar, Chellappan Pillai; Bhavsar, Kaushalkumar; Prabhu, Radhakrishna; Mahadevan Pillai, Vellara Pappukutty Pillai

    2015-01-01

    Background Zinc oxide (ZnO) is a wide, direct band gap II-VI oxide semiconductor. ZnO has large exciton binding energy at room temperature, and it is a good host material for obtaining visible and infrared emission of various rare-earth ions. Methods Europium oxide (Eu2O3) doped ZnO films are prepared on quartz substrate using radio frequency (RF) magnetron sputtering with doping concentrations 0, 0.5, 1, 3 and 5 wt%. The films are annealed in air at a temperature of 773 K for 2 hours. The annealed films are characterized using X-ray diffraction (XRD), micro-Raman spectroscopy, atomic force microscopy, ultraviolet (UV)-visible spectroscopy and photoluminescence (PL) spectroscopy. Results XRD patterns show that the films are highly c-axis oriented exhibiting hexagonalwurtzite structure of ZnO. Particle size calculations using Debye-Scherrer formula show that average crystalline size is in the range 15–22 nm showing the nanostructured nature of the films. The observation of low- and high-frequency E2 modes in the Raman spectra supports the hexagonal wurtzite structure of ZnO in the films. The surface morphology of the Eu2O3 doped films presents dense distribution of grains. The films show good transparency in the visible region. The band gaps of the films are evaluated using Tauc plot model. Optical constants such as refractive index, dielectric constant, loss factor, and so on are calculated using the transmittance data. The PL spectra show both UV and visible emissions. Conclusion Highly textured, transparent, luminescent Eu2O3 doped ZnO films have been synthesized using RF magnetron sputtering. The good optical and structural properties and intense luminescence in the ultraviolet and visible regions from the films suggest their suitability for optoelectronic applications. PMID:25765728

  4. Intrinsic photocatalytic assessment of reactively sputtered TiO₂ films.

    PubMed

    Rafieian, Damon; Driessen, Rick T; Ogieglo, Wojciech; Lammertink, Rob G H

    2015-04-29

    Thin TiO2 films were prepared by DC magnetron reactive sputtering at different oxygen partial pressures. Depending on the oxygen partial pressure during sputtering, a transition from metallic Ti to TiO2 was identified by spectroscopic ellipsometry. The crystalline nature of the film developed during a subsequent annealing step, resulting in thin anatase TiO2 layers, displaying photocatalytic activity. The intrinsic photocatalytic activity of the catalysts was evaluated for the degradation of methylene blue (MB) using a microfluidic reactor. A numerical model was employed to extract the intrinsic reaction rate constants. High conversion rates (90% degradation within 20 s residence time) were observed within these microreactors because of the efficient mass transport and light distribution. To evaluate the intrinsic reaction kinetics, we argue that mass transport has to be accounted for. The obtained surface reaction rate constants demonstrate very high reactivity for the sputtered TiO2 films. Only for the thinnest film, 9 nm, slightly lower kinetics were observed. PMID:25844637

  5. Ion-induced oxidation of aluminum during reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kreiter, Oliver; Grosse-Kreul, Simon; Corbella, Carles; von Keudell, Achim

    2013-04-01

    Particle beam experiments were conducted in an ultra-high-vacuum vessel to mimic target poisoning during reactive magnetron sputtering of aluminum. Aluminum targets were exposed to quantified beams of argon ions, oxygen atoms and molecules, and aluminum vapour. The growth and etch rates were measured in situ by means of an Al-coated quartz crystal microbalance. The chemical state of the target surface was monitored in-situ by real-time Fourier transform infrared spectroscopy. The surface processes were modelled through a set of balance equations providing sputter yields and sticking coefficients. The results indicate that the oxygen uptake of the aluminum surface is enhanced by a factor 1 to 2 by knock-on implantation and that the deposition of aluminum is not affected by the oxidation state of the surface.

  6. Electrochemical and electrochromic behavior of reactively sputtered nickel oxide

    SciTech Connect

    Miller, E.L.; Rocheleau, R.E.

    1997-06-01

    Nickel oxide thin films were deposited by reactive sputtering in a 20% oxygen/argon atmosphere for use as oxygen evolution catalysts in the photoelectrochemical production of hydrogen. The optical properties of the films were also characterized to evaluate their application as window layers. The polycrystalline films deposited at residual gas pressures of 6 or 10 mTorr exhibited moderate activity for oxygen evolution in 1 N KOH and pronounced coloration and bleaching during alternating anodic/cathodic bias. Properties of these films were not sensitive to growth rate over the range studied, 0.5 to 4 {angstrom}/s. In contrast, films deposited at 2 mTorr exhibited poor activity for oxygen evolution and severely limited electrochromic behavior which the authors attribute to marked changes in the morphology and crystallinity in the low-pressure films. The films grown at 6 mTorr and higher tended to be more oriented, to have a higher degree of crystallinity, and higher oxygen content. Strong linkages between the electrochemical and optical behaviors observed in this work provide new insights into the processes involved in oxygen evolution reaction catalysis and electrochromism in reactively sputtered NiO{sub x} films. The results presented indicate that reactive sites located on or near grain boundaries are responsible for both behaviors.

  7. RF Reactive Magnetron Sputter Deposition of Silicon Sub-Oxides

    NASA Astrophysics Data System (ADS)

    van Hattum, E. D.

    2007-01-01

    RF reactive magnetron plasma sputter deposition of silicon sub oxide E.D. van Hattum Department of Physics and Astronomy, Faculty of Sciences, Utrecht University The work described in the thesis has been inspired and stimulated by the use of SiOx layers in the direct inductive printing technology, where the SiOx layer is used as the charge retention layer on the drums for copying and printing devices. The thesis describes investigations of the plasma and of processes taking place on the sputter target and on the SiOx growth surface in the room temperature, RF reactive magnetron plasma sputter deposition technology. The sputtering target consists of silicon and the reactive atmosphere consists of an Ar/O2 mixture. The composition of the grown SiOx layers has been varied between x=0 and x=2 by variation of the O2 partial pressure. The characteristics of the growth process have been related to the nanostructural properties of the grown films. The deposition system enables the characterisation of the plasma (Langmuir probe, energy resolved mass spectrometer) and of the growing film (Elastic Recoil Detection (ERD), Fourier transform infrared absorption spectroscopy) and is connected to a beamline of a 6MV tandem van de Graaff accelerator. Also Rutherford Backscattering Spectrometry and X-ray Photoelectron Spectroscopy have been applied. It is shown how ERD can be used as a real-time in-situ technique. The thesis presents spatially resolved values of the ion density, electron temperature and the quasi-electrostatic potential, determined using a Langmuir probe. The plasma potential has a maximum about 2 cm from the cathode erosion area, and decreases (more than 200 V typically) towards the floating sputter cathode. The potential decreases slightly in the direction towards the grounded growth surface and the positive, mainly Ar+, ions created in the large volume of the plasma closest to the substrate are accelerated towards the growth surface. These ions obtain a few eV of

  8. Photocatalytic efficiency of reusable ZnO thin films deposited by sputtering technique

    NASA Astrophysics Data System (ADS)

    Ahumada-Lazo, R.; Torres-Martínez, L. M.; Ruíz-Gómez, M. A.; Vega-Becerra, O. E.; Figueroa-Torres, M. Z.

    2014-12-01

    The photocatalytic activity of ZnO thin films with different physicochemical characteristics deposited by RF magnetron sputtering on glass substrate was tested for the decolorization of orange G dye aqueous solution (OG). The crystalline phase, surface morphology, surface roughness and the optical properties of these ZnO films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV-visible spectroscopy (UV-Vis), respectively. The dye photodecolorization process was studied at acid, neutral and basic pH media under UV irradiation of 365 nm. Results showed that ZnO films grow with an orientation along the c-axis of the substrate and exhibit a wurtzite crystal structure with a (002) preferential crystalline orientation. A clear relationship between surface morphology and photocatalytic activity was observed for ZnO films. Additionally, the recycling photocatalytic abilities of the films were also evaluated. A promising photocatalytic performance has been found with a very low variation of the decolorization degree after five consecutive cycles at a wide range of pH media.

  9. High rate reactive sputtering in an opposed cathode closed-field unbalanced magnetron sputtering system

    NASA Technical Reports Server (NTRS)

    Sproul, William D.; Rudnik, Paul J.; Graham, Michael E.; Rohde, Suzanne L.

    1990-01-01

    Attention is given to an opposed cathode sputtering system constructed with the ability to coat parts with a size up to 15 cm in diameter and 30 cm in length. Initial trials with this system revealed very low substrate bias currents. When the AlNiCo magnets in the two opposed cathodes were arranged in a mirrored configuration, the plasma density at the substrate was low, and the substrate bias current density was less than 1 mA/sq cm. If the magnets were arranged in a closed-field configuration where the field lines from one set of magnets were coupled with the other set, the substrate bias current density was as high as 5.7 mA/sq cm when NdFeB magnets were used. In the closed-field configuration, the substrate bias current density was related to the magnetic field strength between the two cathodes and to the sputtering pressure. Hard well-adhered TiN coatings were reactively sputtered in the opposed cathode system in the closed-field configuration, but the mirrored configuration produced films with poor adhesion because of etching problems and low plasma density at the substrate.

  10. Resistive switching behavior of RF magnetron sputtered ZnO thin films

    NASA Astrophysics Data System (ADS)

    Rajalakshmi, R.; Angappane, S.

    2015-06-01

    The resistive switching characteristics of RF magnetron sputtered zinc oxide thin films have been studied. The x-ray diffraction studies confirm the formation of crystalline ZnO on Pt/TiO2/SiOx/Si substrate. We have fabricated Cu/ZnO/Pt device using a shadow masking technique for resistive switching study. Our Cu/ZnO/Pt device exhibits a unipolar resistive switching behaviour. The switching observed in our device could be related to oxygen vacancies or Cu ions that generate the conducting filaments responsible for resistive switching. We found HRS to LRS resistance ratio of as high as ˜200 for our Cu/ZnO/Pt device. The higher resistance ratio and stability of Cu/ZnO/Pt device would make our RF magnetron sputtered zinc oxide thin films suitable for non volatile memory applications.

  11. Resistive switching behavior of RF magnetron sputtered ZnO thin films

    SciTech Connect

    Rajalakshmi, R.; Angappane, S.

    2015-06-24

    The resistive switching characteristics of RF magnetron sputtered zinc oxide thin films have been studied. The x-ray diffraction studies confirm the formation of crystalline ZnO on Pt/TiO{sub 2}/SiO{sub x}/Si substrate. We have fabricated Cu/ZnO/Pt device using a shadow masking technique for resistive switching study. Our Cu/ZnO/Pt device exhibits a unipolar resistive switching behaviour. The switching observed in our device could be related to oxygen vacancies or Cu ions that generate the conducting filaments responsible for resistive switching. We found HRS to LRS resistance ratio of as high as ∼200 for our Cu/ZnO/Pt device. The higher resistance ratio and stability of Cu/ZnO/Pt device would make our RF magnetron sputtered zinc oxide thin films suitable for non volatile memory applications.

  12. Effects of a seed layer on the structural properties of RF-sputtered ZnO thin films

    NASA Astrophysics Data System (ADS)

    Ur, Soon-Chul; Yi, Seung-Hwan

    2016-01-01

    Radio-frequency (RF) sputtered deposition combined with sol-gel spin coating has been applied to achieve a high-quality, c-axis-oriented ZnO film. The deposited ZnO films show only a c-axis-oriented ZnO (002) peak. The morphology, structure, and residual stress of the deposited ZnO films are found to depend strongly on the concentration of the precursor. As the concentration of the precursor is increased from 0.1-M to 0.6-M, the residual stress of the ZnO films changes from a compressive (-415 MPa) to a mild tensile (+90 MPa) mode. The deposited ZnO film interestingly shows facets when the concentration of the precursor is 0.6-M. We suggest that the residual stress in sputter-deposited ZnO films can be controlled by using the precursor concentration. This technique is believed to have been used for the first time, and can be applied to control the uniformity during micro speaker fabrication.

  13. Fabrication and characterization of pristine and annealed Ga doped ZnO thin films using sputtering

    NASA Astrophysics Data System (ADS)

    Mishra, Abhisek; Mohapatra, Saswat; Gouda, Himanshu Sekhar; Singh, Udai P.

    2016-05-01

    ZnO is a wide-band gap, transparent, polar semiconductor with unparalleled optoelectronic, piezoelectric, thermal and transport properties, which make it the material of choice for a wide range of applications such as blue/UV optoelectronics, energy conversion, transparent electronics, spintronic, plasmonic and sensor devices. We report, three sets of Ga doped Zinc Oxide (GZO) were fabricated in different sputtering power (100 watt, 200 watt and 300 watt). Thereafter films were annealed in nitrogen ambient for 30 minutes at 400° C. From the optical absorption spectroscopy it was found that pristine films are showing a 75% transmittance in the visible region of light and it increases after the annealing. However, for 300 W grown sample opposite trend has been achieved for the post annealed sample. X-ray diffraction pattern of all the pristine and annealed films showed a preferable growth orientation at (002) phase. Some other weak peaks were also appeared in different angle which indicates that films are polycrystalline in nature. XRD data also reveals that crystallite size increases with sputtering power up to 200 W and thereafter it decreases with the deposition power. It also noted that the crystallite size of the annealed film increases with compare to the non annealed films. At room temperature an enhancement in electrical properties of Ga doped ZnO thin films was noted for the annealed ZnO films except for the film deposited at 300 watt. More significantly, it was found that annealed thin films showed the resistivity in the range of 10-3 ˜ 10-4 ohm-cm. Such a high optical transmittance and conducting zinc-oxide thin film can be used as a window layer in solar cell.

  14. Reactive sputtering of titanium diboride and titanium disilicide

    SciTech Connect

    Maya, L.; Vallet, C.E.; Fiedor, J.N.

    1997-07-01

    Nanocomposite films of titanium nitride in either boron nitride or silicon nitride matrices were prepared by reactive sputtering of titanium diboride or titanium disilicide targets in a nitrogen plasma. These films were expected to have high dielectric constants and in the case of the silicon nitride matrix high hardness. The films were characterized by a variety of physicochemical techniques including photoelectron spectroscopy, Rutherford backscattering spectroscopy, RBS, and transmission electron microscopy. The films derived from titanium diboride incorporated oxygen as an inadvertent impurity in the form of titanium monoxide and dioxide. A silicon oxynitride underlayer is suggested by the RBS analysis of the silicon nitride based film, apparently arising from exposure of the native oxide on silicon to the nitrogen plasma. Capacitance measurements of the films showed moderately high dielectric constants of about 30{endash}60 and a hardness of 11 GPa for the silicon nitride nanocomposite. {copyright} {ital 1997 American Vacuum Society.}

  15. Characteristics of Sputtered ZnO Thin Films for an Inverted Organic Solar Cell.

    PubMed

    Park, Yong Seob; Park, Chul Min; Lee, Jaehyeong

    2016-05-01

    Several research groups have claimed high energy conversion efficiency in organic solar cells. However, it still has low efficiency and is unstable, because organic materials are easily oxidized by atmospheric humidity and UV light. In this work, ZnO thin film as the blocking layer attributed to the interference of the injection of the hole from the P3HT and no charge carrier recombination. We obtained the maximum power conversion efficiency of 1.9% under AM 1.5 G spectral illumination of 100 MWcm(-2), when we used a ZnO film of 60 nm and the optimized P3HT:PCBM, and Au as the back electrode to solve the reaction problem of Al electrode and to control the work function between the HOMO level of P3HT and the energy level of the metal electrode. Power conversion efficiency of inverted organic solar cell (IOSC) is significantly dependent on the thickness of the ZnO thin film deposited by unbalanced magnetron sputtering method. Also, the stability of IOSC is measured under ambient conditions. PMID:27483875

  16. Influence of reactive sputter deposition conditions on crystallization of zirconium oxide thin films

    SciTech Connect

    Sethi, Guneet; Sunal, Paul; Horn, Mark W.; Lanagan, Michael T.

    2009-05-15

    Zirconium oxide thin films were prepared through reactive magnetron sputtering with a zirconium target using pulsed-dc and radio frequency (rf) sources. The film crystallization was studied with respect to sputtering growth variables such as sputtering power, sputtering pressure, source frequency, oxygen pressure, substrate temperature, and substrate material. The crystallization was studied through x-ray diffraction (XRD) 2{theta} scans and was quantified with peak full width at half maximum and crystallite size. Crystallization of the films was found to occur over a broad range of sputter deposition parameters, while the amorphous phase was produced only at high sputtering pressure and low sputtering power. With a decrease in sputtering pressure or power, the crystallite size decreased. Energy dispersive x-ray spectroscopy, electron microscopy, and XRD analysis revealed that at very low pressures, these films are polyphase assemblages of cubic phases of oxygen deficient zirconium oxides such as ZrO and Zr{sub 2}O. When the sputtering oxygen content of these films is increased above 25%, monoclinic-ZrO{sub 2} phase is stabilized in the films and the deposition rate decreases. However, in the case of rf sputtering, an additional peak corresponding to tetragonal phase of ZrO{sub 2} is observed. The sputtering parameters were related to physical parameters such as sputtering mode, ion energy, and substrate temperature, which influence crystallinity.

  17. Effect of substrate temperature on the structural and optical properties of ZnO and Al-doped ZnO thin films prepared by dc magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Li, Xue-Yong; Li, Hong-Jian; Wang, Zhi-Jun; Xia, Hui; Xiong, Zhi-Yong; Wang, Jun-Xi; Yang, Bing-Chu

    2009-01-01

    ZnO and Al-doped ZnO(ZAO) thin films have been prepared on glass substrates by direct current (dc) magnetron sputtering from 99.99% pure Zn metallic and ZnO:3 wt%Al 2O 3 ceramic targets, the effects of substrate temperature on the crystallization behavior and optical properties of the films have been studied. It shows that the surface morphologies of ZAO films exhibit difference from that of ZnO films, while their preferential crystalline growth orientation revealed by X-ray diffraction remains always the (0 0 2). The optical transmittance and photoluminescence (PL) spectra of both ZnO and ZAO films are obviously influenced by the substrate temperature. All films exhibit a transmittance higher than 86% in the visible region, while the optical transmittance of ZAO films is slightly smaller than that of ZnO films. More significantly, Al-doping leads to a larger optical band gap ( Eg) of the films. It is found from the PL measurement that near-band-edge (NBE) emission and deep-level (DL) emission are observed in pure ZnO thin films. However, when Al was doped into thin films, the DL emission of the thin films is depressed. As the substrate temperature increases, the peak of NBE emission has a blueshift to region of higher photon energy, which shows a trend similar to the Eg in optical transmittance measurement.

  18. Strong free-carrier electro-optic response of sputtered ZnO films

    SciTech Connect

    Dominici, Lorenzo; Michelotti, Francesco; Auf der Maur, Matthias

    2012-09-01

    We report on the anisotropic electro-optic response of sputtered ZnO films and its dispersion towards both the frequency of the modulating voltage and the wavelength of the probing beam. The observed dispersion put in evidence two mechanisms. A fast and weak electrorefraction response, due to the nonlinear polarization of bound electrons, and a strong and slow carrier refraction term, ascribed to the modulation of free carriers. The former corresponds to an electro-optical coefficient of approximately -0.5 pm/V, while the latter may reach a magnitude up to 20 times stronger. This term relaxes at about 12 kHz and is largely wavelength dependent, due to a combination of effects. Also bias voltages lead to its quenching, likely extending the depletion regions at grain boundaries.

  19. Surface Texture and Structure of ZnO Films Synthesized by Off-Axis Sputtering Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehoczky, Sandor L.; George, M. A.; Lowndes, D. H.

    1999-01-01

    Morphology and structure of ZnO films deposited on (0001) sapphire and glass substrates by off-axis sputtering are investigated at various temperatures and pressures. All films show highly textured structures on glass substrates and epitaxial growth on sapphire substrates. The full width at half maximum of theta rocking curves for epitaxial films is less than 0.5 degrees. In textured films, it rises to several degrees. The trend of surface textures in films grown at low pressures is similar to those grown at high temperatures. A morphology transition from large well-defined hexagonal grains to flat surface was observed at a pressure of 50 mtorr and temperature of 550 C. The experiment results are explained by the transport behavior of depositing species.

  20. Electrical and optical properties of molybdenum doped zinc oxide films prepared by reactive RF magnetron sputtering

    SciTech Connect

    Reddy, R. Subba; Sreedhar, A.; Uthanna, S.

    2015-08-28

    Molybdenum doped zinc oxide (MZO) films were deposited on to glass substrates held at temperatures in the range from 303 to 673 K by reactive RF magnetron sputtering method. The chemical composition, crystallographic structure and surface morphology, electrical and optical properties of the films were determined. The films contained the molybdenum of 2.7 at. % in ZnO. The films deposited at 303 K were of X-ray amorphous. The films formed at 473 K were of nanocrystalline in nature with wurtzite structure. The crystallite size of the films was increased with the increase of substrate temperature. The optical transmittance of the films was in the visible range was 80–85%. The molybdenum (2.7 at %) doped zinc oxide films deposited at substrate temperature of 573 K were of nanocrystalline with electrical resistivity of 7.2×10{sup −3} Ωcm, optical transmittance of 85 %, optical band gap of 3.35 eV and figure of merit 30.6 Ω{sup −1}cm{sup −1}.

  1. Single domain m-plane ZnO grown on m-plane sapphire by radio frequency magnetron sputtering.

    PubMed

    Lin, B H; Liu, W-R; Lin, C Y; Hsu, S T; Yang, S; Kuo, C C; Hsu, C-H; Hsieh, W F; Chien, F S-S; Chang, C S

    2012-10-24

    High-quality m-plane orientated ZnO films have been successfully grown on m-plane sapphire by using radio frequency magnetron sputtering deposition. The introduction of a nanometer-thick, low-temperature-grown ZnO buffer layer effectively eliminates inclusions of other undesirable orientations. The structure characteristics of the ZnO epi-layers were thoroughly studied by synchrotron X-ray scattering and transmission electron microscopy (TEM). The in-plane epitaxial relationship between ZnO and sapphire follows (0002)(ZnO) [parallel] (112[overline]0)(sapphire) and (112[overline]0)(ZnO) [parallel] (0006)(sapphire) and the ZnO/sapphire interface structure can be described by the domain matching epitaxy along the [112[overline]0](ZnO) direction. The vibrational properties of the films were investigated by polarization dependent micro-Raman spectroscopy. Both XRD and micro-Raman results reveal that the obtained m-ZnO layers are under an anisotropic biaxial strain but still retains a hexagonal lattice. PMID:22989018

  2. Structural and optical properties of Al-doped ZnO films coated by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wu, Yue-Bo; Huang, Bo; Zhang, Liang-Tang; Li, Jing; Wu, Sun-Tao

    2007-12-01

    The Al-doped ZnO (AZO) films were deposited on glass by RF magnetron sputtering under different sputtering power: 75W, 120W, 160W and 200W. During the films deposition, the other sputtering conditions were maintained constant. The crystal structures of the AZO films were characterized and analyzed by X-ray diffraction. The surface morphologies of the films were observed by SEM. The transmission spectra of the films were measured using a spectrophotometer within the range from 200 to 800 nm at room temperature. The results indicate each of the films has a preferential c-axis orientation and the grain size increases with the increase of sputtering power. All the films exhibit a high transmittance in visible region and have sharp ultraviolet absorption characteristics.

  3. Sputtering

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1976-01-01

    The potential of using the sputtering process as a deposition technique is reviewed; however, the manufacturing and sputter etching aspects are also discussed. The basic mechanism for dc and rf sputtering is described. Sputter deposition is presented in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter etching, target geometry (coating and complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also discussed are some of the specific industrial areas which are turning to sputter deposition techniques.

  4. Effects of annealing pressure and Ar+ sputtering cleaning on Al-doped ZnO films

    NASA Astrophysics Data System (ADS)

    Wang, Jiwei; Mei, Yong; Lu, Xuemei; Fan, Xiaoxing; Kang, Dawei; Xu, Panfeng; Tan, Tianya

    2016-11-01

    Post-treatments of Al-doped ZnO films fabricated by sol-gel method were studied in condition of annealing in air, vacuum and protective ambient, as well as the follow-up Ar+ sputtering cleaning. The effect of annealing pressure on resistivity of AZO films was investigated from 105 to 10-4 Pa, where the resistivity decreased four orders of magnitude as the pressure decreased and approached to its minimum at 10 Pa. It was observed that the main decreasing of resistivity occurred in a very narrow range of middle vacuum (between 100 and 10 Pa) and high vacuum was dispensable. The XRD and XPS characterizations demonstrated that the radical increasing of oxygen vacancy, Zn interstitial and substitution of Al3+ for Zn2+ under middle vacuum were responsible for the significant enhancement of conductivity. The follow-up Ar+ sputtering cleaning can further decrease the resistivity through removing the chemisorbed oxygen on film surface and grain boundaries, meanwhile fulfil the surface texture process, and thus improve both electrical and optical performances for applications.

  5. High rate reactive sputtering of MoN(x) coatings

    NASA Technical Reports Server (NTRS)

    Rudnik, Paul J.; Graham, Michael E.; Sproul, William D.

    1991-01-01

    High rate reactive sputtering of MoN(x) films was performed using feedback control of the nitorgen partial pressure. Coatings were made at four different target powers: 2.5, 5.0, 7.5 and 10 kW. No hysteresis was observed in the nitrogen partial pressure vs. flow plot, as is typically seen for the Ti-N system. Four phases were determined by X-ray diffraction: molybdenum, Mo-N solid solution, Beta-Mo2N and gamma-Mo2N. The hardness of the coatings depended upon composition, substrate bias, and target power. The phases present in the hardest films differed depending upon deposition parameters. For example, the Beta-Mo2N phase was hardest (load 25 gf) at 5.0 kW with a value of 3200 kgf/sq mm, whereas the hardest coatings at 10 kW were the gamma-Mo2N phase (3000 kgf/sq mm). The deposition rate generally decreased with increasing nitrogen partial pressure, but there was a range of partial pressures where the rate was relatively constant. At a target power of 5.0 kW, for example, the deposition rates were 3300 A/min for a N2 partial pressure of 0.05 - 1.0 mTorr.

  6. Titanium Nitride Coatings Prepared by Reactive Sputtering on Steel

    NASA Astrophysics Data System (ADS)

    Nadia, Saoula; Karim, Henda; Rafika, Kesri

    2007-10-01

    Titanium nitride is used as coating on cutting tools because of their excellent mechanical properties such as high hardness and high wear resistance. Its chemical inertness gives rise to its application as corrosion protective coating. It's an excellent barrier material with good electrical conductivity in various metallization structures of advanced microelectronic devices. Finally, the golden glance of TiN established its use as decorative coating in the fashion jewellery and in architecture. The deposition process studied, in this work, use RF sputtering of a pure titanium target in a reactive nitrogen/ argon gas mixture, at various conditions. The substrates are steel. The main variables investigated are the composition of the Ar/N2 gas mixture, the total pressure, the deposition time and the discharge power. The aim of this work is to evaluate the performances of a local-made RF plasma reactor. The attention was given to the study of the structure, the composition of titanium nitride deposits, which have a considerable influence on their hardness. The deposited coatings were characterized by X-ray diffraction, energy dispersive spectroscopy (EDS) and micro-indentation.

  7. Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kunj, Saurabh; Sreenivas, K.

    2016-05-01

    Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O2/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

  8. Coating The Inner Walls Of Tubes With TiN Films By Reactive Sputtering

    SciTech Connect

    Kraus, T.; Lindner, J.K.N.; Stritzker, B.; Keckes, J.; Ensinger, W.

    2003-08-26

    It is possible to achieve a homogenous coating of the inner walls of tubes by sputter deposition. For this purpose a conical sputter target is moved through the tube parallel to its axis while an ion beam enters the tube along its axis, impinges onto the target and sputters material onto the tube inner wall. But so far only monatomic coatings were performed with this technique. To improve the mechanical properties of tubes TiN films were deposited by reactive sputtering. Therefore a Ti sputter target is used, the N2 reactive gas is delivered into the tube by a nozzle. The topography of the films is dominated by a ripple structure with the wave vector perpendicular to the tubes length axis. The development of the ripples is discussed in terms of scattered Ar projectiles which impinge onto the substrate as well as the deposited film under grazing incidence angles. Results of RBS, ERD, AFM, and hardness measurements are shown.

  9. Evidence of Negative Capacitance in Piezoelectric ZnO Thin Films Sputtered on Interdigital Electrodes.

    PubMed

    Laurenti, Marco; Verna, Alessio; Chiolerio, Alessandro

    2015-11-11

    The scaling paradigm known as Moore's Law, with the shrinking of transistors and their doubling on a chip every two years, is going to reach a painful end. Another less-known paradigm, the so-called Koomey's Law, stating that the computing efficiency doubles every 1.57 years, poses other important challenges, since the efficiency of rechargeable energy sources is substantially constant, and any other evolution is based on device architecture only. How can we still increase the computational power/reduce the power consumption of our electronic environments? A first answer to this question comes from the quest for new functionalities. Within this aim, negative capacitance (NC) is becoming one of the most intriguing and studied phenomena since it can be exploited for reducing the aforementioned limiting effects in the downscaling of electronic devices. Here we report the evidence of negative capacitance in 80 nm thick ZnO thin films sputtered on Au interdigital electrodes (IDEs). Highly (002)-oriented ZnO thin films, with a fine-grained surface nanostructure and the desired chemical composition, are deposited at room temperature on different IDEs structures. Direct-current electrical measurements highlighted the semiconducting nature of ZnO (current density in the order of 1 × 10(-3) A/cm(2)). When turned into the alternating current regime (from 20 Hz to 2 MHz) the presence of NC values is observed in the low-frequency range (20-120 Hz). The loss of metal/semiconductor interface charge states under forward bias conditions, together with the presence of oxygen vacancies and piezoelectric/electrostriction effects, is believed to be at the basis of the observed negative behavior, suggesting that ZnO thin-film-based field-effect transistors can be a powerful instrument to go beyond the Boltzmann limit and the downscaling of integrated circuit elements required for the fabrication of portable and miniaturized electronic devices, especially for electric household

  10. Mechanical and transparent conductive properties of ZnO and Ga-doped ZnO films sputtered using electron-cyclotron-resonance plasma on polyethylene naphtalate substrates

    SciTech Connect

    Akazawa, Housei

    2014-03-15

    Transparent conductive ZnO and Ga-doped ZnO (GZO) films were deposited on polyethylene naphtalate (PEN) sheet substrates using electron cyclotron resonance plasma sputtering. Both ZnO and GZO films were highly adhesive to the PEN substrates without inserting an intermediate layer in the interface. When compared at the same thickness, the transparent conductive properties of GZO films on PEN substrates were only slightly inferior to those on glass substrates. However, the carrier concentration of ZnO films on PEN substrates was 1.5 times that of those on glass substrates, whereas their Hall mobility was only 60% at a thickness of 300 nm. The depth profile of elements measured by secondary ion mass spectroscopy revealed the diffusion of hydrocarbons out of the PEN substrate into the ZnO film. Hence, doped carbons may act as donors to enhance carrier concentration, and the intermixing of elements at the interface may deteriorate the crystallinity, resulting in the lower Hall mobility. When the ZnO films were thicker than 400 nm, cracks became prevalent because of the lattice mismatch strain between the film and the substrate, whereas GZO films were free of cracks. The authors investigated how rolling the films around a cylindrical pipe surface affected their conductive properties. Degraded conductivity occurred at a threshold pipe radius of 10 mm when tensile stress was applied to the film, but it occurred at a pipe radius of 5 mm when compressive stress was applied. These values are guidelines for bending actual devices fabricated on PEN substrates.

  11. Comparative studies of nonpolar (10-10) ZnO films grown by using atomic layer deposition and radio-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Choi, Nak-Jung; Son, Hyo-Soo; Choi, Hyun-Jun; Kim, Kyoung-Kook; Lee, Sung-Nam

    2014-08-01

    We comparatively investigated the crystal and the optical properties of nonpolar (10-10) ZnO films grown on m-plane sapphire substrates by using atomic layer deposition (ALD) and radio frequency (RF) magnetron sputtering. From high-resolution X-ray ω/2 θ scans, the (100) peak of the ALD-grown ZnO film was clearly developed at ~ 15.9 ° while that of the RF sputter-grown ZnO was broadly observed at 15.6 ~ 15.9 °, indicating that a nonpolar (10-10) ZnO film would be preferentially grown on an m-plane sapphire substrate. The photoluminescence bandedge emission intensity of the ALD-grown (10-10) ZnO film was ten times higher than that of the RF sputtergrown ZnO film. In addition, the electroluminescence intensity of a semipolar (11-22) GaN-based light-emitting diode (LED) with an ALD-grown (10-10) ZnO film as a transparent conductive oxide material was much higher than that of a semipolar (11-22) GaN-based LED with RF sputter-grown (10-10) ZnO film.

  12. Reactive sputtering of titanium in Ar/CH4 gas mixture: Target poisoning and film characteristics

    SciTech Connect

    Fouad, O.A.; Rumaiz, A.; Shah, S.

    2009-03-01

    Reactive sputtering of titanium target in the presence of Ar/CH{sub 4} gas mixture has been investigated. With the addition of methane gas to above 1.5% of the process gas a transition from the metallic sputtering mode to the poison mode was observed as indicated by the change in cathode current. As the methane gas flow concentration increased up to 10%, the target was gradually poisoned. The hysteresis in the cathode current could be plotted by first increasing and then subsequently decreasing the methane concentration. X-ray diffraction and X-ray photoelectron spectroscopy analyses of the deposited films confirmed the formation of carbide phases and the transition of the process from the metallic to compound sputtering mode as the methane concentration in the sputtering gas is increased. The paper discusses a sputtering model that gives a rational explanation of the target poisoning phenomenon and shows an agreement between the experimental observations and calculated results.

  13. Improved optical and electrical properties of rf sputtered Al doped ZnO films on polymer substrates by low-damage processes

    SciTech Connect

    Min, Hyung Seob; Yang, Min Kyu; Lee, Jeon-Kook

    2009-03-15

    Three types of low-damage radio-frequency (rf) magnetron sputtering processes--an interruptive process, a rotating cylindrical holder method, and an off-axis sputtering method--were designed and studied to reduce the film surface temperature during deposition. Low-damage sputtering processes were investigated to improve the resistivity and optical transmittance in the visible range of Al doped ZnO (AZO) thin films deposited on polymer substrates. In the case of the polyethersulfone substrate, AZO films with a resistivity of 1.0x10{sup -3} {omega} cm and an optical transmittance of 75% were obtained by the rotating repeat holder method during rf sputtering.

  14. Using the Multipole Resonance Probe to Stabilize the Electron Density During a Reactive Sputter Process

    NASA Astrophysics Data System (ADS)

    Oberberg, Moritz; Styrnoll, Tim; Ries, Stefan; Bienholz, Stefan; Awakowicz, Peter

    2015-09-01

    Reactive sputter processes are used for the deposition of hard, wear-resistant and non-corrosive ceramic layers such as aluminum oxide (Al2O3) . A well known problem is target poisoning at high reactive gas flows, which results from the reaction of the reactive gas with the metal target. Consequently, the sputter rate decreases and secondary electron emission increases. Both parameters show a non-linear hysteresis behavior as a function of the reactive gas flow and this leads to process instabilities. This work presents a new control method of Al2O3 deposition in a multiple frequency CCP (MFCCP) based on plasma parameters. Until today, process controls use parameters such as spectral line intensities of sputtered metal as an indicator for the sputter rate. A coupling between plasma and substrate is not considered. The control system in this work uses a new plasma diagnostic method: The multipole resonance probe (MRP) measures plasma parameters such as electron density by analyzing a typical resonance frequency of the system response. This concept combines target processes and plasma effects and directly controls the sputter source instead of the resulting target parameters.

  15. Particle beam experiments for the analysis of reactive sputtering processes in metals and polymer surfaces.

    PubMed

    Corbella, Carles; Grosse-Kreul, Simon; Kreiter, Oliver; de los Arcos, Teresa; Benedikt, Jan; von Keudell, Achim

    2013-10-01

    A beam experiment is presented to study heterogeneous reactions relevant to plasma-surface interactions in reactive sputtering applications. Atom and ion sources are focused onto the sample to expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions, and metal vapor. The heterogeneous surface processes are monitored in situ by means of a quartz crystal microbalance and Fourier transform infrared spectroscopy. Two examples illustrate the capabilities of the particle beam setup: oxidation and nitriding of aluminum as a model of target poisoning during reactive magnetron sputtering, and plasma pre-treatment of polymers (PET, PP). PMID:24182103

  16. Particle beam experiments for the analysis of reactive sputtering processes in metals and polymer surfaces

    SciTech Connect

    Corbella, Carles; Grosse-Kreul, Simon; Kreiter, Oliver; Arcos, Teresa de los; Benedikt, Jan; Keudell, Achim von

    2013-10-15

    A beam experiment is presented to study heterogeneous reactions relevant to plasma-surface interactions in reactive sputtering applications. Atom and ion sources are focused onto the sample to expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions, and metal vapor. The heterogeneous surface processes are monitored in situ by means of a quartz crystal microbalance and Fourier transform infrared spectroscopy. Two examples illustrate the capabilities of the particle beam setup: oxidation and nitriding of aluminum as a model of target poisoning during reactive magnetron sputtering, and plasma pre-treatment of polymers (PET, PP)

  17. Particle beam experiments for the analysis of reactive sputtering processes in metals and polymer surfaces

    NASA Astrophysics Data System (ADS)

    Corbella, Carles; Grosse-Kreul, Simon; Kreiter, Oliver; de los Arcos, Teresa; Benedikt, Jan; von Keudell, Achim

    2013-10-01

    A beam experiment is presented to study heterogeneous reactions relevant to plasma-surface interactions in reactive sputtering applications. Atom and ion sources are focused onto the sample to expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions, and metal vapor. The heterogeneous surface processes are monitored in situ by means of a quartz crystal microbalance and Fourier transform infrared spectroscopy. Two examples illustrate the capabilities of the particle beam setup: oxidation and nitriding of aluminum as a model of target poisoning during reactive magnetron sputtering, and plasma pre-treatment of polymers (PET, PP).

  18. Deposition of F-doped ZnO transparent thin films using ZnF2-doped ZnO target under different sputtering substrate temperatures

    PubMed Central

    2014-01-01

    Highly transparent and conducting fluorine-doped ZnO (FZO) thin films were deposited onto glass substrates by radio-frequency (RF) magnetron sputtering, using 1.5 wt% zinc fluoride (ZnF2)-doped ZnO as sputtering target. Structural, electrical, and optical properties of the FZO thin films were investigated as a function of substrate temperature ranging from room temperature (RT) to 300°C. The cross-sectional scanning electron microscopy (SEM) observation and X-ray diffraction analyses showed that the FZO thin films were of polycrystalline nature with a preferential growth along (002) plane perpendicular to the surface of the glass substrate. Secondary ion mass spectrometry (SIMS) analyses of the FZO thin films showed that there was incorporation of F atoms in the FZO thin films, even if the substrate temperature was 300°C. Finally, the effect of substrate temperature on the transmittance ratio, optical energy gap, Hall mobility, carrier concentration, and resistivity of the FZO thin films was also investigated. PMID:24572004

  19. Physical and Optical Properties of SnO2/ZnO Film Prepared by an RF Magnetron Sputtering Method.

    PubMed

    Park, Jooyoung; Lee, Ikjae; Kim, Jaeyong

    2016-03-01

    Al-, Ga-, and In-doped ZnO thin films are widely used in many technical applications, such as in solar cells and on transparent conducting oxides having high optical transmission and low resistivity values. We prepared SnO2-doped ZnO thin films on quartz substrates by using an RF magnetron sputtering method at a substrate temperature of 350 degrees C. The ratio of SnO2 to ZnO was varied from 0 to 5:5 to investigate the effects of Sn on structure and physical properties of ZnO film. The samples were synthesized at a base pressure of 1.3 x 10(-4) Pa with a working pressure of 1.3 Pa and an RF power of 40 W under Ar atmosphere. The results of X-ray diffraction data revealed that pure ZnO films exhibit a strong (002) orientation and a polycrystalline wurzite hexagonal structure. However, as increasing the SnO2 concentration, ZnO transforms to an amorphous phase. The results of the Hall-effect-measurement system revealed that the resistivity values of the films increased as increasing the doping level of SnO2. The AFM data of morphology and microstructure showed that the grain size decreased with increasing SnO2 contents while the total area of grain the boundary increased. The average value of the transmittance of the films in the visible light range was 80-95% and was shifted toward to the shorter wavelengths of the absorption edges with increasing SnO2 contents. PMID:27455746

  20. Optical properties of silicon titanium oxide mixtures prepared by metallic mode reactive sputtering.

    PubMed

    Rademacher, Daniel; Bräuer, Günter; Fritz, Benjamin; Vergöhl, Michael

    2012-11-20

    In this paper different SiO(2)-TiO(2) mixtures are prepared by metallic mode reactive sputtering. The samples were sputtered from cylindrical targets in a sputter-up configuration using an additional plasma source for oxidization. The different ratios of SiO(2) and TiO(2) in the mixtures are prepared by a target sputtering power variation. Optical film properties of the mixtures such as refractive index, which is determined by ellipsometric measurements, and optical bandgap, which is measured by photometric (transmission) measurements, are investigated. The thin-film structure is investigated by x-ray diffraction analysis and the stress of the films is presented. It is shown that the metallic mode reactive sputtering in the present configuration is applicable to continuously tune optical and mechanical properties. Finally the sputtered mixed materials are compared with other optical standard materials such as Nb(2)O(5), Ta(2)O(5), HfO(2), and Al(2)O(3). PMID:23207316

  1. Effect of sputtering power on the electrical and optical properties of Ca-doped ZnO thin films sputtered from nanopowders compacted target

    NASA Astrophysics Data System (ADS)

    Mahdhi, H.; Ben Ayadi, Z.; Gauffier, J. L.; Djessas, K.; Alaya, S.

    2015-07-01

    In the present work, we have deposited calcium doped zinc oxide thin films by magnetron sputtering technique using nanocrystalline particles elaborated by sol-gel method as a target material. In the first step, the nanoparticles were synthesized by sol-gel method using supercritical drying in ethyl alcohol. The structural properties studied by X-ray diffractometry indicates that Ca doped ZnO has a polycrystalline hexagonal wurzite structure with a grain size of about 30 nm. Transmission electron microscopy (TEM) measurements have shown that the synthesized CZO is a nanosized powder. Then, thin films were deposited onto glass substrates by rf-magnetron sputtering at ambient temperature. The influence of RF sputtering power on structural, morphological, electrical, and optical properties were investigated. It has been found that all the films deposited were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (0 0 2) crystallographic direction. They have a typical columnar structure and a very smooth surface. The as-deposited films show a high transmittance in the visible range over 85% and low electrical resistivity at room temperature.

  2. Penetration, photo-reactivity and photoprotective properties of nanosized ZnO.

    PubMed

    Detoni, C B; Coradini, K; Back, P; Oliveira, C M; Andrade, D F; Beck, R C R; Pohlmann, A R; Guterres, S S

    2014-09-01

    The oxidizing capacity and skin penetration of a commercial nanosized ZnO, Nanosun™ (Micronisers-Australia), were evaluated in vitro using porcine skin. Nanosun™ was initially characterized regarding its photo-reactivity and size distribution. An assay using methylene blue was performed to confirm the Nanosun™ photo-reactivity by exposing the labile molecule to UVA irradiation in the presence and absence of the nanosized ZnO. The nanosized ZnO was photo-reactive, reducing the methylene blue concentration to 7% while its concentration remained constant in the control formulation (without ZnO). The product label states that the average particle size is 30 nm. X-ray diffraction, nitrogen sorption and UV-spectrophotometry confirmed the presence of nanometric particles of approximately 30 nm. On the other hand, laser diffractometry showed micrometric particles in the size distribution profile. These analyses indicated that the nanoparticles are arranged as agglomerates and aggregates of micrometric proportions ranging from 0.6 to 60 μm. The skin lipid peroxidation was determined by the formation of thiobarbituric acid reactive species (TBARS) and quantified by UV-spectrophotometry. When exposed to UVA radiation the nanosized ZnO applied porcine skin showed a lower production of TBARS (7.2 ± 1.5 nmol g(-1)) than the controls, the MCT applied porcine skin (18.4 ± 2.8 nmol g(-1)) and the blank porcine skin (14.0 ± 2.0 nmol g(-1)). The penetration of ZnO nanoparticles was studied by scanning electron microscopy and energy dispersive X-ray spectroscopy. The tested ZnO particles did not penetrate into viable layers of the intact porcine skin. The particles tend to accumulate on the skin folds and in these regions they may penetrate into the horny layer. PMID:24977261

  3. Improved electrochemical performance of LiCoO₂ electrodes with ZnO coating by radio frequency magnetron sputtering.

    PubMed

    Dai, Xinyi; Wang, Liping; Xu, Jin; Wang, Ying; Zhou, Aijun; Li, Jingze

    2014-09-24

    Surface modification of LiCoO2 is an effective method to improve its energy density and elongate its cycle life in an extended operation voltage window. In this study, ZnO was directly coated on as-prepared LiCoO2 composite electrodes via radio frequency (RF) magnetron sputtering. ZnO is not only coated on the electrode as thin film but also diffuses through the whole electrode due to the intrinsic porosity of the composite electrode and the high diffusivity of the deposited species. It was found that ZnO coating can significantly improve the cycling performance and the rate capability of the LiCoO2 electrodes in the voltage range of 3.0-4.5 V. The sample with an optimum coating thickness of 17 nm exhibits an initial discharge capacity of 191 mAh g(-1) at 0.2 C, and the capacity retention is 81% after 200 cycles. It also delivers superior rate performance with a reversible capacity of 106 mAh g(-1) at 10 C. The enhanced cycling performance and rate capability are attributed to the stabilized phase structure and improved lithium ion diffusion coefficient induced by ZnO coating as evidenced by X-ray diffraction, cyclic voltammetry, respectively. PMID:25158228

  4. Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Rafieian, Damon; Ogieglo, Wojciech; Savenije, Tom; Lammertink, Rob G. H.

    2015-09-01

    We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx<2), obtained by sputtering at relatively low oxygen concentration, formed rutile upon annealing in air, whereas stoichiometric films formed anatase. This route therefore presents a formation route for rutile films via lower (<500 °C) temperature pathways. The dynamics of the annealing process were followed by in situ ellipsometry, showing the optical properties transformation. The final crystal structures were identified by XRD. The anatase film obtained by this deposition method displayed high carriers mobility as measured by time-resolved microwave conductance. This also confirms the high photocatalytic activity of the anatase films.

  5. Oxygen vacancy mediated enhanced photo-absorption from ZnO(0001) nanostructures fabricated by atom beam sputtering

    NASA Astrophysics Data System (ADS)

    Solanki, Vanaraj; Joshi, Shalik R.; Mishra, Indrani; Kabiraj, D.; Mishra, N. C.; Avasthi, D. K.; Varma, Shikha

    2016-08-01

    The nanoscale patterns created on the ZnO(0001) surfaces during atom beam irradiation have been investigated here for their photo absorption response. Preferential sputtering, during irradiation, promotes Zn-rich zones that serve as the nucleation centers for the spontaneous creation of nanostructures. Nanostructured surfaces with bigger (78 nm) nanodots, displaying hexagonal ordering and long ranged periodic behavior, show higher photo absorption and a ˜0.09 eV reduced bandgap. These nanostructures also demonstrate higher concentration of oxygen vacancies which are crucial for these results. The enhanced photo-response, as observed here, has been achieved in the absence of any dopant elements.

  6. On performance limitations and property correlations of Al-doped ZnO deposited by radio-frequency sputtering

    NASA Astrophysics Data System (ADS)

    Crovetto, Andrea; Sand Ottsen, Tobias; Stamate, Eugen; Kjær, Daniel; Schou, Jørgen; Hansen, Ole

    2016-07-01

    The electrical properties of RF-sputtered Al-doped ZnO are often spatially inhomogeneous and strongly dependent on deposition parameters. In this work, we study the mechanisms that limit the minimum resistivity achievable under different deposition regimes. In a low- and intermediate-pressure regime, we find a generalized dependence of the electrical properties, grain size, texture, and Al content on compressive stress, regardless of sputtering pressure or position on the substrate. In a high-pressure regime, a porous microstructure limits the achievable resistivity and causes it to increase over time as well. The primary cause of inhomogeneity in the electrical properties is identified as energetic particle bombardment. Inhomogeneity in oxygen content is also observed, but its effect on the electrical properties is small and limited to the carrier mobility.

  7. CuInSe2/ZnSe solar cells using reactively sputter-deposited ZnSe

    NASA Technical Reports Server (NTRS)

    Nouhi, A.; Stirn, R. J.; Hermann, A.

    1987-01-01

    Results on CuInSe2/ZnSe thin-film heterojunction photovoltaic devices are presented. By the use of reactive magnetron cosputtering of Zn and In dopant in Ar/H2Se, ZnSe thin films have been deposited on glass and conducting SnO2-coated glass substrates with resistivity as low as 20 ohm-cm at deposition temperatures as low as 120 C. Preliminary ZnSe depositions onto CuInSe2 films supplied by industrial laboratories are encouraging. Reactive-sputter-deposition parameters for ZnSe have yet to be optimized for CuInSe2 substrates; however, open-circuit voltages as high as 430 mV were obtained. The highest short-circuit current density, as determined by spectral response weighted for AM1.5 global insulation, was 37.4 mA/sq cm. In all cases, a highly conductive ZnO film was overcoated onto the ZnSe to reduce the overall sheet resistance.

  8. Modeling for calculation of vanadium oxide film composition in reactive-sputtering process

    SciTech Connect

    Yu He; Jiang Yadong; Wang Tao; Wu Zhiming; Yu Junsheng; Wei Xiongbang

    2010-05-15

    A modified model describing the changing ratio of vanadium to oxide on the target and substrate as a function of oxygen flow is described. Actually, this ratio is extremely sensitive to the deposition conditions during the vanadium oxide (VO{sub x}) reactive magnetron-sputtering process. The method in this article is an extension of a previously presented Berg's model, where only a single stoichiometry compound layer was taken into consideration. This work deals with reactive magnetron sputtering of vanadium oxide films with different oxygen contents from vanadium metal target. The presence of vanadium mixed oxides at both target and substrate surface produced during reactive-sputtering process are included. It shows that the model can be used for the optimization of film composition with respect to oxygen flow in a stable hysteresis-free reactive-sputtering process. A systematic experimental study of deposition rate of VO{sub x} with respect to target ion current was also made. Compared to experimental results, it was verified that the theoretical calculation from modeling is in good agreement with the experimental counterpart.

  9. Effect of sputtering pressure on crystalline quality and residual stress of AlN films deposited at 823 K on nitrided sapphire substrates by pulsed DC reactive sputtering

    NASA Astrophysics Data System (ADS)

    Ohtsuka, Makoto; Takeuchi, Hiroto; Fukuyama, Hiroyuki

    2016-05-01

    Aluminum nitride (AlN) is a promising material for use in applications such as deep-ultraviolet light-emitting diodes (UV-LEDs) and surface acoustic wave (SAW) devices. In the present study, the effect of sputtering pressure on the surface morphology, crystalline quality, and residual stress of AlN films deposited at 823 K on nitrided a-plane sapphire substrates, which have high-crystalline-quality c-plane AlN thin layers, by pulsed DC reactive sputtering was investigated. The c-axis-oriented AlN films were homoepitaxially grown on nitrided sapphire substrates at sputtering pressures of 0.4–1.5 Pa. Surface damage of the AlN sputtered films increased with increasing sputtering pressure because of arcing (abnormal electrical discharge) during sputtering. The sputtering pressure affected the crystalline quality and residual stress of AlN sputtered films because of a change in the number and energy of Ar+ ions and Al sputtered atoms. The crystalline quality of AlN films was improved by deposition with lower sputtering pressure.

  10. Refractive index of thin films realized by Satisloh SP reactive sputtering system

    NASA Astrophysics Data System (ADS)

    Monaco, Gianni; Colautti, Arturo; Allegro, Cristina; Godin, Tom; Gold, Steffan; Witzany, Michael

    2013-09-01

    Pulsed DC reactive sputtering is a very interesting technique for coating applications. Reactive sputtering can give very dense layers, low stress of the deposited multilayer film, high reproducibility, very high hardness (up to 1200 Vickers hardness) with unbeatable high rates ideal for industrial applications. SP-100 is Satisloh reactive sputtering systems with only one target material but can deposit various film materials simply by using different gases such as argon, as well as the reactive gases nitrogen and oxygen. Silicon-oxides, silicon-nitrides and all kinds of silicon-oxy-nitrides (SiOx-SixOyNz-SixNy) with a refractive index range of 1.44-2.05 in the visible range can be obtained. In the reactive sputtering the material it is usually deposited in the so called "transition mode" where it must be found the correct equilibrium point between the target voltage and the reactive gas flow. The transition mode assures a dense film with a stable rate. Condition to find such equilibrium point is given by the so called "material hysteresis" in which the target voltage is depicted in function of the reactive gas voltage. The hysteresis and the consequent equilibrium point are strongly depended by the power supplied to the target and the inert gas (argon) flow which could affect the optical characteristics and the deposition rate. We checked the refractive indexes of the SiOx and SixNy of very thin (1 QW Optical thickness at 520 nm) and thicker (3, 5 and 9 QW @520 nm) reporting how the different conditions can affect the refractive index and the deposition rate of the different materials.

  11. Determination of reactive oxygen species from ZnO micro-nano structures with shape-dependent photocatalytic activity

    SciTech Connect

    He, Weiwei; Zhao, Hongxiao; Jia, Huimin; Yin, Jun-Jie; Zheng, Zhi

    2014-05-01

    Graphical abstract: ZnO micro/nano structures with shape dependent photocatalytic activity were prepared by hydrothermal reaction. The generations of hydroxyl radical, superoxide and singlet oxygen from irradiated ZnO were identified precisely by electron spin resonance spectroscopy. The type of reactive oxygen species was determined by band gap structure of ZnO. - Highlights: • ZnO micro/nano structures with different morphologies were prepared by solvothermal reaction. • Multi-pod like ZnO structures exhibited superior photocatalytic activity. • The generations of hydroxyl radical, superoxide and singlet oxygen from irradiated ZnO were characterized precisely by electron spin resonance spectroscopy. • The type of reactive oxygen species was determined by band gap structure of ZnO. - Abstract: ZnO micro/nano structures with different morphologies have been prepared by the changing solvents used during their synthesis by solvothermal reaction. Three typical shapes of ZnO structures including hexagonal, bell bottom like and multi-pod formed and were characterized by scanning electron microscopy and X-ray diffraction. Multi pod like ZnO structures exhibited the highest photocatalytic activity toward degradation of methyl orange. Using electron spin resonance spectroscopy coupled with spin trapping techniques, we demonstrate an effective way to identify precisely the generation of hydroxyl radicals, superoxide and singlet oxygen from the irradiated ZnO multi pod structures. The type of reactive oxygen species formed was predictable from the band gap structure of ZnO. These results indicate that the shape of micro-nano structures significantly affects the photocatalytic activity of ZnO, and demonstrate the value of electron spin resonance spectroscopy for characterizing the type of reactive oxygen species formed during photoexcitation of semiconductors.

  12. Duty cycle control in reactive high-power impulse magnetron sputtering of hafnium and niobium

    NASA Astrophysics Data System (ADS)

    Ganesan, R.; Treverrow, B.; Murdoch, B.; Xie, D.; Ross, A. E.; Partridge, J. G.; Falconer, I. S.; McCulloch, D. G.; McKenzie, D. R.; Bilek, M. M. M.

    2016-06-01

    Instabilities in reactive sputtering have technological consequences and have been attributed to the formation of a compound layer on the target surface (‘poisoning’). Here we demonstrate how the duty cycle of high power impulse magnetron sputtering (HiPIMS) can be used to control the surface conditions of Hf and Nb targets. Variations in the time resolved target current characteristics as a function of duty cycle were attributed to gas rarefaction and to the degree of poisoning of the target surface. As the operation transitions from Ar driven sputtering to metal driven sputtering, the secondary electron emission changes and reduces the target current. The target surface transitions smoothly from a poisoned state at low duty cycles to a quasi-metallic state at high duty cycles. Appropriate selection of duty cycle increases the deposition rate, eliminates the need for active regulation of oxygen flow and enables stable reactive deposition of stoichiometric metal oxide films. A model is presented for the reactive HIPIMS process in which the target operates in a partially poisoned mode with different degrees of oxide layer distribution on its surface that depends on the duty cycle. Finally, we show that by tuning the pulse characteristics, the refractive indices of the metal oxides can be controlled without increasing the absorption coefficients, a result important for the fabrication of optical multilayer stacks.

  13. Formation of cubic boron-nitride by the reactive sputter deposition of boron

    SciTech Connect

    Jankowski, A.F.; Hayes, J.P.; Makowiecki, D.W.; McKeman, M.A.

    1997-03-01

    Boron-nitride films are synthesized by RF magnetron sputtering boron targets where the deposition parameters of gas pressure, flow and composition are varied along with substrate temperature and applied bias. The films are analyzed using Auger electron spectroscopy, transmission electron microscopy, nanoindentation, Raman spectroscopy and x-ray absorption spectroscopy. These techniques provide characterization of film composition, crystalline structure, hardness and chemical bonding, respectively. Reactive, rf-sputtering process parameters are established which lead to the growth of crystalline BN phases. The deposition of stable and adherent boron nitride coatings consisting of the cubic phase requires 400 `C substrate heating and the application of a 300 V negative bias.

  14. Oxygen-dependent phosphorus networking in ZnO thin films grown by low temperature rf sputtering

    NASA Astrophysics Data System (ADS)

    Pugel, D. Elizabeth; Vispute, R. D.; Hullavarad, S. S.; Venkatesan, T.; Varughese, B.

    2007-03-01

    Radio frequency (rf) sputtered films of 10at.% P2O5-doped zinc oxide (ZnO) were deposited at temperatures (Td) below the sublimation point of P2O5 (Td<350°C) and at a range of oxygen pressures p(O2). Ultraviolet-visible optical transmission measurements, x-ray photoelectron spectroscopy (XPS), and x-ray diffraction were used to examine the effects of p(O2) during deposition on the band gap and on the bonding behavior of phosphorus. At both deposition temperatures studied (room temperature with unintentional heating and 125°C), an increase in phosphorus concentration with increasing p(O2) was observed. However, the dependence of the band gap behavior on p(O2) was observed to be dramatically different for the two deposition temperatures: room-temperature-deposited films show a redshift while films deposited at 125°C show a blueshift. Analysis of the oxygen 1s XPS peak shows a progressive formation of nonbridging (Zn-O-P) bond networks for room temperature films, whereas films grown at 125°C show increased (P-O-P) bond networks with increasing p(O2). This indicates that a small degree of thermal activation considerably modifies the bonding behavior of phosphorus in ZnO. Implications of these results for the use of phosphorus as a p-type dopant for ZnO are discussed.

  15. Formation of metal nanoparticles by short-distance sputter deposition in a reactive ion etching chamber

    SciTech Connect

    Nie Min; Meng, Dennis Desheng; Sun Kai

    2009-09-01

    A new method is reported to form metal nanoparticles by sputter deposition inside a reactive ion etching chamber with a very short target-substrate distance. The distribution and morphology of nanoparticles are found to be affected by the distance, the ion concentration, and the sputtering time. Densely distributed nanoparticles of various compositions were fabricated on the substrates that were kept at a distance of 130 mum or smaller from the target. When the distance was increased to 510 mum, island structures were formed, indicating the tendency to form continuous thin film with longer distance. The observed trend for nanoparticle formation is opposite to the previously reported mechanism for the formation of nanoparticles by sputtering. A new mechanism based on the seeding effect of the substrate is proposed to interpret the experimental results.

  16. Deposition of ultrahard Ti-Si-N coatings by pulsed high-current reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Oskomov, K. V.; Zakharov, A. N.; Rabotkin, S. V.; Solov'ev, A. A.

    2016-02-01

    We report on the results of investigation of properties of ultrahard Ti-Si-N coatings deposited by pulsed high-current magnetron reactive sputtering (discharge pulse voltage is 300-900 V, discharge pulse current is up to 200 A, pulse duration is 10-100 μs, and pulse repetition rate is 20-2000 Hz). It is shown that for a short sputtering pulse (25 μs) and a high discharge current (160 A), the films exhibit high hardness (66 GPa), wear resistance, better adhesion, and a lower sliding friction coefficient. The reason is an enhancement of ion bombardment of the growing coating due to higher plasma density in the substrate region (1013 cm-3) and a manifold increase in the degree of ionization of the plasma with increasing peak discharge current (mainly due to the material being sputtered).

  17. Properties of AlN films deposited by reactive ion-plasma sputtering

    SciTech Connect

    Bert, N. A.; Bondarev, A. D.; Zolotarev, V. V.; Kirilenko, D. A.; Lubyanskiy, Ya. V.; Lyutetskiy, A. V.; Slipchenko, S. O.; Petrunov, A. N.; Pikhtin, N. A. Ayusheva, K. R.; Arsentyev, I. N.; Tarasov, I. S.

    2015-10-15

    The properties of SiO{sub 2}, Al{sub 2}O{sub 3}, and AlN dielectric coatings deposited by reactive ion-plasma sputtering are studied. The refractive indices of the dielectric coatings are determined by optical ellipsometry. It is shown that aluminum nitride is the optimal material for achieving maximum illumination of the output mirror of a semiconductor laser. A crystalline phase with a hexagonal atomic lattice and oxygen content of up to 10 at % is found by transmission electron microscopy in the aluminum-nitride films. It is found that a decrease in the concentration of residual oxygen in the chamber of the reactive ion-plasma sputtering installation makes it possible to eliminate the appearance of vertical pores in the bulk of the aluminum-nitride film.

  18. Current-voltage-time characteristics of the reactive Ar/N{sub 2} high power impulse magnetron sputtering discharge

    SciTech Connect

    Magnus, F.; Sveinsson, O. B.; Olafsson, S.; Gudmundsson, J. T.

    2011-10-15

    The discharge current and voltage waveforms have been measured in a reactive high power impulse magnetron sputtering (HiPIMS) Ar/N{sub 2} discharge with a Ti target for 400 {mu}s long pulses. We observe that the current waveform in the reactive Ar/N{sub 2} HiPIMS discharge is highly dependent on the pulse repetition frequency, unlike the non-reactive Ar discharge. The current is found to increase significantly as the frequency is lowered. This is attributed to an increase in the secondary electron emission yield during the self-sputtering phase, when the nitride forms on the target at low frequencies. In addition, self-sputtering runaway occurs at lower discharge voltages when nitrogen is added to the discharge. This illustrates the crucial role of self-sputtering in the behavior of the reactive HiPIMS discharge.

  19. Electrochromism Properties of Palladium Doped Tungsten-Oxide Thin Films Prepared with RF Reactive Sputtering

    NASA Astrophysics Data System (ADS)

    Yabumoto, Taihei; Iwai, Yuki; Miura, Noboru; Matsumoto, Setsuko; Nakano, Ryotaro; Matsumoto, Hironaga

    Palladium doped tungsten oxide thin films were prepared by RF reactive sputtering in a mixture of argon and oxygen at room temperature. XRD patterns indicated that these films were amorphous. SEM imaging indicated a smaller grain size of palladium doped thin film compared with that of undoped tungsten oxide thin film. With electrochromism, palladium doped tungsten oxide exhibited a reverse optical modulation with respect to the applied potential.

  20. Effects of Substrate Temperature on ZAO Thin Film Prepared by DC Magnetron Reactive Sputtering

    NASA Astrophysics Data System (ADS)

    Lu, F.; Zhou, X. G.; Xu, C. H.; Wen, L. S.

    The effects of substrate temperature on the resistivity and transmittance of ZAO thin films prepared by DC magnetron reactive sputtering have been investigated. The properties of the samples have been analyzed through Hall effect, X-ray diffraction and SEM. The results show that carrier concentration, Hall mobility and crystallinity of the films depend obviously on the deposition temperature. The film deposited at the range 200-250°C has lower resistivity and higher transmittance.

  1. Reactive sputtering of δ-ZrH{sub 2} thin films by high power impulse magnetron sputtering and direct current magnetron sputtering

    SciTech Connect

    Högberg, Hans Tengdelius, Lina; Eriksson, Fredrik; Broitman, Esteban; Lu, Jun; Jensen, Jens; Hultman, Lars; Samuelsson, Mattias

    2014-07-01

    Reactive sputtering by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a Zr target in Ar/H{sub 2} plasmas was employed to deposit Zr-H films on Si(100) substrates, and with H content up to 61 at. % and O contents typically below 0.2 at. % as determined by elastic recoil detection analysis. X-ray photoelectron spectroscopy reveals a chemical shift of ∼0.7 eV to higher binding energies for the Zr-H films compared to pure Zr films, consistent with a charge transfer from Zr to H in a zirconium hydride. X-ray diffraction shows that the films are single-phase δ-ZrH{sub 2} (CaF{sub 2} type structure) at H content >∼55 at. % and pole figure measurements give a 111 preferred orientation for these films. Scanning electron microscopy cross-section images show a glasslike microstructure for the HiPIMS films, while the DCMS films are columnar. Nanoindentation yield hardness values of 5.5–7 GPa for the δ-ZrH{sub 2} films that is slightly harder than the ∼5 GPa determined for Zr films and with coefficients of friction in the range of 0.12–0.18 to compare with the range of 0.4–0.6 obtained for Zr films. Wear resistance testing show that phase-pure δ-ZrH{sub 2} films deposited by HiPIMS exhibit up to 50 times lower wear rate compared to those containing a secondary Zr phase. Four-point probe measurements give resistivity values in the range of ∼100–120 μΩ cm for the δ-ZrH{sub 2} films, which is slightly higher compared to Zr films with values in the range 70–80 μΩ cm.

  2. Increase of the deposition rate in reactive sputtering of metal oxides using a ceramic nitride target

    SciTech Connect

    Severin, D.; Wuttig, M.; Kappertz, O.; Nyberg, T.; Berg, S.; Pflug, A.

    2009-05-01

    We present a method to eliminate hysteresis effects and to increase the deposition rate for the reactive sputtering of metal oxides. This is achieved by using a ceramic nitride target in an argon-oxygen atmosphere. Although the use of a ceramic nitride target leads to pronounced changes of the processing characteristics, incorporation of nitrogen into the growing film is very small. These observations can be theoretically predicted using an extension of Berg's model [S. Berg and T. Nyberg, Thin Solid Films 476, 215 (2005)] to two different reactive gases and a compound target.

  3. Optical characterization of Mg-doped ZnO thin films deposited by RF magnetron sputtering technique

    NASA Astrophysics Data System (ADS)

    Singh, Satyendra Kumar; Hazra, Purnima; Tripathi, Shweta; Chakrabarti, P.

    2016-05-01

    This paper reports the in-depth analysis on optical characteristics of magnesium (Mg) doped zinc oxide (ZnO) thin films grown on p-silicon (Si) substrates by RF magnetron sputtering technique. The variable angle ellipsometer is used for the optical characterization of as-deposited thin films. The optical reflectance, transmission spectra and thickness of as-deposited thin films are measured in the spectral range of 300-800 nm with the help of the spectroscopic ellipsometer. The effect of Mg-doping on optical parameters such as optical bandgap, absorption coefficient, absorbance, extinction coefficient, refractive Index and dielectric constant for as-deposited thin films are extracted to show its application in optoelectronic and photonic devices.

  4. X-ray absorption spectroscopy of Mn doped ZnO thin films prepared by rf sputtering technique

    SciTech Connect

    Yadav, Ashok Kumar; Jha, S. N.; Bhattacharyya, D.; Haque, Sk Maidul; Shukla, Dinesh; Choudhary, Ram Janay

    2015-11-15

    A set of r.f. sputter deposited ZnO thin films prepared with different Mn doping concentrations have been characterised by Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Spectroscopy (XANES) measurements at Zn, Mn and O K edges and at Mn L{sub 2,3} edges apart from long range structural characterisation by Grazing Incident X-ray Diffraction (GIXRD) technique. Magnetic measurements show room temperature ferromagnetism in samples with lower Mn doping which is however, gets destroyed at higher Mn doping concentration. The results of the magnetic measurements have been explained using the local structure information obtained from EXAFS and XANES measurements.

  5. Transparent photostable ZnO nonvolatile memory transistor with ferroelectric polymer and sputter-deposited oxide gate

    SciTech Connect

    Park, C. H.; Im, Seongil; Yun, Jungheum; Lee, Gun Hwan; Lee, Byoung H.; Sung, Myung M.

    2009-11-30

    We report on the fabrication of transparent top-gate ZnO nonvolatile memory thin-film transistors (NVM-TFTs) with 200 nm thick poly(vinylidene fluoride/trifluoroethylene) ferroelectric layer; semitransparent 10 nm thin AgO{sub x} and transparent 130 nm thick indium-zinc oxide (IZO) were deposited on the ferroelectric polymer as gate electrode by rf sputtering. Our semitransparent NVM-TFT with AgO{sub x} gate operates under low voltage write-erase (WR-ER) pulse of {+-}20 V, but shows some degradation in retention property. In contrast, our transparent IZO-gated device displays very good retention properties but requires anomalously higher pulse of {+-}70 V for WR and ER states. Both devices stably operated under visible illuminations.

  6. Raman, electron microscopy and electrical transport studies of x-ray amorphous Zn-Ir-O thin films deposited by reactive DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Zubkins, M.; Kalendarev, R.; Gabrusenoks, J.; Smits, K.; Kundzins, K.; Vilnis, K.; Azens, A.; Purans, J.

    2015-03-01

    Zn-Ir-O thin films on glass and Ti substrates were deposited by reactive DC magnetron sputtering at room temperature. Structural and electrical properties were investigated as a function of iridium concentration in the films. Raman spectrum of Zn-Ir-O (61.5 at.% Ir) resembles the spectrum of rutile IrO2, without any distinct features of wurtzite ZnO structure. SEM images indicated that morphology of the films surface improves with the iridium content. EDX spectroscopy and cross-section SEM images revealed that the films growing process is homogeneous. Crystallites with approximately 2-5 nm size were discovered in the TEM images. Thermally activated conductivity related to the variable range hopping changes to the non-thermally activated before iridium concentration reaches the 45 at.%.

  7. Fabrication of Visible-Light-Transparent Solar Cells Using p-Type NiO Films by Low Oxygen Fraction Reactive RF Sputtering Deposition

    NASA Astrophysics Data System (ADS)

    Warasawa, Moe; Watanabe, Yousuke; Ishida, Jun; Murata, Yoshitsuna; Chichibu, Shigefusa F.; Sugiyama, Mutsumi

    2013-02-01

    Visible-light-transparent p-type NiO films were deposited by reactive RF sputtering under unintentional heating. An optical transmittance of >80% was obtained in the wavelength range of 500-800 nm when the films were deposited under a very low O2 fraction in the gas phase O2/(Ar+ O2) = 0.5%. This result may reflect a decrease in the concentration of Ni vacancies due to the increase in their formation energy under oxygen-poor deposition conditions. Heterostructure pn junctions consisting of p-type NiO and n-type ZnO layers were also deposited. We eventually observed a slight but noticeable photovoltaic effect.

  8. Synthesizing mixed phase titania nanocomposites with enhanced photoactivity and redshifted photoresponse by reactive DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Chen, Le

    Recent work points out the importance of the solid-solid interface in explaining the high photoactivity of mixed phase TiO2 catalysts. The goal of this research was to probe the synthesis-structure-function relationships of the solid-solid interfaces created by the reactive direct current (DC) magnetron sputtering of titanium dioxide. I hypothesize that the reactive DC magnetron sputtering is a useful method for synthesizing photo-catalysts with unique structure including solid-solid interfaces and surface defects that are associated with enhanced photoreactivity as well as a photoresponse shifted to longer wavelengths of light. I showed that sputter deposition provides excellent control of the phase and interface formation as well as the stoichiometry of the films. I explored the effects exerted by the process parameters of pressure, oxygen partial pressure, target power, substrate bias (RF), deposition incidence angle, and post annealing treatment on the structural and functional characteristics of the catalysts. I have successfully made pure and mixed phase TiO2 films. These films were characterized with UV-Vis, XPS, AFM, SEM, TEM, XRD and EPR, to determine optical properties, elemental stoichiometry, surface morphology, phase distribution and chemical coordination. Bundles of anatase-rutile nano-columns having high densities of dual-scale of interfaces among and within the columns are fabricated. Photocatalytic performance of the sputtered films as measured by the oxidation of the pollutant, acetaldehyde, and the reduction of CO2 for fuel (CH4) production was compared (normalized for surface area) to that of mixed phase TiO2 fabricated by other methods, including flame hydrolysis powders, and solgel deposited TiO 2 films. The sputtered mixed phase materials were far superior to the commercial standard (Degussa P25) and solgel TiO2 based on gas phase reaction of acetaldehyde oxidation under UV light and CO2 reduction under both UV and visible illuminations. The

  9. Structural and mechanical evolution of reactively and non-reactively sputtered Zr–Al–N thin films during annealing☆

    PubMed Central

    Mayrhofer, P.H.; Sonnleitner, D.; Bartosik, M.; Holec, D.

    2014-01-01

    The influence of reactive and non-reactive sputtering on structure, mechanical properties, and thermal stability of Zr1 − xAlxN thin films during annealing to 1500 °C is investigated in detail. Reactive sputtering of a Zr0.6Al0.4 target leads to the formation of Zr0.66Al0.34N thin films, mainly composed of supersaturated cubic (c) Zr1 − xAlxN with small fractions of (semi-)coherent wurtzite (w) AlN domains. Upon annealing, the formation of cubic Zr-rich domains and growth of the (semi-)coherent w-AlN domains indicate spinodal-like decomposition. Loss of coherency can only be observed for annealing temperatures above 1150 °C. Following these decomposition processes, the hardness remains at the as-deposited value of ~ 29 GPa with annealing up to 1100 °C. Using a ceramic (ZrN)0.6(AlN)0.4 target and sputtering in Ar atmosphere allows preparing c-Zr0.68Al0.32N coatings with a well-defined crystalline single-phase cubic structure combined with higher hardnesses of ~ 31 GPa. Due to the absence of (semi-)coherent w-AlN domains in the as-deposited state, which could act as nucleation sites, the decomposition process of c-Zr1 − xAlxN is retarded. Only after annealing at 1270 °C, the formation of incoherent w-AlN can be detected. Hence, their hardness remains very high with ~ 33 GPa even after annealing at 1200 °C. The study highlights the importance of controlling the deposition process to prepare well-defined coatings with high mechanical properties and thermal stability. PMID:24748705

  10. Investigation of the biaxial stress of Al-doped ZnO thin films on a flexible substrate with RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Huang, Kuo-Ting; Chen, Hsi-Chao; Cheng, Po-Wei; Chang, Jhe-Ming

    2016-01-01

    Transparent conductive Al-doped ZnO (AZO) thin films were deposited onto poly(ethylene terephthalate) (PET) substrate, using the radio frequency (RF) magnetron sputtering method. The residual stress of flexible electronics was investigated by a double beam shadow moiré interferometer with phase shifting interferometry (PSI). Moreover, the biaxial stress of AZO thin films can be graphically represented by using Mohr’s circle of stress. The residual stress of AZO thin films becomes more compressive with the increase in sputtering power. The maximum residual stress is -1115.74 MPa, and the shearing stress is 490.57 MPa at a sputtering power of 200 W. The trends of residual stress were evidenced by the X-ray diffraction (XRD) patterns and optical properties of AZO thin films. According to the evaluation results of the refractive index and the extinction coefficient, the AZO thin films have better quality when the sputtering power less than 100 W.

  11. Spatial distribution of electrical properties for Al-doped ZnO films deposited by dc magnetron sputtering using various inert gases

    SciTech Connect

    Sato, Yasushi; Ishihara, Keita; Oka, Nobuto; Shigesato, Yuzo

    2010-07-15

    Spatial distribution of electrical properties of Al-doped ZnO (AZO) films deposited by magnetron sputtering was investigated. To adjust the intensity of bombardment by high-energy particles, the AZO films were deposited using Ar, Kr, or Xe gas with varying plasma impedance. The spatial distribution of the electrical properties clearly depends on the sputtering gas. In the case of using Kr or Xe, the resistivity of the films in front of the target center and erosion areas was significantly enhanced, in contrast with Ar. This was attributed to an enhancement in bombardment damage due to the increased sputtering voltages required for Kr or Xe discharges. The increase in plasma impedance was due to the smaller coefficients for secondary-electron emission of the target surface by Kr or Xe impingements, which leads to the larger sputtering voltage.

  12. Temperature dependent electrical transport studies of self-aligned ZnO nanorods/Si heterostructures deposited by sputtering

    SciTech Connect

    Ranwa, Sapana; Dixit, Vivek; Kumar, Mahesh; Kumar Kulriya, Pawan

    2014-06-21

    Self-aligned ZnO nanorods (NRs) were grown on n-Si(100) substrate by RF sputtering techniques. The NRs are uniformly grown on 2-inch wafer along [0001] direction. Single-crystalline wurtzite structure of ZnO NRs was confirmed by X-ray diffraction. The average diameter, height, and density of NRs are found 48 nm, 750 nm, and 1.26 × 10{sup 10} cm{sup −2}, respectively. The current-voltages (I-V) characteristics of ZnO NRs/Si heterojunction (HJ) were studied in the temperature range of 120–300 K and it shows a rectifying behavior. Barrier height (ϕ{sub B}) and ideality factor (η) were estimated from thermionic emission model and found to be highly temperature dependent in nature. Richardson constant (A{sup *}) was evaluated using Richardson plot of ln(I{sub o}/T{sup 2}) versus q/kT plot by linear fitting in two temperature range 120–180 K and 210–300 K. Large deviation in Richardson constant from its theoretical value of n-Si indicates the presence of barrier inhomogeneities at HJ. Double Gaussian distribution of barrier height with thermionic equation gives mean barrier heights of 0.55 ± 0.01 eV and 0.86 ± 0.02 eV for two different temperature regions 120–180 K and 210–300 K, respectively. Modified Richardson plot provided two values of Richardson constant for two temperature regions. However, for higher temperature range (210–300 K), the calculated value of Richardson constant ∼123 A cm{sup −2} K{sup −2} was close to the ideal Richardson constant for n-Si.

  13. RF reactive sputter deposition and characterization of transparent CuAlO2 thin films

    NASA Astrophysics Data System (ADS)

    Lu, Y. M.; He, Y. B.; Yang, B.; Polity, A.; Volbers, N.; Neumann, C.; Hasselkamp, D.; Meyer, B. K.

    2006-09-01

    CuAlO2 thin films have been prepared on quartz glass and sapphire substrates by radio-frequency (RF) reactive sputtering using a CuAlO2 ceramic target. The deposition process was optimized by varying the sputter parameters, such as the substrate temperature and the oxygen flow. In addition a post-growth annealing has been carried out. X-ray diffraction (XRD) revealed that the as-sputtered films are amorphous, and crystallize in the delafossite-type CuAlO2 or in a phase mixture of CuAlO2 and CuAl2O4 after annealing in air at 1100°C. The surface morphology of the films was characterized by scanning electron microscopy (SEM). The as-grown films are nearly stoichiometric in terms of Cu to Al ratio and have good depth homogeneity as examined by Rutherford backscattering spectroscopy (RBS) and secondary ion mass spectroscopy (SIMS), respectively. The optical bandgap of the films was estimated by wavelength-dependent transmission measurements at room temperature, which revealed a direct bandgap of 3.38 and 3.80 eV for the as-sputtered and post-growth annealed CuAlO2 films, respectively.

  14. Homoepitaxial growth of ZnO films with reduced impurity concentrations by helicon-wave-excited-plasma sputtering epitaxy using a crystalline ZnO target prepared by hydrothermal technique

    NASA Astrophysics Data System (ADS)

    Furusawa, Kentaro; Nakasawa, Hayato; Ishikawa, Yoichi; Chichibu, Shigefusa F.

    2014-10-01

    Homoepitaxial growth of reduced donor concentration ZnO films exhibiting atomically smooth surface is demonstrated by helicon-wave-excited-plasma sputtering epitaxy. Using a crystalline ZnO target prepared by hydrothermal method, concentrations of B, C, Cr, Li, and Si in the films underran the detection limits of secondary-ion-mass spectrometry. Consequently, low temperature photoluminescence spectra were dominated by sharp emission peaks originating from the recombination of excitons bound to a neutral Al donor, of which concentration was 2 × 1016 cm-3. Nonradiative lifetime dominated the recombination process above 50 K, which is most likely due to the presence of lifetime killers such as Ni and Fe.

  15. Structure and mechanical properties of 3dTM ion doped RF sputtered ZnO thin films on Si (100)

    SciTech Connect

    Venkaiah, M. Singh, R.

    2014-04-24

    Mn, Fe and Mn-Fe doped ZnO thin films were deposited on Si (100) substrates by rf- magnetron sputtering using ceramic target in pure oxygen gas environment. The X-ray diffraction shows the polycrystalline wurtzite structure films. The average grain size varies from 32-50 nm, with lower grain size for Fe doped ZnO films. The room temperature loading and unloading curve are continuous without any pop-in. The Young's modulus and hardness are in the range 156-178 GPa and 14-15.5 GPa respectively.

  16. Hysteresis-free high rate reactive sputtering of niobium oxide, tantalum oxide, and aluminum oxide

    SciTech Connect

    Särhammar, Erik Berg, Sören; Nyberg, Tomas

    2014-07-01

    This work reports on experimental studies of reactive sputtering from targets consisting of a metal and its oxide. The composition of the targets varied from pure metal to pure oxide of Al, Ta, and Nb. This combines features from both the metal target and oxide target in reactive sputtering. If a certain relation between the metal and oxide parts is chosen, it may be possible to obtain a high deposition rate, due to the metal part, and a hysteresis-free process, due to the oxide part. The aim of this work is to quantify the achievable boost in oxide deposition rate from a hysteresis-free process by using a target consisting of segments of a metal and its oxide. Such an increase has been previously demonstrated for Ti using a homogeneous substoichiometric target. The achievable gain in deposition rate depends on transformation mechanisms from oxide to suboxides due to preferential sputtering of oxygen. Such mechanisms are different for different materials and the achievable gain is therefore material dependent. For the investigated materials, the authors have demonstrated oxide deposition rates that are 1.5–10 times higher than what is possible from metal targets in compound mode. However, although the principle is demonstrated for oxides of Al, Ta, and Nb, a similar behavior is expected for most oxides.

  17. Facing-target mid-frequency magnetron reactive sputtered hafnium oxide film: Morphology and electrical properties

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Xu, Jun; Wang, You-Nian; Choi, Chi Kyu; Zhou, Da-Yu

    2016-03-01

    Amorphous hafnium dioxide (HfO2) film was prepared on Si (100) by facing-target mid-frequency reactive magnetron sputtering under different oxygen/argon gas ratio at room temperature with high purity Hf target. 3D surface profiler results showed that the deposition rates of HfO2 thin film under different O2/Ar gas ratio remain unchanged, indicating that the facing target midfrequency magnetron sputtering system provides effective approach to eliminate target poisoning phenomenon which is generally occurred in reactive sputtering procedure. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) demonstrated that the gradual reduction of oxygen vacancy concentration and the densification of deposited film structure with the increase of oxygen/argon (O2/Ar) gas flow ratio. Atomic force microscopy (AFM) analysis suggested that the surface of the as-deposited HfO2 thin film tends to be smoother, the root-meansquare roughness (RMS) reduced from 0.876 nm to 0.333 nm while O2/Ar gas flow ratio increased from 1/4 to 1/1. Current-Voltage measurements of MOS capacitor based on Au/HfO2/Si structure indicated that the leakage current density of HfO2 thin films decreased by increasing of oxygen partial pressure, which resulted in the variations of pore size and oxygen vacancy concentration in deposited thin films. Based on the above characterization results the leakage current mechanism for all samples was discussed systematically.

  18. Hall mobility of cuprous oxide thin films deposited by reactive direct-current magnetron sputtering

    SciTech Connect

    Lee, Yun Seog; Winkler, Mark T.; Siah, Sin Cheng; Brandt, Riley; Buonassisi, Tonio

    2011-05-09

    Cuprous oxide (Cu{sub 2}O) is a promising earth-abundant semiconductor for photovoltaic applications. We report Hall mobilities of polycrystalline Cu{sub 2}O thin films deposited by reactive dc magnetron sputtering. High substrate growth temperature enhances film grain structure and Hall mobility. Temperature-dependent Hall mobilities measured on these films are comparable to monocrystalline Cu{sub 2}O at temperatures above 250 K, reaching 62 cm{sup 2}/V s at room temperature. At lower temperatures, the Hall mobility appears limited by carrier scattering from ionized centers. These observations indicate that sputtered Cu{sub 2}O films at high substrate growth temperature may be suitable for thin-film photovoltaic applications.

  19. Deposition of highly textured AlN thin films by reactive high power impulse magnetron sputtering

    SciTech Connect

    Moreira, Milena A.; Törndahl, Tobias; Katardjiev, Ilia; Kubart, Tomas

    2015-03-15

    Aluminum nitride thin films were deposited by reactive high power impulse magnetron sputtering (HiPIMS) and pulsed direct-current on Si (100) and textured Mo substrates, where the same deposition conditions were used for both techniques. The films were characterized by x-ray diffraction and atomic force microscopy. The results show a pronounced improvement in the AlN crystalline texture for all films deposited by HiPIMS on Si. Already at room temperature, the HiPIMS films exhibited a strong preferred (002) orientation and at 400 °C, no contributions from other orientations were detected. Despite the low film thickness of only 200 nm, an ω-scan full width at half maximum value of 5.1° was achieved on Si. The results are attributed to the high ionization of sputtered material achieved in HiPIMS. On textured Mo, there was no significant difference between the deposition techniques.

  20. Tribological properties of reactively sputtered nitrides and carbides of titanium, zirconium and hafnium. Final report

    SciTech Connect

    Graham, M.E.; Chang, P.; Sproul, W.D.

    1994-06-01

    Objective was to determine the tribological properties of hard, wear-resistant coatings on steel substrates in order to expedite their use on coated roller bearings, transmission gears, cams, etc. Specific coatings investigated were TiN, TiC, ZrN, ZrC, HfN, and HfC; they were deposited by high-rate-reactive magnetron sputtering. Both nitrides and carbides improved the wear performance of steel, often by orders of magnitude. These coatings have proven to be beneficial for dry sliding, lubricated sliding, rolling, and mixed rolling/sliding wear. The rolling contact fatigue studies showed remarkable improvements of lifetime that could be achieved with very thin coatings (less than one micron); thicker coatings were not useful. Coating and substrate properties (hardness) should be matched for best performance. Properties and performance of the hard coatings are controlled by process parameter settings; these parameters can be controlled in magnetron sputtering to achieve excellent results.

  1. Intrinsic anomalous surface roughening of TiN films deposited by reactive sputtering

    SciTech Connect

    Auger, M. A.; Vazquez, L.; Sanchez, O.; Cuerno, R.; Castro, M.; Jergel, M.

    2006-01-15

    We study surface kinetic roughening of TiN films grown on Si(100) substrates by dc reactive sputtering. The surface morphology of films deposited for different growth times under the same experimental conditions were analyzed by atomic force microscopy. The TiN films exhibit intrinsic anomalous scaling and multiscaling. The film kinetic roughening is characterized by a set of local exponent values {alpha}{sub loc}=1.0 and {beta}{sub loc}=0.39, and global exponent values {alpha}=1.7 and {beta}=0.67, with a coarsening exponent of 1/z=0.39. These properties are correlated to the local height-difference distribution function obeying power-law statistics. We associate this intrinsic anomalous scaling with the instability due to nonlocal shadowing effects that take place during thin-film growth by sputtering.

  2. Amorphous stainless steel coatings prepared by reactive magnetron-sputtering from austenitic stainless steel targets

    NASA Astrophysics Data System (ADS)

    Cusenza, Salvatore; Schaaf, Peter

    2009-01-01

    Stainless steel films were reactively magnetron sputtered in argon/methane gas flow onto oxidized silicon wafers using austenitic stainless-steel targets. The deposited films of about 200 nm thickness were characterized by conversion electron Mössbauer spectroscopy, magneto-optical Kerr-effect, X-ray diffraction, scanning electron microscopy, Rutherford backscattering spectrometry, atomic force microscopy, corrosion resistance tests, and Raman spectroscopy. These complementary methods were used for a detailed examination of the carburization effects in the sputtered stainless-steel films. The formation of an amorphous and soft ferromagnetic phase in a wide range of the processing parameters was found. Further, the influence of the substrate temperature and of post vacuum-annealing were examined to achieve a comprehensive understanding of the carburization process and phase formation.

  3. Modeling and experiments of N-doped vanadium oxide prepared by a reactive sputtering process

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Yu, He; Dong, Xiang; Jiang, Ya-Dong; Wu, Rui-Lin

    2015-03-01

    An original numerical model, based on the standard Berg model, is used to simulate the growth mechanism of N-doped VOx deposited with changing oxygen flow in the reactive gas mixture. In order to compare with the numerical model, N-doped VOx films are prepared by reactive magnetron sputtering from a metallic vanadium target immersed in a reactive gas mixture of Ar+O2+N2. Both experimental and numerical results show that the addition of N2 to the process alleviates the hysteresis effect with respect to the oxygen supply. Film compositions obtained from the XPS analysis are compared to the numerical results and the agreement is satisfactory. The results also show that the compound of VN is only found at very low O concentration because of the replacement reaction of VN by O2 atoms with higher oxygen flow rate.

  4. Modeling for V—O2 reactive sputtering process using a pulsed power supply

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Yu, He; Dong, Xiang; Jiang, Ya-Dong; Chen, Chao; Wu, Ro-Land

    2014-08-01

    In this article, we present a time-dependent model that enables us to describe the dynamic behavior of pulsed DC reactive sputtering and predict the film compositions of VOx prepared by this process. In this modeling, the average current J is replaced by a new parameter of Jeff. Meanwhile, the four species states of V, V2O3, VO2, and V2O5 in the vanadium oxide films are taken into consideration. Based on this work, the influences of the oxygen gas supply and the pulsed power parameters including the duty cycle and frequency on film compositions are discussed. The model suggests that the time to reach process equilibrium may vary substantially depending on these parameters. It is also indicated that the compositions of VOx films are quite sensitive to both the reactive gas supply and the duty cycle when the power supply works in pulse mode. The ‘steady-state’ balance values obtained by these simulations show excellent agreement with the experimental data, which indicates that the experimentally obtained dynamic behavior of the film composition can be explained by this time-dependent modeling for pulsed DC reactive sputtering process. Moreover, the computer simulation results indicate that the curves will essentially yield oscillations around the average value of the film compositions with lower pulse frequency.

  5. Control of silicon oxynitrides refractive index by reactive-assisted ion beam sputter deposition

    NASA Astrophysics Data System (ADS)

    Ida, Michel; Chaton, Patrick; Rafin, B.

    1994-11-01

    This paper presents the properties of silicon oxynitrides obtained by reactive ion beam sputter deposition: Dual Ion Beam System. Control of refractive index was achieved by adjusting the process parameters as ion beam current, ion beam energy and reactive gas partial pressure of oxygen and nitrogen. The main difficulty was to achieve stoichiometric nitride, it has been shown that energetic ionized nitrogen was needed to obtain silicon nitride. The major parameter, to obtain variable compositions between silica and silicon nitride, was the oxygen partial pressure with a fixed nitrogen partial pressure. Optical constants in the visible range, refractive index and extinction coefficient, have been measured by spectrophotometry and spectroscopic ellipsometry. Stoichiometry, contamination and packing density have been measured by Rutherford Backscattering and Nuclear Reaction Analysis. The correlation between the film composition and optical constants is shown. Various test results indicate that silicon oxynitrides obtained by reactive assisted ion beam sputtering are high quality optical materials. These films are homogeneous isotropic, with a high packing density. The extinction coefficient is in the order of 10-4 after 300 degree(s)C annealing. All values of refractive index between 1.49 and 2.1 can be chosen.

  6. Tribological Properties of CrN/AlN Films Produced by Reactive Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Rojo, A.; Solís, J.; Oseguera, J.; Salas, O.; Reichelt, R.

    2010-04-01

    The microstructure of CrN/AlN films, prepared by reactive magnetron sputtering under various conditions, was analyzed and related to the wear behavior of the films. One set of films was prepared by conventional reactive magnetron sputtering, a second set adding an extra amount of reactive gas to the initial Ar + N2 mixture and a third set adding an extra source of nitrogen near the substrate during sputtering. The samples were analyzed by scanning electron microscopy + energy dispersive microanalysis, high resolution scanning electron microscopy, atomic force microscopy, and x-ray diffraction. The results of the microstructural analysis revealed a clear difference in the morphology growth of the films when extra nitrogen was used compared to the conventionally prepared films. Formation of CrN was significantly faster than that of AlN. The most effective method to produce AlN was to introduce extra nitrogen. Pin-on-disk wear experiments were carried out in ambient air, to investigate the tribological behavior of the CrN/AlN system against a steel ball under dry conditions for various loads and a constant sliding speed. The results revealed that tribological properties of the layers improved unlike those of the untreated H13 steel. The friction behavior is closely related to the structure of the deposited films. The thicker CrN layer contributed to the higher load capacity of the coated steel when compared to the unmodified steel. However, wear life for the coating system was very short, denoted by the fairly poor adhesion of the film system to the steel substrate.

  7. Plasma reactivity in high-power impulse magnetron sputtering through oxygen kinetics

    SciTech Connect

    Vitelaru, Catalin; Lundin, Daniel; Brenning, Nils; Minea, Tiberiu

    2013-09-02

    The atomic oxygen metastable dynamics in a Reactive High-Power Impulse Magnetron Sputtering (R-HiPIMS) discharge has been characterized using time-resolved diode laser absorption in an Ar/O{sub 2} gas mixture with a Ti target. Two plasma regions are identified: the ionization region (IR) close to the target and further out the diffusion region (DR), separated by a transition region. The μs temporal resolution allows identifying the main atomic oxygen production and destruction routes, which are found to be very different during the pulse as compared to the afterglow as deduced from their evolution in space and time.

  8. Reactively sputtered silicon oxy-nitride films for solar absorber anti-reflection coatings

    NASA Astrophysics Data System (ADS)

    Wilson, A. D.

    1984-05-01

    The optical properties of films of SiO(x)N(y) produced by reactive sputtering in argon/oxygen/nitrogen are reported. The refractive index of the films can be continuously varied between 1.46 and 3.4. This large range of index allows considerable freedom in the design of multilayer thin film stacks. The practical use of these films is demonstrated by the fabrication of double layer antireflection coatings for amorphous silicon based solar thermal absorbers. An AM1 solar absorptance of 0.95 has been obtained with an emittance increment due to the antireflecting layers of only 0.055. Other possible uses are also identified.

  9. Nonpolar resistive switching of reactively sputtered amorphous Nb2O5

    NASA Astrophysics Data System (ADS)

    Deswal, Sweety; Kumar, Ashok; Kumar, Ajeet

    2016-05-01

    Reactively sputtered amorphous Nb2O5 thin films were studied for resistive switching behaviour. These films show nonpolar resistive switching behaviour in low voltage range of ±(1.5-2.5) V. The threshold switching voltages were independent of polarity of sweep voltage. The Pt/Nb2O5/Al devices showed repeatable nonpolar switching with ON/OFF resistance ratio of 104 or higher. The switching behaviour was found to be independent of electrode material suggesting that switching mechanism does not involve the oxygen ion migration.

  10. Synthesis of bamboo-leaf-shaped ZnO nanostructures by oxidation of Zn/SiO 2 composite films deposited with radio frequency magnetron co-sputtering

    NASA Astrophysics Data System (ADS)

    Shi, Liwei; Li, Yuguo; Xue, Chengshan; Zhuang, Huizhao; He, Jianting; Tian, Dengheng

    2006-02-01

    Bamboo-leaf-shaped ZnO nanostructures were synthesized by oxidation of metal Zn/SiO 2 matrix composite thin films deposited on Si(1 1 1) substrates with radio frequency magnetron co-sputtering. The synthesized bamboo-leaf-shaped ZnO are single crystalline in nature with widths ranging from 30 to 60 nm and lengths of up to 5-10 μm, room temperature photoluminescence spectrum of the nanostructures shows a strong and sharp UV emission band at 372 nm and a weak and broad green emission band at about 520 nm which indicates relatively excellent crystallization and optical quality of the ZnO nanostructures synthesized by this novel method.

  11. Wavelength tunable photoluminescence of ZnO{sub 1-x}S{sub x} alloy thin films grown by reactive sputtering

    SciTech Connect

    Xu, Hongbin; Zhu, Liping; Jiang, Jie; Cai, Hui; Chen, Wenfeng; Hu, Liang; Guo, Yanmin; Ye, Zhizhen

    2013-08-28

    ZnO{sub 1−x}S{sub x} alloy thin films with various S contents were deposited on glass substrates by reactive sputtering. The films were grown in high crystalline quality and strong preferential crystallographic orientation. Variations of the lattice constant c followed Vegard's law. X-ray photoelectron spectroscopy confirmed the substitution of O by S in ZnO. The composition dependence of the band gap energy in ZnO{sub 1−x}S{sub x} system was investigated and the band gap bowing parameter was estimated to be about 1.46 eV. The incorporation of S led to the expected redshift of the band gap related photoluminescence emission of ZnO{sub 1−x}S{sub x} films up to 320 meV. The results indicate that ZnO{sub 1−x}S{sub x} films could hold the prospect for the development of ZnO based quantum structures.

  12. Modeling the reactive sputter deposition of Ti-doped VOx thin films

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Yu, He; Gu, De-En; Guo, Rui; Dong, Xiang; Jiang, Ya-Dong; Wu, Rui-Lin

    2015-06-01

    In this paper an original numerical model, based on the standard Berg model, is used to simulate the growth mechanism of Ti-doped VOx deposited with changing oxygen flow during reactive sputtering deposition. Ti-doped VOx thin films are deposited using a V target with Ti inserts. The effects of titanium inserts on the discharge voltage, deposition rate, and the ratio of V/Ti are investigated. By doping titanium in the vanadium target, the average sputtering yield decreases. In this case, the sputter erosion reduces, which is accompanied by a reduction in the deposition rate. The ratio between V content and Ti content in the film is measured using energy-dispersive x-ray spectroscopy (EDX). A decrease in the vanadium concentration with the increasing of the oxygen flow rate is detected using EDX. Results show a reasonable agreement between numerical and experimental data. Project partially supported by the National Natural Science Foundation of China (Grant Nos. 61405027, 61421002, and 61235006) and the Postdoctoral Science Foundation of China (Grant No. 2014M562296).

  13. Negative oxygen ion formation in reactive magnetron sputtering processes for transparent conductive oxides

    SciTech Connect

    Welzel, Thomas; Ellmer, Klaus

    2012-11-15

    Reactive d.c. magnetron sputtering in Ar/O{sub 2} gas mixtures has been investigated with energy-resolved mass spectrometry. Different metal targets (Mg, Ti, Zn, In, InSn, and Sn), which are of importance for transparent conductive oxide thin film deposition, have been used to study the formation of negative ions, mainly high-energetic O{sup -}, which are supposed to induce radiation damage in thin films. Besides their energy distribution, the ions have been particularly investigated with respect to their intensity in comparison of the different target materials. To realize the comparability, various calibration factors had to be introduced. After their application, major differences in the negative ion production have been observed for the target materials. The intensity, especially of O{sup -}, differs by about two orders of magnitude. It is shown that this difference results almost exclusively from ions that gain their energy in the target sheath. Those may gain additional energy from the sputtering process or reflection at the target. Low-energetic negative ions are, however, less affected by changes of the target material. The results concerning O{sup -} formation are discussed in term of the sputtering rate from the target and are compared to models for negative ion formation.

  14. Deposition and Properties of Reactively Sputtered Ruthenium Dioxide Thin Films as an Electrode for Ferroelectric Capacitors

    NASA Astrophysics Data System (ADS)

    Lee, Jeong-gun; Min, Suk-ki; Choh, Sung

    1994-12-01

    Ruthenium dioxide (RuO2) films are studied for use as a bottom electrode of the (Ba, Sr)TiO3 thin-film capacitor. RuO2 films have been deposited by reactive DC magnetron sputtering of ruthenium at a relatively low sputtering power. Stoichiometric RuO2 films are obtained at oxygen partial pressures as low as 0.6 mTorr. The properties of the films have been investigated using techniques such as Rutherford backscattering spectrometry, Auger electron spectrometry, X-ray diffraction, and scanning electron microscopy. The oxygen composition in as-deposited RuOx films increases from 2.0 to 2.4 with the increase of initial O2 partial pressure from 1.2 to 5.6 mTorr at a sputtering power of 200 W. The films deposited under low oxygen partial pressures followed by annealing show preferential crystal growth in the [110] direction, whereas those deposited in high oxygen partial pressures show growth in the [101] direction. A resistivity of 65 µΩ·cm is obtained after annealing at 800°C. Even after high-temperature deposition and subsequent annealing processes, clear interfaces between (Ba, Sr)TiO3 and RuO2 films are obtained.

  15. Decorative black TiCxOy film fabricated by DC magnetron sputtering without importing oxygen reactive gas

    NASA Astrophysics Data System (ADS)

    Ono, Katsushi; Wakabayashi, Masao; Tsukakoshi, Yukio; Abe, Yoshiyuki

    2016-02-01

    Decorative black TiCxOy films were fabricated by dc (direct current) magnetron sputtering without importing the oxygen reactive gas into the sputtering chamber. Using a ceramic target of titanium oxycarbide (TiC1.59O0.31), the oxygen content in the films could be easily controlled by adjustment of total sputtering gas pressure without remarkable change of the carbon content. The films deposited at 2.0 and 4.0 Pa, those are higher pressure when compared with that in conventional magnetron sputtering, showed an attractive black color. In particular, the film at 4.0 Pa had the composition of TiC1.03O1.10, exhibited the L* of 41.5, a* of 0.2 and b* of 0.6 in CIELAB color space. These values were smaller than those in the TiC0.29O1.38 films (L* of 45.8, a* of 1.2 and b* of 1.2) fabricated by conventional reactive sputtering method from the same target under the conditions of gas pressure of 0.3 Pa and optimized oxygen reactive gas concentration of 2.5 vol.% in sputtering gas. Analysis of XRD and XPS revealed that the black film deposited at 4.0 Pa was the amorphous film composed of TiC, TiO and C. The adhesion property and the heat resisting property were enough for decorative uses. This sputtering process has an industrial advantage that the decorative black coating with color uniformity in large area can be easily obtained by plain operation because of unnecessary of the oxygen reactive gas importing which is difficult to be controlled uniformly in the sputtering chamber.

  16. Determination of the number density of excited and ground Zn atoms during rf magnetron sputtering of ZnO target

    SciTech Connect

    Maaloul, L.; Gangwar, R. K.; Stafford, L.

    2015-07-15

    A combination of optical absorption spectroscopy (OAS) and optical emission spectroscopy measurements was used to monitor the number density of Zn atoms in excited 4s4p ({sup 3}P{sub 2} and {sup 3}P{sub 0}) metastable states as well as in ground 4s{sup 2} ({sup 1}S{sub 0}) state in a 5 mTorr Ar radio-frequency (RF) magnetron sputtering plasma used for the deposition of ZnO-based thin films. OAS measurements revealed an increase by about one order of magnitude of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms by varying the self-bias voltage on the ZnO target from −115 to −300 V. Over the whole range of experimental conditions investigated, the triplet-to-singlet metastable density ratio was 5 ± 1, which matches the statistical weight ratio of these states in Boltzmann equilibrium. Construction of a Boltzmann plot using all Zn I emission lines in the 200–500 nm revealed a constant excitation temperature of 0.33 ± 0.04 eV. In combination with measured populations of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms, this temperature was used to extrapolate the absolute number density of ground state Zn atoms. The results were found to be in excellent agreement with those obtained previously by actinometry on Zn atoms using Ar as the actinometer gas [L. Maaloul and L. Stafford, J. Vac. Sci. Technol., A 31, 061306 (2013)]. This set of data was then correlated to spectroscopic ellipsometry measurements of the deposition rate of Zn atoms on a Si substrate positioned at 12 cm away from the ZnO target. The deposition rate scaled linearly with the number density of Zn atoms. In sharp contrast with previous studies on RF magnetron sputtering of Cu targets, these findings indicate that metastable atoms play a negligible role on the plasma deposition dynamics of Zn-based coatings.

  17. Influence of process parameters on properties of reactively sputtered tungsten nitride thin films

    SciTech Connect

    Addonizio, Maria L.; Castaldo, Anna; Antonaia, Alessandro; Gambale, Emilia; Iemmo, Laura

    2012-05-15

    Tungsten nitride (WN{sub x}) thin films were produced by reactive dc magnetron sputtering of tungsten in an Ar-N{sub 2} gas mixture. The influence of the deposition power on the properties of tungsten nitride has been analyzed and compared with that induced by nitrogen content variation in the sputtering gas. A combined analysis of structural, electrical and optical properties on thin WN{sub x} films obtained at different deposition conditions has been performed. It was found that at an N{sub 2} content of 14% a single phase structure of W{sub 2}N films was formed with the highest crystalline content. This sputtering gas composition was subsequently used for fabricating films at different deposition powers. Optical analysis showed that increasing the deposition power created tungsten nitride films with a more metallic character, which is confirmed with resistivity measurements. At low sputtering powers the resulting films were crystalline whereas, with an increase of power, an amorphous phase was also present. The incorporation of an excess of nitrogen atoms resulted in an expansion of the W{sub 2}N lattice and this effect was more pronounced at low deposition powers. Infrared analysis revealed that in WN{sub x} films deposited at low power, chemisorbed N{sub 2} molecules did not behave as ligands whereas at high deposition power they clearly appeared as ligands around metallic tungsten. In this study, the influence of the most meaningful deposition parameters on the phase transformation reaction path was established and deposition conditions suitable for producing thermally stable and highly crystalline W{sub 2}N films were found.

  18. Controlling ion fluxes during reactive sputter-deposition of SnO{sub 2}:F

    SciTech Connect

    Jäger, Timo Romanyuk, Yaroslav E.; Tiwari, Ayodhya N.; Anders, André

    2014-07-21

    Magnetron sputtering of fluorine-doped tin oxide (FTO) is a scalable deposition method for large-area transparent conducting films used in fenestration, photovoltaics, and other applications. The electrical conductivity of sputtered FTO is, however, lower than that of spray-pyrolized FTO because of the ion damage induced by high energy ions leading to a reduction of the crystal quality in sputtered FTO films. In this study, various ion species present during the reactive sputtering of a metallic tin target in a mixed Ar/O{sub 2}/CF{sub 4} atmosphere are systematically characterized by energy and mass spectrometry, and possible ways of controlling the ion fluxes are explored. Ion energy distribution functions (IEDFs) of the negative ions F{sup −} and O{sup −} exhibit large peaks at an energy corresponding to the full target voltage. Although the applied partial pressure of CF{sub 4} is about 1/30 than that of O{sub 2}, the obtained IEDFs of F{sup −} and O{sup −} have comparable peak height, which can be attributed to a higher electronegativity of F. The IEDFs of positively charged O{sup +}, O{sub 2}{sup +}, Ar{sup +}, and Sn{sup +} species have their peaks around 2–8 eV. To control ion fluxes a solenoid or permanent magnets were placed between the target and the mass spectrometer. The flux of positive ions could be varied by several orders of magnitude as a function of the applied current through the solenoid, whereas the high-energy (>100 eV) negative F{sup −} and O{sup −} ions were not notably deflected. By using permanent magnets with the B-field orthogonal to the ion trajectory, the flux of O{sup −} ions could be decreased by two orders and the exposure to the high-energy F{sup −} ions was completely suppressed.

  19. Raman spectroscopy of copper oxide films deposited by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Levitskii, V. S.; Shapovalov, V. I.; Komlev, A. E.; Zav'yalov, A. V.; Vit'ko, V. V.; Komlev, A. A.; Shutova, E. S.

    2015-11-01

    Raman spectroscopy has been used to study the influence of partial oxygen pressure during deposition and isothermal treatment on the chemical composition of copper oxide films deposited by reactive dc magnetron sputtering of copper target in a reactive gaseous medium. Three series of films deposited at various partial oxygen pressures (from 0.06 to 0.16 mTorr) possessed different chemical compositions. The subsequent thermal treatment of all samples was performed for 30 min in air at a constant temperature in a 300?500°C interval. An increase in the annealing temperature led to chemical changes in the films. After isothermal treatment at 450°C, the films in all series acquired stoichiometric CuO composition.

  20. Process-structure-property correlations in pulsed dc reactive magnetron sputtered vanadium oxide thin films

    SciTech Connect

    Venkatasubramanian, Chandrasekaran; Cabarcos, Orlando M.; Drawl, William R.; Allara, David L.; Ashok, S.; Horn, Mark W.; Bharadwaja, S. S. N.

    2011-11-15

    Cathode hysteresis in the reactive pulsed dc sputtering of a vanadium metal target was investigated to correlate the structural and electrical properties of the resultant vanadium oxide thin films within the framework of Berg's model [Berg et al., J. Vac. Sci. Technol. A 5, 202 (1987)]. The process hysteresis during reactive pulsed dc sputtering of a vanadium metal target was monitored by measuring the cathode (target) current under different total gas flow rates and oxygen-to-argon ratios for a power density of {approx}6.6.W/cm{sup 2}. Approximately 20%-25% hysteretic change in the cathode current was noticed between the metallic and oxidized states of the V-metal target. The extent of the hysteresis varied with changes in the mass flow of oxygen as predicted by Berg's model. The corresponding microstructure of the films changed from columnar to equiaxed grain structure with increased oxygen flow rates. Micro-Raman spectroscopy indicates subtle changes in the film structure as a function of processing conditions. The resistivity, temperature coefficient of resistance, and charge transport mechanism, obeying the Meyer-Neldel relation [Meyer and Neldel, Z. Tech. Phys. (Leipzig) 12, 588 (1937)], were correlated with the cathode current hysteric behavior.

  1. Silicon- and aluminum-nitride films deposited by reactive low-voltage ion plating and reactive dc-magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Vogl, G. W.; Monz, K. H.; Nguyen, Quang D.; Huter, Michael; Rille, Eduard P.; Pulker, Hans K.

    1994-11-01

    In this work the properties of Si3N4 and AIN thin films deposited onto unheated substrates by Reactive Low Voltage Ion Plating (RLVIP) and Reactive DC-Magnetron Sputtering (RDCMS) were investigated. In both experimental setups pure silicon and aluminum were used as starting materials. Working and reactive gas were argon and nitrogen respectively. All Si3N4 films showed amorphous structure in X-ray and electron diffraction whereas AIN films were found to be polycrystalline and could be indexed to the bulk hexagonal AIN lattice. The values of the film refractive index at 550 nm are 2.08 for RLVIP Si3N4, 2.12 for RLVIP AIN, 2.02 for RDCMS Si3N4, and 1.98 or 2.12 for AIN depending on the total pressure in the range of 8 E - 1 Pa and 1 E - 1 Pa during the process. The high optical transmission region for the Si3N4 films lies between 0.23 and 9.5 micrometers , and for AIN films between 0.2 and 12.5 micrometers . Purity and composition were measured by electron microprobe, infrared transmission, nuclear reactions, elastic recoil detection analysis and Rutherford backscattering spectroscopy. Transmission electron micrographs of Pt-C replicas of fracture cross sections of the films show their different microstructure and surface topography. Environmental tests proved the RLVIP Si3N4 films to be very hard, of high density and of strong adherence to glass.

  2. A Comparison of the Reactivity of Pd Supported on ZnO(10(1)over-bar0) and ZnO(0001)

    SciTech Connect

    Hyman, Matthew P.; Lebarbier, Vanessa MC; Wang, Yong; Datye, Abhaya K.; Vohs, John M.

    2009-04-30

    The dependence of ZnO surface structure on Pd/ZnO catalyzed methanol decomposition was investigated using model catalysts consisting of Pd films and particles on ZnO and ZnO(0001) single crystals. XPS studies showed that vapor-deposited Pd grows two dimensionally at 300 K and agglomerates into particles upon heating. Temperature programmed desorption (TPD) experiments showed that CO adsorption was weaker on Pd/ZnO(0001) relative to Pd/ZnO and that PdZn alloy formation was more facile on the ZnO(0001) compared to ZnO . Large differences in the amount of CO produced during methanol TPD on the Pd/ZnO(0001) and Pd/ZnO samples was also observed and attributed to the presence of highly active sites at the Pd-ZnO(0001) interface. Comparisons to high surface area Pd/ZnO catalysts indicate that similar structural effects may also influence their reactivity.

  3. Photocatalytic degradation of reactive brilliant blue X-BR in aqueous solution using quantum-sized ZnO

    SciTech Connect

    Su, S.; Lu, S.X. Xu, W.G.

    2008-08-04

    Quantum-sized ZnO was prepared using sol-gel method with zinc acetate dehydrate (Zn(CH{sub 3}COO){sub 2}.2H{sub 2}O) and lithium hydroxide monohydrate (LiOH.H{sub 2}O) as raw material. The ZnO particles annealed at different temperature were characterized by means of X-ray diffraction (XRD), Infrared absorption spectroscopy (IR) and UV-vis spectroscopy. The degradation rate of reactive brilliant blue X-BR in aqueous solution was used to evaluate the photocatalytic performance of the quantum-sized ZnO. The experimental results indicated that the photocatalytic property of the ZnO was excellent. The photocatalytic efficiency of quantum-sized ZnO was significantly influenced by the calcining heat. When calcined at 300 deg. C, its size is 6.78 nm and the photocatalytic performance is the best. The degradation rate of reactive brilliant blue X-BR could exceed 90% in 15 min at 35 deg. C, when the concentration of the quantum-sized ZnO was 0.35 mg/L.

  4. A parametric model for reactive high-power impulse magnetron sputtering of films

    NASA Astrophysics Data System (ADS)

    Kozák, Tomáš; Vlček, Jaroslav

    2016-02-01

    We present a time-dependent parametric model for reactive HiPIMS deposition of films. Specific features of HiPIMS discharges and a possible increase in the density of the reactive gas in front of the reactive gas inlets placed between the target and the substrate are considered in the model. The model makes it possible to calculate the compound fractions in two target layers and in one substrate layer, and the deposition rate of films at fixed partial pressures of the reactive and inert gas. A simplified relation for the deposition rate of films prepared using a reactive HiPIMS is presented. We used the model to simulate controlled reactive HiPIMS depositions of stoichiometric \\text{Zr}{{\\text{O}}2} films, which were recently carried out in our laboratories with two different configurations of the {{\\text{O}}2} inlets in front of the sputtered target. The repetition frequency was 500 Hz at the deposition-averaged target power densities of 5 Wcm-2and 50 Wcm-2 with a pulse-averaged target power density up to 2 kWcm-2. The pulse durations were 50 μs and 200 μs. Our model calculations show that the to-substrate {{\\text{O}}2} inlet provides systematically lower compound fractions in the target surface layer and higher compound fractions in the substrate surface layer, compared with the to-target {{\\text{O}}2} inlet. The low compound fractions in the target surface layer (being approximately 10% at the deposition-averaged target power density of 50 Wcm-2 and the pulse duration of 200 μs) result in high deposition rates of the films produced, which are in agreement with experimental values.

  5. Development of mid-frequency AC reactive magnetron sputtering for fast deposition of Y2O3 buffer layers

    NASA Astrophysics Data System (ADS)

    Xiong, Jie; Xia, Yudong; Xue, Yan; Zhang, Fei; Guo, Pei; Zhao, Xiaohui; Tao, Bowan

    2014-02-01

    A reel-to-reel magnetron sputtering system with mid-frequency alternating current (AC) power supply was used to deposit double-sided Y2O3 seed layer on biaxially textured Ni-5 at.%W tape for YBa2Cu3O7-δ coated conductors. A reactive sputtering process was carried out using two opposite symmetrical sputtering guns with metallic yttrium targets and water vapor for oxidizing the sputtered metallic atoms. The voltage control mode of the power supply was used and the influence of the cathode voltage and ArH2 pressure were systematically investigated. Subsequently yttrium-stabilized zirconia (YSZ) barrier and CeO2 cap layers were deposited on the Y2O3 buffered substrates in sequence, indicating high quality and uniform double-sided structure and surface morphology of such the architecture.

  6. Influence of the magnetron on the growth of aluminum nitride thin films deposited by reactive sputtering

    SciTech Connect

    Iriarte, G. F.

    2010-03-15

    Aluminum nitride (AlN) thin films deposited on high-vacuum systems without substrate heating generally exhibit a poor degree of c-axis orientation. This is due to the nonequilibrium conditions existing between the energy of the sputtered particles and the energy at the substrate surface. The application of substrate bias or substrate temperature is known to improve the adatom mobility by delivering energy to the substrate; both are hence well-established crystal growth promoting factors. It is well known that low sputtering pressures can be used as a parameter improving the growth of highly c-axis oriented aluminum nitride films at room temperature even without applying bias voltage to the substrate. Generally, the use of high pressures implies thermalization of particles within the gas phase and is considered to increase the energy gap between these and the substrate surface. However, in later experiments we have learned that the use of high processing pressures does not necessarily implies a detriment of crystallographic orientation in the films. By measuring (for the first time to the author's knowledge) the full width at half maximum value of the rocking curve of the 0002-AlN peak at several positions along the 100 mm diameter (100)-silicon wafers on which aluminum nitride thin films were deposited by reactive sputtering, a new effect was observed. Under certain processing conditions, the growth of the AlN thin films is influenced by the target magnetron. More precisely, their degree of c-axis orientation varies at wafer areas locally coincident under the target magnetron. This effect should be considered, especially where large area substrates are employed such as in silicon wafer foundry manufacturing processes.

  7. Magnetic field strength influence on the reactive magnetron sputter deposition of Ta2O5

    NASA Astrophysics Data System (ADS)

    Hollerweger, R.; Holec, D.; Paulitsch, J.; Rachbauer, R.; Polcik, P.; Mayrhofer, P. H.

    2013-08-01

    Reactive magnetron sputtering enables the deposition of various thin films to be used for protective as well as optical and electronic applications. However, progressing target erosion during sputtering results in increased magnetic field strengths at the target surface. Consequently, the glow discharge, the target poisoning, and hence the morphology, crystal structure and stoichiometry of the prepared thin films are influenced. Therefore, these effects were investigated by varying the cathode current Im between 0.50 and 1.00 A, the magnetic field strength B between 45 and 90 mT, and the O2/(Ar + O2) flow rate ratio Γ between 0% and 100%. With increasing oxygen flow ratio a substoichiometric TaOx oxide forms at the metallic Ta target surface which further transfers to a non-conductive tantalum pentoxide Ta2O5, impeding a stable dc glow discharge. These two transition zones (from Ta to TaOx and from TaOx to Ta2O5) shift to higher oxygen flow rates for increasing target currents. In contrast, increasing the magnetic field strength (e.g., due to sputter erosion) mainly shifts the TaOx to Ta2O5 transition to lower oxygen flow rates while marginally influencing the Ta to TaOx transition. To allow for a stable dc glow discharge (and to suppress the formation of non-conductive Ta2O5 at the target) even at Γ = 100% either a high target current (Im ⩾ 1 A) or a low magnetic field strength (B ⩽ 60 mT) is necessary. These conditions are required to prepare stoichiometric and fully crystalline Ta2O5 films.

  8. Effect of process conditions on the microstructural formation of dc reactively sputter deposited AlN

    SciTech Connect

    Ekpe, Samuel D.; Jimenez, Francisco J.; Dew, Steven K.

    2010-09-15

    Thin film aluminum nitride (AlN), because of its attractive properties, is a material with many applications. Its microstructure and hence properties are greatly influenced by the deposition process conditions. In this work, AlN was reactively deposited in a dc magnetron sputtering system at different proportions of nitrogen in the process gas mixture and at different process conditions. The microstructure and composition of the films were analyzed using x-ray diffraction data, energy dispersive spectroscopy, and scanning electron microscopy. Results show that for a process gas pressure of 0.67 Pa, a magnetron power of 100 W, and a substrate-target distance of 10 cm, a near stoichiometeric AlN can be prepared at nitrogen proportions as low as 20%. At these process conditions, (002) was the preferred crystal orientation. Dense fibrous structures were obtained, especially at low deposition rates with high proportions of nitrogen. Increase in magnetron power and decrease in distance result in a more porous structure. High kinetic energies (average) of the sputtered Al particles and high deposition rates tend to favor AlN(101) formation, while low kinetic energies of the Al particles and low deposition rates generally favor more of the AlN(100) formation.

  9. Thermally stable narrow-bandpass filter prepared by reactive ion-assisted sputtering.

    PubMed

    Tsai, R Y; Chang, C S; Chu, C W; Chen, T; Dai, F; Lin, D; Yan, S; Chang, A

    2001-04-01

    Thermal stabilities of three-cavity narrow-bandpass (NB) filters with high-index half-wave spacers and 78-102 layers of Ta(2)O(5) and SiO(2) prepared by reactive ion-assisted bipolar direct-current (dc) magnetron sputtering of tantalum and silicon targets, respectively, were investigated. Pure argon and pure oxygen were used as the sputtering gas and the reactant, respectively. The oxygen gas was introduced and ionized through the ion gun and toward the unheated BK7 glass substrate. The refractive indices of single-layer Ta(2)O(5) and SiO(2) films were 2.1 and 1.45, respectively, at 1550 nm, which were comparable with those of films prepared by other ion-assisted coating techniques. The moisture-resistant properties of the films were excellent as evidenced from the water-immersion test, implying that the packing density of the films was close to that of their bulk materials. The temperature-dependant wavelength shifts of the NB filters were <3 x 10(-3) nm/ degrees C at temperatures of <75 degrees C, indicating that the temperature-induced wavelength shift of the filter was <0.15 nm when the temperatures were raised from room temperature to 75 degrees C, which was compliant with Bellcore GR-1209-CORE generic requirements of NB filters used for optical-fiber communication systems. PMID:18357152

  10. Low Temperature Reactive Sputtering of Thin Aluminum Nitride Films on Metallic Nanocomposites

    PubMed Central

    Ramadan, Khaled Sayed Elbadawi; Evoy, Stephane

    2015-01-01

    Piezoelectric aluminum nitride thin films were deposited on aluminum-molybdenum (AlMo) metallic nanocomposites using reactive DC sputtering at room temperature. The effect of sputtering parameters on film properties was assessed. A comparative study between AlN grown on AlMo and pure aluminum showed an equivalent (002) crystallographic texture. The piezoelectric coefficients were measured to be 0.5±0.1 C m-2 and 0.9±0.1 C m-2, for AlN deposited on Al/0.32Mo and pure Al, respectively. Films grown onto Al/0.32Mo however featured improved surface roughness. Roughness values were measured to be 1.3nm and 5.4 nm for AlN films grown on AlMo and on Al, respectively. In turn, the dielectric constant was measured to be 8.9±0.7 for AlN deposited on Al/0.32Mo seed layer, and 8.7±0.7 for AlN deposited on aluminum; thus, equivalent within experimental error. Compatibility of this room temperature process with the lift-off patterning of the deposited AlN is also reported. PMID:26193701

  11. Reactive ion-beam-sputtering of fluoride coatings for the UV/VUV range

    NASA Astrophysics Data System (ADS)

    Schink, Harald; Kolbe, Jurgen; Zimmermann, F.; Ristau, Detlev; Welling, Herbert

    1991-06-01

    Fluoride coatings produced by thermal evaporation suffer from high scatter losses ageing and cracking due to high tensile stress. These problems impose severe limitations to the production of low loss multilayer coatings for the VUV range. A key position for improved performance is the microstructure of the layers. The aim of our investigations is to improve the microstructure of A1F3- and LaF3-'' films by ionbeamsputtering. Scatter measurements of single layers revealed lower values for lBS than for boat evaporation. Unfortunately sputtered fluoride films nave high absorption losses caused by decomposition of the coating material. By sputtering in reactive atmospheres and annealing we were able to reduce the absorption losses significantly. Antireflective as well as high reflective coatings were produced. Reflection and transmission values were obtained with a VUV-spectrophotometer. Damage tests at the 193 mu ArF laser wavelength were performed at the Laser-Laboratorium Gttingen. Key words: ion-beamsputtering fluoride films UVcoatings VUV-coatings color-center laser damage A]. F3 MgF2 LaF3. 1.

  12. Optical and electron transport properties of reactively sputtered Cu/sub x/S

    SciTech Connect

    Leong, J.Y.C.

    1980-06-30

    Thin films of Cu/sub x/S were deposited on glass slides by sputtering Cu in a reactive H/sub 2/S/Ar environment. Optical transmittance and reflectance measurements were used to explore the infrared absorption spectra of the material. Analysis of the absorption edge characteristics resulted in the identification of an indirect bandgap at 1.15 (+-.05) eV, a direct bandgap at 1.30 (+-.05) eV, and an electron effective mass of 1.0 (+-0.2) m/sub 0/. Electrical data consisting of resistivity and Hall effect measurements from liquid nitrogen to room temperature were analyzed to determine the dominant scattering mechanisms limiting the hole mobility in the material. Ionized impurity scattering was the dominant mechanism at low temperatures (T < 100/sup 0/K) and polar optical phonon scattering was most effective at high temperatures (T > 150/sup 0/K). All films were p-type. Effects of sputtering gas pressure, heat treatments, and temperature on the properties were studied.

  13. Elastic properties of B-C-N films grown by N{sub 2}-reactive sputtering from boron carbide targets

    SciTech Connect

    Salas, E.; Jiménez Riobóo, R. J.; Jiménez-Villacorta, F.; Prieto, C.; Sánchez-Marcos, J.; Muñoz-Martín, A.; Prieto, J. E.; Joco, V.

    2013-12-07

    Boron-carbon-nitrogen films were grown by RF reactive sputtering from a B{sub 4}C target and N{sub 2} as reactive gas. The films present phase segregation and are mechanically softer than boron carbide films (a factor of more than 2 in Young's modulus). This fact can turn out as an advantage in order to select buffer layers to better anchor boron carbide films on substrates eliminating thermally induced mechanical tensions.

  14. Studies on optoelectronic properties of DC reactive magnetron sputtered chromium doped CdO thin films

    SciTech Connect

    Hymavathi, B. Rao, T. Subba; Kumar, B. Rajesh

    2014-10-15

    Cr doped CdO thin films were deposited on glass substrates by DC reactive magnetron sputtering method and subsequently annealed from 200 °C to 500 °C. X-ray diffraction analysis showed that the films exhibit (1 1 1) preferred orientation. The optical transmittance of the films increases from 64% to 88% with increasing annealing temperature. The optical band gap values were found to be decreased from 2.77 to 2.65 eV with the increase of annealing temperature. The decrease in optical band gap energy with increasing annealing temperature can be attributed to improvement in the crystallinity of the films and may also be due to quantum confinement effect. A minimum resistivity of 2.23 × 10{sup −4} Ω.cm and sheet resistance of 6.3 Ω/sq is obtained for Cr doped CdO film annealed at 500 °C.

  15. Electrical and structural properties of zirconia thin films prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hembram, K. P. S. S.; Dutta, Gargi; Waghmare, Umesh V.; Mohan Rao, G.

    2007-10-01

    Thin films of ZrO 2 were prepared by reactive magnetron sputtering. Annealing of the films exhibited a drastic change in the properties due to improved crystallinity and packing density. The root mean square roughness of the sample observed from atomic force microscope is about 5.75 nm which is comparable to the average grain size of the thin film which is about 6 nm obtained from X-ray diffraction. The film annealed at 873 K exhibits an optical band gap of around 4.83 eV and shows +4 oxidation state of zirconium indicating fully oxidized zirconium, whereas higher annealing temperatures lead to oxygen deficiency in the films and this is reflected in their properties. A discontinuity in the imaginary part of the AC conductivity was observed in the frequency range of tens of thousands of Hz, where as, the real part does not show such behavior.

  16. Surface treatment method for 1/f noise suppression in reactively sputtered nickel oxide film

    NASA Astrophysics Data System (ADS)

    Kim, Dong Soo; Park, Seung-Man; Lee, Hee Chul

    2012-07-01

    A surface treatment method combined with O2 plasma treatment and Ar+ bombardment is proposed for 1/f noise suppression in a reactively sputtered NiO film as a micro-bolometer sensing material. The 1/f noise power spectral density on a sample prepared by the proposed surface treatment method prior to the contact formation is suppressed to a level roughly 18 times lower than that on an untreated sample. The improved noise characteristic can be ascribed to the cooperative effects of the two steps in the proposed surface treatment method. In its effects, the oxygen plasma treatment is supposed to increase the Ni3+ component on the surface of the NiO film, which in turn increases the hole concentration on the surface. Additional Ar+ bombardment is expected to remove contaminants on the surface of the NiO film, leading to a low contact resistance.

  17. Research on titanium nitride thin films deposited by reactive magnetron sputtering for MEMS applications

    NASA Astrophysics Data System (ADS)

    Merie, Violeta; Pustan, Marius; Negrea, Gavril; Bîrleanu, Corina

    2015-12-01

    Titanium nitride can be used among other materials as diffusion barrier for MEMS (microelectromechanical systems) applications. The aim of this study is to elaborate and to characterize at nanoscale titanium nitride thin films. The thin films were deposited by reactive magnetron sputtering on silicon substrates using a 99.99% purity titanium target. Different deposition parameters were employed. The deposition temperature, deposition time, substrate bias voltage and the presence/absence of a titanium buffer layer are the parameters that were modified. The so-obtained films were then investigated by atomic force microscopy. A significant impact of the deposition parameters on the determined mechanical and tribological characteristics was highlighted. The results showed that the titanium nitride thin films deposited for 20 min at room temperature without the presence of a titanium buffer layer when a negative bias of -90 V was applied to the substrate is characterized by the best tribological and mechanical behavior.

  18. Effect of Reactive Sputtering Parameters on TiAlN Nanocoating Structure and Morphology

    SciTech Connect

    Budi, Esmar; Razali, M. Mohd.; Nizam, A. R. Md.

    2010-10-24

    The effect of substrate bias and nitrogen flow rate on the TiAlN nanocoating structure and morphology has been investigated by using reactive unbalance DC magnetron sputtering. TiAlN nanocoating was deposited on the tungsten carbide insert tool and the structure and morphology were characterized by using XRD and AFM, respectively. The substrate bias was varied between 0 to -221 V and the nitrogen flow rate was varied between 30 to 72 sccm. The results showed that the structure of TiAlN nanocoating consisted of mainly (111) and (200) plane. The structure was significatly influenced by substrate bias in promoting finer crystal size and increased crystal plane spacing while the rms roughness of nanocoating was influenced by substrate bias and nitrogen flow rate.

  19. Mo-doped BiVO4 photoanodes synthesized by reactive sputtering.

    PubMed

    Chen, Le; Toma, Francesca M; Cooper, Jason K; Lyon, Alan; Lin, Yongjing; Sharp, Ian D; Ager, Joel W

    2015-03-01

    We report a scalable and reproducible method for reactive co-sputtering of Mo-doped BiVO4 thin films with broad compositional control. Optimal photoanode performance is achieved at a Mo concentration of 3 at. %. Incorporation of Mo promotes growth of large grains and reduces majority carrier transport limitations, resulting in maximum AM1.5G photocurrent densities of 3.5 mA cm(-2) at 1.23 V vs. RHE in pH 6.8 buffer solution containing 0.1 M Na2 SO3 as a hole scavenger. Operation as a front-illuminated water oxidation photoanode is achieved by balancing the operational stability, catalytic activity, and parasitic optical absorption of a FeOOH oxygen evolution catalyst. FeOOH/Mo:BiVO4 thin film photoanodes enable water oxidation under the front-side illumination conditions used in integrated tandem water splitting devices. PMID:25705871

  20. Multilayered Al/CuO thermite formation by reactive magnetron sputtering: Nano versus micro

    NASA Astrophysics Data System (ADS)

    Petrantoni, M.; Rossi, C.; Salvagnac, L.; Conédéra, V.; Estève, A.; Tenailleau, C.; Alphonse, P.; Chabal, Y. J.

    2010-10-01

    Multilayered Al/CuO thermite was deposited by a dc reactive magnetron sputtering method. Pure Al and Cu targets were used in argon-oxygen gas mixture plasma and with an oxygen partial pressure of 0.13 Pa. The process was designed to produce low stress (<50 MPa) multilayered nanoenergetic material, each layer being in the range of tens nanometer to one micron. The reaction temperature and heat of reaction were measured using differential scanning calorimetry and thermal analysis to compare nanostructured layered materials to microstructured materials. For the nanostructured multilayers, all the energy is released before the Al melting point. In the case of the microstructured samples at least 2/3 of the energy is released at higher temperatures, between 1036 and 1356 K.

  1. Structural and thermal properties of nanocrystalline CuO synthesized by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Verma, M.; Gupta, V. K.; Gautam, Y. K.; Dave, V.; Chandra, R.

    2014-01-01

    Recent research has shown immense application of metal oxides like CuO, MgO, CaO, Al2O3, etc. in different areas which includes chemical warfare agents, medical drugs, magnetic storage media and solar energy transformation. Among the metal oxides, CuO nanoparticles are of special interest because of their excellent gas sensing and catalytic properties. In this paper we report structural and thermal properties of CuO synthesized by reactive magnetron DC sputtering. The synthesized nanoparticles were characterized by X-ray diffractometer. The XRD result reveals that as DC power increased from 30W to 80W, size of the CuO nanoparticles increased. The same results have been verified through TEM analysis. Thermal properties of these particles were studied using thermogravimetry.

  2. Structural and thermal properties of nanocrystalline CuO synthesized by reactive magnetron sputtering

    SciTech Connect

    Verma, M.; Gupta, V. K.; Gautam, Y. K.; Dave, V.; Chandra, R.

    2014-01-28

    Recent research has shown immense application of metal oxides like CuO, MgO, CaO, Al{sub 2}O{sub 3}, etc. in different areas which includes chemical warfare agents, medical drugs, magnetic storage media and solar energy transformation. Among the metal oxides, CuO nanoparticles are of special interest because of their excellent gas sensing and catalytic properties. In this paper we report structural and thermal properties of CuO synthesized by reactive magnetron DC sputtering. The synthesized nanoparticles were characterized by X-ray diffractometer. The XRD result reveals that as DC power increased from 30W to 80W, size of the CuO nanoparticles increased. The same results have been verified through TEM analysis. Thermal properties of these particles were studied using thermogravimetry.

  3. Deposition of vanadium oxide films by direct-current magnetron reactive sputtering

    NASA Technical Reports Server (NTRS)

    Kusano, E.; Theil, J. A.; Thornton, John A.

    1988-01-01

    It is demonstrated here that thin films of vanadium oxide can be deposited at modest substrate temperatures by dc reactive sputtering from a vanadium target in an O2-Ar working gas using a planar magnetron source. Resistivity ratios of about 5000 are found between a semiconductor phase with a resistivity of about 5 Ohm cm and a metallic phase with a resistivity of about 0.001 Ohm cm for films deposited onto borosilicate glass substrates at about 400 C. X-ray diffraction shows the films to be single-phase VO2 with a monoclinic structure. The VO2 films are obtained for a narrow range of O2 injection rates which correspond to conditions where cathode poisoning is just starting to occur.

  4. Physical properties of erbium implanted tungsten oxide filmsdeposited by reactive dual magnetron sputtering

    SciTech Connect

    Mohamed, Sodky H.; Anders, Andre

    2006-11-08

    Amorphous and partially crystalline WO3 thin films wereprepared by reactive dual magnetron sputtering and successively implantedby erbium ions with a fluence in the range from 7.7 x 1014 to 5 x 1015ions/cm2. The electrical and optical properties were studied as afunction of the film deposition parameters and the ion fluence. Ionimplantation caused a strong decrease of the resistivity, a moderatedecrease of the index of refraction and a moderate increase of theextinction coefficient in the visible and near infrared, while theoptical band gap remained almost unchanged. These effects could belargely ascribed to ion-induced oxygen deficiency. When annealed in air,the already low resistivities of the implanted samples decreased furtherup to 70oC, whereas oxidation, and hence a strong increase of theresistivity, was observed at higher annealing temperatures.

  5. Characteristics of DLC containing Ti and Zr films deposited by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ma, Guojia; Lin, Guoqiang; Sun, Gang; Zhang, Huafang; Wu, Hongchen

    The purpose of this paper is to investigate metal doping effects on micro-structural, mechanical and corrosive behavior of the DLC film. Ti and Zr doped DLC films were prepared on NiTi alloys by reactive magnetron sputtering combined with plasma source ion implantation (PSII) technology used to improve the coherent strength, respectively. The mechanical properties of the doped DLC films were investigated by means of nano-indentation technique, microscratch and frictional wear testing. The potentiodynamic polarization measurement was employed to value the corrosion resistance of DLC with Ti and Zr films in Hank's simulated body fluid. It was found that Ti-doped DLC films embraced higher nano-hardness, somewhat lower coefficient of friction and better corrosion resistance than Zr-doped DLC films.

  6. Electron transport and defect structure in highly conducting reactively sputtered ultrathin tin oxide films

    SciTech Connect

    Bansal, Shikha; Pandya, Dinesh K. Kashyap, Subhash C.

    2014-02-24

    Electrical conduction behavior of ultrathin (5–110 nm) SnO{sub 2} films reactively sputtered at 150–400 °C substrate temperatures is presented. The surface roughness studies revealed that the films with lower thickness were smoother (≤0.6 nm). Stoichiometry/defect structure of the films obtained from X-ray photoelectron spectroscopy data and electron mobility are found to be dependent on film thickness and substrate temperature. The observed increase in conductivity of semi-metallic films with decrease in film thickness is attributed to changes in defect structure and surface roughness. Highest value of conductivity of about 715 Ω{sup −1} cm{sup −1} is obtained for 5 nm thick films deposited at 300 °C.

  7. Effect of Reactive Sputtering Parameters on TiAlN Nanocoating Structure and Morphology

    NASA Astrophysics Data System (ADS)

    Budi, Esmar; Razali, M. Mohd.; Nizam, A. R. Md.

    2010-10-01

    The effect of substrate bias and nitrogen flow rate on the TiAlN nanocoating structure and morphology has been investigated by using reactive unbalance DC magnetron sputtering. TiAlN nanocoating was deposited on the tungsten carbide insert tool and the structure and morphology were characterized by using XRD and AFM, respectively. The substrate bias was varied between 0 to -221 V and the nitrogen flow rate was varied between 30 to 72 sccm. The results showed that the structure of TiAlN nanocoating consisted of mainly (111) and (200) plane. The structure was significatly influenced by substrate bias in promoting finer crystal size and increased crystal plane spacing while the rms roughness of nanocoating was influenced by substrate bias and nitrogen flow rate.

  8. Bolometric properties of reactively sputtered TiO2-x films for thermal infrared image sensors

    NASA Astrophysics Data System (ADS)

    Reddy, Y. Ashok Kumar; Kang, In-Ku; Shin, Young Bong; Lee, Hee Chul

    2015-09-01

    A heat-sensitive layer (TiO2-x ) was successfully deposited by RF reactive magnetron sputtering for infrared (IR) image sensors at different relative mass flow of oxygen gas (R O2) levels. The deposition rate was decreased with an increase in the percentage of R O2 from 3.4% to 3.7%. TiO2-x samples deposited at room temperature exhibited amorphous characteristics. Oxygen deficiency causes a change in the oxidation state and is assumed to decrease the Ti4+ component on the surfaces of TiO2-x films. The oxygen stoichiometry (x) in TiO2-x films decreased from 0.35 to 0.05 with increasing the R O2 level from 3.4% to 3.7%, respectively. In TiO2-x -test-patterned samples, the resistivity decreased with the temperature, confirming the typical semiconducting property. The bolometric properties of the resistivity, temperature coefficient of resistance (TCR), and the flicker (1/ f) noise parameter were determined at different x values in TiO2-x samples. The rate of TCR dependency with regard to the 1/ f noise parameter is a universal bolometric parameter (β), acting as the dynamic element in a bolometer. It is high when a sample has a relatively low resistivity (0.82 Ω·cm) and a lower 1/ f noise parameter (3.16   ×   10-12). The results of this study indicate that reactively sputtered TiO2-x is a viable bolometric material for uncooled IR image sensor devices.

  9. Defect analysis by transmission electron microscopy of epitaxial Al-doped ZnO films grown on (0001) ZnO and a-sapphire by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Rengachari, Mythili; Bikowski, André; Ellmer, Klaus

    2016-07-01

    Microstructural investigations by cross section Transmission Electron Microscopy have been carried out on Al-doped ZnO films epitaxially grown on (0001) ZnO and a-sapphire by RF magnetron sputtering, since it is known that crystallographic defects influence the physical properties of ZnO films. Threading dislocations and basal stacking faults were the predominant defects observed in these films, which were dependent on the type of the substrate and its orientation. The orientational relationship between the ZnO:Al film and the a-sapphire was determined to be ( 11 2 ¯ 0 )sapphire||(0001)ZnO:Al and [0001]sapphire||[ 11 2 ¯ 0 ]ZnO:Al. The density of dislocations in the heteroepitaxial film of ZnO:Al on a-sapphire was higher than that of the homoepitaxial film of ZnO:Al on undoped ZnO, due to the difference in the lattice mismatch, which also affected the crystallinity of the film.

  10. DC sputtering assisted nano-branched core-shell TiO2/ZnO electrodes for application in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Zengming; Hu, Yong; Qin, Fuyu; Ding, Yutian

    2016-07-01

    TiO2/ZnO core-shell photo-anodes with a large surface area were synthesised by a combination of chemical growth and direct current (DC) magnetron sputtering (MS). The use of these combined methods for the advancement of dye-sensitized solar cells (DSSCs) was discussed. An understanding of the morphology and structure of this core-shell material was obtained from the use of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the thickness of the ZnO nanoshells (as assessed by using TEM), prepared by MS, has a significant effect on improvements in the conversion efficiency. The conversion efficiency can be greatly improved from 0.06% to 0.72% by optimising different experimental conditions, such as ZnO nanoshell MS time and chemical bath deposition time. The enhanced efficiency may be attributed to the emergence of a ZnO energy barrier and the improvement of the photo-anode surface area.

  11. The impact of oxygen incorporation during intrinsic ZnO sputtering on the performance of Cu(In,Ga)Se{sub 2} thin film solar cells

    SciTech Connect

    Lee, Kkotnim; Ok, Eun-A; Park, Jong-Keuk; Kim, Won Mok; Baik, Young-Joon; Jeong, Jeung-hyun; Kim, Donghwan

    2014-08-25

    We investigated the impact of incorporating 2% oxygen during intrinsic ZnO sputtering on the efficiency of Cu(In,Ga)Se{sub 2} solar cells. The added oxygen not only reduced the optical absorption loss of the Al-doped ZnO overlaying layer but also improved the electronic properties of the underlying CdS/Cu(In,Ga)Se{sub 2} by increasing carrier density, lowering defect level, and increasing diffusion length, eventually enhancing J{sub SC}, V{sub OC}, and fill factor. It was found that the Na doping concentration was significantly increased around the CdS/Cu(In,Ga)Se{sub 2} junction due to the plasma-activated oxygen. The improved electronic properties are better explained by the increased Na concentration than simply the oxygen-related defect passivation.

  12. Transparent conducting Si-codoped Al-doped ZnO thin films prepared by magnetron sputtering using Al-doped ZnO powder targets containing SiC

    SciTech Connect

    Nomoto, Jun-ichi; Miyata, Toshihiro; Minami, Tadatsugu

    2009-07-15

    Transparent conducting Al-doped ZnO (AZO) thin films codoped with Si, or Si-codoped AZO (AZO:Si), were prepared by radio-frequency magnetron sputtering using a powder mixture of ZnO, Al{sub 2}O{sub 3}, and SiC as the target; the Si content (Si/[Si+Zn] atomic ratio) was varied from 0 to 1 at. %, but the Al content (Al/[Al+Zn] atomic ratio) was held constant. To investigate the effect of carbon on the electrical properties of AZO:Si thin films prepared using the powder targets containing SiC, the authors also prepared thin films using a mixture of ZnO, Al{sub 2}O{sub 3}, and SiO{sub 2} or SiO powders as the target. They found that when AZO:Si thin films were deposited on glass substrates at about 200 degree sign C, both Al and Si doped into ZnO acted as effective donors and the atomic carbon originating from the sputtered target acted as a reducing agent. As a result, sufficient improvement was obtained in the spatial distribution of resistivity on the substrate surface in AZO:Si thin films prepared with a Si content (Si/[Si+Zn] atomic ratio) of 0.75 at. % using powder targets containing SiC. The improvement in resistivity distribution was mainly attributed to increases in both carrier concentration and Hall mobility at locations on the substrate corresponding to the target erosion region. In addition, the resistivity stability of AZO: Si thin films exposed to air for 30 min at a high temperature was found to improve with increasing Si content.

  13. Transparent conducting Al-doped ZnO thin films prepared by magnetron sputtering with dc and rf powers applied in combination

    SciTech Connect

    Minami, Tadatsugu; Ohtani, Yuusuke; Miyata, Toshihiro; Kuboi, Takeshi

    2007-07-15

    A newly developed Al-doped ZnO (AZO) thin-film magnetron-sputtering deposition technique that decreases resistivity, improves resistivity distribution, and produces high-rate depositions has been demonstrated by dc magnetron-sputtering depositions that incorporate rf power (dc+rf-MS), either with or without the introduction of H{sub 2} gas into the deposition chamber. The dc+rf-MS preparations were carried out in a pure Ar or an Ar+H{sub 2} (0%-2%) gas atmosphere at a pressure of 0.4 Pa by adding a rf component (13.56 MHz) to a constant dc power of 80 W. The deposition rate in a dc+rf-MS deposition incorporating a rf power of 150 W was approximately 62 nm/min, an increase from the approximately 35 nm/min observed in dc magnetron sputtering with a dc power of 80 W. A resistivity as low as 3x10{sup -4} {omega} cm and an improved resistivity distribution could be obtained in AZO thin films deposited on substrates at a low temperature of 150 deg. C by dc+rf-MS with the introduction of hydrogen gas with a content of 1.5%. This article describes the effects of adding a rf power component (i.e., dc+rf-MS deposition) as well as introducing H{sub 2} gas into dc magnetron-sputtering preparations of transparent conducting AZO thin films.

  14. Substrate temperature effects on reactively sputtered Cr2O3/n-Si heterojunctions

    NASA Astrophysics Data System (ADS)

    Ocak, Yusuf Selim; Issa, Ali Ahmed; Genisel, Mustafa Fatih; Tombak, Ahmet; Kilicoglu, Tahsin

    2016-04-01

    To see the effects of substrate temperature on Cr2O3/n-Si heterojunctions, Cr2O3 thin films were formed on n-Si and glass substrates at 40, 150 and 250 °C by radio frequency (RF) reactive sputtering technique. High purity Cr was used as target and oxygen was used as reactive gas. Optical properties of Cr2O3/n-Si thin films were analyzed using UV-vis data. The band gaps of the films were compared. The electrical properties of Cr2O3/n-Si heterojunction were tested by their current voltage (I-V) measurements in dark. It was observed that the heterojunction which was fabricated by forming Cr2O3 thin film at 250 °C gave better rectification. The characteristic electrical parameters such as barrier height, ideality factor and series resistance were calculated by using its I-V data. The influence of light intensity on photovoltaic effect behavior of the device was also calculated, finally the barrier height value of the structure obtained from capacitance-voltage (C-V) data were compared with the one calculated from I-V measurements.

  15. Study on amorphous TiAlN films produced by radiofrequency reactive sputtering

    NASA Astrophysics Data System (ADS)

    Garcia-Gonzalez, L.; Morales-Hernandez, J.; Bartolo-Perez, J. P.; Ceh-Soberanis, O.; Munoz-Saldana, J.; Espinoza-Beltran, F. J.

    2004-06-01

    Using the reactive magnetron rf sputtering technique, we prepared TiAlN films with amorphous structure on Corning glass and steel substrates in a reactive atmosphere of nitrogen and argon using a target of Ti-Al (40/60 wt. %). The average temperature of the substrates was about 25degreesC, with the purpose of obtaining amorphous films. The ratio of partial pressure of nitrogen to argon, P-N/P-Ar, was varied according to these values: 0.14, 0.28, and 0.43; fixing these values during whole the evaporation. Further on, films were prepared introducing nitrogen in periodic pulses with maximum values of P-N/P-Ar approximate to 4.7 during 45 seconds, with fixed periods of 10, 15 and 20 minutes. In all cases amorphous films were obtained, according to X-ray Diffraction. The chemical composition of the samples was measured by electron dispersive spectroscopy, showing a clear dependence with the evaporation conditions. In spite of the amorphous structure of the material, atomic force microscopy measurements showed a surface morphology dependent on the nitrogen content. Additionally, measurements of electronic spectroscopy for chemical analysis and Raman scattering spectroscopy for identification of chemical bonds were carried out. Measurements of mechanical properties of the samples were carried out using nanoindentation and micro-hardness Vicker's tests.

  16. Structural and ellipsometric study on tailored optical properties of tantalum oxynitride films deposited by reactive sputtering

    NASA Astrophysics Data System (ADS)

    Bousquet, Angélique; Zoubian, Fadi; Cellier, Joël; Taviot-Gueho, Christine; Sauvage, T.; Tomasella, Eric

    2014-11-01

    Oxynitride materials, which offer the possibility of merging oxide and nitride properties, are increasingly studied for this reason. This paper focuses on assessing the optical properties of tantalum oxynitride thin films deposited by pure tantalum target sputtering in an Ar/O2/N2 reactive atmosphere. First, by changing the oxygen to reactive gas flow rate ratio, and using thermal post-treatment, we deposited films with elemental compositions studied by Rutherford backscattering spectroscopy, ranging from a nitride (close to Ta3N5) to an oxide (close to Ta2O5) with various structures analyzed by x-ray diffraction. Their optical properties were investigated in depth by spectroscopic ellipsometry and UV-visible spectroscopy. For the ellipsometry investigation, we propose a model combining the Tauc-Lorentz law and additional Lorentz oscillator: the first contribution is linked to a semi-conductor or insulator film matrix, and the second one to the presence of conductive TaN crystals. Ellipsometry thus appears as a powerful tool to investigate complex materials such as tantalum oxynitrides. Moreover, we demonstrated that using this deposition method we were able to finely tune the film refractive index from 3.4 to 2.0 (at 1.96 eV) and the optical band gap, specifically from 1.3 to 2.7 eV.

  17. Reactive sputter deposition of pyrite structure transition metal disulfide thin films: Microstructure, transport, and magnetism

    SciTech Connect

    Baruth, A.; Manno, M.; Narasimhan, D.; Shankar, A.; Zhang, X.; Johnson, M.; Aydil, E. S.; Leighton, C.

    2012-09-01

    Transition metal disulfides crystallizing in the pyrite structure (e.g., TMS{sub 2}, with TM = Fe, Co, Ni, and Cu) are a class of materials that display a remarkably diverse array of functional properties. These properties include highly spin-polarized ferromagnetism (in Co{sub 1-x}Fe{sub x}S{sub 2}), superconductivity (in CuS{sub 2}), an antiferromagnetic Mott insulating ground state (in NiS{sub 2}), and semiconduction with close to optimal parameters for solar absorber applications (in FeS{sub 2}). Exploitation of these properties in heterostructured devices requires the development of reliable and reproducible methods for the deposition of high quality pyrite structure thin films. In this manuscript, we report on the suitability of reactive sputter deposition from metallic targets in an Ar/H{sub 2}S environment as a method to achieve exactly this. Optimization of deposition temperature, Ar/H{sub 2}S pressure ratio, and total working gas pressure, assisted by plasma optical emission spectroscopy, reveals significant windows over which deposition of single-phase, polycrystalline, low roughness pyrite films can be achieved. This is illustrated for the test cases of the ferromagnetic metal CoS{sub 2} and the diamagnetic semiconductor FeS{sub 2}, for which detailed magnetic and transport characterization are provided. The results indicate significant improvements over alternative deposition techniques such as ex situ sulfidation of metal films, opening up exciting possibilities for all-sulfide heterostructured devices. In particular, in the FeS{sub 2} case it is suggested that fine-tuning of the sputtering conditions provides a potential means to manipulate doping levels and conduction mechanisms, critical issues in solar cell applications. Parenthetically, we note that conditions for synthesis of phase-pure monosulfides and thiospinels are also identified.

  18. The influence of growth temperature on structural and optical properties of sputtered ZnO QDs embedded in SiO2 matrix

    NASA Astrophysics Data System (ADS)

    Samavati, Alireza; Othaman, Zulkafli; Ghoshal, S. K.; Mustafa, M. K.

    2015-10-01

    We report the influence of growth temperature on surface morphology, structural and optical properties of ZnO QDs embedded with SiO2/Si matrix fabricated by radio frequency (RF) magnetron sputtering method. The fragmentation due to elastic strain relaxation compensate adatom diffusion length at higher temperature causes the decrement of the ZnO QDs sizes from ∼41 nm to ∼12 nm and number density enhancement from ∼0.2 to ∼15.4 × 1010 cm-2 by increasing the growth temperature. ZnO QDs shows a well-defined hexagonal close packed wurtzite structure with lattice parameters close to those of bulk ZnO, confirming their high crystalline quality. Increasing growth parameters causes to decrease the lattice parameters due to change in interatomic distances explained by elimination of defects and structural relaxation. The room temperature photoluminescence (PL) spectra shows strong UV accompanied by weaker green peak originated from recombination of free excitons and dominative deep-level emissions respectively. As the growth temperature increased to 500 °C, an emission intensity in the ultraviolet and green region enhanced which is due to increment in the numbers of photo-carriers by increasing the number density of QDs. Calculated band gap using an optical transmittance measurement indicates that the bandgap shift to higher energies is not taken placed because of large size of dots. The Urbach energy increases considerably in samples with increasing growth temperature which is attributed to higher degree of surface disorder in smaller QDs. The excellent features of the results suggest that our systematic analysis method may constitute a basis for the tunable growth of ZnO QDs suitable in nanophotonics.

  19. Conversion efficiency improvement of inverted CH3NH3PbI3 perovskite solar cells with room temperature sputtered ZnO by adding the C60 interlayer

    NASA Astrophysics Data System (ADS)

    Lai, Wei-Chih; Lin, Kun-Wei; Guo, Tzung-Fang; Chen, Peter; Wang, Yuan-Ting

    2015-12-01

    We have demonstrated the performance of inverted CH3NH3PbI3 perovskite-based solar cells (SCs) with a room temperature (RT) sputtered ZnO electron transport layer by adding fullerene (C60) interlayer. ZnO exhibits a better matched conduction band level with perovskite and Al work function and around energy offset of 2.2 eV between highest occupied molecular orbital level of CH3NH3PbI3 perovskite and valance band level of ZnO. However, the CH3NH3PbI3 perovskite layer will be damaged during direct RT sputtering deposition of ZnO. Therefore, the C60 interlayer having matched conduction band level with ZnO and CH3NH3PbI3 perovskite added between the CH3NH3PbI3 perovskite and RT sputtered ZnO layers for protection prevents sputtering damages on the CH3NH3PbI3 perovskite layer. The short-circuit current density (JSC, 19.41 mA/cm2) and open circuit voltage (VOC, 0.91 V) of the SCs with glass/ITO/poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS)/perovskite/C60/RT sputtered ZnO/Al structure is higher than the JSC (16.23 mA/cm2) and VOC (0.90 V) of the reference SC with glass/ITO/PEDOT:PSS/perovskite/C60/bathocuproine (BCP)/Al structure. Although the SCs with the former structure has a lower fill factor (FF%) than the SCs with the latter structure, its conversion efficiency η% (10.93%) is higher than that (10.6%) of the latter.

  20. Relating cytotoxicity, zinc ions, and reactive oxygen in ZnO nanoparticle-exposed human immune cells.

    PubMed

    Shen, Cenchao; James, Simon A; de Jonge, Martin D; Turney, Terence W; Wright, Paul F A; Feltis, Bryce N

    2013-11-01

    Although zinc oxide (ZnO) nanoparticles (NPs) have been widely formulated in sunscreens, the relationship between reactive oxygen species (ROS) generation induced by these particles, zinc ions, and cytotoxicity is not clearly understood. This study explores whether these factors can be accurately quantified and related. The study demonstrates a strong correlation between ZnO NP-induced cytotoxicity and free intracellular zinc concentration (R (2) = .945) in human immune cells, indicating a requirement for NP dissolution to precede cytotoxicity. In addition, although direct exposure to ZnO NPs was found to induce cytotoxicity at relatively high concentrations, indirect exposure (via dialysis) was not cytotoxic, even at extremely high concentrations, highlighting a requirement for NP-to-cell contact. Elevated levels of ROS present in NP-exposed cells also correlated to both cytotoxicity and intracellular free zinc. Although the addition of antioxidant was able to reduce ROS, cytotoxicity to ZnO NPs was unaffected, suggesting ROS may be, in part, a result of cytotoxicity rather than a causal factor. This study highlights both the requirement and role of intracellular dissolution of zinc nanomaterials to elicit a cytotoxic response. This response is only partially ROS dependent, and therefore, modification of NP uptake and their intracellular solubility are key components in modulating the bioactivity of ZnO NPs. PMID:23997113

  1. Photocatalytic degradation of Reactive Black 5 and Malachite Green with ZnO and lanthanum doped nanoparticles

    NASA Astrophysics Data System (ADS)

    Kaneva, N.; Bojinova, A.; Papazova, K.

    2016-02-01

    Here we report the preparation of ZnO particles with different concentrations of La3+ doping (0, 0.5 and 1 wt%) via sol-gel method. The nanoparticles are synthesized directly from Zn(CH3COO)2.2H2O in the presence of 1-propanol and triethylamine at 80°C. The conditions are optimized to obtain particles of uniform size, easy to isolate and purify. The nanoparticles are characterized by SEM, XRD and UV-Vis analysis. The photocatalytic properties of pure and La-doped ZnO are studied in the photobleaching of Malachite Green (MG) and Reactive Black 5 (RB5) dyes in aqueous solutions upon UV illumination. It is observed that the rate constant increases with the La loading up to 1 wt%. The doping helps to achieve complete mineralization of MG within a short irradiation time. 1 wt% La-doped ZnO nanoparticles show highest photocatalytic activity. The La3+ doped ZnO particles degrade faster RB5 than MG. The reason is weaker N=N bond in comparison with the C-C bond between the central carbon atom and N,N-dimethylaminobenzyl in MG. The as-prepared ZnO particles can find practical application in photocatalytic purification of textile wastewaters.

  2. Impact of low temperature annealing on structural, optical, electrical and morphological properties of ZnO thin films grown by RF sputtering for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Purohit, Anuradha; Chander, S.; Sharma, Anshu; Nehra, S. P.; Dhaka, M. S.

    2015-11-01

    This paper presents effect of low temperature annealing on the physical properties of ZnO thin films for photovoltaic applications. The thin films of thickness 50 nm were grown on glass and indium tin oxide (ITO) coated glass substrates employing radio frequency magnetron sputtering technique followed by thermal annealing within low temperature range 150-450 °C. These as-grown and annealed films were subjected to the X-ray diffraction (XRD), UV-Vis spectrophotometer, source meter and scanning electron microscopy (SEM) for structural, optical, electrical and surface morphological analysis respectively. The compositional analysis of the as-grown ZnO film was also carried out using energy dispersive spectroscopy (EDS). The XRD patterns reveal that the films have wurtzite structure of hexagonal phase with preferred orientation (1 0 0) and polycrystalline in nature. The crystallographic and optical parameters are calculated and discussed in detail. The optical band gap was found in the range 3.30-3.52 eV and observed to decrease with annealing temperature except 150 °C. The current-voltage characteristics show that the films exhibit approximately ohmic behavior. The SEM studies show that the films are uniform, homogeneous and free from crystal defects and voids. The experimental results reveal that ZnO thin films may be used as alternative materials for eco-friendly buffer layer to the thin film solar cell applications.

  3. High-rate reactive magnetron sputtering of zirconia films for laser optics applications

    NASA Astrophysics Data System (ADS)

    Juškevičius, K.; Audronis, M.; Subačius, A.; Drazdys, R.; Juškėnas, R.; Matthews, A.; Leyland, A.

    2014-09-01

    ZrO2 exhibits low optical absorption in the near-UV range and is one of the highest laser-induced damage threshold (LIDT) materials; it is, therefore, very attractive for laser optics applications. This paper reports explorations of reactive sputtering technology for deposition of ZrO2 films with low extinction coefficient k values in the UV spectrum region at low substrate temperature. A high deposition rate (64 % of the pure metal rate) process is obtained by employing active feedback reactive gas control which creates a stable and repeatable deposition processes in the transition region. Substrate heating at 200 °C was found to have no significant effect on the optical ZrO2 film properties. The addition of nitrogen to a closed-loop controlled process was found to have mostly negative effects in terms of deposition rate and optical properties. Open-loop O2 gas-regulated ZrO2 film deposition is slow and requires elevated (200 °C) substrate temperature or post-deposition annealing to reduce absorption losses. Refractive indices of the films were distributed in the range n = 2.05-2.20 at 1,000 nm and extinction coefficients were in the range k = 0.6 × 10-4 and 4.8 × 10-3 at 350 nm. X-ray diffraction analysis showed crystalline ZrO2 films consisted of monoclinic + tetragonal phases when produced in Ar/O2 atmosphere and monoclinic + rhombohedral or a single rhombohedral phase when produced in Ar/O2 + N2. Optical and physical properties of the ZrO2 layers produced in this study are suitable for high-power laser applications in the near-UV range.

  4. Deposition of LaMnO 3 buffer layer on IBAD-MgO template by reactive DC sputtering

    NASA Astrophysics Data System (ADS)

    Kim, H. S.; Oh, S. S.; Ha, H. S.; Ko, R. K.; Ha, D. W.; Kim, T. H.; Youm, D. J.; Lee, N. J.; Moon, S. H.; Yoo, S. I.; Park, C.

    2009-10-01

    The deposition conditions of LaMnO 3 (LMO) buffer layer on Ion Beam Assisted Deposition (IBAD)-MgO template by reactive DC sputtering were investigated. We developed a specially designed chamber for reactive DC magnetron sputtering. The deposition chamber was composed of two sputtering guns with the mixed metallic target of La (50 at%) + Mn (50 at%), halogen lamp heater, QCM (Quartz Crystal Microbalance), RGA (Residual Gas Analyzer) and reel to reel tape moving system. We investigated the effect of oxygen flow rate on the deposition rate of LMO layer. We found that there was an optimal range of oxygen flow rate to have the desired layer. Above the range, the deposition rate decreased sharply and plasma was unstable. Below the range, the deposited layer was partially metallic. We investigated the effect of substrate temperature on the texturing of LMO layer. The texturing of LMO layer was improved by increasing the substrate temperature. We investigated the effect of deposition rate on the texturing of LMO layer. The LMO layer has a good texture in the deposition rate range of 0.07-0.21 nm/s. We confirmed that deposition rate had little effect on the texturing of LMO layer in the deposition rate range. Sm 1Ba 2Cu 3O 7-d superconducting layer was deposited on the LMO(reactive)/IBAD-MgO template. I c and J c were 81.6 A and 1 MA/cm 2. This means that LMO layer deposited by reactive DC sputtering shows a good performance in superconductor coated conductor.

  5. Reactively-sputtered zinc semiconductor films of high conductivity for heterojunction devices

    NASA Technical Reports Server (NTRS)

    Stirn, Richard J. (Inventor)

    1986-01-01

    A high conductivity, n-doped semiconductor film is produced from zinc, or Zn and Cd, and group VI elements selected from Se, S and Te in a reactive magnetron sputtering system having a chamber with one or two targets, a substrate holder, means for heating the substrate holder, and an electric field for ionizing gases in the chamber. Zinc or a compound of Zn and Cd is placed in the position of one of the two targets and doping material in the position of the other of the two targets. Zn and Cd may be placed in separate targets while a dopant is placed in the third target. Another possibility is to place an alloy of Zn and dopant, or Zn, Cd and dopant in one target, thus using only one target. A flow of the inert gas is ionized and directed toward said targets, while a flow of a reactant gas consisting of hydrides of the group VI elements is directed toward a substrate on the holder. The targets are biased to attract negatively ionized inert gas. The desired stochiometry for high conductivity is achieved by controlling the temperature of the substrate, and partial pressures of the gases, and the target power and total pressure of the gases in the chamber.

  6. Cu/TiO2 thin films prepared by reactive RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Sreedhar, M.; Reddy, I. Neelakanta; Bera, Parthasarathi; Ramachandran, D.; Gobi Saravanan, K.; Rabel, Arul Maximus; Anandan, C.; Kuppusami, P.; Brijitta, J.

    2015-08-01

    Cu/TiO2 thin films were deposited on glass substrates by reactive RF magnetron sputtering technique. Crystalline structure, surface morphology and electronic structure were studied using X-ray diffraction (XRD), field emission scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy (XPS). Transmittance and absorptance of these films were characterized by UV-Vis spectroscopy. XRD patterns demonstrate that TiO2 films deposited on glass substrate at 300 °C are observed to be in pure anatase phase, whereas Cu/TiO2 films are amorphous in nature at 300 °C substrate temperature. The crystallinity of Cu/TiO2 thin films decreases with increasing the dopant concentrations of Cu in TiO2 films. XPS studies show that Cu is in +2 oxidation state in all films. The optical band gap of Cu/TiO2 films decreases from ~3.3 to ~2.0 eV with the increase in the copper concentration. Further, antimicrobial studies of Cu/TiO2 films with ~3.9 at.% Cu exhibit high transmittance and best antimicrobial activity against E. coli and S. aureus compared to other doped films.

  7. Preparation and Optical Properties of Zirconium-Titanium-Oxide Thin Films by Reactive Sputtering

    NASA Astrophysics Data System (ADS)

    Matsumoto, Hironaga; Sekine, Masato; Miura, Noboru; Nakano, Ryotaro; Matsumoto, Setsuko

    2005-02-01

    Zirconium-titanium-oxide thin films were prepared by multi-target rf reactive sputtering using metallic targets of zirconium and titanium. The compositional ratio of zirconium to titanium in the thin films was precisely controlled through rf power. Zirconium and titanium in the thin films were found to exist as mixtures of chemically bonded ZrO2 and TiO2 from XPS spectra. The zirconium-titanium-oxide thin films with compositional ratio x<0.42 were identified to have a tetragonal crystal structure, whereas those with x≥q 0.42 were identified to be in the amorphous state. The refractive index of the zirconium-titanium-oxide thin film at a wavelength of 550 nm changed from 2.25 to 2.55 according to compositional ratio x, and the dispersion of the refractive index was analyzed using the Lorentz oscillator model with four oscillators. It was clarified that the estimated oscillator energies E1 (10.5 eV) and E2 (6.5 eV) correspond to zirconium oxide, and that E3 (5.5 eV) and E4 (4.3 eV) correspond to titanium oxide from fundamental absorption spectra and photoconductivity.

  8. Innovative technique for tailoring intrinsic stress in reactively sputtered piezoelectric aluminum nitride films

    SciTech Connect

    Felmetsger, V. V.; Laptev, P. N.; Tanner, S. M.

    2009-05-15

    Novel technical and technological solutions enabling effective stress control in highly textured polycrystalline aluminum nitride (AlN) thin films deposited with ac (40 kHz) reactive sputtering processes are discussed. Residual stress in the AlN films deposited by a dual cathode S-Gun magnetron is well controlled by varying Ar gas pressure, however, since deposition rate and film thickness uniformity depend on gas pressure too, an independent stress control technique has been developed. The technique is based on regulation of the flux of the charged particles from ac plasma discharge to the substrate. In the ac powered S-Gun, a special stress adjustment unit (SAU) is employed for reducing compressive stress in the film by means of redistribution of discharge current between electrodes of the S-Gun leading to controllable suppression of bombardment of the growing film. This technique is complementary to AlN deposition with rf substrate bias which increases ion bombardment and shifts stress in the compressive direction, if required. Using SAU and rf bias functions ensures tailoring intrinsic stress in piezoelectric AlN films for a particular application from high compressive -700 MPa to high tensile +300 MPa and allows the gas pressure to be adjusted independently to fine control the film uniformity. The AlN films deposited on Si substrates and Mo electrodes have strong (002) texture with full width at half maximum ranging from 2 degree sign for 200 nm to 1 degree sign for 2000 nm thick films.

  9. Thermal Stability of a RuO2 Electrode Prepared by DC Reactive Sputtering

    NASA Astrophysics Data System (ADS)

    Matsui, Yuichi; Hiratani, Masahiko; Kimura, Shinichiro

    2000-01-01

    RuO2 films were deposited by reactive DC sputtering, and the formation process and the thermal stability were investigated. In the RuO2/Ti/SiO2 structure, the Ti surface was preferentially oxidized at the initial stage of RuO2 growth. Insertion of Ru and TiN layers between the RuO2 and Ti layers can suppress the oxygen diffusion toward the Ti layer during the film growth. However, when the RuO2/Ru/TiN/Ti/Si structure was heat-treated, the RuO2 was partially reduced to form RuO2-X and the TiN was oxidized to TiO2 while generating N2 and O2 gases, resulting in voids formation at the RuO2/Ru interface, regardless of the heat-treatment atmosphere. We found this was caused by internal oxygen diffusion within the stacked layers. This reaction is governed by the transference of oxygen to the TiN and Ti layers by the difference in the Gibbs’ formation free energy, and by the oxygen diffusion enhancement.

  10. Synthesis of copper nitride films doped with Fe, Co, or Ni by reactive magnetron sputtering

    SciTech Connect

    Yang, Jianbo; Huang, Saijia; Wang, Zhijiao; Hou, Yuxuan; Shi, Yuyu; Zhang, Jian; Yang, Jianping Li, Xing'ao

    2014-09-01

    Copper nitride (Cu{sub 3}N) and Fe-, Co-, and Ni-doped Cu{sub 3}N films were prepared by reactive magnetron sputtering. The films were deposited on silicon substrates at room temperature using pure Cu target and metal chips. The molar ratio of Cu to N atoms in the as-prepared Cu{sub 3}N film was 2.7:1, which is comparable with the stoichiometry ratio 3:1. X-ray diffraction measurements showed that the films were composed of Cu{sub 3}N crystallites with anti-ReO{sub 3} structure and adopted different preferred orientations. The reflectance of the four samples decreased in the wavelength range of 400–830 nm, but increased rapidly within wavelength range of 830–1200 nm. Compared with the Cu{sub 3}N films, the resistivity of the doped Cu{sub 3}N films decreased by three orders of magnitude. These changes have great application potential in optical and electrical devices based on Cu{sub 3}N films.

  11. Structural and optical properties of DC reactive magnetron sputtered zinc aluminum oxide thin films

    SciTech Connect

    Kumar, B. Rajesh; Rao, T. Subba

    2014-10-15

    Highly transparent conductive Zinc Aluminum Oxide (ZAO) thin films have been deposited on glass substrates using DC reactive magnetron sputtering method. The thin films were deposited at 200 °C and post-deposition annealing from 15 to 90 min. XRD patterns of ZAO films exhibit only (0 0 2) diffraction peak, indicating that they have c-axis preferred orientation perpendicular to the substrate. Scanning electron microscopy (SEM) is used to study the surface morphology of the films. The grain size obtained from SEM images of ZAO thin films are found to be in the range of 20 - 26 nm. The minimum resistivity of 1.74 × 10{sup −4} Ω cm and an average transmittance of 92% are obtained for the thin film post annealed for 30 min. The optical band gap of ZAO thin films increased from 3.49 to 3.60 eV with the increase of annealing time due to Burstein-Moss effect. The optical constants refractive index (n) and extinction coefficient (k) were also determined from the optical transmission spectra.

  12. Structural and optical properties of DC reactive magnetron sputtered zinc aluminum oxide thin films

    NASA Astrophysics Data System (ADS)

    Kumar, B. Rajesh; Rao, T. Subba

    2014-10-01

    Highly transparent conductive Zinc Aluminum Oxide (ZAO) thin films have been deposited on glass substrates using DC reactive magnetron sputtering method. The thin films were deposited at 200 °C and post-deposition annealing from 15 to 90 min. XRD patterns of ZAO films exhibit only (0 0 2) diffraction peak, indicating that they have c-axis preferred orientation perpendicular to the substrate. Scanning electron microscopy (SEM) is used to study the surface morphology of the films. The grain size obtained from SEM images of ZAO thin films are found to be in the range of 20 - 26 nm. The minimum resistivity of 1.74 × 10-4 Ω cm and an average transmittance of 92% are obtained for the thin film post annealed for 30 min. The optical band gap of ZAO thin films increased from 3.49 to 3.60 eV with the increase of annealing time due to Burstein-Moss effect. The optical constants refractive index (n) and extinction coefficient (k) were also determined from the optical transmission spectra.

  13. Mechanical and Tribological Behavior of VN and HfN Films Deposited via Reactive Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Escobar, C.; Villarreal, M.; Caicedo, J. C.; Esteve, J.; Prieto, P.

    2013-08-01

    HfN and VN thin films were deposited onto silicon and 4140 steel substrates with r.f. reactive magnetron sputtering by using Hf and V metallic targets with 4-inch diameter and 99.9% purity in argon/nitrogen atmosphere, applying a substrate temperature of 250°C and a pressure of 1.2 × 10-3 mbar. In order to evaluate the structural, chemical, morphological, mechanical and tribological properties, we used X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM), scanning electron microscopy (SEM), nanoindentation, pin-on-disc and scratch tests. Film structure determined by XRD showed that FCC (NaCl-type) films are formed in both the cases by δ-HfN and δ-VN phases. Hardness and elastic modulus values obtained for both the films were 21 and 224 GPa for the HfN film and 19 and 205 GPa for the VN film, respectively. Additionally, the films showed low friction coefficient of 0.44 for HfN and 0.62 for VN when these films were evaluated against 100 Cr6 steel, and finally the critical load was found at 41 N for the HfN film and 34 N for the VN film.

  14. Structure, mechanical and tribological properties of HfCx films deposited by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Shuo, Wang; Kan, Zhang; Tao, An; Chaoquan, Hu; Qingnan, Meng; Yuanzhi, Ma; Mao, Wen; Weitao, Zheng

    2015-02-01

    Hafnium carbide (HfC) films have been deposited on Si (1 0 0) substrates by direct current reactive magnetron sputtering. The microstructure, compressive stress, hardness and tribological behaviors show great dependence on carbon (C) concentration and chemical bonding state. With C content in HfCx films rising, phase transforms from hexagonal-close-packed (HCP) Hf(C) to face-centered-cubic (FCC) HfC, and nanocomposite structure consisting of HfCx nanocrystalline grains encapsulated by amorphous carbon (a-C) matrix forms at moderate C content. The hardness of HfCx films increases significantly from 10.4 GPa (14 at.% C) to 34.4 GPa (58 at.% C) and then keeps dropping with further increasing C content. a-C appears in HfCx films with more than 32 at.% C and it obviously lowers coefficient of friction (COF). The wear resistance can be remarkably worsened by high compressive stress. The film with 76 at.% C exhibits relatively high hardness and low compressive stress, good fracture toughness and self-lubrication transfer layer, showing great combination of the lowest COF of 0.10 and lowest wear rate of 1.10 × 10-6 mm3/Nm.

  15. Nanostructured and wide bandgap CdS:O thin films grown by reactive RF sputtering

    SciTech Connect

    Islam, M. A.; Rahman, K. S.; Haque, F.; Rashid, M. J.; Akhtaruzzaman, M.; Sopian, K.; Sulaiman, Y.; Amin, N.

    2015-05-15

    In this study, CdS:O thin films were prepared from a 99.999% CdS target by reactive sputtering in a Ar:O{sub 2} (99:1) ambient with different RF power at room temperature. The deposited films were studied by means of XRD, SEM, EDX, Hall Effect and UV-Vis spectrometry. The incorporations of O{sub 2} into the films were observed to increase with the decrease of deposition power. The cryatallinity of the films were reduced, whereas the band gaps of the films were increased by the increase of O{sub 2} content on the films. The films were found in nano-structured grains with a compact surface. It has been seen that the highest carrier density is observed in the film with O{sub 2} at.% 21.10, while the values decreased with the further increase or decrease of O{sub 2} content on the films; indicating that specific amount of donor like O{sub 2} atoms substitute to the S atoms can improve the carrier density of the CdS:O thin film.

  16. Nanocharacterization of Titanium Nitride Thin Films Obtained by Reactive Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Merie, Violeta Valentina; Pustan, Marius Sorin; Bîrleanu, Corina; Negrea, Gavril

    2015-05-01

    Titanium nitride thin films are used in applications such as tribological layers for cutting tools, coating of some medical devices (scalpel blades, prosthesis, implants, etc.), sensors, electrodes for bioelectronics, microelectronics, diffusion barrier, bio-micro-electromechanical systems, and so on. This work is a comparative study concerning the influence of substrate temperature on some mechanical and tribological characteristics of titanium nitride thin films. The researched thin films were obtained by the reactive magnetron sputtering method. The experiments employed two kinds of substrates: a steel substrate and a silicon one. The elaboration of titanium nitride thin films was done at two temperatures. First, when the substrates were at room temperature, and second, when the substrates were previously heated at 250°C. The temperature of 250°C was kept constant during the deposition of the films. The samples were then investigated by atomic force microscopy in order to establish their mechanical and tribological properties. The nanohardness, Young's modulus, roughness, and friction force were some of the determined characteristics. The results demonstrated that the substrate which was previously heated at 250°C led to the obtaining of more adherent titanium nitride thin films than the substrate used at room temperature. The preheating of both substrates determined the decrease of thin films roughness. The friction force, nanohardness and Young's modulus of the tested samples increased when the substrates were preheated at 250°C.

  17. Nanocharacterization of titanium nitride thin films obtained by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Merie, V. V.; Pustan, M. S.; Bîrleanu, C.; Negrea, G.

    2014-08-01

    Titanium nitride thin films are used in applications such as tribological layers for cutting tools, coating of some medical devices (scalpel blades, prosthesis, implants etc.), sensors, electrodes for bioelectronics, microelectronics, diffusion barrier, bio-microelectromechanical systems (Bio-MEMS) and so on. This work is a comparative study concerning the influence of substrate temperature on some mechanical and tribological characteristics of titanium nitride thin films. The researched thin films were obtained by reactive magnetron sputtering method. The experiments employed two kinds of substrates: a steel substrate and a silicon one. The elaboration of titanium nitride thin films was done at two temperatures. First, the obtaining was realized when the substrates were at room temperature, and second, the obtaining was realized when the substrates were previously heated at 250 °C. The elaborated samples were then investigated by atomic force microscopy in order to establish their mechanical and tribological properties. The nanohardness, roughness, friction force are some of the determined characteristics. The results marked out that the substrate which was previously heated at 250 °C led to the obtaining of more adherent titanium nitride thin films than the substrate used at room temperature.

  18. Growth dynamics of reactive-sputtering-deposited AlN films

    SciTech Connect

    Auger, M.A.; Vazquez, L.; Sanchez, O.; Jergel, M.; Cuerno, R.; Castro, M.

    2005-06-15

    We have studied the surface kinetic roughening of AlN films grown on Si(100) substrates by dc reactive sputtering within the framework of the dynamic scaling theory. Films deposited under the same experimental conditions for different growth times were analyzed by atomic force microscopy and x-ray diffraction. The AlN films display a (002) preferred orientation. We have found two growth regimes with a crossover time of 36 min. In the first regime, the growth dynamics is unstable and the films present two types of textured domains, well textured and randomly oriented, respectively. In contrast, in the second regime the films are homogeneous and well textured, leading to a relative stabilization of the surface roughness characterized by a growth exponent {beta}=0.37{+-}0.03. In this regime a superrough scaling behavior is found with the following exponents: (i) Global exponents: roughness exponent {alpha}=1.2{+-}0.2 and {beta}=0.37{+-}0.03 and coarsening exponent 1/z=0.32{+-}0.05; (ii) local exponents: {alpha}{sub loc}=1, {beta}{sub loc}=0.32{+-}0.01. The differences between the growth modes are found to be related to the different main growth mechanisms dominating their growth dynamics: sticking anisotropy and shadowing, respectively.

  19. Synthesis and characterization of petal type CZTS by stacked layer reactive sputtering

    NASA Astrophysics Data System (ADS)

    Singh, Om Pal; Parmar, R.; Gour, K. S.; Dalai, M. K.; Tawale, Jai; Singh, S. P.; Singh, Vidya Nand

    2015-12-01

    Here we present a method to grow the petal type structure of CZTS thin film on soda lime glass substrate using the stacked layer reactive sputtering and post-depostion annealing in N2 atmosphere. Optical bandgap of the petal type structure of CZTS was determined using UV-VIS spectroscopy and the value was 1.5 eV. In XRD analysis, (112) plane having highest intensity and other supporting planes with low intensity peaks corresponding to (200), (220) and (312) revealed the presence of CZTS phase. It was further confirmed by the Raman analysis, where the Raman peaks at 288 cm-1, 335 cm-1 and 353 cm-1 revealed the presence of CZTS phase. Petal type growth was observed in the scanning electron microscopy analysis. Elemental analysis was done by the EDAX. In EDAX analysis, It is observed that sample was Sn rich which may be responsible for petal type growth. Petal type growth of CZTS may be helpful in increasing the performance of the CZTS based thin film solar cell by phenomena of light scattering and enhanced surface area.

  20. Structural defect control and photosensitivity in reactively sputtered germanosilicate glass films

    SciTech Connect

    Potter, B.G. Jr.; Simmons-Potter, K.; Warren, W.L.; Ruffner, J.A.

    1997-02-01

    The optical performance of refractive index structures induced in photosensitive (PS) glasses ultimately depends on the index modulation depth attainable. In germanosilicate materials, the photosensitive response is linked to the presence of oxygen-deficient germanium point defect centers. Prior efforts to increase PS in these materials, e.g., hydrogen loading, rely on a chemical reduction of the glass structure to enhance the population of oxygen deficient centers and thus increase the saturated refractive index change. We have previously reported the development of highly photosensitive, as-deposited germanosilicate glass films through reactive atmosphere (O{sub 2}/Ar) sputtering from a Ge/Si alloy target. The present work details our investigation of the effect of substrate temperature during deposition on the material structure and propensity for photosensitivity. Using optical absorption/bleaching, Raman, electron paramagnetic resonance (EPR) and selective charge injection techniques we show that the predominate defect states responsible for the PS response can be varied through substrate temperature control. We find that two regimes of photosensitive behavior can be accessed which exhibit dramatically different uv-bleaching characteristics. Thus, the corresponding dispersion of the refractive index change as well as its magnitude can be controlled using our synthesis technique. Tentative defect models for the photosensitive process in materials deposited at both ambient temperature and at elevated substrate temperatures will be presented.

  1. Structural, optical and electrical properties of WOxNy filmsdeposited by reactive dual magnetron sputtering

    SciTech Connect

    Mohamed, Sodky H.; Anders, Andre

    2006-06-05

    Thin films of tungsten oxynitride were prepared by dual magnetron sputtering of tungsten using argon/oxygen/nitrogen gas mixtures with various nitrogen/oxygen ratios. The presence of even small amounts of oxygen had a great effect not only on the composition but on the structure of WOxNy films, as shown by Rutherford backscattering and x-ray diffraction, respectively. Significant incorporation of nitrogen occurred only when the nitrogen partial pressure exceeded 89 percent of the total reactive gas pressure. Sharp changes in the stoichiometry, deposition rate, room temperature resistivity, electrical activation energy and optical band gap were observed when the nitrogen/oxygen ratio was high.The deposition rate increased from 0.31 to 0.89 nm/s, the room temperature resistivity decreased from 1.65 x 108 to 1.82 x 10-2 ?cm, the electrical activation energy decreased from 0.97 to 0.067 eV, and the optical band gap decreased from 3.19 to 2.94 eV upon nitrogen incorporation into the films. WOxNy films were highly transparent as long as the nitrogen incorporation was low, and were brownish (absorbing) and partially reflecting as nitrogen incorporation became significant.

  2. Aluminium nitride piezoelectric thin films reactively deposited in closed field unbalanced magnetron sputtering for elevated temperature 'smart' tribological applications

    NASA Astrophysics Data System (ADS)

    Hasheminiasari, Masood

    "Smart" high temperature piezoelectric aluminum nitride (AlN) thin films were synthesized by reactive magnetron sputtering using DC; pulsed-DC, and deep oscillation modulated pulsed power (DOMPP) systems on variety of substrate materials. Process optimization was performed to obtain highly c-axis texture films with improved piezoelectric response via studying the interplay between process parameters, microstructure and properties. AlN thin films were sputtered with DC and pulsed-DC systems to investigate the effect of various deposition parameters such as reactive gas ratio, working pressure, target power, pulsing frequency, substrate bias, substrate heating and seed layers on the properties and performance of the film device. The c-axis texture, orientation, microstructure, and chemical composition of AlN films were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). A Michelson laser interferometer was designed and built to obtain the converse piezoelectric response of the deposited AlN thin films. Thin films with narrow AlN-(002) rocking curve of 2.5° were obtained with preliminary studies of DOMPP reactive sputtering. In-situ high temperature XRD showed excellent thermal stability and oxidation resistance of AlN films up to 1000 °C. AlN films with optimized processing parameters yielded an inverse piezoelectric coefficient, d33 of 4.9 pm/V close to 90 percent of its theoretical value.

  3. ICP-Enhanced Sputter Deposition for Reactivity Control and Low-Temperature Formation of a-IGZO Films

    NASA Astrophysics Data System (ADS)

    Setsuhara, Yuichi; Nakata, Keitaro; Satake, Yoshikatsu; Takenaka, Kosuke; Uchida, Giichiro; Ebe, Akinori

    2015-09-01

    Inductively coupled plasma (ICP) - enhanced sputter deposition for a-IGZO channel TFTs fabrication have been performed. This advantage of fine control of reactivity during the deposition process is of great significance for film deposition of the transparent amorphous oxide semiconductor, a-InGaZnOx (a-IGZO), whose electrical properties are significantly sensitive to the reactivity during the film deposition. The a-IGZO film deposition with addition of H2 gas were performed in order to control oxidation process during a-IGZO film formation via balance between oxidation-reduction. The results of optical emission spectrum indicate the possibility for the suppression of oxidation by oxygen atoms of a-IGZO films during deposition due to addition of H2 gas. The characteristics of TFT fabricated with IGZO film via plasma-enhanced magnetron sputter deposition system have been investigated. The result exhibits that the possibility of expanding process window for control of balance between oxidization and reduction by addition of H2 gas. The a-IGZO channel TFTs fabricated plasma-enhanced reactive sputtering system with addition of H2 gas exhibited good performance of field-effect mobility 15.3 cm2(Vs)-1 and subthreshold gate voltage swing (S) of 0.48 V decade-1. This work was partly supported by ASTEP (JST) and Grant-in-Aid for Challenging Exploratory Research (JSPS).

  4. Process stabilization by peak current regulation in reactive high-power impulse magnetron sputtering of hafnium nitride

    NASA Astrophysics Data System (ADS)

    Shimizu, T.; Villamayor, M.; Lundin, D.; Helmersson, U.

    2016-02-01

    A simple and cost effective approach to stabilize the sputtering process in the transition zone during reactive high-power impulse magnetron sputtering (HiPIMS) is proposed. The method is based on real-time monitoring and control of the discharge current waveforms. To stabilize the process conditions at a given set point, a feedback control system was implemented that automatically regulates the pulse frequency, and thereby the average sputtering power, to maintain a constant maximum discharge current. In the present study, the variation of the pulse current waveforms over a wide range of reactive gas flows and pulse frequencies during a reactive HiPIMS process of Hf-N in an Ar-N2 atmosphere illustrates that the discharge current waveform is a an excellent indicator of the process conditions. Activating the reactive HiPIMS peak current regulation, stable process conditions were maintained when varying the N2 flow from 2.1 to 3.5 sccm by an automatic adjustment of the pulse frequency from 600 Hz to 1150 Hz and consequently an increase of the average power from 110 to 270 W. Hf-N films deposited using peak current regulation exhibited a stable stoichiometry, a nearly constant power-normalized deposition rate, and a polycrystalline cubic phase Hf-N with (1 1 1)-preferred orientation over the entire reactive gas flow range investigated. The physical reasons for the change in the current pulse waveform for different process conditions are discussed in some detail.

  5. Microstructural, optical, and electrical properties of Ni–Al co-doped ZnO films prepared by DC magnetron sputtering

    SciTech Connect

    Jo, Young Dae; Hui, K.N.; Hui, K.S.; Cho, Y.R.; Kim, Kwang Ho

    2014-03-01

    Graphical abstract: - Highlights: • Ni–Al co-doped ZnO (NiAl:ZnO) composite thin films were deposited by DC magnetron sputtering at room temperature. • All films showed a highly preferential (0 0 2) c-axis orientation. • XPS revealed the presence of metallic Ni, NiO, and Ni{sub 2}O{sub 3} states, and Ni atoms were successfully doped in the NiAl:ZnO films. • NiAl:ZnO (3 wt% Ni) film showed the lowest electrical resistivity of 2.59 × 10{sup −3} Ω cm. • Band gap widening (4.18 eV) was observed in the NiAl:ZnO films with 5 wt% Ni. - Abstract: Ni–Al co-doped ZnO (NiAl:ZnO) films with fixed Al content at 2 wt% and different Ni contents (2.5, 3, and 5 wt%) were deposited by DC magnetron sputtering in an argon atmosphere at room temperature. X-ray diffraction revealed that all films showed a highly preferential (0 0 2) c-axis orientation. XPS revealed the presence of metallic Ni, NiO, and Ni{sub 2}O{sub 3} states, and Ni atoms were successfully doped in NiAl:ZnO films, which did not result in a change in ZnO crystal structure and orientation. The electrical resistivity of NiAl:ZnO film was decreased to 2.59 × 10{sup −3} Ω cm at a Ni doping concentration of 3 wt% compared with undoped Al-doped ZnO film (5.58 × 10{sup −3} Ω cm). The mean optical transmittance in the visible range was greater than 80% for all films. Band gap widening (4.18 eV) was observed in the NiAl:ZnO films with 5 wt% Ni, attributed to the Burstein–Moss shift due to the increase of carrier concentration.

  6. Annealing effect on structural, morphological, and optical properties of reactive sputtered WO{sub 3} films for mediated heterogeneous photocatalyst

    SciTech Connect

    Prabakar, K.; Takahashi, T.; Takahashi, K.; Nezuka, T.; Nakashima, T.; Kubota, Y.; Fujishima, A.

    2007-07-15

    The reactive facing-target sputtering method was used to deposit WO{sub 3} thin films from a metal tungsten disk in an Ar+O{sub 2} mixture gas atmosphere at different sputtering pressures. X-ray diffraction, scanning electron microscopy (SEM), UV-visible spectrophotometer, and Raman studies were performed to study structural, surface morphology, and optical properties of the as-deposited and annealed samples. Annealing treatments were done in oxygen atmospheres. All the as-deposited films were amorphous in structure. The films annealed at 400 deg. C and deposited at 200 W show preferential orientation. SEM images show nanorodlike growth for the films deposited at a sputtering pressure of 0.15 Pa and annealed at 400 deg. C. The optical absorption edge of the as-deposited films prepared at the sputtering pressures of 0.8-0.15 Pa varied between 340 and 380 nm and shifted up to 480 nm when the samples were annealed at 400 deg. C. From Raman spectra, we observed the O-W{sup 6+}-O bonds, and the W{sup 6+}=O stretching mode of terminal atoms on the surface of WO{sub 3} microcrystalline grains. The crystal structures of the annealed films were of monoclinic phase. The suitability of the films for the WO{sub 3}/TiO{sub 2} heterogeneous photocatalyst are analyzed and discussed.

  7. Limits of carrier mobility in Sb-doped SnO{sub 2} conducting films deposited by reactive sputtering

    SciTech Connect

    Bissig, B. Jäger, T.; Tiwari, A. N.; Romanyuk, Y. E.; Ding, L.

    2015-06-01

    Electron transport in Sb-doped SnO{sub 2} (ATO) films is studied to unveil the limited carrier mobility observed in sputtered films as compared to other deposition methods. Transparent and conductive ATO layers are deposited from metallic tin targets alloyed with antimony in oxygen atmosphere optimized for reactive sputtering. The carrier mobility decreases from 24 cm{sup 2} V{sup −1} s{sup −1} to 6 cm{sup 2} V{sup −1} s{sup −1} when increasing the doping level from 0 to 7 at. %, and the lowest resistivity of 1.8 × 10{sup −3} Ω cm corresponding to the mobility of 12 cm{sup 2} V{sup −1} s{sup −1} which is obtained for the 3 at. % Sb-doped ATO. Temperature-dependent Hall effect measurements and near-infrared reflectance measurements reveal that the carrier mobility in sputtered ATO is limited by ingrain scattering. In contrast, the mobility of unintentionally doped SnO{sub 2} films is determined mostly by the grain boundary scattering. Both limitations should arise from the sputtering process itself, which suffers from the high-energy-ion bombardment and yields polycrystalline films with small grain size.

  8. Laser-induced fluorescence monitoring of the gas phase in a glow discharge during reactive sputtering of vanadium

    NASA Astrophysics Data System (ADS)

    Khvostikov, V. A.; Grazhulene, S. S.; Burmii, Zh. P.; Marchenko, V. A.

    2011-11-01

    Processes in the gas phase of a glow discharge during diode and magnetron reactive sputtering of vanadium in an Ar-O2 atmosphere have been investigated by laser-induced fluorescence (LIF) as a function of the parameters of the glow discharge and the composition of the atmosphere. The intensity of the fluorescence spectra increased by 1.5-2.0 orders of magnitude in the magnetron sputtering process compared with that of diode sputtering. Under continuous sputtering conditions, the dependences of the intensities and relative compositions of the fluorescence spectra on the discharge parameters (discharge voltage and current) have been investigated. In pulsed mode of the glow discharge, the dynamics of changes in the spectra have been studied versus variations in the discharge duration and the lag time for recording the fluorescence signal. The dependence of the spectral line intensities on the partial pressure of oxygen has been found for vanadium and its oxide. The cathode surface at pressures of 0.03-0.04 Pa was shown to convert to the oxidized state.

  9. Low-temperature growth of gallium nitride films by inductively coupled-plasma-enhanced reactive magnetron sputtering

    SciTech Connect

    Ni, Chih-Jui; Chau-Nan Hong, Franklin

    2014-05-15

    Gallium nitride (GaN) films were grown on sapphire substrate by reactive magnetron sputtering. Inductively coupled-plasma (ICP) source was installed between the substrate holder and the sputtering target to increase the plasma density and the degree of ionization of nitrogen gas. Liquid Ga and Ar/N{sub 2} were used as the sputtering target and sputtering gases, respectively. X-ray diffraction measurements confirmed that the authors could grow high quality GaN crystallites at 500 °C. However, the crystalline GaN (0002) peak remained even by lowering the growth temperature down to 300 °C. The N:Ga ratio of the film grown at 500 °C was almost 1:1, and the nitrogen composition became higher toward the 1:1 N:Ga ratio with increasing the growth temperature. The high degree of ionization induced by ICP source was essential to the growth of high crystalline quality GaN films.

  10. P-type doping of hydrogenated amorphous silicon films with boron by reactive radio-frequency co-sputtering

    NASA Astrophysics Data System (ADS)

    Ohmura, Y.; Takahashi, M.; Suzuki, M.; Sakamoto, N.; Meguro, T.

    2001-12-01

    B has been successfully doped into the hydrogenated amorphous Si films without using explosive and/or toxic gases SiH 4 or B 2H 6 by reactive radio-frequency co-sputtering. The target used for co-sputtering was a composite target composed of a B-doped Si wafer and B chips attached on the Si wafer with silver powder bond. The maximum area fraction of B chips used was 0.11. Argon and hydrogen pressures were 5×10 -3 and 5×10 -4 Torr, respectively. Substrates were kept at 200°C or 250°C during sputtering. The maximum B concentration in the film obtained was 2×10 19 cm -3 from secondary ion mass spectroscopy measurement. Films with resistivity of 10 4-10 5 Ω cm were obtained, which was low for the above acceptor concentration, compared with other group III impurities doping, indicating the high doping efficiency of B. A heterostructure, which was prepared by co-sputtering these B-doped films on an n-type crystalline Si, shows a good rectification characteristic. A small photovoltaic effect is also observed.

  11. Bioactivity response of Ta1-xOx coatings deposited by reactive DC magnetron sputtering.

    PubMed

    Almeida Alves, C F; Cavaleiro, A; Carvalho, S

    2016-01-01

    The use of dental implants is sometimes accompanied by failure due to periimplantitis disease and subsequently poor esthetics when soft-hard tissue margin recedes. As a consequence, further research is needed for developing new bioactive surfaces able to enhance the osseous growth. Tantalum (Ta) is a promising material for dental implants since, comparing with titanium (Ti), it is bioactive and has an interesting chemistry which promotes the osseointegration. Another promising approach for implantology is the development of implants with oxidized surfaces since bone progenitor cells interact with the oxide layer forming a diffusion zone due to its ability to bind with calcium which promotes a stronger bond. In the present report Ta-based coatings were deposited by reactive DC magnetron sputtering onto Ti CP substrates in an Ar+O2 atmosphere. In order to assess the osteoconductive response of the studied materials, contact angle and in vitro tests of the samples immersed in Simulated Body Fluid (SBF) were performed. Structural results showed that oxide phases where achieved with larger amounts of oxygen (70 at.% O). More compact and smooth coatings were deposited by increasing the oxygen content. The as-deposited Ta coating presented the most hydrophobic character (100°); with increasing oxygen amount contact angles progressively diminished, down to the lowest measured value, 63°. The higher wettability is also accompanied by an increase on the surface energy. Bioactivity tests demonstrated that highest O-content coating, in good agreement with wettability and surface energy values, showed an increased affinity for apatite adhesion, with higher Ca/P ratio formation, when compared to the bare Ti substrates. PMID:26478293

  12. Gas barrier properties of titanium oxynitride films deposited on polyethylene terephthalate substrates by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lin, M.-C.; Chang, L.-S.; Lin, H. C.

    2008-03-01

    Titanium oxynitride (TiN xO y) films were deposited on polyethylene terephthalate (PET) substrates by means of a reactive radio frequency (RF) magnetron sputtering system in which the power density and substrate bias were the varied parameters. Experimental results show that the deposited TiN xO y films exhibited an amorphous or a columnar structure with fine crystalline dependent on power density. The deposition rate increases significantly in conjunction as the power density increases from 2 W/cm 2 to 7 W/cm 2. The maximum deposition rate occurs, as the substrate bias is -40 V at a certain power densities chosen in this study. The film's roughness slightly decreases with increasing substrate bias. The TiN xO y films deposited at power densities above 4 W/cm 2 show a steady Ti:N:O ratio of about 1:1:0.8. The water vapor and oxygen transmission rates of the TiN xO y films reach values as low as 0.98 g/m 2-day-atm and 0.60 cm 3/m 2-day-atm which are about 6 and 47 times lower than those of the uncoated PET substrate, respectively. These transmission rates are comparable to those of DLC, carbon-based and Al 2O 3 barrier films. Therefore, TiN xO y films are potential candidates to be used as a gas permeation barrier for PET substrate.

  13. Deposition and properties of yttria-stabilized zirconia thin films using reactive direct current magnetron sputtering

    SciTech Connect

    Thiele, E.S.; Wang, L.S.; Mason, T.O.; Barnett, S.A. . Dept. of Materials Science Northwestern Univ., Evanston, IL . Materials Research Center)

    1991-11-01

    Yttria-stabilized zirconia (YSZ) thin films were deposited by reactive magnetron sputter deposition from a composite Zr--Y target in Ar--O{sub 2} mixtures. Hysteresis was observed as a function of oxygen flow rate {ital f}. For a discharge current of 0.4 A and a total pressure {ital P} of 5 mTorr, for example, the target oxidized at {ital f}{gt}2.3 ml/min, with the reverse transition from an oxidized to a metallic target surface occurring at 1.95 ml/min. The deposition rate was 2.7 {mu}m/h in the metallic mode and 0.1 {mu}m/h in the oxide mode. Fully oxidized (Y{sub 2}O{sub 3}){sub 0.1}(ZrO{sub 2}){sub 0.9} was obtained for {ital f}{gt}2.0 ml/min, even in the metallic mode. While films deposited with {ital P}=3--20 mTorr were continuous, for {ital P}{gt}20 mTorr crazing was apparent as expected for a ceramic film in a tensile stress state. For {ital P}{lt}3 mTorr, the films delaminated due to excessive compressive stress. X-ray diffraction and electron microscopy results showed that the films were polycrystalline cubic YSZ with a columnar structure and an average grain diameter of 15 nm. Fully dense films were obtained at a deposition temperature of 350 {degree}C. Temperature-dependent impedance spectroscopy analysis of YSZ films with Ag electrodes showed that the oxygen ion conductivity was as expected for YSZ.

  14. Studies on optoelectronic properties of DC reactive magnetron sputtered CdTe thin films

    SciTech Connect

    Kumar, B. Rajesh; Hymavathi, B.; Rao, T. Subba

    2014-01-28

    Cadmium telluride continues to be a leading candidate for the development of cost effective photovoltaics for terrestrial applications. In the present work two individual metallic targets of Cd and Te were used for the deposition of CdTe thin films on mica substrates from room temperature to 300 °C by DC reactive magnetron sputtering method. XRD patterns of CdTe thin films deposited on mica substrates exhibit peaks at 2θ = 27.7°, 46.1° and 54.6°, which corresponds to reflection on (1 1 1), (2 2 0) and (3 1 1) planes of CdTe cubic structure. The intensities of XRD patterns increases with the increase of substrate temperature upto 150 °C and then it decreases at higher substrate temperatures. The conductivity of CdTe thin films measured from four probe method increases with the increase of substrate temperature. The activation energies (ΔE) are found to be decrease with the increase of substrate temperature. The optical transmittance spectra of CdTe thin films deposited on mica have a clear interference pattern in the longer wavelength region. The films have good transparency (T > 85 %) exhibiting interference pattern in the spectral region between 1200 – 2500 nm. The optical band gap of CdTe thin films are found to be in the range of 1.48 – 1.57. The refractive index, n decreases with the increase of wavelength, λ. The value of n and k increases with the increase of substrate temperature.

  15. Effect Of Process Gas Mixture On Reactively DC Magnetron Sputtered (Al1_xSix)OyNz Thin Films

    NASA Astrophysics Data System (ADS)

    Bjornard, Erik

    1989-02-01

    (A1 1-x Si x )0yNz films have properties which make them desirable as durable overcoats and corrosion barriers in optical thin film structures. (Al, Si )O N films were reactively DC sputtered from Al, Si targets (x = 0.0, 0.117, 0.30) in Ar/N2/O2 atmospheres. Nitride films had sputter efficiencies three times that of the oxides and ESCA analysis of the films showed that the film composition varied non-linearly with reactive gas ratio and sputter rate, incorporating more oxygen than nitrogen for a given gas flow. This behavior is correlated with the hysteresis curves for the oxide and nitride states. Optical properties of the films were also found to vary with index dropping disproportionately to the 0/(0+N) flow ratio, but linearly with the ratio of atomic percent of 0 and N in the films. Durability properties of (A1 1_x Si x)0 NZ films were tested at several compositions. It was found that with high nitrogen context the wear resistance increased with Si content and the oxides were generally less wear resistant than the nitrides. The corrosion resistance also increased with Si content, but in this case, the oxides were generally more stable. Film stress became more compressive with 0 and Si content. Analysis of ESCA binding energy data indicates that the Si forms alumino-silicate bonds in the film, which apparently contributes to the durability properties.

  16. Influence of in-situ annealing ambient on p-type conduction in dual ion beam sputtered Sb-doped ZnO thin films

    SciTech Connect

    Pandey, Sushil Kumar; Kumar Pandey, Saurabh; Awasthi, Vishnu; Mukherjee, Shaibal; Gupta, M.; Deshpande, U. P.

    2013-08-12

    Sb-doped ZnO (SZO) films were deposited on c-plane sapphire substrates by dual ion beam sputtering deposition system and subsequently annealed in-situ in vacuum and in various proportions of O{sub 2}/(O{sub 2} + N{sub 2})% from 0% (N{sub 2}) to 100% (O{sub 2}). Hall measurements established all SZO films were p-type, as was also confirmed by typical diode-like rectifying current-voltage characteristics from p-ZnO/n-ZnO homojunction. SZO films annealed in O{sub 2} ambient exhibited higher hole concentration as compared with films annealed in vacuum or N{sub 2} ambient. X-ray photoelectron spectroscopic analysis confirmed that Sb{sup 5+} states were more preferable in comparison to Sb{sup 3+} states for acceptor-like Sb{sub Zn}-2V{sub Zn} complex formation in SZO films.

  17. In-situ post-annealing technique for improving piezoelectricity and ferroelectricity of Li-doped ZnO thin films prepared by radio frequency magnetron sputtering system

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Cheng; Chang, Chia-Chiang; Wu, Chin-Jyi; Tseng, Zong-Liang; Tang, Jian-Fu; Chu, Sheng-Yuan; Chen, Yi-Chun; Qi, Xiaoding

    2013-03-01

    Li-doped zinc oxide (L0.03Z0.97O) thin films are deposited onto Pt/Ti/SiO2/Si substrates via the radio frequency magnetron sputtering method. The structure evolution with annealing temperature of the predominantly (002)-oriented Li-doped ZnO (LZO) films after in-situ post-annealing process is determined. The largest values of the piezoelectric coefficient (d33) and the remnant polarization (Pr) (22.85 pm/V and 0.655 μC/cm2, respectively) are obtained for LZO films post-annealed at 600 °C, which can be attributed to the predominant (002)-oriented crystalline structure, the release of intrinsic residual compressive stress, and less non-lattice oxygen.

  18. Optical properties and surface morphology of Li-doped ZnO thin films deposited on different substrates by DC magnetron sputtering method

    NASA Astrophysics Data System (ADS)

    Mohamed, Galal A.; Mohamed, El-Maghraby; Abu El-Fadl, A.

    2001-12-01

    Thin films of zinc oxide doped with Zn 1- xLi xO with x=0.2 (ZnO : Li), have been prepared on sapphire, MgO and quartz substrates by DC magnetron sputtering method at 5 mTorr. The substrate temperatures were fixed to about 573 K. We have measured the transmission and reflection spectra and determined the absorption coefficient, optical band-gap ( Egdopt), the high frequency dielectric constant ε‧ ∞ and the carrier concentration N for the as-prepared films at room temperature. The films show direct allowed optical transitions with Egdopt values of 3.38, 3.43 and 3.29 eV for films deposited on sapphire, MgO and quartz substrates, respectively. The dependence of the obtained results on the substrate type are discussed.

  19. Enhanced electrical and noise properties of nanocomposite vanadium oxide thin films by reactive pulsed-dc magnetron sputtering

    SciTech Connect

    Basantani, H. A.; Kozlowski, S.; Lee, Myung-Yoon; Li, J.; Dickey, E. C.; Jackson, T. N.; Bharadwaja, S. S. N.; Horn, M.

    2012-06-25

    Thin films of VO{sub x} (1.3 {<=} x {<=} 2) were deposited by reactive pulsed-dc magnetron sputtering of a vanadium metal target while RF-biasing the substrate. Rutherford back scattering, glancing angle x-ray, and cross-sectional transmission electron microscopy measurements revealed the formation of nanocolumns with nanotwins within VO{sub x} samples. The resistivity of nanotwinned VO{sub x} films ranged from 4 m{Omega}{center_dot}cm to 0.6 {Omega}{center_dot}cm and corresponding temperature coefficient of resistance between -0.1% and -2.6% per K, respectively. The 1/f electrical noise was analyzed in these VO{sub x} samples using the Hooge-Vandamme relation. These VO{sub x} films are comparable or surpass commercial VO{sub x} films deposited by ion beam sputtering.

  20. Low-temperature-deposited insulating films of silicon nitride by reactive sputtering and plasma-enhanced CVD: Comparison of characteristics

    NASA Astrophysics Data System (ADS)

    Sato, Masaru; Takeyama, Mayumi B.; Nakata, Yoshihiro; Kobayashi, Yasushi; Nakamura, Tomoji; Noya, Atsushi

    2016-04-01

    The characteristics of SiN x films deposited by reactive sputtering and plasma-enhanced chemical vapor deposition (PECVD) are examined to obtain high-density films at low deposition temperatures. PECVD SiN x films deposited at 200 °C show low densities of 2.14-2.20 g/cm3 regardless of their composition, while their refractive index varies depending on their composition. PECVD requires the substrate temperature to obtain high-density films, because a possible cause of low-density films is the amount of Si-H bond, rather than that of N-H bond, in the films originating from hydrogen incorporated by the insufficient decomposition of SiH4 molecules at low temperatures. The sputtered SiN x films with high density are obtained at a temperature lower than 200 °C and considered a promising candidate for insulating films at low process temperatures.

  1. Silicon oxynitride films deposited by reactive high power impulse magnetron sputtering using nitrous oxide as a single-source precursor

    SciTech Connect

    Hänninen, Tuomas Schmidt, Susann; Jensen, Jens; Hultman, Lars; Högberg, Hans

    2015-09-15

    Silicon oxynitride thin films were synthesized by reactive high power impulse magnetron sputtering of silicon in argon/nitrous oxide plasmas. Nitrous oxide was employed as a single-source precursor supplying oxygen and nitrogen for the film growth. The films were characterized by elastic recoil detection analysis, x-ray photoelectron spectroscopy, x-ray diffraction, x-ray reflectivity, scanning electron microscopy, and spectroscopic ellipsometry. Results show that the films are silicon rich, amorphous, and exhibit a random chemical bonding structure. The optical properties with the refractive index and the extinction coefficient correlate with the film elemental composition, showing decreasing values with increasing film oxygen and nitrogen content. The total percentage of oxygen and nitrogen in the films is controlled by adjusting the gas flow ratio in the deposition processes. Furthermore, it is shown that the film oxygen-to-nitrogen ratio can be tailored by the high power impulse magnetron sputtering-specific parameters pulse frequency and energy per pulse.

  2. Enhanced electrical and noise properties of nanocomposite vanadium oxide thin films by reactive pulsed-dc magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Basantani, H. A.; Kozlowski, S.; Lee, Myung-Yoon; Li, J.; Dickey, E. C.; Jackson, T. N.; Bharadwaja, S. S. N.; Horn, M.

    2012-06-01

    Thin films of VOx (1.3 ≤ x ≤ 2) were deposited by reactive pulsed-dc magnetron sputtering of a vanadium metal target while RF-biasing the substrate. Rutherford back scattering, glancing angle x-ray, and cross-sectional transmission electron microscopy measurements revealed the formation of nanocolumns with nanotwins within VOx samples. The resistivity of nanotwinned VOx films ranged from 4 mΩ.cm to 0.6 Ω.cm and corresponding temperature coefficient of resistance between -0.1% and -2.6% per K, respectively. The 1/f electrical noise was analyzed in these VOx samples using the Hooge-Vandamme relation. These VOx films are comparable or surpass commercial VOx films deposited by ion beam sputtering.

  3. Vapor-liquid-solid growth of GaN nanowires by reactive sputtering of GaAs

    NASA Astrophysics Data System (ADS)

    Mohanta, P.; Chaturvedi, P.; Major, S. S.; Srinivasa, R. S.

    2013-02-01

    Uniformly distributed nanosized Au-Ga alloy particles were formed on ultrathin Au coated quartz substrate by sputtering of GaAs with argon at 700 °C. Subsequent deposition of GaN by reactive sputtering of GaAs in 100 % nitrogen results in the growth of GaN nanowires. X-ray diffraction analysis confirmed the formation of hexagonal GaN. Field emission gun scanning electron microscopy studies show that the nanowires are of average length 400±50 nm and average diameter 40±5 nm. The presence of spherical Au-Ga nanoparticles of diameter ˜ 50 nm at the top of the nanowires suggests that the growth takes place by vapor-liquid-solid mechanism.

  4. Measurements of sputtered neutrals and ions and investigation of their roles on the plasma properties during rf magnetron sputtering of Zn and ZnO targets

    SciTech Connect

    Maaloul, L.; Stafford, L.

    2013-11-15

    Langmuir probe and optical absorption spectroscopy measurements were used to determine the line-integrated electron density, electron temperature, and number density of Ar atoms in metastable {sup 3}P{sub 2} and {sup 3}P{sub 0} levels in a 5 mTorr, rf magnetron sputtering plasmas used for the deposition of ZnO-based thin films. While the average electron energy and density of Ar atoms in {sup 3}P{sub 2} and {sup 3}P{sub 0} excited states were fairly independent of self-bias voltage, the Ar {sup 3}P{sub 2}-to-electron number density ratio decreased by approximately a factor of 5 when going from −115 V to −300 V. This decrease was correlated to an increase by about one order of magnitude of the number density of sputtered Zn atoms determined by absolute actinometry measurements on Zn I using either Ar or Xe as the actinometer gas. These results were also found to be in excellent agreement with the predictions of a global model accounting for Penning ionization of sputtered Zn particles. The importance of the latter reactions was further confirmed by plasma sampling mass spectrometry showing a double peak structure for Zn ions: a low-energy component ascribed to thermalized ions created in the gas phase (by direct electron impact and by Penning ionization) and a high-energy tail due to ions ejected from the target and reaching quasi-collisionlessly the substrate surface.

  5. Silver Nanowires Binding with Sputtered ZnO to Fabricate Highly Conductive and Thermally Stable Transparent Electrode for Solar Cell Applications.

    PubMed

    Singh, Manjeet; Rana, Tanka R; Kim, SeongYeon; Kim, Kihwan; Yun, Jae Ho; Kim, JunHo

    2016-05-25

    Silver nanowire (AgNW) film has been demonstrated as excellent and low cost transparent electrode in organic solar cells as an alternative to replace scarce and expensive indium tin oxide (ITO). However, the low contact area and weak adhesion with low-lying surface as well as junction resistance between nanowires have limited the applications of AgNW film to thin film solar cells. To resolve this problem, we fabricated AgNW film as transparent conductive electrode (TCE) by binding with a thin layer of sputtered ZnO (40 nm) which not only increased contact area with low-lying surface in thin film solar cell but also improved conductivity by connecting AgNWs at the junction. The TCE thus fabricated exhibited transparency and sheet resistance of 92% and 20Ω/□, respectively. Conductive atomic force microscopy (C-AFM) study revealed the enhancement of current collection vertically and laterally through AgNWs after coating with ZnO thin film. The CuInGaSe2 solar cell with TCE of our AgNW(ZnO) demonstrated the maximum power conversion efficiency of 13.5% with improved parameters in comparison to solar cell fabricated with conventional ITO as TCE. PMID:27149372

  6. Structural, electrical and optical properties of Al-Ti codoped ZnO (ZATO) thin films prepared by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Jiang, Minhong; Liu, Xinyu

    2008-12-01

    Al-Ti codoped ZnO (ZATO) thin films were grown on glass substrates at room temperature by radio frequency (RF) magnetron sputtering technique and annealed under vacuum (˜10 -1 Pa) at 400 °C for 3 h. The X-ray diffraction (XRD) patterns show that Al-doped ZnO (ZAO) and ZATO thin films are highly textured along the c-axis and perpendicular to the surface of the substrate. After annealing in a vacuum condition at 400 °C for 3 h, the lowest resistivity of 7.96 and 8.7 × 10 -4 Ω cm are observed for ZATO and ZAO films, respectively. But after annealing in air, the resistivity of ZATO and ZAO is higher than 10 5 Ω cm. In the visible region, the ZAO films show the average transmittance of the order of 90%, while ZATO films were of the order of 75%, which illustrates that the additional Ti doping reduces the optical properties. The optical band gap was found to be 3.46 eV for ZAO film and it increases to 3.53 eV for ZATO films.

  7. In situ plasma sputtering synthesis of ZnO nanorods-Ag nanoparticles hybrids and their application in non-enzymatic hydrogen peroxide sensing.

    PubMed

    Zhang, Dan; Zhang, Yuxia; Yang, Chi; Ge, Cunwang; Wang, Yuanhong; Wang, Hao; Liu, Hongying

    2015-08-21

    In this paper, ZnO nanorods-Ag nanoparticles hybrids were first synthesized via a facile, rapid, and in situ plasma sputtering method without using any silver precursor. The obtained materials were then characterized by scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, and cyclic voltammetry. Based on the electrochemical catalytic properties of the obtained nanohybrids, a non-enzymatic hydrogen peroxide biosensor was constructed by immobilizing the obtained ZnO nanorods-Ag nanoparticles hybrids on the surface of a glassy carbon electrode. Under optimal conditions, the resulting biosensor displayed a good response for H2O2 with a linear range of 0.2 to 12.8 mM, and a detection limit of 7.8 μM at a signal-to-noise ratio of 3. In addition, it exhibited excellent anti-interference ability and fast response. The current work provides a feasible platform to fabricate a variety of non-enzymatic biosensors. PMID:26225726

  8. In situ plasma sputtering synthesis of ZnO nanorods-Ag nanoparticles hybrids and their application in non-enzymatic hydrogen peroxide sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Dan; Zhang, Yuxia; Yang, Chi; Ge, Cunwang; Wang, Yuanhong; Wang, Hao; Liu, Hongying

    2015-08-01

    In this paper, ZnO nanorods-Ag nanoparticles hybrids were first synthesized via a facile, rapid, and in situ plasma sputtering method without using any silver precursor. The obtained materials were then characterized by scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, and cyclic voltammetry. Based on the electrochemical catalytic properties of the obtained nanohybrids, a non-enzymatic hydrogen peroxide biosensor was constructed by immobilizing the obtained ZnO nanorods-Ag nanoparticles hybrids on the surface of a glassy carbon electrode. Under optimal conditions, the resulting biosensor displayed a good response for H2O2 with a linear range of 0.2 to 12.8 mM, and a detection limit of 7.8 μM at a signal-to-noise ratio of 3. In addition, it exhibited excellent anti-interference ability and fast response. The current work provides a feasible platform to fabricate a variety of non-enzymatic biosensors.

  9. Effect of Sn Doping on the Properties of Nano-Structured ZnO Thin Films Deposited by Co-Sputtering Technique.

    PubMed

    Islam, M A; Rahman, K S; Haque, F; Khan, N A; Akhtaruzzaman, M; Alam, M M; Ruslan, H; Sopian, K; Amin, N

    2015-11-01

    In this study, tin doped zinc oxide (ZnO:Sn) nano-structured thin films were successfully deposited by co-sputtering of ZnO and Sn on top of glass substrate. The effect of Sn doping on the microstructure, phase, morphology, optical and electrical properties of the films were extensively investigated by means of XRD, EDX, SEM, AFM, Hall Effect measurement, and UV-Vis spectrometry. The results showed that the undoped ZnO film exhibited preferred orientation along the c-axis of the hexagonal wurtzite structure. With increase of Sn doping, the peak position of the (002) plane was shifted to the higher 20 values, and ultimately changed to amorphous structure. The absorption edge was shifted to blue region which confirmed the excitonic quantum confinement effect in the films. Consequently, improved surface morphology with optical bandgap, reduced average particle size, reduced resistivity, enhanced Hall mobility and carrier concentration were observed in the doped films after vacuum annealing. Among all of the as-deposited and annealed ZnO:Sn films investigated in this study, annealed film doped with 8 at.% of Sn concentration exhibited the best properties with a bandgap of 3.84 eV, RMS roughness of 2.51 nm, resistivity of 2.36 ohm-cm, and Hall mobility of 83 cm2 V(-1) s(-1). PMID:26726665

  10. Control Capabilities of Reactive Sputter Deposition Process via ICPs Driven by Low-Inductance Antenna for Large-Area Formation of Thin Film Devices

    NASA Astrophysics Data System (ADS)

    Setsuhara, Yuichi; Takenaka, Kosuke; Ebe, Akinori

    2012-10-01

    Novel plasma-enhanced reactive sputter-deposition system has been developed with a new type of low-inductance antenna (inner-type LIA) consisting of an RF antenna conductor with a length much shorter than the RF wavelength, which is embedded in a hall region dug in the chamber wall and the dielectric window plate for insulation. This new type of the reactive sputter-deposition system has been developed for enhancement of sputter discharge and excellent control of reactivity during film growth. The ICP-enhanced sputter system has been applied to film formations of micro-crystalline silicon (intrinsic layer) and transparent amorphous oxide semiconductor, a-InGaZnO4 (a-IGZO), aiming at low-temperature formation of high-quality functional films for development of next-generation flexible devices. The newly developed process can offer independent control of the flux ratio of the reactive species (ions and radicals) to the deposited species sputtered out of the target. With this new method, micro-crystalline silicon films with crystallinity of 74% and a-IGZO films with mobility as high as 18 cm^2(Vs)-1 have been successfully formed without substrate heating. Furthermore, for development of large-area deposition, uniformity control capabilities with a linear rectangular sputter target with 500 mm length have been examined via variation of power deposition profiles with multiple LIAs.

  11. Formation of ST12 phase Ge nanoparticles in ZnO thin films

    NASA Astrophysics Data System (ADS)

    Ceylan, Abdullah; Gumrukcu, Emre; Ozcan, Sadan

    2015-03-01

    In this work, we investigate the effects of reactive and nonreactive growth of ZnO on the rapid thermal annealing (RTA) induced formation of Ge nanoparticles (Ge-np) in ZnO: Ge nanocomposite thin films. The samples were deposited by sequential sputtering of ZnO and Ge thin film layers with a total thickness of about 600 nm on Si substrates followed by an ex-situ (RTA) at 600°C for 30, 60, 90, 120, 150, 180, and 210 s under forming gas atmosphere. In order for the reactive sputtering of ZnO layer, 5 mTorr Oxygen was introduced to the growth chamber. XRD and Raman analyses were utilized to investigate the effect of RTA time on the structural evolution of the samples. It has been realized that crystal structure of Ge nanoparticles is significantly affected by the growth method of the embedding ZnO layer. While reactive deposition of ZnO layers results in a mixture of diamond cubic (DC) and simple tetragonal (ST12) Ge-np, nonreactive deposition of ZnO layers leads to the formation of pure DC Ge-np upon RTA process. Formation of these two phases has been discussed based on the existence of native point defects such as oxygen vacancies and Zn interstitials.

  12. Reactive ion etching of sputtered silicon carbide and tungsten thin films for device applications

    SciTech Connect

    Pan, W.S.

    1988-01-01

    For high temperature processing and device applications refractory materials, silicon carbide (SiC) and tungsten (W), are considered or evaluated as the basic semiconductor and metallization materials for integrated circuits. In order to pattern fine lines in SiC and W thin films, a selective and anisotropic etching technique is needed. First, materials properties, such as crystallinity, conductivity, refractive index, optical bandgap, etc., of sputtered silicon carbide (SiC) and tungsten (W) thin films have been investigated in conjunction with the rapid thermal annealing (RTA) technique. The RTA temperature dependence of the optical bandgap of SiC thin films has been obtained. High crystallinity W thin of low resistivity films were obtained using by RTA. Reactive ion etching (RIE) of SiC thin films in a variety of fluorinated gas plasmas, such as SF{sub 6}, CBrF{sub 3} and CHF{sub 3} mixed with oxygen has been investigated in depth. The emission spectra and induced DC bias of the RF plasma were monitored to explore the etching mechanisms. A SiC:Si etch ratio higher than unity was obtained for the first time by using CBrF{sub 3}/75%O{sub 2} and CHF{sub 3}/90%O{sub 2} at 200W, 20 sccm, 20mTorr plasma conditions. The best anisotropic profile was observed by using CHF{sub 3} gas in the RIE mode. A typical DC bias, -300V, is concluded from etching experiments to determine the dependence of SiC etch rate and physical reaction under RIE mode. RIE of tungsten (W) thin film was investigated by using the different fluorinated gas plasmas, such as CF{sub 4}, SF{sub 6}, CBrF{sub 3} and CHF{sub 3} mixed with oxygen. We have achieved our goal of selective patterning of tungsten films over SiC, Si, SiO{sub 2}, which required in order to use W in SiC device applications. A very good W:Si and W:SiO{sub 2} selective ratio, 4:1 and 4.8:1, were observed by using CHF{sub 3}/70%O{sub 2} gases under different Plasma conditions.

  13. Corrosion and wear behaviours of a reactive-sputter-deposited Ta2O5 nanoceramic coating

    NASA Astrophysics Data System (ADS)

    Hu, Wei; Xu, Jiang; Lu, Xiaolin; Hu, Dongsheng; Tao, Hongliang; Munroe, Paul; Xie, Zong-Han

    2016-04-01

    In order to improve the wear and corrosion resistance of Ti-6Al-4V, a novel β-Ta2O5 nanoceramic coating was synthesised using reactive sputter deposition enabled by double glow discharge plasma technique. The surface topography, chemical composition, and microstructure of the newly developed coating were characterised by a variety of surface analytical techniques. The coating microstructure was found to exhibit a compact striated pattern extending in a direction perpendicular to coating surface, which is composed of equiaxed β-Ta2O5 grains with an average grain size of ∼20 nm, well adhered to the Ti-6A1-4V substrate. The hardness and the Young's modulus of the as-deposited coating were obtained by nanoindentation, and the adhesion strength between the coating and substrate was determined by a scratch tester. The dry sliding wear behaviours of the coating were investigated at room temperature against Si3N4 ceramic balls at room temperature under applied loads ranging from 2.3 N to 5.3 N using a ball-on-disc tribometer. The specific wear rates of the coating exhibited only a slight increase with applied normal load, and were shown to be two orders of magnitude lower than that for Ti-6Al-4V under the same loading condition. Furthermore, the electrochemical behaviour of the coating immersed in 3.5 wt.% NaCl solution was systematically examined by using a range of complementary electrochemical techniques including potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis as well as potential of zero charge (PZC). The results showed that the corrosion resistance of the β-Ta2O5 nanoceramic coating was better than that of Ti-6Al-4V alloy in 3.5 wt.% NaCl solution. Hence, by possessing higher mechanical properties and good wear and corrosion resistance, the β-Ta2O5 nanoceramic coating is considered to be a promising candidate for protection of engineering components operating under harsh conditions.

  14. Microstructure and tribological properties of NbN-Ag composite films by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ju, Hongbo; Xu, Junhua

    2015-11-01

    Recently, the chameleon thin films were developed with the purpose of adjusting their chemistry at self-mating interfaces in response to environmental changes at a wide temperature range. However, very few studies have focused on what state the lubricious noble metal exists in the films and the tribological properties at room temperature (RT). Composite NbN-Ag films with various Ag content (Ag/(Nb + Ag)) were deposited using reactive magnetron sputtering to investigate the crystal structure, mechanical and tribological properties. A combination of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM) analyses showed that face-centered cubic (fcc) NbN, hexagonal close-packed (hcp) NbN and fcc silver coexisted in NbN-Ag films. The incorporation of soft Ag into NbN matrix led to the hardness decrease from 29.6 GPa at 0 at.% Ag to 11.3 GPa at 19.9 at.% Ag. Tribological properties of NbN-Ag films performed using dry pin-on-disc wear tests against Al2O3 depended on Ag content to a large extent. The average friction coefficient and wear rate of NbN-Ag films decreased as Ag content increased from 4.0 to 9.2 at.%. With a further increase of Ag content, the average friction coefficient further decreased, while the wear rate increased gradually. The optimal Ag content was found to be 9.2-13.5 at.%, which showed low average friction coefficient values of 0.46-0.40 and wear rate values of 1.1 × 10-8 to 1.7 × 10-8 mm3/(mm N). 3D Profiler and Raman spectroscopy measurements revealed that the lubricant tribo-film AgNbO3 detected on the surface of the wear tracks could lead to the friction coefficient curve stay constant and decrease the average friction coefficients. The decrease of wear rate was mainly attributed to the lubricant tribo-film AgNbO3 as Ag content increased from 4.0 to 9.2 at.%; with a further increase in Ag content, the wear rate increased with increasing Ag content in NbN-Ag films because a

  15. Electrical and optical properties of Ta-Si-N thin films deposited by reactive magnetron sputtering

    SciTech Connect

    Oezer, D.; Sanjines, R.; Ramirez, G.; Rodil, S. E.

    2012-12-01

    The electrical and optical properties of Ta{sub x}Si{sub y}N{sub z} thin films deposited by reactive magnetron sputtering from individual Ta and Si targets were studied in order to investigate the effects of nitrogen and silicon contents on both properties and their correlation to the film microstructure. Three sets of fcc-Ta{sub x}Si{sub y}N{sub z} thin films were prepared: sub-stoichiometric Ta{sub x}Si{sub y}N{sub 0.44}, nearly stoichiometric Ta{sub x}Si{sub y}N{sub 0.5}, and over-stoichiometric Ta{sub x}Si{sub y}N{sub 0.56}. The optical properties were investigated by near-normal-incidence reflectivity and ellipsometric measurements in the optical energy range from 0.375 eV to 6.8 eV, while the d.c. electrical resistivity was measured in the van der Pauw configuration from 20 K to 300 K. The optical and electrical measurements were interpreted using the standard Drude-Lorentz model and the so-called grain boundary scattering model, respectively. The electronic properties were closely correlated with the compositional and structural modifications of the Ta{sub x}Si{sub y}N{sub z} films due to variations in the stoichiometry of the fcc-TaN{sub z} system and the addition of Si atoms. According to the nitrogen and silicon contents, fcc-Ta{sub x}Si{sub y}N{sub z} films can exhibit room temperature resistivity values ranging from 10{sup 2} {mu}{Omega} cm to about 6 Multiplication-Sign 10{sup 4} {mu}{Omega} cm. The interpretation of the experimental temperature-dependent resistivity data within the Grain Boundary Scattering model, combined with the results from optical investigations, showed that the mean electron transmission probability G and the free carriers concentration, N, are the main parameters that control the transport properties of these films. The results indicated that the correlation between electrical and optical measurements with the chemical composition and the nanostructure of the Ta{sub x}Si{sub y}N{sub z} thin films provides a pertinent and

  16. Pulsed DC reactively sputtered tantalum oxide thin films for embedded capacitors

    NASA Astrophysics Data System (ADS)

    Jain, Pushkar

    Embedded capacitor technology, where thin film capacitors are integrated at on-chip and/or off-chip levels, offers high packaging densities and improved electrical performance at potentially reduced costs of capacitor fabrication and integration. This research explores and establishes the leverages of using thin film embedded capacitors over currently used surface mount discrete capacitors. In particular, this thesis focuses on developing pulsed dc reactively sputtered tantalum oxide (Ta2O5) thin film capacitors to be integrated into established interconnect technologies of IC chips and packages. A correlation between electrical breakdown field and dielectric constant, EBR (MV/cm) = (20/ 3r ) is empirically determined and used to establish a design space for breakdown voltage and capacitance density of planar capacitors, with film thickness and material dielectric constant as parameters. This design space sets the limits for "best one can achieve" (BOCA) breakdown voltages and capacitance densities using a particular dielectric. The validity of the developed design space is experimentally verified with Ta2O 5 thin films over a wide range of film thickness (0.05 to 5.4 mum). High frequency test vehicles were designed and fabricated to evaluate the electrical performance of Ta2O5, SiO 2, and Si3N4 thin film capacitors over a wide range of frequencies (dc to 20 GHz). Ta2O5, SiO 2, and Si3N4 show no dispersion at least up to 20 GHz. The total inductance of power connect vias is determined to be less than 50 pH/mum of via, which is at least two orders of magnitude lower than most discrete capacitors along with connection leads (>4 nH). The extent of Cu diffusion/drift into Ta2O5 films is determined and compared with Al, Ta, and Ti at various biasing and temperature conditions using bias-temperature-stress (BTS) and triangular voltage sweep (TVS) techniques. No Cu diffusion was detected at 150°C at least till 0.75 MV/cm. (Abstract shortened by UMI.)

  17. Physical properties of epitaxial ZrN/MgO(001) layers grown by reactive magnetron sputtering

    SciTech Connect

    Mei, A. B.; Zhang, C.; Sardela, M.; Eckstein, J. N.; Rockett, A.; Howe, B. M.; Hultman, L.; Petrov, I.; Greene, J. E.

    2013-11-15

    Single-crystal ZrN films, 830 nm thick, are grown on MgO(001) at 450 °C by magnetically unbalanced reactive magnetron sputtering. The combination of high-resolution x-ray diffraction reciprocal lattice maps, high-resolution cross-sectional transmission electron microscopy, and selected-area electron diffraction shows that ZrN grows epitaxially on MgO(001) with a cube-on-cube orientational relationship, (001){sub ZrN}‖(001){sub MgO} and [100]{sub ZrN}‖[100]{sub MgO}. The layers are essentially fully relaxed with a lattice parameter of 0.4575 nm, in good agreement with reported results for bulk ZrN crystals. X-ray reflectivity results reveal that the films are completely dense with smooth surfaces (roughness = 1.3 nm, consistent with atomic-force microscopy analyses). Based on temperature-dependent electronic transport measurements, epitaxial ZrN/MgO(001) layers have a room-temperature resistivity ρ{sub 300K} of 12.0 μΩ-cm, a temperature coefficient of resistivity between 100 and 300 K of 5.6 × 10{sup −8}Ω-cm K{sup −1}, a residual resistivity ρ{sub o} below 30 K of 0.78 μΩ-cm (corresponding to a residual resistivity ratio ρ{sub 300Κ}/ρ{sub 15K} = 15), and the layers exhibit a superconducting transition temperature of 10.4 K. The relatively high residual resistivity ratio, combined with long in-plane and out-of-plane x-ray coherence lengths, ξ{sub ‖} = 18 nm and ξ{sub ⊥} = 161 nm, indicates high crystalline quality with low mosaicity. The reflectance of ZrN(001), as determined by variable-angle spectroscopic ellipsometry, decreases slowly from 95% at 1 eV to 90% at 2 eV with a reflectance edge at 3.04 eV. Interband transitions dominate the dielectric response above 2 eV. The ZrN(001) nanoindentation hardness and modulus are 22.7 ± 1.7 and 450 ± 25 GPa.

  18. Electrical and optical properties of Ta-Si-N thin films deposited by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Oezer, D.; Ramírez, G.; Rodil, S. E.; Sanjinés, R.

    2012-12-01

    The electrical and optical properties of TaxSiyNz thin films deposited by reactive magnetron sputtering from individual Ta and Si targets were studied in order to investigate the effects of nitrogen and silicon contents on both properties and their correlation to the film microstructure. Three sets of fcc-TaxSiyNz thin films were prepared: sub-stoichiometric TaxSiyN0.44, nearly stoichiometric TaxSiyN0.5, and over-stoichiometric TaxSiyN0.56. The optical properties were investigated by near-normal-incidence reflectivity and ellipsometric measurements in the optical energy range from 0.375 eV to 6.8 eV, while the d.c. electrical resistivity was measured in the van der Pauw configuration from 20 K to 300 K. The optical and electrical measurements were interpreted using the standard Drude-Lorentz model and the so-called grain boundary scattering model, respectively. The electronic properties were closely correlated with the compositional and structural modifications of the TaxSiyNz films due to variations in the stoichiometry of the fcc-TaNz system and the addition of Si atoms. According to the nitrogen and silicon contents, fcc-TaxSiyNz films can exhibit room temperature resistivity values ranging from 102 μΩ cm to about 6 × 104 μΩ cm. The interpretation of the experimental temperature-dependent resistivity data within the Grain Boundary Scattering model, combined with the results from optical investigations, showed that the mean electron transmission probability G and the free carriers concentration, N, are the main parameters that control the transport properties of these films. The results indicated that the correlation between electrical and optical measurements with the chemical composition and the nanostructure of the TaxSiyNz thin films provides a pertinent and consistent description of the evolution of the Ta-Si-N system from a solid solution to a nanocomposite material due to the addition of Si atoms.

  19. Thermal conductivity of nitride films of Ti, Cr, and W deposited by reactive magnetron sputtering

    SciTech Connect

    Jagannadham, Kasichainula

    2015-05-15

    Nitride films of Ti, Cr, and W were deposited using reactive magnetron sputtering from metal targets in argon and nitrogen plasma. TiN films with (200) orientation were achieved on silicon (100) at the substrate temperature of 500 and 600 °C. The films were polycrystalline at lower temperature. An amorphous interface layer was observed between the TiN film and Si wafer deposited at 600 °C. TiN film deposited at 600 °C showed the nitrogen to Ti ratio to be near unity, but films deposited at lower temperature were nitrogen deficient. CrN film with (200) orientation and good stoichiometry was achieved at 600 °C on Si(111) wafer but the film deposited at 500 °C showed cubic CrN and hexagonal Cr{sub 2}N phases with smaller grain size and amorphous back ground in the x-ray diffraction pattern. An amorphous interface layer was not observed in the cubic CrN film on Si(111) deposited at 600 °C. Nitride film of tungsten deposited at 600 °C on Si(100) wafer was nitrogen deficient, contained both cubic W{sub 2}N and hexagonal WN phases with smaller grain size. Nitride films of tungsten deposited at 500 °C were nonstoichiometric and contained cubic W{sub 2}N and unreacted W phases. There was no amorphous phase formed along the interface for the tungsten nitride film deposited at 600 °C on the Si wafer. Thermal conductivity and interface thermal conductance of all the nitride films of Ti, Cr, and W were determined by transient thermoreflectance technique. The thermal conductivity of the films as function of deposition temperature, microstructure, nitrogen stoichiometry and amorphous interaction layer at the interface was determined. Tungsten nitride film containing both cubic and hexagonal phases was found to exhibit much higher thermal conductivity and interface thermal conductance. The amorphous interface layer was found to reduce effective thermal conductivity of TiN and CrN films.

  20. Modification of the optical and structural properties of ZnO nanowires by low-energy Ar+ ion sputtering

    PubMed Central

    2013-01-01

    The effects of low-energy (≤2 kV) Ar+ irradiation on the optical and structural properties of zinc oxide (ZnO) nanowires (NWs) grown by a simple and cost-effective low-temperature technique were investigated. Both photoluminescence spectra from ZnO NW-coated films and cathodoluminescence analysis of individual ZnO NWs demonstrated obvious evidences of ultraviolet/visible luminescent enhancement with respect to irradiation fluence. Annihilation of the thinner ZnO NWs after the ion bombardment was appreciated by means of high-resolution scanning electron microscopy and transmission electron microscopy (TEM), which results in an increasing NW mean diameter for increasing irradiation fluences. Corresponding structural analysis by TEM pointed out not only significant changes in the morphology but also in the microstructure of these NWs, revealing certain radiation-sensitive behavior. The possible mechanisms accounting for the decrease of the deep-level emissions in the NWs with the increasing irradiation fluences are discussed according to their structural modifications. PMID:23570658

  1. Ion-enhanced oxidation of aluminum as a fundamental surface process during target poisoning in reactive magnetron sputtering

    SciTech Connect

    Kuschel, Thomas; Keudell, Achim von

    2010-05-15

    Plasma deposition of aluminum oxide by reactive magnetron sputtering (RMS) using an aluminum target and argon and oxygen as working gases is an important technological process. The undesired oxidation of the target itself, however, causes the so-called target poisoning, which leads to strong hysteresis effects during RMS operation. The oxidation occurs by chemisorption of oxygen atoms and molecules with a simultaneous ion bombardment being present. This heterogenous surface reaction is studied in a quantified particle beam experiment employing beams of oxygen molecules and argon ions impinging onto an aluminum-coated quartz microbalance. The oxidation and/or sputtering rates are measured with this microbalance and the resulting oxide layers are analyzed by x-ray photoelectron spectroscopy. The sticking coefficient of oxygen molecules is determined to 0.015 in the zero coverage limit. The sputtering yields of pure aluminum by argon ions are determined to 0.4, 0.62, and 0.8 at 200, 300, and 400 eV. The variation in the effective sticking coefficient and sputtering yield during the combined impact of argon ions and oxygen molecules is modeled with a set of rate equations. A good agreement is achieved if one postulates an ion-induced surface activation process, which facilitates oxygen chemisorption. This process may be identified with knock-on implantation of surface-bonded oxygen, with an electric-field-driven in-diffusion of oxygen or with an ion-enhanced surface activation process. Based on these fundamental processes, a robust set of balance equations is proposed to describe target poisoning effects in RMS.

  2. Observation of a periodic runaway in the reactive Ar/O{sub 2} high power impulse magnetron sputtering discharge

    SciTech Connect

    Shayestehaminzadeh, Seyedmohammad E-mail: shayesteh@mch.rwth-aachen.de; Arnalds, Unnar B.; Magnusson, Rögnvaldur L.; Olafsson, Sveinn

    2015-11-15

    This paper reports the observation of a periodic runaway of plasma to a higher density for the reactive discharge of the target material (Ti) with moderate sputter yield. Variable emission of secondary electrons, for the alternating transition of the target from metal mode to oxide mode, is understood to be the main reason for the runaway occurring periodically. Increasing the pulsing frequency can bring the target back to a metal (or suboxide) mode, and eliminate the periodic transition of the target. Therefore, a pulsing frequency interval is defined for the reactive Ar/O{sub 2} discharge in order to sustain the plasma in a runaway-free mode without exceeding the maximum power that the magnetron can tolerate.

  3. Conversion efficiency improvement of inverted CH{sub 3}NH{sub 3}PbI{sub 3} perovskite solar cells with room temperature sputtered ZnO by adding the C{sub 60} interlayer

    SciTech Connect

    Lai, Wei-Chih Chen, Peter; Lin, Kun-Wei; Wang, Yuan-Ting; Guo, Tzung-Fang

    2015-12-21

    We have demonstrated the performance of inverted CH{sub 3}NH{sub 3}PbI{sub 3} perovskite-based solar cells (SCs) with a room temperature (RT) sputtered ZnO electron transport layer by adding fullerene (C{sub 60}) interlayer. ZnO exhibits a better matched conduction band level with perovskite and Al work function and around energy offset of 2.2 eV between highest occupied molecular orbital level of CH{sub 3}NH{sub 3}PbI{sub 3} perovskite and valance band level of ZnO. However, the CH{sub 3}NH{sub 3}PbI{sub 3} perovskite layer will be damaged during direct RT sputtering deposition of ZnO. Therefore, the C{sub 60} interlayer having matched conduction band level with ZnO and CH{sub 3}NH{sub 3}PbI{sub 3} perovskite added between the CH{sub 3}NH{sub 3}PbI{sub 3} perovskite and RT sputtered ZnO layers for protection prevents sputtering damages on the CH{sub 3}NH{sub 3}PbI{sub 3} perovskite layer. The short-circuit current density (J{sub SC}, 19.41 mA/cm{sup 2}) and open circuit voltage (V{sub OC}, 0.91 V) of the SCs with glass/ITO/poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS)/perovskite/C{sub 60}/RT sputtered ZnO/Al structure is higher than the J{sub SC} (16.23 mA/cm{sup 2}) and V{sub OC} (0.90 V) of the reference SC with glass/ITO/PEDOT:PSS/perovskite/C{sub 60}/bathocuproine (BCP)/Al structure. Although the SCs with the former structure has a lower fill factor (FF%) than the SCs with the latter structure, its conversion efficiency η% (10.93%) is higher than that (10.6%) of the latter.

  4. Influence of inert gases on the reactive high power pulsed magnetron sputtering process of carbon-nitride thin films

    SciTech Connect

    Schmidt, Susann; Czigany, Zsolt; Greczynski, Grzegorz; Jensen, Jens; Hultman, Lars

    2013-01-15

    The influence of inert gases (Ne, Ar, Kr) on the sputter process of carbon and carbon-nitride (CN{sub x}) thin films was studied using reactive high power pulsed magnetron sputtering (HiPIMS). Thin solid films were synthesized in an industrial deposition chamber from a graphite target. The peak target current during HiPIMS processing was found to decrease with increasing inert gas mass. Time averaged and time resolved ion mass spectroscopy showed that the addition of nitrogen, as reactive gas, resulted in less energetic ion species for processes employing Ne, whereas the opposite was noticed when Ar or Kr were employed as inert gas. Processes in nonreactive ambient showed generally lower total ion fluxes for the three different inert gases. As soon as N{sub 2} was introduced into the process, the deposition rates for Ne and Ar-containing processes increased significantly. The reactive Kr-process, in contrast, showed slightly lower deposition rates than the nonreactive. The resulting thin films were characterized regarding their bonding and microstructure by x-ray photoelectron spectroscopy and transmission electron microscopy. Reactively deposited CN{sub x} thin films in Ar and Kr ambient exhibited an ordering toward a fullerene-like structure, whereas carbon and CN{sub x} films deposited in Ne atmosphere were found to be amorphous. This is attributed to an elevated amount of highly energetic particles observed during ion mass spectrometry and indicated by high peak target currents in Ne-containing processes. These results are discussed with respect to the current understanding of the structural evolution of a-C and CN{sub x} thin films.

  5. Photocatalytic Properties of TiO2 Films Deposited by Reactive Sputtering in Mid-Frequency Mode with Dual Cathodes

    NASA Astrophysics Data System (ADS)

    Ohno, Shingo; Sato, Daisuke; Kon, Masato; Sato, Yasushi; Yoshikawa, Masato; Frach, Peter; Shigesato, Yuzo

    2004-12-01

    Titanium dioxide (TiO2) films were deposited on unheated nonalkali glass substrates by reactive midfrequency (mf) magnetron sputtering using dual cathodes with two Ti metal targets. In order to maintain the very high deposition rate, the depositions were successfully carried out stably in the “transition region” between the metallic and reactive (oxide) sputter modes using plasma control units (PCU). Very high-rate depositions of 12-70 nm/min were successfully achieved in the deposition of TiO2 films throughout the whole “transition region”. The as-deposited films deposited in the “oxide mode” had a polycrystalline anatase structure and exhibited both photoinduced hydrophilicity and photodecomposition of acetaldehyde. Whereas, all the as-deposited TiO2 films deposited in the “transition region” had amorphous structure, which did not exhibit photocatalytic activity. Such amorphous films deposited in the transition region were crystallized by postannealing in air at 200°C or 300°C and were then shown to have photocatalytic activity. Very thin TiO2 films with a thickness of 25 nm deposited in the transition region and postannealed at 300°C exhibited photoinduced hydrophilicity, whereas there was a clear thickness dependence of photodecomposition and the rather thick films of 300 nm exhibited pronounced photodecomposition.

  6. Optimized structure stability and electrochemical performance of LiNi0.8Co0.15Al0.05O2 by sputtering nanoscale ZnO film

    NASA Astrophysics Data System (ADS)

    Lai, Yan-Qing; Xu, Ming; Zhang, Zhi-An; Gao, Chun-Hui; Wang, Peng; Yu, Zi-Yang

    2016-03-01

    LiNi0.8Co0.15Al0.05O2 (NCA) is one of the most promising cathode material for lithium-ion batteries (LIBs) in electric vehicles, which is successfully adopted in Tesla. However, the dissolution of the cation into the electrolyte is still a one of the major challenges (fading capacity and poor cyclability, etc.) presented in pristine NCA. Herein, a homogeneous nanoscale ZnO film is directly sputtered on the surface of NCA electrode via the magnetron sputtering (MS). This ZnO film is evidenced by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results clearly demonstrate that ZnO film is fully and uniformly covered on the NCA electrodes. After 90 cycles at 1.0C, the optimized MS-2min coated NCA electrode delivers much higher discharge capacity with 169 mAh g-1 than that of the pristine NCA electrode with 127 mAh g-1. In addition, the discharge capacity also reaches 166 mAh g-1 at 3.0C, as compared to that of 125 mAh g-1 for the pristine electrode. The improved electrochemical performance can be ascribed to the superiority of the MS ZnO film that reduce charge transfer resistance and protect the NCA electrode from cation dissolution.

  7. p-type conduction from Sb-doped ZnO thin films grown by dual ion beam sputtering in the absence of oxygen ambient

    SciTech Connect

    Kumar Pandey, Sushil; Kumar Pandey, Saurabh; Awasthi, Vishnu; Kumar, Ashish; Mukherjee, Shaibal; Deshpande, Uday P.; Gupta, Mukul

    2013-10-28

    Sb-doped ZnO (SZO) thin films were deposited on c-plane sapphire substrates by dual ion beam sputtering deposition system in the absence of oxygen ambient. The electrical, structural, morphological, and elemental properties of SZO thin films were studied for films grown at different substrate temperatures ranging from 200 °C to 600 °C and then annealed in situ at 800 °C under vacuum (pressure ∼5 × 10{sup −8} mbar). Films grown for temperature range of 200–500 °C showed p-type conduction with hole concentration of 1.374 × 10{sup 16} to 5.538 × 10{sup 16} cm{sup −3}, resistivity of 66.733–12.758 Ω cm, and carrier mobility of 4.964–8.846 cm{sup 2} V{sup −1} s{sup −1} at room temperature. However, the film grown at 600 °C showed n-type behavior. Additionally, current-voltage (I–V) characteristic of p-ZnO/n-Si heterojunction showed a diode-like behavior, and that further confirmed the p-type conduction in ZnO by Sb doping. X-ray diffraction measurements showed that all SZO films had (002) preferred crystal orientation. X-ray photoelectron spectroscopy analysis confirmed the formation of Sb{sub Zn}–2V{sub Zn} complex caused acceptor-like behavior in SZO films.

  8. Relation between surface and bulk electronic properties of Al doped ZnO films deposited at varying substrate temperature by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Singh, C. C.; Patel, T. A.; Panda, E.

    2015-06-01

    In this study, a qualitative relationship between the surface and bulk electronic states for Al-doped ZnO (AZO) thin films (thickness < 260 nm) is established. To this end, AZO films were deposited on soda lime glass substrates by varying substrate temperature (Ts) from 303 K to 673 K in RF magnetron sputtering. All these AZO films are found to have grown in ZnO hexagonal wurtzite structure with strong (002) orientation of the crystallites and with an average transmittance of 84%-91% in the visible range. Room temperature scanning tunneling spectroscopy measurements reveal semiconducting behavior for the films deposited at Ts ≤ 373 K and semi-metallic behavior for those deposited at Ts > 373 K. Further, these films show two modes of electron tunneling, (a) direct tunneling at lower bias voltage and (b) FN tunneling at higher bias voltage, with transition voltage ( Vtrans ) shifting towards lower bias voltage (and thereby reducing the barrier height ( Φ)) with increasing Ts. This is attributed to additional (local) density of states near the Fermi level of these AZO films because of higher carrier concentration ( ne ) at increased Ts. Thus, qualitatively, the behavior in both the local surface electronic states and bulk state electronic properties for these deposited AZO films are found to follow similar trends with increasing Ts. The variation in local barrier heights (indicative of the local surface electronic structures) across the AZO film surface is found to be smaller for the films deposited at Ts ≤ 373 K, where semiconducting behavior is observed and wider for the semi-metallic AZO films deposited at higher Ts > 373 K, indicating a larger inhomogeneity of local surface electronic properties at higher bulk carrier concentration.

  9. Effects of NIR annealing on the characteristics of al-doped ZnO thin films prepared by RF sputtering.

    PubMed

    Jun, Min-Chul; Koh, Jung-Hyuk

    2012-01-01

    Aluminum-doped zinc oxide (AZO) thin films have been deposited on glass substrates by employing radio frequency (RF) sputtering method for transparent conducting oxide applications. For the RF sputtering process, a ZnO:Al2O3 (2 wt.%) target was employed. In this paper, the effects of near infrared ray (NIR) annealing technique on the structural, optical, and electrical properties of the AZO thin films have been researched. Experimental results showed that NIR annealing affected the microstructure, electrical resistance, and optical transmittance of the AZO thin films. X-ray diffraction analysis revealed that all films have a hexagonal wurtzite crystal structure with the preferentially c-axis oriented normal to the substrate surface. Optical transmittance spectra of the AZO thin films exhibited transmittance higher than about 80% within the visible wavelength region, and the optical direct bandgap (Eg) of the AZO films was increased with increasing the NIR energy efficiency. PMID:22673232

  10. Effects of NIR annealing on the characteristics of al-doped ZnO thin films prepared by RF sputtering

    PubMed Central

    2012-01-01

    Aluminum-doped zinc oxide (AZO) thin films have been deposited on glass substrates by employing radio frequency (RF) sputtering method for transparent conducting oxide applications. For the RF sputtering process, a ZnO:Al2O3 (2 wt.%) target was employed. In this paper, the effects of near infrared ray (NIR) annealing technique on the structural, optical, and electrical properties of the AZO thin films have been researched. Experimental results showed that NIR annealing affected the microstructure, electrical resistance, and optical transmittance of the AZO thin films. X-ray diffraction analysis revealed that all films have a hexagonal wurtzite crystal structure with the preferentially c-axis oriented normal to the substrate surface. Optical transmittance spectra of the AZO thin films exhibited transmittance higher than about 80% within the visible wavelength region, and the optical direct bandgap (Eg) of the AZO films was increased with increasing the NIR energy efficiency. PMID:22673232

  11. Effect of substrate temperature on transparent conducting Al and F co-doped ZnO thin films prepared by rf magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wang, Fang-Hsing; Chang, Chiao-Lu

    2016-05-01

    ZnO is a wide bandgap semiconductor that has many potential applications such as solar cells, thin film transistors, light emitting diodes, and gas/biological sensors. In this study, a composite ceramic ZnO target containing 1 wt% Al2O3 and 1.5 wt% ZnF2 was prepared and used to deposit transparent conducting Al and F co-doped zinc oxide (AFZO) thin films on glass substrates by radio frequency magnetron sputtering. The effect of substrate temperatures ranging from room temperature (RT) to 200 °C on structural, morphological, electrical, chemical, and optical properties of the deposited thin films were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Hall effect measurement, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and UV-vis spectrophotometer. The XRD results showed that all the AFZO thin films had a (0 0 2) diffraction peak, indicating a typical wurtzite structure with a preferential orientation of the c-axis perpendicular to the substrate. The FE-SEM and AFM analyses indicated that the crystallinity and grain size of the films were enhanced while the surface roughness decreased as the substrate temperature increased. Results of Hall effect measurement showed that Al and F co-doping decreased the resistivity more effectively than single-doping (either Al or F doping) in ZnO thin films. The resistivity of the AFZO thin films decreased from 5.48 × 10-4 to 2.88 × 10-4 Ω-cm as the substrate temperature increased from RT to 200 °C due to the increased carrier concentration and Hall mobility. The optical transmittances of all the AFZO thin films were over 92% in the wavelength range of 400-800 nm regardless of substrate temperature. The blue-shift of absorption edge accompanied the rise of the optical band gap, which conformed to the Burstein-Moss effect. The developed AFZO thin films are suitable as transparent conducting electrodes for various optoelectronic

  12. Study of hysteresis behavior in reactive sputtering of cylindrical magnetron plasma

    NASA Astrophysics Data System (ADS)

    Kakati, H.; M. Borah, S.

    2015-12-01

    In order to make sufficient use of reactive cylindrical magnetron plasma for depositing compound thin films, it is necessary to characterize the hysteresis behavior of the discharge. Cylindrical magnetron plasmas with different targets namely titanium and aluminium are studied in an argon/oxygen and an argon/nitrogen gas environment respectively. The aluminium and titanium emission lines are observed at different flows of reactive gases. The emission intensity is found to decrease with the increase of the reactive gas flow rate. The hysteresis behavior of reactive cylindrical magnetron plasma is studied by determining the variation of discharge voltage with increasing and then reducing the flow rate of reactive gas, while keeping the discharge current constant at 100 mA. Distinct hysteresis is found to be formed for the aluminium target and reactive gas oxygen. For aluminium/nitrogen, titanium/oxygen and titanium/nitrogen, there is also an indication of the formation of hysteresis; however, the characteristics of variation from metallic to reactive mode are different in different cases. The hysteresis behaviors are different for aluminium and titanium targets with the oxygen and nitrogen reactive gases, signifying the difference in reactivity between them. The effects of the argon flow rate and magnetic field on the hysteresis are studied and explained. Project supported by the Department of Science and Technology, Government of India and Council of Scientific and Industrial Research, India.

  13. Insight into the Mechanism of Antibacterial Activity of ZnO: Surface Defects Mediated Reactive Oxygen Species Even in the Dark.

    PubMed

    Lakshmi Prasanna, V; Vijayaraghavan, Rajagopalan

    2015-08-25

    A systematic and complete antibacterial study on well-designed and well-characterized microparticle (micro), nanoparticle (nano), and capped nano ZnO has been carried out in both dark and light conditions with the objective of arriving at the mechanism of the antibacterial activity of ZnO, particularly in the dark. The present systematic study has conclusively proved that reactive oxygen species (ROS) such as (•)OH, (•)O2(-), and H2O2 are significantly produced from aqueous suspension of ZnO even in the dark and are mainly responsible for the activity in the dark up to 17%, rather than Zn(2+) ion leaching as proposed earlier. This work further confirms that surface defects play a major role in the production of ROS both in the presence and absence of light. In the dark, superoxide ((•)O2(-)) radical mediated ROS generation through singly ionized oxygen vacancy is proposed for the first time, and it is confirmed by EPR and scavenger studies. ROS such as (•)O2(-), H2O2, and (•)OH have been estimated by UV-visible spectroscopy using nitro blue tetrazolium (NBT), KMnO4 titrations, and fluorescence spectroscopy, respectively. These are correlated to the antibacterial activity of ZnO in the dark and light. The activity is found to be highest for nano ZnO and least for micro ZnO, with capped ZnO between the two, highlighting the important role of surface defects in generation of ROS. The surface charge density of ZnO in dark and light has been estimated for the first time to the best of our knowledge, and it can influence antibacterial activity. Our work proposes a new mechanism mediated by superoxide species, for antibacterial activity of ZnO especially in the dark. PMID:26222950

  14. BiVO4 photoanodes for water splitting with high injection efficiency, deposited by reactive magnetron co-sputtering

    NASA Astrophysics Data System (ADS)

    Gong, Haibo; Freudenberg, Norman; Nie, Man; van de Krol, Roel; Ellmer, Klaus

    2016-04-01

    Photoactive bismuth vanadate (BiVO4) thin films were deposited by reactive co-magnetron sputtering from metallic Bi and V targets. The effects of the V-to-Bi ratio, molybdenum doping and post-annealing on the crystallographic and photoelectrochemical (PEC) properties of the BiVO4 films were investigated. Phase-pure monoclinic BiVO4 films, which are more photoactive than the tetragonal BiVO4 phase, were obtained under slightly vanadium-rich conditions. After annealing of the Mo-doped BiVO4 films, the photocurrent increased 2.6 times compared to undoped films. After optimization of the BiVO4 film thickness, the photocurrent densities (without a catalyst or a blocking layer or a hole scavenger) exceeded 1.2 mA/cm2 at a potential of 1.23 VRHE under solar AM1.5 irradiation. The surprisingly high injection efficiency of holes into the electrolyte is attributed to the highly porous film morphology. This co-magnetron sputtering preparation route for photoactive BiVO4 films opens new possibilities for the fabrication of large-scale devices for water splitting.

  15. Effect of duty cycle on the electrical and optical properties of VOx film deposited by pulsed reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Dong, Xiang; Wu, Zhiming; Xu, Xiangdong; Wei, Xiongbang; Jiang, Yadong

    2013-12-01

    Vanadium oxide (VOx) films were deposited onto well cleaned glass substrates by bipolar pulsed reactive magnetron sputtering at room temperature. Dependence of the structure, composition, optical and electrical properties of the films on the pulsed power's duty cycle has been investigated. The results from the X-ray diffraction (XRD) analysis show that there was no remarkable change in the amorphous structure in the films with duty cycle can be observed. But chemical analysis of the surface evaluated with x-ray photoelectron spectroscopy (XPS) indicates that decrease the duty cycle favors to enhance the oxidation of the vanadium. The optical and electrical properties of the films were characterized by spectroscopic ellipsometry and temperature dependent resistivity measurements, respectively. The evolution of the transmittance, optical band gap, optical constants, resistivity and temperature coefficient of resistance (TCR) of the deposited films with duty cycle was analyzed and discussed. In comparison with conventional DC sputtering, under the same discharge atmosphere and power level, these parameters of the VOx films can be modified over a broad range by duty cycle. Therefore adjusting the duty cycle during deposition, which is an effective way to control and optimize the performances of the VOx film for various optoelectronic devices applications.

  16. Visible light-induced photocatalytic properties of WO{sub 3} films deposited by dc reactive magnetron sputtering

    SciTech Connect

    Imai, Masahiro; Kikuchi, Maiko; Oka, Nobuto; Shigesato, Yuzo

    2012-05-15

    The authors examined the photocatalytic activity of WO{sub 3} films (thickness 500-600 nm) deposited on a fused quartz substrate heated at 350-800 deg. C by dc reactive magnetron sputtering using a W metal target under the O{sub 2} gas pressure from 1.0 to 5.0 Pa. Films deposited at 800 deg. C under 5.0 Pa have excellent crystallinity of triclinic, P1(1) structure and a large surface area, as confirmed by x-ray diffraction, scanning electron microscopy, and atomic force microscopy. Exposure of acetaldehyde (CH{sub 3}CHO) adsorbed onto the film surface to ultraviolet, visible, or standard fluorescence light induces oxidative photocatalytic decomposition indicated by a decrease in CH{sub 3}CHO concentration and generation of CO{sub 2} gas. For all three types of irradiation, concentration ratio of decreased CH{sub 3}CHO to increased CO{sub 2} is about 1:1, suggesting the possible presence of intermediates. The sputter-deposited WO{sub 3} film can be a good candidate as a visible light-responsive photocatalyst.

  17. Effects of Ti addiction in WO 3 thin film ammonia gas sensor prepared by dc reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hu, Ming; Yong, Cholyun; Feng, Youcai; Lv, Yuqiang; Han, Lei; Liang, Jiran; Wang, Haopeng

    2006-11-01

    WO 3 sensing films (1500 Å) were deposited using dc reactive magnetron sputtering method on alumina substrate on which patterned interdigital Pt electrodes were previously formed. The additive Ti was sputtered with different thickness (100-500 Å) onto WO 3 thin films and then the films as-deposited were annealed at 400°C in air for 3h. The crystal structure and chemical composition of the films were characterized by XRD and XPS analysis. The effect of Ti addition on sensitive properties of WO 3 thin film to the NH 3 gas was then discussed. WO 3 thin films added Ti revealed excellent sensitivity and response characteristics in the presence of low concentration of NH 3 (5-400 ppm) gas in air at 200°C operating temperature. Especially,in case 300 Å thickness of additive Ti, WO 3 thin films have a promotional effect on the response speed to NH 3 and selectivity enhanced with respect to other gases (CO, C IIH 5OH, CH 4). The influence of different substrates, including alumina, silicon and glass, on sensitivity to NH 3 gas has also been investigated.

  18. Preparation of RF reactively sputtered indium-tin oxide thin films with optical properties suitable for heat mirrors

    NASA Astrophysics Data System (ADS)

    Boyadzhiev, S.; Dobrikov, G.; Rassovska, M.

    2008-05-01

    Technologies are discussed for preparing and characterizing indium-tin oxide (ITO) thin films with properties appropriate for usage as heat mirrors in solar thermal collectors. The samples were prepared by means of radio frequency (RF) reactive sputtering of indium-tin targets in oxygen. The technological parameters were optimized to obtain films with optimal properties for heat mirrors. The optical properties of the films were studied by visible and infra-red (IR) spectrophotometry and laser ellipsometry. The reflectance of the films in the thermal IR range was investigated by a Fourier transform infra-red (FTIR) spectrophotometer. Heating of the substrates during the sputtering and their post deposition annealing in different environments were also studied. The ultimate purpose of the present research being the development of a technological process leading to low-cost ITO thin films with high transparency in the visible and near IR (0.3-2.4 μm) and high reflection in the thermal IR range (2.5-25 μm), we investigated the correlation of the ITO thin films structural and optical properties with the technological process parameters - target composition and heat treatment.

  19. Reactive pulsed-DC sputtered Nb-doped VO2 coatings for smart thermochromic windows with active solar control.

    PubMed

    Batista, C; Carneiro, J; Ribeiro, R M; Teixeira, V

    2011-10-01

    Thermochromic VO2 thin films have successfully been grown on SiO2-coated float glass by reactive pulsed-DC magnetron sputtering. Different Nb doping amounts were introduced in the VO2 solid solution during the film growing which resulted in films with distinct semiconducting-metal phase transition temperatures. Pure VO2 showed improved thermochromic behavior as compared with VO2 films prepared by conventional DC sputtering. The transition temperatures were linearly decreased from 59 down to 34 degrees C with the increase in Nb content. However, the luminous transmittance and the infrared modulation efficiency were markedly affected. The surface morphology of the films was examined by scanning electron microscopy (SEM) and showed a tendency for grain sized reduction due to Nb addition. Moreover, the films were found to be very dense with no columnar microstructure. Structural analyses carried out by X-ray diffractometry (XRD) revealed that Nb introduces significant amount of defects in the crystal lattice which clearly degrade the optical properties. PMID:22400299

  20. Substrate biasing effect on the physical properties of reactive RF-magnetron-sputtered aluminum oxide dielectric films on ITO glasses.

    PubMed

    Liang, Ling Yan; Cao, Hong Tao; Liu, Quan; Jiang, Ke Min; Liu, Zhi Min; Zhuge, Fei; Deng, Fu Ling

    2014-02-26

    High dielectric constant (high-k) Al2O3 thin films were prepared on ITO glasses by reactive RF-magnetron sputtering at room temperature. The effect of substrate bias on the subband structural, morphological, electrode/Al2O3 interfacial and electrical properties of the Al2O3 films is systematically investigated. An optical method based on spectroscopic ellipsometry measurement and modeling is adopted to probe the subband electronic structure, which facilitates us to vividly understand the band-tail and deep-level (4.8-5.0 eV above the valence band maximum) trap states. Well-selected substrate biases can suppress both the trap states due to promoted migration of sputtered particles, which optimizes the leakage current density, breakdown strength, and quadratic voltage coefficient of capacitance. Moreover, high porosity in the unbiased Al2O3 film is considered to induce the absorption of atmospheric moisture and the consequent occurrence of electrolysis reactions at electrode/Al2O3 interface, as a result ruining the electrical properties. PMID:24490685

  1. Growth Behavior of Ga-Doped ZnO Thin Films Deposited on Au/SiN/Si(001) Substrates by Radio Frequency Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Seo, Seon Hee; Kang, Hyon Chol

    2013-11-01

    This paper reports the growth behavior of Ga-doped ZnO (ZnO:Ga) thin films deposited on Au/SiN/Si(001) substrates by radio-frequency magnetron sputtering. The microstructures of the overgrown ZnO:Ga thin films were investigated by performing X-ray diffraction, scanning electron microcopy, and transmission electron microscopy analyses. It was confirmed that the growth process proceeds through three stages. In the first stage, nano-scale ZnO:Ga islands were grown on the SiN layer, while a fairly continuous flat structure was formed on the Au nanoparticles (NPs). In the second stage of the growth process, ZnO:Ga domains with different growth orientations, depending strongly on the crystalline planes of the host Au NPs, were nucleated. These domains then grew at different rates, resulting in a change in the morphology from the initial shape reflecting that of the Au NPs to a sunflower-type shape. In the final stage, columnar growth with a preferred (0002) orientation along the surface normal direction became dominant.

  2. Correlations between 1/f noise and thermal treatment of Al-doped ZnO thin films deposited by direct current sputtering

    SciTech Connect

    Barhoumi, A. Guermazi, S.; Leroy, G.; Gest, J.; Carru, J. C.; Yang, L.; Boughzala, H.; Duponchel, B.

    2014-05-28

    Al-doped ZnO thin films (AZO) have been deposited on amorphous glass substrates by DC sputtering at different substrate temperatures T{sub s}. X-Ray diffraction results reveal that AZO thin films have a hexagonal wurtzite structure with (002) preferred orientation. (002) peaks indicate that the crystalline structure of the films is oriented with c-axis perpendicular to the substrate. Three-dimensional (3D) atomic force microscopy images of AZO thin films deposited on glass substrate at 200 °C, 300 °C, and 400 °C, respectively, shows the improvement of the crystallinity and the homogeneity of AZO thin films with T{sub s} which is in agreement with the noise measurements. The noise was characterized between 1 Hz and 100 kHz and we have obtained 1/f spectra. The noise is very sensitive to the crystal structure especially to the orientation of the crystallites which is perpendicular to the substrate and to the grain boundaries which generate a high current flow and a sharp increase in noise. Through time, R{sub sh} and [αμ]{sub eff} increase with the modification of the crystallinity of AZO thin films. Study of noise aging shows that the noise is more sensitive than resistivity for all AZO thin films.

  3. Correlations between 1/f noise and thermal treatment of Al-doped ZnO thin films deposited by direct current sputtering

    NASA Astrophysics Data System (ADS)

    Barhoumi, A.; Leroy, G.; Yang, L.; Gest, J.; Boughzala, H.; Duponchel, B.; Guermazi, S.; Carru, J. C.

    2014-05-01

    Al-doped ZnO thin films (AZO) have been deposited on amorphous glass substrates by DC sputtering at different substrate temperatures Ts. X-Ray diffraction results reveal that AZO thin films have a hexagonal wurtzite structure with (002) preferred orientation. (002) peaks indicate that the crystalline structure of the films is oriented with c-axis perpendicular to the substrate. Three-dimensional (3D) atomic force microscopy images of AZO thin films deposited on glass substrate at 200 °C, 300 °C, and 400 °C, respectively, shows the improvement of the crystallinity and the homogeneity of AZO thin films with Ts which is in agreement with the noise measurements. The noise was characterized between 1 Hz and 100 kHz and we have obtained 1/f spectra. The noise is very sensitive to the crystal structure especially to the orientation of the crystallites which is perpendicular to the substrate and to the grain boundaries which generate a high current flow and a sharp increase in noise. Through time, Rsh and [αμ]eff increase with the modification of the crystallinity of AZO thin films. Study of noise aging shows that the noise is more sensitive than resistivity for all AZO thin films.

  4. Superior electrochemical performance of LiCoO2 electrodes enabled by conductive Al2O3-doped ZnO coating via magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Dai, Xinyi; Zhou, Aijun; Xu, Jin; Yang, Bin; Wang, Liping; Li, Jingze

    2015-12-01

    A conductive Al2O3-doped ZnO (AZO) layer is coated directly on the LiCoO2 (LCO) porous composite electrode by magnetron sputtering of an AZO target, offering more efficient electron transfer and a stabilized interface layer. Up to 90% of the initial capacity of the AZO-coated electrode can be retained (173 mAh g-1) after 150 cycles between 3.0 and 4.5 V vs. Li/Li+. Meanwhile, the rate performance is remarkably improved showing a reversible capacity of 112 mAh g-1 at 12 C. The formation of amorphous solid electrolyte interface (SEI) observed on the uncoated LCO electrode is effectively impeded on the AZO-coated one. Acting as an intermediate barrier, the AZO layer can prevent chemical dissolution of the active materials by forming a thin passivation layer on the electrode surface containing some metal fluorides which are chemically inactive and ionically conductive. The positive role of the AZO coating is still effective under a more severe condition tested with an upper cut-off potential of 4.7 V.

  5. Change of scattering mechanism and annealing out of defects on Ga-doped ZnO films deposited by radio-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Nulhakim, Lukman; Makino, Hisao

    2016-06-01

    This study examines the change of carrier scattering mechanism and defects states in Ga-doped ZnO (GZO) thin films deposited by radio-frequency magnetron sputtering as a function of the substrate temperature (Ts) during deposition. The GZO films deposited at room temperature exhibited a high defect density that resulted in a lower carrier concentration, lower Hall mobility, and optical absorption in visible wavelength range. Such defects were created by ion bombardment and were eliminated by increasing the Ts. The defects related to the optical absorption disappeared at a Ts of 125 °C. The defects responsible for the suppression of the carrier concentration gradually decreased with increasing Ts up to 200 °C. As a result, the carrier concentration and in-grain carrier mobility gradually increased. The Hall mobility was also influenced by film structural properties depending on the Ts. In addition to the c-axis preferred orientation, other oriented grains such as the (10 1 ¯ 1 ) plane parallel to the substrate surface appeared below 150 °C. This orientation of the (10 1 ¯ 1 ) plane significantly reduced the Hall mobility via grain boundary scattering. The films deposited at a Ts higher than 175 °C exhibited perfect c-axis orientation and grain boundary scattering was thus negligible in these films. The appearance of the 10 1 ¯ 1 peak in x-ray diffraction profile was correlated with the contribution of grain boundary scattering in heavily doped GZO films.

  6. Compositional study of vacuum annealed Al doped ZnO thin films obtained by RF magnetron sputtering

    SciTech Connect

    Shantheyanda, B. P.; Todi, V. O.; Sundaram, K. B.; Vijayakumar, A.; Oladeji, I.

    2011-09-15

    Aluminum doped zinc oxide (AZO) thin films were obtained by RF magnetron sputtering. The effects of deposition parameters such as power, gas flow conditions, and substrate heating have been studied. Deposited and annealed films were characterized for composition as well as microstructure using x ray photoelectron spectroscopy and x ray diffraction. Films produced were polycrystalline in nature. Surface imaging and roughness studies were carried out using SEM and AFM, respectively. Columnar grain growth was predominantly observed. Optical and electrical properties were evaluated for transparent conducting oxide applications. Processing conditions were optimized to obtain highly transparent AZO films with a low resistivity value of 6.67 x 10{sup -4}{Omega} cm.

  7. Origin of the butterfly-shaped magnetoresistance in reactive sputtered epitaxial Fe{sub 3}O{sub 4} films

    SciTech Connect

    Li, P.; Zhang, L. T.; Mi, W. B.; Jiang, E. Y.; Bai, H. L.

    2009-08-01

    Epitaxial Fe{sub 3}O{sub 4} thin films were synthesized by facing-target reactive sputtering Fe targets. The epitaxy of the Fe{sub 3}O{sub 4} film on MgO (100) was examined macroscopically using x-ray diffraction, including conventional theta-2theta scan, tilting 2theta scan, phi scan, and pole figure. The observed low-field butterfly-shaped magnetoresistance (MR) are explained by the primary fast rotation of the spins far away from antiphase boundaries and the high-field MR changing linearly with magnetic field can be understood by the gradual rotation of the spins near the antiphase boundaries. It is magnetocrystalline anisotropy that causes an increase in MR below Verwey transition temperature.

  8. Reactive magnetron sputtering of Cu{sub 2}O: Dependence on oxygen pressure and interface formation with indium tin oxide

    SciTech Connect

    Deuermeier, Jonas; Gassmann, Juergen; Broetz, Joachim; Klein, Andreas

    2011-06-01

    Thin films of copper oxides were prepared by reactive magnetron sputtering and structural, morphological, chemical, and electronic properties were analyzed using x-ray diffraction, atomic force microscopy, in situ photoelectron spectroscopy, and electrical resistance measurements. The deposition conditions for preparation of Cu(I)-oxide (Cu{sub 2}O) are identified. In addition, the interface formation between Cu{sub 2}O and Sn-doped In{sub 2}O{sub 3} (ITO) was studied by stepwise deposition of Cu{sub 2}O onto ITO and vice versa. A type II (staggered) band alignment with a valence band offset {Delta}E{sub VB} 2.1-2.6 eV depending on interface preparation is observed. The band alignment explains the nonrectifying behavior of p-Cu{sub 2}O/n-ITO junctions, which have been investigated for thin film solar cells.

  9. Bimodal substrate biasing to control γ-Al{sub 2}O{sub 3} deposition during reactive magnetron sputtering

    SciTech Connect

    Prenzel, Marina; Kortmann, Annika; Stein, Adrian; Keudell, Achim von; Nahif, Farwah; Schneider, Jochen M.

    2013-09-21

    Al{sub 2}O{sub 3} thin films have been deposited at substrate temperatures between 500 °C and 600 °C by reactive magnetron sputtering using an additional arbitrary substrate bias to tailor the energy distribution of the incident ions. The films were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The film structure being amorphous, nanocrystalline, or crystalline was correlated with characteristic ion energy distributions. The evolving crystalline structure is connected with different levels of displacements per atom (dpa) in the growing film as being derived from TRIM simulations. The boundary between the formation of crystalline films and amorphous or nanocrystalline films was at 0.8 dpa for a substrate temperature of 500 °C. This threshold shifts to 0.6 dpa for films grown at 550 °C.

  10. Epitaxial growth and orientation of AlN thin films on Si(001) substrates deposited by reactive magnetron sputtering

    SciTech Connect

    Valcheva, E.; Birch, J.; Persson, P. O. A ring .; Tungasmita, S.; Hultman, L.

    2006-12-15

    Epitaxial domain formation and textured growth in AlN thin films deposited on Si(001) substrates by reactive magnetron sputtering was studied by transmission electron microscopy and x-ray diffraction. The films have a wurtzite type structure with a crystallographic orientation relationship to the silicon substrate of AlN(0001)(parallel sign)Si(001). The AlN film is observed to nucleate randomly on the Si surface and grows three dimensionally, forming columnar domains. The in-plane orientation reveals four domains with their a axes rotated by 15 deg. with respect to each other: AlN<1120>(parallel sign)Si[110], AlN<0110>(parallel sign)Si[110], AlN<1120>(parallel sign)Si[100], and AlN<0110>(parallel sign)Si[100] An explanation of the growth mode based on the large lattice mismatch and the topology of the substrate surface is proposed.

  11. Reactive magnetron sputtering of Cu2O: Dependence on oxygen pressure and interface formation with indium tin oxide

    NASA Astrophysics Data System (ADS)

    Deuermeier, Jonas; Gassmann, Jürgen; Brötz, Joachim; Klein, Andreas

    2011-06-01

    Thin films of copper oxides were prepared by reactive magnetron sputtering and structural, morphological, chemical, and electronic properties were analyzed using x-ray diffraction, atomic force microscopy, in situ photoelectron spectroscopy, and electrical resistance measurements. The deposition conditions for preparation of Cu(I)-oxide (Cu2O) are identified. In addition, the interface formation between Cu2O and Sn-doped In2O3 (ITO) was studied by stepwise deposition of Cu2O onto ITO and vice versa. A type II (staggered) band alignment with a valence band offset ΔEVB = 2.1-2.6 eV depending on interface preparation is observed. The band alignment explains the nonrectifying behavior of p-Cu2O/n-ITO junctions, which have been investigated for thin film solar cells.

  12. Potential for reactive pulsed-dc magnetron sputtering of nanocomposite VO{sub x} microbolometer thin films

    SciTech Connect

    Jin, Yao O. Ozcelik, Adem; Horn, Mark W.; Jackson, Thomas N.

    2014-11-01

    Vanadium oxide (VO{sub x}) thin films were deposited by reactive pulsed-dc sputtering a metallic vanadium target in argon/oxygen mixtures with substrate bias. Hysteretic oxidation of the vanadium target surface was assessed by measuring the average cathode current during deposition. Nonuniform oxidization of the target surface was analyzed by Raman spectroscopy. The VO{sub x} film deposition rate, resistivity, and temperature coefficient of resistance were correlated to oxygen to argon ratio, processing pressure, target-to-substrate distance, and oxygen inlet positions. To deposit VO{sub x} in the resistivity range of 0.1–10 Ω-cm with good uniformity and process control, lower processing pressure, larger target-to-substrate distance, and oxygen inlet near the substrate are useful.

  13. A study of structure and properties of Ti-doped DLC film by reactive magnetron sputtering with ion implantation

    NASA Astrophysics Data System (ADS)

    Ma, Guojia; Gong, Shuili; Lin, Guoqiang; Zhang, Lin; Sun, Gang

    2012-01-01

    Ti-doped diamond-like carbon (DLC) films were prepared on Ti alloys by reactive magnetron sputtering combined with PSII technology. The structure and properties of unmodified and Ti-doped DLC films were analyzed in a systematic way by different testing, such as TEM, XPS, frictional wear testing, contact angle measurement and so on. The results showed that Ti-doped DLC was a typical a-C:H film containing TiC nanometer grains, whose mechanical properties were obviously improved, such as hardness, wear resistance and cohesive strength, still kept good wear resistance at the ambient temperature of 450 °C, and held a rather large mean water contact angle of 104.2 ± 1°.

  14. Reactive Sputter Deposition of WO3/Ag/WO3 Film for Indium Tin Oxide (ITO)-Free Electrochromic Devices.

    PubMed

    Yin, Yi; Lan, Changyong; Guo, Huayang; Li, Chun

    2016-02-17

    Functioning both as electrochromic (EC) and transparent-conductive (TC) coatings, WO3/Ag/WO3 (WAW) trilayer film shows promising potential application for ITO-free electrochromic devices. Reports on thermal-evaporated WAW films revealed that these bifunctional WAW films have distinct EC characteristics; however, their poor adhesive property leads to rapid degradation of coloring-bleaching cycling. Here, we show that WAW film with improved EC durability can be prepared by reactive sputtering using metal targets. We find that, by introducing an ultrathin tungsten (W) sacrificial layer before the deposition of external WO3, the oxidation of silver, which leads to film insulation and apparent optical haze, can be effectively avoided. We also find that the luminous transmittance and sheet resistance were sensitive to the thicknesses of tungsten and silver layers. The optimized structure for TC coating was obtained to be WO3 (45 nm)/Ag (10 nm)/W (2 nm)/WO3 (45 nm) with a sheet resistance of 16.3 Ω/□ and a luminous transmittance of 73.7%. Such film exhibits compelling EC performance with decent luminous transmittance modulation ΔTlum of 29.5%, fast switching time (6.6 s for coloring and 15.9 s for bleaching time), and long-term cycling stability (2000 cycles) with an applied potential of ±1.2 V. Thicker external WO3 layer (45/10/2/100 nm) leads to larger modulation with maximum ΔTlum of 46.4%, but at the cost of significantly increasing the sheet resistance. The strategy of introducing ultrathin metal sacrificial layer to avoid silver oxidation could be extended to fabricating other oxide-Ag-oxide transparent electrodes via low-cost reactive sputtering. PMID:26726834

  15. Microstructural studies of nanocomposite thin films of Ni/CrN prepared by reactive magnetron sputtering.

    PubMed

    Kuppusami, P; Thirumurugesan, R; Divakar, R; Kataria, S; Ramaseshan, R; Mohandas, E

    2009-09-01

    Synthesis and characterization of nanocomposites of Ni/CrN thin films prepared by DC magnetron sputtering from a target of 50 wt.%Ni-50 wt.%Cr is investigated. The films prepared as a function of nitrogen flow rate and substrate temperature showed that the films contained Ni and CrN phases with crystallite sizes in the nanometer range. Measurement of nanomechanical properties of the composite films exhibited a significant decrease in the values of hardness and Young's modulus than those of pure CrN films. PMID:19928270

  16. Structural parameters and polarization properties of TiN thin films prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Solovan, M. M.; Brus, V. V.; Pidkamin, L. J.; Maryanchuk, P. D.; Dobrovolsky, Yu. G.

    2015-11-01

    We report the results of the investigation of morphological, structural, optical and plarimeteric properties of titanium nitride thin films deposited on silicon and glass substrates. The magnetron sputtered titanium nitride thin films were established to possess crystalline structure with the average grain size about D = 15 nm. The method of correlation matrix is was applied for the analysis of polarization properties of scattered light by the titanium nitride thin film. The obtained experimental result, can be explained by the presence of the effects of linear and circular dichroism in the material of the titanium nitride thin films under investigations.

  17. The effects of the pressure and the oxygen content of the sputtering gas on the structure and the properties of zinc oxy-nitride thin films deposited by reactive sputtering of zinc

    NASA Astrophysics Data System (ADS)

    Jiang, Nanke; Georgiev, Daniel G.; Jayatissa, Ahalapitiya H.

    2013-02-01

    Zinc nitride and oxy-nitride thin films were prepared by reactive magnetron rf sputtering of zinc in either nitrogen-argon or nitrogen-argon-oxygen ambient. The effects of varying the total sputtering pressure and the oxygen fraction in the total sputtering gas mixture on the microstructure, electrical and optical properties were investigated. With increasing the sputtering pressure, the dominant phase comprising the film material changes from the crystalline zinc nitride phase to crystalline zinc oxide. The characteristic pressure, at which this change in the dominant phase is observed, decreases with the increase of the oxygen fraction in the total sputtering gas mixture. The increase of the oxygen content in the films (from 5 at.% to a maximum of 40 at.%) and the downward shift in the optical absorption edge (from 920 to 400 nm), combined with the x-ray diffraction data, support these observations, indicating the controllable fabrication of an oxy-nitride film material. Correlations between the films’ fabrication conditions, including post-deposition annealing, their structure and composition, and their electrical properties are examined as well.

  18. Hydrogen induced electric conduction in undoped ZnO and Ga-doped ZnO thin films: Creating native donors via reduction, hydrogen donors, and reactivating extrinsic donors

    SciTech Connect

    Akazawa, Housei

    2014-09-01

    The manner in which hydrogen atoms contribute to the electric conduction of undoped ZnO and Ga-doped ZnO (GZO) films was investigated. Hydrogen atoms were permeated into these films through annealing in an atmospheric H{sub 2} ambient. Because the creation of hydrogen donors competes with the thermal annihilation of native donors at elevated temperatures, improvements to electric conduction from the initial state can be observed when insulating ZnO films are used as samples. While the resistivity of conductive ZnO films increases when annealing them in a vacuum, the degree of increase is mitigated when they are annealed in H{sub 2}. Hydrogenation of ZnO crystals was evidenced by the appearance of OH absorption signals around a wavelength of 2700 nm in the optical transmittance spectra. The lowest resistivity that was achieved by H{sub 2} annealing was limited to 1–2 × 10{sup −2} Ω cm, which is one order of magnitude higher than that by native donors (2–3 × 10{sup −3} Ω cm). Hence, all native donors are converted to hydrogen donors. In contrast, GZO films that have resistivities yet to be improved become more conductive after annealing in H{sub 2} ambient, which is in the opposite direction of GZO films that become more resistive after vacuum annealing. Hydrogen atoms incorporated into GZO crystals should assist in reactivating Ga{sup 3+} donors.

  19. [Effect of oxygen partial pressure on the band-gap of the TiO2 films prepared by DC reactive sputtering].

    PubMed

    Zhao, Qing-nan; Li, Chun-ling; Liu, Bao-shun; Zhao, Xiu-jian

    2004-05-01

    TiO2 films have been deposited on glass substrates using DC reactive magnetron sputtering at different oxygen partial pressures from 0.10 to 0.65 Pa. The photoluminescence (PL) spectra of the films were recorded. The results of the PL spectra showed that there were three emission peaks at 370, 472 and 514 nm for the films sputtered at 0.35 and 0.65 Pa, and there were two peaks at 370 and 490 nm for the films sputtered at 0.10 and 0.15 Pa. The band-gap for the films was 3.35 eV. For the films sputtered at 0.35 and 0.65 Pa there were two defect energy levels at 2.63 and 2.41 eV, corresponding to 0.72 and 0.94 eV below conduction band for the band-gap, respectively. For the films sputtered at 0.10 and 0.15 Pa, there was an energy band formed between 3.12 and 2.06 eV, corresponding to 0.23 and 1.29 eV below the conduction band. With increasing the oxygen partial pressure, the defect energy band changed to two energy levels, and the energy levels nearly disappeared for the film sputtered at 0.65 Pa of oxygen partial pressure. PMID:15769058

  20. Highly oriented {delta}-Bi{sub 2}O{sub 3} thin films stable at room temperature synthesized by reactive magnetron sputtering

    SciTech Connect

    Lunca Popa, P.; Kerdsongpanya, S.; Lu, J.; Eklund, P.; Sonderby, S.; Bonanos, N.

    2013-01-28

    We report the synthesis by reactive magnetron sputtering and structural characterization of highly (111)-oriented thin films of {delta}-Bi{sub 2}O{sub 3}. This phase is obtained at a substrate temperature of 150-200 Degree-Sign C in a narrow window of O{sub 2}/Ar ratio in the sputtering gas (18%-20%). Transmission electron microscopy and x-ray diffraction reveal a polycrystalline columnar structure with (111) texture. The films are stable from room temperature up to 250 Degree-Sign C in vacuum and 350 Degree-Sign C in ambient air.

  1. Obtaining Au thin films in atmosphere of reactive nitrogen through magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Quintero, J. H.; Ospina, R.; Mello, A.

    2016-02-01

    4d and 5d series of the transition metals are used to the obtaining nitrides metallic, due to the synthesis of PtN, AgN and AuN in the last years. Different nitrides are obtained in the Plasma Assisted Physics Vapour Deposition system, due to its ionization energy which is necessary for their formation. In this paper a Magnetron Sputtering system was used to obtain Au thin films on Si wafers in Nitrogen atmosphere. The substrate temperature was varied between 500 to 950°C. The samples obtained at high temperatures (>500°C) show Au, Si and N elements, as it is corroborated in the narrow spectrum obtained for X-Ray Photoelectron Spectroscopy; besides the competition of orientation crystallographic texture between (111) and (311) directions was present in the X-Ray Diffraction analysis to the sample heated at 950°C.

  2. Structure and Properties of Ti-O-N Coatings Produced by Reactive Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Konischev, M. E.; Kuzmin, O. S.; Pustovalova, A. A.; Morozova, N. S.; Evdokimov, K. E.; Surmenev, R. A.; Pichugin, V. F.; Epple, M.

    2014-02-01

    Results of an experimental study of the optical characteristics of gas discharges are presented. The study was aimed at optimizing the operating modes of a mid-frequency magnetron sputtering system to efficiently deposit Ti-O-N coatings. The conditions for maintaining the intensity of the chosen spectroscopic lines that ensure synthesis of titanium oxide and titanium oxynitride coatings have been revealed. The morphology, structure, contact angle, and free surface energy of titanium oxide and titanium oxynitride coatings on type 12Kh18N10T stainless steel substrates were examined by using scanning and transmission electron microscopy and infrared spectroscopy, and by measuring the wetting angle. The results of examination of the structure and properties of the synthesized films and their physicomechanical and optical characteristics are given.

  3. Characterization of reactively sputtered c-axis aligned nanocrystalline InGaZnO{sub 4}

    SciTech Connect

    Lynch, David M.; Zhu, Bin; Ast, Dieter G.; Thompson, Michael O.; Levin, Barnaby D. A.; Muller, David A.; Greene, Raymond G.

    2014-12-29

    Crystallinity and texturing of RF sputtered c-axis aligned crystal InGaZnO{sub 4} (CAAC IGZO) thin films were quantified using X-ray diffraction techniques. Above 190 °C, nanocrystalline films with an X-ray peak at 2θ = 30° (009 planes) developed with increasing c-axis normal texturing up to 310 °C. Under optimal conditions (310 °C, 10% O{sub 2}), films exhibited a c-axis texture full-width half-maximum of 20°. Cross-sectional high-resolution transmission electron microscopy confirmed these results, showing alignment variation of ±9° over a 15 × 15 nm field of view and indicating formation of much larger aligned domains than previously reported. At higher deposition temperatures, c-axis alignment was gradually lost as polycrystalline films developed.

  4. Hysteresis behavior during reactive magnetron sputtering of Al{sub 2}O{sub 3} using a rotating cylindrical magnetron

    SciTech Connect

    Depla, D.; Haemers, J.; Buyle, G.; Gryse, R. de

    2006-07-15

    Rotating cylindrical magnetrons are used intensively on industrial scale. A rotating cylindrical magnetron on laboratory scale makes it possible to study this deposition technique in detail and under well controlled conditions. Therefore, a small scale rotating cylindrical magnetron was designed and used to study the influence of the rotation speed on the hysteresis behavior during reactive magnetron sputtering of aluminum in Ar/O{sub 2} in dc mode. This study reveals that the hysteresis shifts towards lower oxygen flows when the rotation speed of the target is increased, i.e., target poisoning occurs more readily when the rotation speed is increased. The shift is more pronounced for the lower branch of the hysteresis loop than for the upper branch of the hysteresis. This behavior can be understood qualitatively. The results also show that the oxidation mechanism inside the race track is different from the oxidation mechanism outside the race track. Indeed, outside the race track the oxidation mechanism is only defined by chemisorption while inside the race track reactive ion implantation will also influence the oxidation mechanism.

  5. Stoichiometric silicon oxynitride thin films reactively sputtered in Ar/N2O plasmas by HiPIMS

    NASA Astrophysics Data System (ADS)

    Hänninen, Tuomas; Schmidt, Susann; Wissting, Jonas; Jensen, Jens; Hultman, Lars; Högberg, Hans

    2016-04-01

    Silicon oxynitride (SiO x N y , x=0.2-1.3, y=0.2 -0.7) thin films were synthesized by reactive high power impulse magnetron sputtering from a pure silicon target in Ar/N2O atmospheres. It was found that the composition of the material can be controlled by the reactive gas flow and the average target power. X-ray photoelectron spectroscopy (XPS) shows that high average powers result in more silicon-rich films, while lower target powers yield silicon-oxide-like material due to more pronounced target poisoning. The amount of nitrogen in the films can be controlled by the percentage of nitrous oxide in the working gas. The nitrogen content remains at a constant level while the target is operated in the transition region between metallic and poisoned target surface conditions. The extent of target poisoning is gauged by the changes in peak target current under the different deposition conditions. XPS also shows that varying concentrations and ratios of oxygen and nitrogen in the films result in film chemical bonding structures ranging from silicon-rich to stoichiometric silicon oxynitrides having no observable Si-Si bond contributions. Spectroscopic ellipsometry shows that the film optical properties depend on the amount and ratio of oxygen and nitrogen in the compound, with film refractive indices measured at 633 nm ranging between those of SiO2 and Si3N4.

  6. Preparation and study of Titanium Nitride films by reactive sputtering and an investigation of target poisoning during the process

    NASA Astrophysics Data System (ADS)

    Aziz, Tareque; Rumaiz, Abdul

    Titanium Nitride (TiNx) thin films were prepared by reactive dc sputtering in presence of Ar-N2 plasma. The thin films were grown on Quartz and pure Si surfaces. The Ar-N2 content ratio was gradually varied while the substrate and the Titanium target were kept at room temperature. Structural properties, optical and electrical properties of the thin films were studied by using X-ray Photoelectron Spectroscopy (XPS) and XRD and 4 probe resistivity measurement. Target poisoning of the Ti target was also studied by varying reactive gas concentration and measuring the target current. A study of target current vs growth rate of the films was performed to investigate the onset of ``poison'' mode.Although there was an insignificant drop in plasma current, we noticed a drop in the deposition rate. This result was tested against Monte Carlo simulations using SRIM simulations. Effects of annealing on the crystallinity and the sheet resistance will also be discussed. The work has been supported by BSA,DOE.

  7. Growth of Homoepitaxial ZnO Semiconducting Films

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehoczky, S. L.; Harris, M. T.; George, Michael A.; McCarty, P.

    1999-01-01

    As a high temperature semiconductor, ZnO has been used for many applications such as wave-guide, solar cells, and surface acoustic wave devices. Since the ZnO material has an energy gap of 3.3 eV at room temperature and an excitonic binding energy (60 meV) that is possible to make excitonic lasering at room temperature a recent surge of interest is to synthesize ZnO films for electro-optical devices. These applications require films with a smooth surface, good crystal quality, and low defect density. Homoepitaxial films have been studied in terms of morphology, crystal structure, and electrical and optical properties. ZnO single crystals are grown by the hydrothermal method. Substrates are mechanically polished and annealed in air for four hours before deposited films. The annealing temperature-dependence of ZnO substrates is studied. Films are synthesized by the off-axis reactive sputtering deposition. The films have very smooth surface with a roughness ZnO films grown of (0001) ZnO and (0001) sapphire substrates will be also compared and discussed in the presentation.

  8. Effects of Mg Doping on the Performance of InGaN Films Made by Reactive Sputtering

    NASA Astrophysics Data System (ADS)

    Kuo, Dong-Hau; Li, Cheng-Che; Tuan, Thi Tran Anh; Yen, Wei-Chun

    2015-01-01

    Mg-doped InGaN (Mg-InGaN) films have been deposited directly on Si (100) substrates by radio-frequency reactive sputtering technique with single cermet targets in an Ar/N2 atmosphere. The cermet targets with a constant 5% indium content were made by hot pressing the mixture of metallic In, Ga, and Mg powders and ceramic GaN powder. The Mg-InGaN films had a wurtzite structure with a preferential () growth plane. The SEM images showed that Mg-InGaN films were smooth, continuous, free from cracks and holes, and composed of nanometer-sized grains. As the Mg dopant content in Mg-InGaN increased to 7.7 at.%, the film was directly transformed into p-type conduction without a post-annealing process. It had high hole concentration of 5.53 × 1018 cm-3 and electrical mobility of 15.7 ± 4.2 cm2 V-1 s-1. The over-doping of Mg in InGaN degraded the electrical properties. The bandgap of Mg-InGaN films decreased from 2.92 eV to 2.84 eV, as the Mg content increased from 7.7% to 18.2%. The constructed p-type Mg-InGaN/ n-type GaN diode was used to confirm the realization of the p-type InGaN by sputtering technique.

  9. Growth and characterization of chromium oxide coatings prepared by pulsed-direct current reactive unbalanced magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Barshilia, Harish C.; Rajam, K. S.

    2008-12-01

    Approximately 0.2-3.2 μm thick single phase chromium oxide (Cr 2O 3) coatings with different oxygen flow rates were deposited on silicon and mild steel substrates at low substrate temperature (˜60 °C) by pulsed-direct current (DC) reactive unbalanced magnetron sputtering. Two asymmetric bipolar-pulsed DC generators were used to co-sputter two Cr targets, in Ar + O 2 plasma. The coatings were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation hardness tester, optical microscopy, atomic force microscopy, micro-Raman spectroscopy, spectroscopic ellipsometry and potentiodynamic polarization techniques. The XRD data showed the presence of mixture of crystalline (rhombohedral Cr 2O 3) and amorphous phases for the coatings prepared with oxygen flow rate less than 10 sccm. A complete transformation to amorphous phase was observed at higher oxygen flow rates. The XRD results were supported by Raman spectroscopy data. The XPS data suggested that the chemical state of Cr was in the form of Cr 3+. The chromium oxide coatings exhibited a maximum hardness of 22 GPa and an elastic modulus of 208 GPa. The coatings exhibited high thermal stability upon annealing in vacuum up to 500 °C and retained hardness as high as 17 GPa. Spectroscopic ellipsometry data indicated that coatings prepared at higher oxygen flow rates were dielectric in nature and those prepared at low oxygen flow rates exhibited an intermediate character, i.e., a transition between the dielectric and the metallic behavior. The corrosion behavior of Cr 2O 3 coating deposited on mild steel substrates was investigated using potentiodynamic polarization in 3.5% NaCl solution. The results indicated that Cr 2O 3 coating exhibited superior corrosion resistance as compared to the uncoated substrate.

  10. In situ analyses on negative ions in the sputtering process to deposit Al-doped ZnO films

    SciTech Connect

    Tsukamoto, Naoki; Watanabe, Daisuke; Saito, Motoaki; Sato, Yasushi; Oka, Nobuto; Shigesato, Yuzo

    2010-07-15

    The origin of high energy negative ions during deposition of aluminum doped zinc oxide (AZO) films by dc magnetron sputtering of an AZO (Al{sub 2}O{sub 3}: 2.0 wt %) target was investigated by in situ analyses using the quadrupole mass spectrometer combined with the electrostatic energy analyzer. High energy negative oxygen (O{sup -}) ions which possessed the kinetic energy corresponding to the cathode sheath voltage were detected. The maximum flux of the O{sup -} ions was clearly observed at the location opposite to the erosion track area on the target. The flux of the O{sup -} ions changed hardly with increasing O{sub 2} flow ratio [O{sub 2}/(Ar+O{sub 2})] from 0% to 5%. The kinetic energy of the O{sup -} ions decreased with decreasing cathode sheath voltage from 403 to 337 V due to the enhancement of the vertical maximum magnetic field strength at the cathode surface from 0.025 to 0.100 T. The AZO films deposited with the lower O{sup -} bombardment energy showed the higher crystallinity and improved the electrical conductivity.

  11. Comparative study of RF reactive magnetron sputtering and sol-gel deposition of UV induced superhydrophilic TiOx thin films

    NASA Astrophysics Data System (ADS)

    Vrakatseli, V. E.; Amanatides, E.; Mataras, D.

    2016-03-01

    TiOx and TiOx-like thin films were deposited on PEEK (Polyether ether ketone) substrates by low-temperature RF reactive magnetron sputtering and the sol-gel method. The resulting films were compared in terms of their properties and photoinduced hydrophilicity. Both techniques resulted in uniform films with good adhesion that can be switched to superhydrophilic after exposure to UVA radiation for similar time periods. In addition, the sputtered films can also be activated and switched to superhydrophilic by natural sunlight due to the higher absorption in the visible spectrum compared to the sol-gel films. On the other hand, the as deposited sol-films remain relatively hydrophilic for a longer time in dark compared to the sputtered film due to the differences in the morphology and the porosity of the two materials. Thus, depending on the application, either method can be used in order to achieve the desirable TiOx properties.

  12. Electrochromism in surface modified crystalline WO3 thin films grown by reactive DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Karuppasamy, A.

    2013-10-01

    In the present work, tungsten oxide thin films were deposited at various oxygen chamber pressures (1.0-5.0 × 10-3 mbar) by maintaining the sputtering power density and argon pressure constant at 3.0 W/cm2 and 1.2 × 10-2 mbar, respectively. The role of surface morphology and porosity on the electrochromic properties of crystalline tungsten oxide thin films has been investigated. XRD and Raman studies reveal that all the samples post annealed at 450 ̊C in air for 3.0 h settle in monoclinic crystal system of tungsten oxide (W18O49). Though the phase of material is indifferent to oxygen pressure variations (PO2), morphology and film density shows a striking dependence on PO2. A systematic study on plasma (OES), morphology, optical and electrochromic properties of crystalline tungsten oxide reveal that the films deposited at PO2 of 2.0 × 10-3 mbar exhibit better coloration efficiency (58 cm2/C), electron/ion capacity (Qc: -25 mC/cm2), and reversibility (92%). This is attributed to the enhanced surface properties like high density of pores and fine particulates (100 nm) and to lesser bulk density of the film (ρ/ρo = 0.84) which facilitates the process of intercalation/de-intercalation of protons and electrons. These results show good promise toward stable and efficient crystalline tungsten oxide based electrochromic device applications.

  13. Structural and gasochromic properties of WO3 films prepared by reactive sputtering deposition

    NASA Astrophysics Data System (ADS)

    Yamamoto, S.; Hakoda, T.; Miyashita, A.; Yoshikawa, M.

    2015-02-01

    The effects of deposition temperature and film thickness on the structural and gasochromic properties of tungsten trioxide (WO3) films used for the optical detection of diluted cyclohexane gas have been investigated. The WO3 films were prepared on SiO2 substrates by magnetron sputtering, with the deposition temperature ranging from 300 to 550 °C in an Ar and O2 gas mixture. The films were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and Rutherford backscattering spectroscopy (RBS). The gasochromic properties of the WO3 films, coated with a catalytic Pt layer, were examined by exposing them to up to 5% cyclohexane in N2 gas. It was found that (001)-oriented monoclinic WO3 films, with a columnar structure, grew at deposition temperatures between 400 and 450 °C. Furthermore, (010)-oriented WO3 films were preferably formed at deposition temperatures higher than 500 °C. The gasochromic characterization of the Pt/WO3 films revealed that (001)-oriented WO3 films, with cauliflower-like surface morphology, were appropriate for the optical detection of cyclohexane gas.

  14. Effect of reactive magnetron sputtering parameters on structural and electrical properties of hafnium oxide thin films

    NASA Astrophysics Data System (ADS)

    Szymańska, Magdalena; Gierałtowska, Sylwia; Wachnicki, Łukasz; Grobelny, Marcin; Makowska, Katarzyna; Mroczyński, Robert

    2014-05-01

    The purpose of this work was to compare the structural and electrical properties of magnetron sputtered hafnium oxide (HfOx) and hafnium oxynitride (HfOxNy) thin films. A careful analysis of the influence of deposition process parameters, among them: pressure in the reactor chamber, Ar and O2 flow rate, power applied to the reactor chamber and deposition time, on electro-physical properties of HfOx and HfOxNy layers has been performed. In the course of this work we performed number of experiments by means of Taguchi's orthogonal arrays approach. Such a method allowed for the determination of dielectric layers properties depending on process parameters with relatively low amount of experiments. Moreover, the effects of post-deposition annealing on electrical characteristics of metal-insulator-semiconductor (MIS) structures with HfOx or HfOxNy gate dielectric and its structural properties have also been reported. Investigated hafnia thin films were characterized by means of spectroscopic ellipsometry (SE), electrical characteristics measurements, atomic force microscopy (AFM), X-ray diffraction spectroscopy (XRD) and Rutherford backscattering spectrometry (RBS).

  15. On the phase formation of titanium oxide thin films deposited by reactive DC magnetron sputtering: influence of oxygen partial pressure and nitrogen doping

    NASA Astrophysics Data System (ADS)

    Pandian, Ramanathaswamy; Natarajan, Gomathi; Rajagopalan, S.; Kamruddin, M.; Tyagi, A. K.

    2014-09-01

    This work describes about the control on phase formation in titanium oxide thin films deposited by reactive dc magnetron sputtering. Various phases of titanium oxide thin films were deposited by controlling the oxygen partial pressure during the sputtering process. By adding nitrogen gas to sputter gas mixture of oxygen and argon, the oxygen partial pressure was decreased further below the usual critical value, below and above which the sputtering yields metallic and oxide films, respectively. Furthermore, nitrogen addition eliminated the typical hysteretic behaviour between the flow rate and oxygen partial pressure, and significantly influenced the sputter rate. On increasing the oxygen partial pressure, the ratio between anatase and rutile fraction and grain size increases. The fracture cross-sectional scanning electron microscopy together with the complementary information from X-ray diffraction and micro-Raman investigations revealed the evolution and spatial distribution of the anatase and rutile phases. Both the energy delivered to the growing film and oxygen vacancy concentrations are correlated with the formation of various phases upon varying the oxygen partial pressure.

  16. Bioactivity and Surface Reactivity of RF-sputtered Calcium Phosphate Thin Films

    NASA Astrophysics Data System (ADS)

    van der Wal, Edwin

    2003-10-01

    Calcium phosphates (CaP) are known to be bioactive, i.e. able to bond to bone. This makes CaPs very suitable to be aplied as thin coatings on bone-implants. In this work we studied the physicochemical behaviour of CaP coatings applied with radio frequency (RF) magnetron sputtering, a deposition technique that can produce thin ( 100 nm), homogeneous, and well-adhereing coatings. As-deposited CaP coatings are amorphous and can be crystallized by a heat-treatment of 30 minutes at 650C, resulting in a mainly apatitic structure. Firstly, we have studied the behaviour of these CaP coatings in so-called simulated body fluid (SBF or SBF1), an anorganic equivalent of human blood plasma. Amorphous CaP coatings dissolve in SBF and even in SBF with twice the Ca and PO4 concentrations (SBF2). After a heat-treatment CaP coatings remain inert in SBF for days, i.e. coatings do not dissolve and no crystals are formed from the solution on the coating surface. However, formation of crystals is possible in SBF2. At room temperature, the formation of crystals is preceeded by an induction time, in which rod-shaped sediments can be found on the coating surface, but no significant growth is observed. Only after completion of the induction period growth of CaP crystals is allowed. Growth can proceed in solutions with lower concentrations like SBF1. Only within a limited range of Ca over PO4 ratio of the coatings, formation of CaP crystals from SBF2 is possible. In a rat bone marrow (RBM) cell-culture CaP was compared to RF-sputtered coatings of other bioceramics like alumina (Al2O3) and titania (TiO2). Alumina is a known bioinert material. However, there is still discussion on the biocompatibility of titania. It was found that cell behavior on CaP coatings significantly differed from alumina. CaP coatings showed decreased early proliferation, increased differentiation, and increased mature osteoblast activity compared to alumina. Results for titania were intermediate compared to CaP and

  17. Composition and Structure Control of Cu-Al-O Films Prepared by Reactive Sputtering and Annealing

    NASA Astrophysics Data System (ADS)

    Tsuboi, Nozomu; Itoh, Yuji; Ogata, Junya; Kobayashi, Satoshi; Shimizu, Hidehiko; Kato, Keizo; Kaneko, Futao

    2007-01-01

    Cu-Al-O films were prepared on quartz glass substrates at 500-700 °C by sputtering the Cu and Al targets alternately on atomic-layer scale under an Ar-diluted O2 (5-20%) gas atmosphere, and then annealed at 1050 °C under a nitrogen atmosphere. The [Cu]/[Al] ratio was controlled by changing the Cu and Al deposition periods. The composition of as-deposited films corresponded to the slightly oxygen-rich region of the CuO-CuAl2O4-Al2O3 system. Films as-deposited at 500 °C had an amorphous structure, while films as-deposited at 700 °C had CuAl2O4 and CuO phases. After thermal annealing in a nitrogen atmosphere, the composition of the films approached that of the Cu2O-CuAlO2-Al2O3 system line, causing a noticeable appearance of the CuAlO2 phase along with the disappearance of the CuAl2O4 and CuO phases. Cu- and Al-rich annealed films had in addition a Cu2O phase and an amorphous Al2O3 phase, respectively. All annealed films exhibited p-type conductivity. The annealed films with [Cu]/[Al]≈ 1 had an absorption edge corresponding to the energy gap of CuAlO2. These results indicate that the change in the Cu ion from divalent to monovalent through nitrogen annealing results in the preparation of transparent conductive films dominated by CuAlO2.

  18. Single- and bi-layer memristive devices with tunable properties using TiO{sub x} switching layers deposited by reactive sputtering

    SciTech Connect

    Jiang, Hao; Xia, Qiangfei

    2014-04-14

    The authors systematically studied reactive sputtering deposition of TiO{sub x} thin films using a mixture of Ar and O{sub 2} gases under different ratios of O{sub 2} flow. As directly revealed by X-ray photoelectron spectroscopy, the deposition changed from a metallic Ti target mode to an oxide target mode when the O{sub 2} flow ratio was beyond 40%, resulting in TiO{sub x} thin films with different chemical compositions. Consequently, metal/oxide/metal devices with a single TiO{sub x} layer exhibited a broad spectrum of electrical characteristics such as Ohmic, rectifying, and memristive behavior. The reactive sputtering deposited TiO{sub x} thin films were also used in a bilayer memristive device structure, and a transition from bipolar to unipolar switching behavior was observed for devices based on thin films prepared with different oxygen flow.

  19. Evaluation of momentum effects on material properties of titanium-silicon-nitrogen nanocrystalline composites prepared by pulsed dc reactive sputtering

    NASA Astrophysics Data System (ADS)

    Sunal, Paul Dennis

    The investigation had as a general goal the deposition of thin films that possess high erosion wear resistance. The fabrication technique used for this purpose was an industry-compatible process called reactive sputtering physical vapor deposition (PVD). The study specifically involved depositing Ti-Si-N nc-composite thin films according to generic design principles that specify using a transition metal nitride and a covalent nitride material system in order to produce hard coatings (˜50 GPa Vickers hardness). Thin films were deposited using reactive pulsed, do sputtering to avoid arcing issues and for wider control over the process properties such as the deposition rate and level of bombardment. Two sputter guns used synchronized pulsed do signals, which were asymmetric and bipolar with positive voltages of less than +100 V and negative voltages of -500 to -1000 V. The pulsing frequency was varied in this co-deposition system as a possible means to control the nanocrystalline composite thin film properties by controlling the level of bombardment. The thin films were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM) to determine the crystallinity of the films. XRD results show the presence of the (111), (220), and (200) orientations with the later being most common. TEM bright-field images show nanocrystals in the 10 to 40 nm range, depending on the pulsing frequency. A columnar morphology (50--120 nm diameters) was observed in the nc-composite films from images taken with a scanning electron microscope. Verification of the TiN and SiN phases was accomplished using XPS to analyze the binding energies of Ti 2p and Si 2p electrons, respectively. Oxygen was detected in the films, (2--9 at.%) depending on pulsing frequency, and it severely worsened the mechanical properties, specifically the hardness, by reacting with some of the silicon in the SiN phase. A maximum Vickers hardness, Hv, of 32 GPa and reduced elastic modulus, Er, of

  20. SiNx Coatings Deposited by Reactive High Power Impulse Magnetron Sputtering: Process Parameters Influencing the Nitrogen Content.

    PubMed

    Schmidt, Susann; Hänninen, Tuomas; Goyenola, Cecilia; Wissting, Jonas; Jensen, Jens; Hultman, Lars; Goebbels, Nico; Tobler, Markus; Högberg, Hans

    2016-08-10

    Reactive high power impulse magnetron sputtering (rHiPIMS) was used to deposit silicon nitride (SiNx) coatings for biomedical applications. The SiNx growth and plasma characterization were conducted in an industrial coater, using Si targets and N2 as reactive gas. The effects of different N2-to-Ar flow ratios between 0 and 0.3, pulse frequencies, target power settings, and substrate temperatures on the discharge and the N content of SiNx coatings were investigated. Plasma ion mass spectrometry shows high amounts of ionized isotopes during the initial part of the pulse for discharges with low N2-to-Ar flow ratios of <0.16, while signals from ionized molecules rise with the N2-to-Ar flow ratio at the pulse end and during pulse-off times. Langmuir probe measurements show electron temperatures of 2-3 eV for nonreactive discharges and 5.0-6.6 eV for discharges in transition mode. The SiNx coatings were characterized with respect to their composition, chemical bond structure, density, and mechanical properties by X-ray photoelectron spectroscopy, X-ray reflectivity, X-ray diffraction, and nanoindentation, respectively. The SiNx deposition processes and coating properties are mainly influenced by the N2-to-Ar flow ratio and thus by the N content in the SiNx films and to a lower extent by the HiPIMS frequencies and power settings as well as substrate temperatures. Increasing N2-to-Ar flow ratios lead to decreasing growth rates, while the N content, coating densities, residual stresses, and the hardness increase. These experimental findings were corroborated by density functional theory calculations of precursor species present during rHiPIMS. PMID:27414283

  1. Reactive sputter magnetron reactor for preparation of thin films and simultaneous in situ structural study by X-ray diffraction.

    PubMed

    Bürgi, J; Neuenschwander, R; Kellermann, G; García Molleja, J; Craievich, A F; Feugeas, J

    2013-01-01

    The purpose of the designed reactor is (i) to obtain polycrystalline and∕or amorphous thin films by controlled deposition induced by a reactive sputtering magnetron and (ii) to perform a parallel in situ structural study of the deposited thin films by X-ray diffraction, in real time, during the whole growth process. The designed reactor allows for the control and precise variation of the relevant processing parameters, namely, magnetron target-to-sample distance, dc magnetron voltage, and nature of the gas mixture, gas pressure and temperature of the substrate. On the other hand, the chamber can be used in different X-ray diffraction scanning modes, namely, θ-2θ scanning, fixed α-2θ scanning, and also low angle techniques such as grazing incidence small angle X-ray scattering and X-ray reflectivity. The chamber was mounted on a standard four-circle diffractometer located in a synchrotron beam line and first used for a preliminary X-ray diffraction analysis of AlN thin films during their growth on the surface of a (100) silicon wafer. PMID:23387690

  2. Temperature-dependent microstructural evolution of Ti2AlN thin films deposited by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Zhang, Zheng; Jin, Hongmei; Chai, Jianwei; Pan, Jisheng; Seng, Hwee Leng; Goh, Glen Tai Wei; Wong, Lai Mun; Sullivan, Michael B.; Wang, Shi Jie

    2016-04-01

    Ti2AlN MAX-phase thin films have been deposited on MgO (1 1 1) substrates between 500 and 750 °C using DC reactive magnetron sputtering of a Ti2Al compound target in a mixed N2/Ar plasma. The composition, crystallinity, morphology and hardness of the thin films have been characterized by X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy and nano-indentation, respectively. The film initially forms a mixture of Ti, Al and (Ti,Al)N cubic solid solution at 500 °C and nucleates into polycrystalline Ti2AlN MAX phases at 600 °C. Its crystallinity is further improved with an increase in the substrate temperature. At 750 °C, a single-crystalline Ti2AlN (0 0 0 2) thin film is formed having characteristic layered hexagonal surface morphology, high hardness, high Young's modulus and low electrical resistivity. The mechanism behind the evolution of the microstructure with growth temperature is discussed in terms of surface energies, lattice mismatch and enhanced adatom diffusion at high growth temperatures.

  3. Role of carbon in the formation of hard Ge1-xCx thin films by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hu, Chaoquan; Qiao, Liang; Tian, Hongwei; Lu, Xianyi; Jiang, Qing; Zheng, Weitao

    2011-07-01

    We have deposited germanium carbide (Ge1-xCx) films on Si(1 0 0) substrate via radio-frequency (RF) reactive magnetron sputtering in a CH4/Ar mixture discharge, and explored the effects of carbon content (x) on the chemical bonding and hardness for the obtained films. We find that x significantly influences the chemical bonding, which leads to a pronounced change in the hardness of the film. To reveal the relationship between the chemical bonding and hardness, first-principles calculations have been carried out. It is shown that as x increases from 0 to 0.33, the fraction of sp3 C-Ge bonds in the film increases at the expense of Ge-Ge bonds, which promotes formation of a strong covalently bonded network, and thus enhances the hardness of the film. However, as x further increases from 0.33 to 0.59, the fraction of sp3 C-Ge bonds in the film gradually reduces, while that of sp3 C-H and graphite-like sp2 C-C bonds increases, which damages the compact network structure, resulting in a sharp decrease in the hardness. This investigation suggests that the medium x (0.17

  4. Proton conductive tantalum oxide thin film deposited by reactive DC magnetron sputtering for all-solid-state switchable mirror

    NASA Astrophysics Data System (ADS)

    Tajima, K.; Yamada, Y.; Bao, S.; Okada, M.; Yoshimura, K.

    2008-03-01

    Our developed all-solid-state switchable mirror as a smart window is consisted in multi-layer of Mg4Ni/Pd/Ta2O5/WO3/ITO/glass and can switch reversibly from the reflective state to the transparent one. The development of high performance solid electrolyte thin film of Ta2O5 is important for fast speed switching and high durability of the device. In this work, we have investigated the electrochemical property of Ta2O5 thin film deposited by reactive DC magnetron sputtering. The effect of thickness on electrochemical and proton conductivities of Ta2O5 thin film was investigated. The Ta2O5 thin film with a thickness of 400 nm had better proton conductivity of 1.5×10-9 S/cm measured by AC impedance method. The transmittance at wavelength of 670 nm of the device with 400 nm thick Ta2O5 thin film was changed from 0.1% (reflective state) to 51% (transparent state) within 10 s by applying voltage of 5 V. The device showed high durability up to two-thousand switching cycles.

  5. Correlation of photothermal conversion on the photo-induced deformation of amorphous carbon nitride films prepared by reactive sputtering

    SciTech Connect

    Harata, T.; Aono, M. Kitazawa, N.; Watanabe, Y.

    2014-08-04

    The photo-induced deformation of hydrogen-free amorphous carbon nitride (a-CN{sub x}) films was investigated under visible-light illumination. The films gave rise to photothermal conversion by irradiation. In this study, we investigated the effects of thermal energy generated by irradiation on the deformation of a-CN{sub x}/ultrathin substrate bimorph specimens. The films were prepared on both ultrathin Si and SiO{sub 2} substrates by reactive radio-frequency magnetron sputtering from a graphite target in the presence of pure nitrogen gas. The temperature of the film on the SiO{sub 2} substrate increased as the optical band-gap of the a-CN{sub x} was decreased. For the film on Si, the temperature remained constant. The deformation degree of the films on Si and SiO{sub 2} substrates were approximately the same. Thus, the deformation of a-CN{sub x} films primarily induced by photon energy directly.

  6. Study of Fluorine Addition Influence in the Dielectric Constant of Diamond-Like Carbon Thin Film Deposited by Reactive Sputtering

    NASA Astrophysics Data System (ADS)

    Trippe, S. C.; Mansano, R. D.

    The hydrogenated amorphous carbon films (a-C:H) or DLC (Diamond-Like Carbon) films are well known for exhibiting high electrical resistivity, low dielectric constant, high mechanical hardness, low friction coefficient, low superficial roughness and also for being inert. In this paper, we produced fluorinated DLC films (a-C:F), and studied the effect of adding CF4 on the above-mentioned properties of DLC films. These films were produced by a reactive RF magnetron sputtering system using a target of pure carbon in stable graphite allotrope. We performed measurements of electrical characteristic curves of capacitance as a function of applied tension (C-V) and current as a function of the applied tension (I-V). We showed the dielectric constant (k) and the resistivity (ρ) as functions of the CF4 concentration. On films with 65% CF4, we found that k = 2.7, and on films with 70% CF4, ρ = 12.3 × 1011 Ω cm. The value of the electrical breakdown field to films with 70% CF4 is 5.3 × 106 V/cm.

  7. Effect of Duty Cycle on Characteristics of CrNx Thin Films Deposited by Pulsed Direct Current Reactive Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Chang, Chi-Lung; Wu, Bo-Yi; Chen, Pin-Hung; Chen, Wei-Chih; Ho, Chun-Ta; Wu, Wan-Yu

    2013-11-01

    CrNx thin films have been deposited on silicon wafer, 304 stainless steel, and tungsten carbide substrates using pulsed DC reactive magnetron sputtering. A 10 kHz unipolar mode and a N2/Ar ratio of 17.5% were used. During the deposition, the substrate was not biased and not heated during the entire deposition time of 30 min. The microstructure, crystalline phase, and mechanical properties of the obtained CrNx thin films were examined to investigate the effect of the duty cycle. The results show that the maximum current and power density increase with decreasing duty cycle from 100% (DC) to 5%. Although the thickness of the CrNx thin films decreases with decreasing duty cycle, the ratio of the thickness to the pulse on-time shows a maximum of 273.3 nm/min at the lowest duty cycle of 5%. The obtained CrNx thin films show a mixture of the Cr2N and CrN phases. Moreover, the Cr-N bonding state and the percentages of CrN and Cr2N vary with the duty cycle. The effects of the duty cycle on the hardness, coefficient of friction, and corrosion behavior of the CrNx thin films are also investigated in this study.

  8. Atomistic growth phenomena of reactively sputtered RuO{sub 2} and MnO{sub 2} thin films

    SciTech Connect

    Music, Denis Bliem, Pascal; Geyer, Richard W.; Schneider, Jochen M.

    2015-07-07

    We have synthesized RuO{sub 2} and MnO{sub 2} thin films under identical growth conditions using reactive DC sputtering. Strikingly different morphologies, namely, the formation of RuO{sub 2} nanorods and faceted, nanocrystalline MnO{sub 2}, are observed. To identify the underlying mechanisms, we have carried out density functional theory based molecular dynamics simulations of the growth of one monolayer. Ru and O{sub 2} molecules are preferentially adsorbed at their respective RuO{sub 2} ideal surface sites. This is consistent with the close to defect free growth observed experimentally. In contrast, Mn penetrates the MnO{sub 2} surface reaching the third subsurface layer and remains at this deep interstitial site 3.10 Å below the pristine surface, resulting in atomic scale decomposition of MnO{sub 2}. Due to this atomic scale decomposition, MnO{sub 2} may have to be renucleated during growth, which is consistent with experiments.

  9. () preferential orientation of polycrystalline AlN grown on SiO2/Si wafers by reactive sputter magnetron technique

    NASA Astrophysics Data System (ADS)

    Bürgi, Juan; García Molleja, Javier; Bolmaro, Raúl; Piccoli, Mattia; Bemporad, Edoardo; Craievich, Aldo; Feugeas, Jorge

    2016-04-01

    Aluminum nitride (AlN) is a ceramic compound that could be used as a processing material for semiconductor industry. However, the AlN crystalline structure plays a crucial role in its performance. In this paper, polycrystalline AlN films have been grown onto Si(1 1 1) and Si(1 0 0) (with an oxide native coverage of SiO2) wafers by RSM (reactive sputter magnetron) technique using a small (5 L) reactor. The development of polycrystalline AlN films with a good texture along () planes, i.e., semi-polar structure, was shown. Analyses were done using X-ray diffraction in the Bragg-Brentano mode and in the GIXRD (grazing incidence X-ray diffraction) one, and the texture was determined through pole figures. The structure and composition of these films were also studied by TEM and EDS techniques. Nevertheless, the mapping of the magnetic field between the magnetron and the substrate has shown a lack of symmetry at the region near the substrate. This lack of symmetry can be attributable to the small dimensions of the chamber, and the present paper suggests that this phenomenon is the responsible for the unusual () texture developed.

  10. Reactively sputtered nickel nitride as electrocatalytic counter electrode for dye- and quantum dot-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Soo Kang, Jin; Park, Min-Ah; Kim, Jae-Yup; Ha Park, Sun; Young Chung, Dong; Yu, Seung-Ho; Kim, Jin; Park, Jongwoo; Choi, Jung-Woo; Jae Lee, Kyung; Jeong, Juwon; Jae Ko, Min; Ahn, Kwang-Soon; Sung, Yung-Eun

    2015-05-01

    Nickel nitride electrodes were prepared by reactive sputtering of nickel under a N2 atmosphere at room temperature for application in mesoscopic dye- or quantum dot- sensitized solar cells. This facile and reliable method led to the formation of a Ni2N film with a cauliflower-like nanostructure and tetrahedral crystal lattice. The prepared nickel nitride electrodes exhibited an excellent chemical stability toward both iodide and polysulfide redox electrolytes. Compared to conventional Pt electrodes, the nickel nitride electrodes showed an inferior electrocatalytic activity for the iodide redox electrolyte; however, it displayed a considerably superior electrocatalytic activity for the polysulfide redox electrolyte. As a result, compared to dye-sensitized solar cells (DSCs), with a conversion efficiency (η) = 7.62%, and CdSe-based quantum dot-sensitized solar cells (QDSCs, η = 2.01%) employing Pt counter electrodes (CEs), the nickel nitride CEs exhibited a lower conversion efficiency (η = 3.75%) when applied to DSCs, but an enhanced conversion efficiency (η = 2.80%) when applied to CdSe-based QDSCs.

  11. Effects of pulse frequency on the microstructure, composition and optical properties of pulsed dc reactively sputtered vanadium oxide thin films

    NASA Astrophysics Data System (ADS)

    Dong, Xiang; Wu, Zhiming; Jiang, Yadong; Xu, Xiangdong; Yu, He; Gu, Deen; Wang, Tao

    2014-09-01

    Vanadium oxide (VOx) thin films were prepared on unheated glass substrate by pulsed dc reactive magnetron sputtering using different pulse frequency. Field emission scanning electron microscopy (FESEM), x-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE) measurements were made on the deposited VOx films to characterize the microstructure, composition and optical properties, respectively. It was found that under the same discharge power and argon-oxygen atmosphere, with the increase of pulse frequency, the vertical column-like structure in the films will gradually disappear and the ratio of high-valent VOx to low-valent VOx will obviously elevate. Optical parameters of the VOx films have been obtained by fitting the ellipsometric data (Ψ andΔ) using the Tauc-Lorentz dispersion relation and a multilayer model (air/roughness layer/VOx/glass). The results demonstrated that pulse frequency plays a critical role in determining the transmittance, refractive index, extinction coefficient and optical band gap etc. The correlations between the microstructure, composition, optical properties and pulse frequency are also given by our experiment results. And the mechanisms for the evolution of the microstructure, composition and optical properties with pulse frequency have been discussed. Overall, due to the pulse frequency had a great effect not only on the growth characteristics but also on the optical properties of the VOx films, thus through variation of the pulse frequency during deposition which provide a convenient and efficient approach to control and optimize the performances of the VOx films.

  12. Annealing effects on the bonding structures, optical and mechanical properties for radio frequency reactive sputtered germanium carbide films

    NASA Astrophysics Data System (ADS)

    Hu, C. Q.; Zhu, J. Q.; Zheng, W. T.; Han, J. C.

    2009-01-01

    The effects of thermal annealing in vacuum on the bonding structures, optical and mechanical properties for germanium carbide (Ge 1- xC x) thin films, deposited by radio frequency (RF) reactive sputtering of pure Ge(1 1 1) target in a CH 4/Ar mixture discharge, are investigated. We find that there are no significant changes in the bonding structure of the films annealed below 300 °C. The fraction of Ge-H bonds for the film annealed at temperatures ( Ta) above 300 °C decreases, whereas that of C-H bonds show a decrease only when Ta exceeds 400 °C. The out-diffusion of hydrogen promotes the formation of Ge-C bonds at Ta above 400 °C and thus leads to a substantial increase in the compressive stress and hardness for the film. The refractive indices and optical gaps for Ge 1- xC x films are almost constant against Ta, which can be ascribed to the unchanged ratios of Ge/C and sp 2-C/sp 3-C concentrations. Furthermore, we also find that the excellent optical transmission for an antireflection Ge 1- xC x double-layer film on ZnS substrate is still maintained after annealing at 700 °C.

  13. In situ deposition of PbTiO3 thin films by direct current reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Iljinas, Aleksandras; Marcinauskas, Liutauras; Stankus, Vytautas

    2016-09-01

    The lead titanate thin films were deposited using in situ layer-by-layer reactive magnetron sputtering. The synthesis of films was performed on platinized silicon (Pt/Ti/SiO2/Si) substrates at 450-600 °C temperatures using Ti2O seed layer. The influence of the substrate temperature on the surface morphology, phase composition, and electrical properties of PbTiO3 films were investigated. Experimental results demonstrated that the deposition at higher substrate temperatures resulted in the formation of films with the lower surface roughness values. The increase of the substrate temperature has no effect on the tetragonality value of the films. The preferential orientation in the films was changed and the crystallites size slightly increased with the increased substrate temperature from 450 °C to 550 °C. Hysteresis measurements show that the films exhibit ferroelectric properties with a maximum coercive field of Ec = 150 kV/cm and of Pr = 60 μC/cm2. Coercive field dependence on the frequency measurements indicated that the creep regime of domain wall motions dominated till 1 kHz of frequency.

  14. Study on MoO{sub 3-x} films deposited by reactive sputtering for organic light-emitting diodes

    SciTech Connect

    Oka, Nobuto; Watanabe, Hiroki; Sato, Yasushi; Yamaguchi, Hiroshi; Ito, Norihiro; Tsuji, Hiroya; Shigesato, Yuzo

    2010-07-15

    The authors investigate the role of reduced molybdenum trioxide [MoO{sub 3-x} (x{<=}1)] films in organic light-emitting diodes, particularly from the viewpoint of the oxidation state of Mo. MoO{sub 3-x} films were deposited by reactive sputtering under a mixture of argon (Ar) and oxygen (O{sub 2}). The O{sub 2} gas-flow ratio (GFR) [O{sub 2}/(Ar+O{sub 2})] was adjusted between 10% and 100%. Mo with six, five, and four valence electrons was detected in MoO{sub 3-x} film deposited with an O{sub 2} GFR of 10% and 12.5%, whereas, under higher O{sub 2} GFRs, only six valence electrons for Mo in the MoO{sub 3-x} film were detected. N,N{sup '}-di(1-naphthyl)-N,N{sup '}-diphenylbenzidine ({alpha}-NPD) layer, hole-transport material, were deposited over the MoO{sub 3-x} layer by subsequent vacuum evaporation. At the {alpha}-NPD/MoO{sub 3-x} interface, it was found that {alpha}-NPD cations were generated and that MoO{sub 3-x} was reduced, which provided evidence of charge transfer across the interface by Raman spectroscopy and x-ray photoelectron spectroscopy.

  15. Investigations on opto-electronical properties of DC reactive magnetron sputtered zinc aluminum oxide thin films annealed at different temperatures

    NASA Astrophysics Data System (ADS)

    Kumar, B. Rajesh; Rao, T. Subba

    2013-01-01

    In the present study transparent conducting zinc aluminum oxide (ZAO) thin films were prepared by DC reactive magnetron sputtering technique. The films were deposited on glass substrates at 200 °C and annealed from 200 °C to 500 °C. XRD patterns of ZAO films shows (0 0 2) diffraction peak of hexagonal wurtzite, meaning that the films have c-axis orientation perpendicular to the substrate. Crystallite size was calculated from X-ray diffraction (XRD) spectra using the Scherrer formula. The surface morphology of the films was observed by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The electrical conductivity increases with increase of annealing temperature. The activation energies of conduction were obtained from an Arrhenius equation. The best characteristics of ZAO films have been obtained for the films annealed at 400 °C with an average transmittance of 88% and a minimum resistivity of 2.2 × 10-4 Ω cm. The optical band gap, optical constants, and electron concentrations of ZAO films are obtained from UV-vis-IR spectrophotometer data.

  16. Reactive sputter magnetron reactor for preparation of thin films and simultaneous in situ structural study by X-ray diffraction

    SciTech Connect

    Buergi, J.; Molleja, J. Garcia; Feugeas, J.; Neuenschwander, R.; Kellermann, G.; Craievich, A. F.

    2013-01-15

    The purpose of the designed reactor is (i) to obtain polycrystalline and/or amorphous thin films by controlled deposition induced by a reactive sputtering magnetron and (ii) to perform a parallel in situ structural study of the deposited thin films by X-ray diffraction, in real time, during the whole growth process. The designed reactor allows for the control and precise variation of the relevant processing parameters, namely, magnetron target-to-sample distance, dc magnetron voltage, and nature of the gas mixture, gas pressure and temperature of the substrate. On the other hand, the chamber can be used in different X-ray diffraction scanning modes, namely, {theta}-2{theta} scanning, fixed {alpha}-2{theta} scanning, and also low angle techniques such as grazing incidence small angle X-ray scattering and X-ray reflectivity. The chamber was mounted on a standard four-circle diffractometer located in a synchrotron beam line and first used for a preliminary X-ray diffraction analysis of AlN thin films during their growth on the surface of a (100) silicon wafer.

  17. High mobility field effect transistors of SnOx on glass substrates made by reactive sputtering of Sn metal

    NASA Astrophysics Data System (ADS)

    Ju, Chanjong; Park, Chulkwon; Yang, Hyeonseok; Kim, Useong; Kim, Young Mo; Char, Kookrin

    2015-03-01

    We report on the electrical properties of SnOx thin films and the performance of their field effect transistors on glass substrates made by reactive sputtering of a Sn metal target. We investigated the electrical properties of SnOx films as a function of the oxygen pressure. The mobility of the SnOx films on glass substrates after post-deposition annealing at 400 C was as high as 15.3 cm2/Vs while its carrier density was 4.42 × 1018 cm-3. By x-ray diffraction, we have found that the films are mixture of SnO and SnO2 phases, suggesting possibility of further enhancement of the electrical properties if the phase can be controlled. Nevertheless, we will report on the performance of thin film transistors using polycrystalline SnOx as the channel layer and the atomic-layer-deposited AlOx and HfOx as the gate oxide.

  18. Characterization of reactively sputtered molybdenum oxide films for solar cell application

    SciTech Connect

    Simchi, H.; Boyle, J. H.; Shafarman, W. N.; McCandless, B. E.; Meng, T.

    2013-07-07

    Molybdenum oxide (MoO{sub 3}) thin films were prepared via Radio Frequency (RF) sputtering at different ambient composition and post-deposition annealing. The effects on the structural, optical, and surface properties of the deposited films were investigated. The ambient oxygen concentration O{sub 2}/(O{sub 2} + Ar) was varied from 10% to 100% at 10 mTorr. Post deposition anneals were performed in Ar at 300-500 Degree-Sign C. The films were analyzed using glancing incidence x-ray diffraction (GIXRD), UV/Vis/NIR spectrophotometry, and x-ray photoelectron spectroscopy (XPS). As-deposited films have amorphous structures, independent of the oxygen partial pressure. Annealing at 300 Degree-Sign C in air resulted in crystallization of the molybdenum oxide films to the monoclinic {beta}-MoO{sub 3} phase. Samples annealed at 400 and 500 Degree-Sign C were identified as pure orthorhombic {alpha}-MoO{sub 3} phase with (020) preferred orientation. High resolution XPS studies showed the presence of Mo{sup 6+} (MoO{sub 3}) and Mo{sup 5+} (Mo{sub 4}O{sub 11}) oxidation states at the surface of as deposited and low temperature (300 Degree-Sign C) annealed films, and the Mo{sup 6+} to Mo{sup 5+} did not change much with deposition oxygen partial pressure. Annealing at 400-500 Degree-Sign C suppressed the oxygen deficiency at the surface, resulting in films with composition close to stoichiometric phases. UV/Vis/NIR spectrophotometry revealed that all films have a high optical transmittance (>80%) in the visible range, followed by a steep drop at {lambda} Almost-Equal-To 400 nm indicating a strong absorption due to band-to-band transition. Increasing the oxygen partial pressure had no significant effect on optical transmittance of the films, and the bandgaps in the range of 2.6 eV to 2.9 eV were obtained. Annealing at 300 Degree-Sign C had a negligible effect on the optical properties of the MoO{sub 3} films, but samples annealed at 400 Degree-Sign C and 500 Degree-Sign C exhibited

  19. Process monitoring during AlN{sub x}O{sub y} deposition by reactive magnetron sputtering and correlation with the film's properties

    SciTech Connect

    Borges, Joel Vaz, Filipe; Marques, Luis; Martin, Nicolas

    2014-03-15

    In this work, AlN{sub x}O{sub y} thin films were deposited by reactive magnetron sputtering, using an aluminum target and an Ar/(N{sub 2}+O{sub 2}) atmosphere. The direct current magnetron discharge parameters during the deposition process were investigated by optical emission spectroscopy and a plasma floating probe was used. The discharge voltage, the electron temperature, the ion flux, and the optical emission lines were recorded for different reactive gas flows, near the target and close to the substrate. This information was correlated with the structural features of the deposits as a first step in the development of a system to control the structure and properties of the films during reactive magnetron sputtering. As the target becomes poisoned, the discharge voltage suffers an important variation, due to the modification of the secondary electron emission coefficient of the target, which is also supported by the evolution of the electron temperature and ion flux to the target. The sputtering yield of the target was also affected, leading to a reduction of the amount of Al atoms arriving to the substrate, according to optical emission spectroscopy results for Al emission line intensity. This behavior, together with the increase of nonmetallic elements in the films, allowed obtaining different microstructures, over a wide range of compositions, which induced different electrical and optical responses of films.

  20. Composition, structure and properties of SiN x films fabricated by pulsed reactive closed-field unbalanced magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Yao, Zh. Q.; Yang, P.; Huang, N.; Sun, H.; Wan, G. J.; Leng, Y. X.; Chen, J. Y.

    2005-11-01

    Silicon nitride (SiNx) thin films are of special interest in both scientific research and industrial applications due to their remarkable properties such as high thermal stability, chemical inertness, high hardness and good dielectric properties. In this work, SiNx films were fabricated by pulsed reactive closed-field unbalanced magnetron sputtering of high purity single crystal silicon targets in an Ar-N2 mixture. The effect of N2 partial pressure on the film composition, chemical bonding configurations, surface morphology, surface free energy, optical and mechanical properties were investigated. We showed that with increased N2 partial pressure, the N to Si ratio (N/Si) in the film increased and N atoms are preferentially incorporated in the NSi3 stoichiometric configuration. It leads the Si-N network a tendency to chemical order. Films deposited at a high N2 fraction were consistently N-rich. The film surface transformed from a loose granular structure with microporosity to a homogeneous, continuous, smooth and dense structure. A progressive densification of the film microstructure occurs as the N2 fraction is increased. The reduced surface roughness and the increased N incorporation in the film give rise to the increased contact angle with double-distilled water from 24° to 49.6°. To some extent, the SiNx films deposited by pulsed magnetron sputtering are hydrophilic in nature. The as-deposited SiNx films exhibit good optical transparency in the visible region and the optical band gap Eopt can be varied from 1.68 eV for a-Si to 3.62 eV for SiNx films, depending on the synthesis parameters. With the increase of the N/Si atomic ratio, wear resistance of the SiNx films was improved, a consequence of increased hardness and elastic modulus. The SiNx films have lower friction coefficient and better wear resistance than 316L stainless steel under dry sliding friction, where the SiNx films experienced only fatigue wear.

  1. Influence of stress in ZnO thin films on its biosensing application.

    PubMed

    Saha, Shibu; Tomar, Monika; Gupta, Vinay

    2015-11-01

    Highly c-axis oriented zinc oxide (ZnO) thin films deposited by radio frequency (RF) magnetron sputtering, under varying ambient atmosphere (oxygen and argon reactive gas mixture), were studied for biosensing application. The as-grown ZnO thin films were found to be under compressive stress. Glucose oxidase was chosen as model enzyme for studying biosensing response properties of the ZnO thin films. The present study reveals a good correlation between stress induced during thin film growth and its biosensing response characteristic. The bio-electrodes based on ZnO thin films which are under the influence of higher stress, show better sensitivity and higher enzyme loading along with a prolonged shelf life. The study highlights the importance of physical properties of thin film matrix on its biosensing application. PMID:26320716

  2. Dopant source choice for formation of p-type ZnO: Li acceptor

    NASA Astrophysics Data System (ADS)

    Zeng, Y. J.; Ye, Z. Z.; Xu, W. Z.; Li, D. Y.; Lu, J. G.; Zhu, L. P.; Zhao, B. H.

    2006-02-01

    Li-doped, p-type ZnO thin films have been realized via dc reactive magnetron sputtering. An optimized result with a resistivity of 16.4Ωcm, Hall mobility of 2.65cm2/Vs, and hole concentration of 1.44×1017cm-3 was achieved, and electrically stable over a month. Hall-effect measurements supported by secondary ion mass spectroscopy indicated that the substrate temperature played a key role in optimizing the p-type conduction of Li-doped ZnO thin films. Furthermore, ZnO-based p-n homojunction was fabricated by deposition of a Li-doped p-type ZnO layer on an Al-doped n-type ZnO layer.

  3. Realization of p-type ZnO films via monodoping of Li acceptor

    NASA Astrophysics Data System (ADS)

    Zeng, Yu-Jia; Ye, Zhi-Zhen; Xu, Wei-Zhong; Chen, Lan-Lan; Li, Dan-Ying; Zhu, Li-Ping; Zhao, Bing-Hui; Hu, Ying-Lin

    2005-09-01

    p-Type ZnO thin films have been realized via monodoping of Li acceptor by adopting DC reactive magnetron sputtering. The lowest room-temperature resistivity was found to be 17.6 Ω cm with a Hall mobility of 3.47 cm2 V-1 s-1 and carrier concentration of 1.01×1017 cm-3 for Li-doped p-type ZnO film deposited on glass substrate. The Li-doped ZnO film possessed a good crystallinity with c-axis orientation and a high transmittance (90%) in the visible region. Moreover, the effects of Li content on the crystallinity, electrical and optical properties of p-type ZnO films were discussed.

  4. Low-temperature deposition of low resistivity ZnSe films by reactive sputtering

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.; Nouhi, A.

    1986-01-01

    The use of reactive dc magnetron cosputtering of Zn and the dopant In in an H2Se/Ar gaseous mixture is described. It is observed that initial deposition using pure Zn targets produced yellowish transparent ZnSe films on glass with a film resistivity of 10 to the 8th ohms cm and deposition using a Zn target doped with a fixed 1 percent of In produced ZnSe films with resistivities of about 10,000 ohms cm. The improvement of film conductivity by optimizing the In content in the ZnSe films is discussed; the ZnSe resistivity dependence on In flux is studied. Optical absorption/transmission measurements reveal a photon energy band gap of 2.65 eV at room temperature and X-ray diffraction show highly oriented polycrystalline films on glass with the c axis parallel to the plane of the film. Compositional analysis was performed and the Zn/Se ratio is measure as 48.8/49.0 with an In concentration of 1.16 percent. ZnSe films deposited on glass and conducting SnO2-coated glass substrates with a resistance of 20 ohms cm and a substrate temperature of 120 C have been fabricated.

  5. ZrO2-ZnO composite thin films for humidity sensing

    NASA Astrophysics Data System (ADS)

    Velumani, M.; Meher, S. R.; Balakrishnan, L.; Sivacoumar, R.; Alex, Z. C.

    2016-05-01

    ZrO2-ZnO composite thin films were grown by reactive DC magnetron sputtering. X-ray diffraction studies reveal the composite nature of the films with separate ZnO and ZrO2 phase. Scanning electron microscopy studies confirm the nanocrystalline structure of the films. The films were studied for their impedometric relative humidity (RH) sensing characteristics. The complex impedance plot was fitted with a standard equivalent circuit consisting of an inter-granular resistance and a capacitance in parallel. The DC resistance was found to be decreasing with increase in RH.

  6. Influence of oxygen flow rate on the structural, optical and electrical properties of ZnO films grown by DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gobbiner, Chaya Ravi; Ali Avanee Veedu, Muhammed; Kekuda, Dhananjaya

    2016-04-01

    Zinc oxide thin films were deposited on glass substrates at different oxygen flow rates by DC reactive magnetron sputtering. The oxygen flow rate was found to be one of the crucial parameters which influence structural, optical and electrical properties of grown films. The structural and optical characterization of the deposited films was carried out using X-ray diffraction and UV-visible spectroscopy, respectively. Swanepoel envelope and Drude-Lorentz (DL) models were applied to extract the optoelectronic parameters such as refractive index, dispersion energy and plasma frequency. Structurally, grain size was found to decrease with increase in oxygen flow rate during deposition. Moreover, all the films exhibited preferred (002) orientation confirming c-axis orientation of the films perpendicular to the substrate. For a particular range of oxygen flow rates, columnar growth was achieved. Marginal increase in the optical band gap from 3.14 to 3.22 eV was observed as the oxygen flow rate increased from 3 to 10 sccm. Calculated plasma frequency from the DL model was found to be in the infrared region. It has decreased as oxygen flow rate increased with the value from 1.625 × 1014 rad/s (862 cm-1) to 1.072 × 1014 rad/s (568 cm-1).

  7. Polarity Effects of Substrate Surface in Epitaxial ZnO Film Growth

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, C.-H.; Lehoczky, S. L.; Harris, M. T.; Callahan, M. J.; George, M. A.; McCarty, P.

    1999-01-01

    Epitaxial ZnO films were grown on the two polar surfaces (0-face and Zn-face) of (0001) ZnO single crystal substrates using off-axis magnetron sputtering deposition. As a comparison, films are also deposited on the (000 I) Al203 substrates. It is found that the two polar surfaces have different photoluminescence (PL) spectrum, surface structure and morphology, which are strongly inference the epitaxial film growth. The morphology and structure of epitaxial films on the ZnO substrates are different from the film on the Al203 substrates. An interesting result shows that high temperature annealing of ZnO single crystals will improve the surface structure on the O-face surface rather than the opposite Surface. The measurements of PL, low-angle incident x-ray diffraction, and atomic force microscopy of ZnO films indicate that the O-terminated surface is better for ZnO epitaxial film growth using reactive sputtering deposition.

  8. Visible-light active thin-film WO{sub 3} photocatalyst with controlled high-rate deposition by low-damage reactive-gas-flow sputtering

    SciTech Connect

    Oka, Nobuto Murata, Akiyo; Nakamura, Shin-ichi; Jia, Junjun; Shigesato, Yuzo; Iwabuchi, Yoshinori; Kotsubo, Hidefumi

    2015-10-01

    A process based on reactive gas flow sputtering (GFS) for depositing visible-light active photocatalytic WO{sub 3} films at high deposition rates and with high film quality was successfully demonstrated. The deposition rate for this process was over 10 times higher than that achieved by the conventional sputtering process and the process was highly stable. Furthermore, Pt nanoparticle-loaded WO{sub 3} films deposited by the GFS process exhibited much higher photocatalytic activity than those deposited by conventional sputtering, where the photocatalytic activity was evaluated by the extent of decomposition of CH{sub 3}CHO under visible light irradiation. The decomposition time for 60 ppm of CH{sub 3}CHO was 7.5 times more rapid on the films deposited by the GFS process than on the films deposited by the conventional process. During GFS deposition, there are no high-energy particles bombarding the growing film surface, whereas the bombardment of the surface with high-energy particles is a key feature of conventional sputtering. Hence, the WO{sub 3} films deposited by GFS should be of higher quality, with fewer structural defects, which would lead to a decrease in the number of centers for electron-hole recombination and to the efficient use of photogenerated holes for the decomposition of CH{sub 3}CHO.

  9. Visible-light active thin-film WO3 photocatalyst with controlled high-rate deposition by low-damage reactive-gas-flow sputtering

    NASA Astrophysics Data System (ADS)

    Oka, Nobuto; Murata, Akiyo; Nakamura, Shin-ichi; Jia, Junjun; Iwabuchi, Yoshinori; Kotsubo, Hidefumi; Shigesato, Yuzo

    2015-10-01

    A process based on reactive gas flow sputtering (GFS) for depositing visible-light active photocatalytic WO3 films at high deposition rates and with high film quality was successfully demonstrated. The deposition rate for this process was over 10 times higher than that achieved by the conventional sputtering process and the process was highly stable. Furthermore, Pt nanoparticle-loaded WO3 films deposited by the GFS process exhibited much higher photocatalytic activity than those deposited by conventional sputtering, where the photocatalytic activity was evaluated by the extent of decomposition of CH3CHO under visible light irradiation. The decomposition time for 60 ppm of CH3CHO was 7.5 times more rapid on the films deposited by the GFS process than on the films deposited by the conventional process. During GFS deposition, there are no high-energy particles bombarding the growing film surface, whereas the bombardment of the surface with high-energy particles is a key feature of conventional sputtering. Hence, the WO3 films deposited by GFS should be of higher quality, with fewer structural defects, which would lead to a decrease in the number of centers for electron-hole recombination and to the efficient use of photogenerated holes for the decomposition of CH3CHO.

  10. A Study on the Adhesion Properties of Reactive Sputtered Molybdenum Thin Films with Nitrogen Gas on Polyimide Substrate as a Cu Barrier Layer.

    PubMed

    Kim, Hong Sik; Kim, Byoung O; Seo, Jong Hyun

    2015-11-01

    NiCr, Mo, and Mo-N thin copper diffusion barrier films are deposited on 200 um thick polyimide films spin-coated on glass substrates by dc reactive magnetron sputtering. The adhesion forces for three systems are measured by micro-scratch test analysis depending on oxygen plasma pretreatment, sputtering power density, moisture contents, and post annealing treatment. The values of adhesion forces for the three systems are linearly proportional to the oxygen plasma treatment time. As deposition power density increases, measured adhesion forces also increase. The existence of moisture adsorbed in the polymer substrate prior to initiating the sputtering process significantly reduces the adhesion force for all systems. Post annealing treatment at 150 degrees C for 12 hours after sputtering also deteriorates the adhesion between the barrier films and polymer substrate. Auger electron spectroscopy reveals that adhesion forces are significantly dependent on the types of compounds formed at the barrier layer/polymer interface. Changes in the adhesion properties of the MoN system as a function of the nitrogen content are explained in terms of the mechanical stability of the MoN(x)O(y) interface layer on the polymer substrate. PMID:26726588

  11. Phase map, composition and resistivity of reactively magnetron sputtered and annealed Ta–N films

    NASA Astrophysics Data System (ADS)

    Salamon, K.; Radić, N.; Bogdanović Radović, I.; Očko, M.

    2016-05-01

    Thin films of tantalum nitride (Ta–N) have been prepared by reactive magnetron deposition under various nitrogen partial pressures p{{\\text{N}}2} (0-1) and subsequently annealed (T a   =  450–950 °C). The structure, density, composition and electrical resistivity of the prepared films were systematically investigated. A p{{\\text{N}}2}-{{T}a} phase map was constructed from the results of structural analysis. With increasing of p{{\\text{N}}2} from 0 to 0.2, a single-phase or two-phase mixture films of tetragonal Ta, Ta2N ({{T}a}≥slant 450 °C), ɛ-TaN ({{T}a}≥slant 850 °C), θ-TaN ({{T}a}≥slant 850 °C) and fcc δ-TaN are sequentially observed. For p{{\\text{N}}2}=0.25 –0.45, the as grown and annealed films exhibit δ-TaN structure. Amorphous films grown in the p{{\\text{N}}2}=0.45 –0.75 range crystallize as cubic Ta2N3 upon annealing at {{T}a}≥slant 650 °C or as δ-TaN at {{T}a}≥slant 850 °C. A cubic Ta2N3 is grown at highest p{{\\text{N}}2} (≥slant 0.85), which decomposes to δ-TaN at {{T}a}≥slant 850 °C. The N     / Ta atomic ratio in the film linearly increases for p{{\\text{N}}2}=0 –0.5, ranging from 0 to 2.1, while the mass density monotonically decreases with p{{\\text{N}}2} . Upon annealing, a part of N atoms out-diffuses from the films deposited at p{{\\text{N}}2}≥slant 0.3 . The electrical resistivity strongly depends on both p{{\\text{N}}2} and T a . However, in the as grown and annealed δ-TaN films the resistivity was of the order of 100–1000 μ Ω cm. In these films, a correlation between the resistivity and the average number of defects (Ta vacancies and N atom excess) is observed. Finally, the influence of thermally introduced oxygen on the films resistivity has been revealed.

  12. Reproducible resistive switching in nonstoichiometric nickel oxide films grown by rf reactive sputtering for resistive random access memory applications

    SciTech Connect

    Park, Jae-Wan; Park, Jong-Wan; Kim, Dal-Young; Lee, Jeon-Kook

    2005-09-15

    Ni{sub 1-{delta}}O binary oxide films were deposited on Pt/Ti/SiO{sub 2}/Si substrates by radio-frequency reactive magnetron sputtering. The NiO-based metal-oxide-metal structures were fabricated for measurement of electrical properties. The electrical properties of the Pt/Ni{sub 1-{delta}}O/Pt structure as a function of growth temperature were investigated. The growth temperature was varied from room temperature to 400 deg. C. From all samples, negative resistance phenomenon and nonvolatile memory switching behavior were observed. The ratios between the high-resistance state (OFF state) and the low-resistance state (ON state) were larger than. 10{sup 2}. As the growth temperature was increased, both SET and RESET voltages increased due to the decrease of defects in nickel oxide films. On the basis of x-ray diffraction patterns, we confirmed that the defects in Ni{sub 1-{delta}}O film decreased with increasing the growth temperature due to sufficient diffusion and redistribution of adatoms. X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy analysis revealed that the nickel oxide films were Ni deficient and that Ni had three different Ni bond states caused by various defects in nickel oxide films. In order to investigate the influence of the upper limit of SET current (i.e., Compliance SET current), the compliance SET current was varied from 1 to 50 mA. This result showed that the ON-state current and the RESET voltage were strongly dependent on the magnitude of the compliance SET current. As the compliance SET current was increased, both the ON-state current and the RESET voltage increased due to the increase of the conducting path. The results suggest that the resistance switching behavior is related to the formation and fracture of the conducting path which is composed of defects in the nickel oxide film.

  13. High-rate deposition of MgO by reactive ac pulsed magnetron sputtering in the transition mode

    SciTech Connect

    Kupfer, H.; Kleinhempel, R.; Richter, F.; Peters, C.; Krause, U.; Kopte, T.; Cheng, Y.

    2006-01-15

    A reactive ac pulsed dual magnetron sputtering process for MgO thin-film deposition was equipped with a closed-loop control of the oxygen flow rate (F{sub O2}) using the 285 nm magnesium radiation as input. Owing to this control, most of the unstable part of the partial pressure versus flowrate curve became accessible. The process worked steadily and reproducible without arcing. A dynamic deposition rate of up to 35 nm m/min could be achieved, which was higher than in the oxide mode by about a factor of 18. Both process characteristics and film properties were investigated in this work in dependence on the oxygen flow, i.e., in dependence on the particular point within the transition region where the process is operated. The films had very low extinction coefficients (<5x10{sup -5}) and refractive indices close to the bulk value. They were nearly stoichiometric with a slight oxygen surplus (Mg/O=48/52) which was independent of the oxygen flow. X-ray diffraction revealed a prevailing (111) orientation. Provided that appropriate rf plasma etching was performed prior to deposition, no other than the (111) peak could be detected. The intensity of this peak increased with increasing F{sub O{sub 2}}, indicating an even more pronounced (111) texture. The ion-induced secondary electron emission coefficient (iSEEC) was distinctly correlated with the markedness of the (111) preferential orientation. Both refractive index and (111) preferred orientation (which determines the iSEEC) were found to be improved in comparison with the MgO growth in the fully oxide mode. Consequently, working in the transition mode is superior to the oxide mode not only with respect to the growth rate, but also to most important film properties.

  14. Niobium sputtered Havar foils for the high-power production of reactive [18F]fluoride by proton irradiation of [18O]H2O targets.

    PubMed

    Wilson, J S; Avila-Rodriguez, M A; Johnson, R R; Zyuzin, A; McQuarrie, S A

    2008-05-01

    Niobium sputtered Havar entrance foils were used for the production of reactive [(18)F]fluoride by proton irradiation of [(18)O]H(2)O targets under pressurized conditions. The synthesis yield in the routine production of 2-[(18)F]fluoro-2-deoxy-glucose (FDG) was used as an indicative parameter of the reactivity of (18)F. The yield of FDG obtained with (18)F produced in a target with Havar foil was used as a baseline. No statistically significant difference was found in the saturated yields of (18)F when using Havar or Havar-Nb sputtered entrance foils. However, the amount of long-lived radionuclidic impurities decreased more than 10-fold using the Havar-Nb entrance foil. The average decay corrected synthesis yield of FDG, evaluated over a period of more than 2 years, was found to be approximately 5% higher when using a Havar-Nb entrance foil and a marked improvement on the FDG yield consistency was noted. In addition, the frequency of target rebuilding was greatly diminished when using the Nb sputtered entrance foil. PMID:18242099

  15. Process controllability of inductively coupled plasma-enhanced reactive sputter deposition for the fabrication of amorphous InGaZnOx channel thin-film transistors

    NASA Astrophysics Data System (ADS)

    Takenaka, Kosuke; Nakata, Keitaro; Otani, Hirofumi; Osaki, Soichiro; Uchida, Giichiro; Setsuhara, Yuichi

    2016-01-01

    The process controllability of inductively coupled plasma-enhanced reactive sputter deposition for the fabrication of amorphous InGaZnOx (a-IGZO) channel thin-film transistors (TFTs) was investigated. a-IGZO film deposition with the addition of H2 gas was performed using a plasma-assisted reactive sputtering system to control the oxidation process during a-IGZO film formation by balancing the oxidation and reduction reactions. Optical emission spectroscopy measurements indicate the possibility for the oxidation reaction to be inhibited by a decrease in the density of oxygen atoms and the reduction effect of hydrogen during a-IGZO film deposition due to the addition of H2 gas. The characteristics of TFTs fabricated using a-IGZO films deposited with a plasma-enhanced magnetron sputtering deposition system were investigated. The results indicate the possibility of expanding the process window by controlling the balance between oxidation and reduction with the addition of H2 gas. TFTs with a-IGZO films that were deposited with the addition of H2 gas exhibited good performance with a field-effect mobility (μFE) of 15.3 cm2 V-1 s-1 and a subthreshold gate voltage swing (S) of 0.48 V decade-1.

  16. Preliminary results on CuInSe2/ZnSe solar cells using reactively sputter-deposited ZnSe

    NASA Technical Reports Server (NTRS)

    Nouhi, A.; Stirn, R. J.

    1987-01-01

    In this paper preliminary results on CuInSe2/ZnSe thin film heterojunction photovoltaic devices are presented. High-conductivity ZnSe films were reactively sutter-deposited onto CuInSe2 films and overcoated with ZnO to reduce the sheet resistance. The highest short-circuit current density, as determined from a spectral response weighted for air mass 1.5 global insolation, was 37.4 mA/sq cm. The highest pen-circuit voltage observed was 430 mV.

  17. Correlation between Microstructure and Mechanical Properties ofTiC Films Produced by Vacuum arc Deposition and Reactive MagnetronSputtering

    SciTech Connect

    Monteiro, O.R.; Delplancke-Ogletree, M.P.; Winand, R.; Brown, I.G.

    1999-07-29

    We have studied the synthesis of TiC films by vacuum arc deposition and reactive magnetron sputtering over a wide range of compositions. The films were deposited on silicon and tool steel. The films were characterized by various techniques: Auger electron and X-ray photoelectron spectroscopies, Rutherford backscattering, transmission electron diffraction and X-ray diffraction. Mechanical properties such as stress, adhesion, friction coefficient and wear resistance were obtained by carrying measurements of the curvature of the silicon substrate, pull tests, and ball-on-disk tests, respectively.

  18. Deposition and characterization of zirconium nitride (ZrN) thin films by reactive magnetron sputtering with linear gas ion source and bias voltage

    SciTech Connect

    Kavitha, A.; Kannan, R.; Subramanian, N. Sankara; Loganathan, S.

    2014-04-24

    Zirconium nitride thin films have been prepared on stainless steel substrate (304L grade) by reactive cylindrical magnetron sputtering method with Gas Ion Source (GIS) and bias voltage using optimized coating parameters. The structure and surface morphologies of the ZrN films were characterized using X-ray diffraction, atomic microscopy and scanning electron microscopy. The adhesion property of ZrN thin film has been increased due to the GIS. The coating exhibits better adhesion strength up to 10 N whereas the ZrN thin film with bias voltage exhibits adhesion up to 500 mN.

  19. Growth and characterization of TiAlN/CrAlN superlattices prepared by reactive direct current magnetron sputtering

    SciTech Connect

    Barshilia, Harish C.; Deepthi, B.; Rajam, K. S.; Bhatti, Kanwal Preet; Chaudhary, Sujeet

    2009-01-15

    TiAlN and CrAlN coatings were prepared using a reactive direct current magnetron sputtering system from TiAl and CrAl targets. Structural characterization of the coatings using x-ray diffraction (XRD) revealed the B1 NaCl structure of TiAlN and CrAlN coatings with a prominent reflection along the (111) plane. The XPS data confirmed the bonding structures of TiAlN and CrAlN single layer coatings. Subsequently, nanolayered multilayer coatings of TiAlN/CrAlN were deposited on silicon and mild steel (MS) substrates at different modulation wavelengths ({lambda}) with a total thickness of approximately 1.0 {mu}m. The modulation wavelengths were calculated from the x-ray reflectivity data using modified Bragg's law. TiAlN/CrAlN multilayer coatings were textured along (111) for {lambda}<200 A and the XRD patterns showed the formation of superlattice structure for coatings deposited at {lambda}=102 A. The x-ray reflectivity data showed reflections of fifth and seventh orders for multilayer coatings deposited at {lambda}=102 and 138 A, respectively, indicating the formation of sharp interfaces between TiAlN and CrAlN layers. The cross-sectional scanning electron microscopy image of TiAlN/CrAlN multilayer coatings indicated a noncolumnar and dense microstructure. A maximum hardness of 39 GPa was observed for TiAlN/CrAlN multilayer coatings deposited at {lambda}=93 A, which was higher than the rule-of-mixture value (30 GPa) for TiAlN and CrAlN. Study of thermal stability of the coatings in air using micro-Raman spectroscopy indicated that the TiAlN/CrAlN multilayer coatings were stable up to 900 deg. C in air. TiAlN/CrAlN multilayer coatings also exhibited improved corrosion resistance when compared to the MS substrate.

  20. Co and Cu co-doped ZnO epitaxial films—A magnetically soft nano-composite

    NASA Astrophysics Data System (ADS)

    Ney, V.; Venkataraman, V.; Henne, B.; Ollefs, K.; Wilhelm, F.; Rogalev, A.; Ney, A.

    2016-04-01

    A series of Co/Cu co-doped ZnO epitaxial films has been grown on sapphire substrates to investigate the possibilities of tailoring the magnetic properties in functional ZnO-Co/Cu nano-composites. The growth was performed using reactive magnetron sputtering varying the oxygen partial pressure to tune the incorporation of the dopants and the resulting valence state. At high oxygen pressures, Co2+ is formed and the resulting magnetic properties are very similar to phase pure paramagnetic Co-doped ZnO samples. However, the formation of a secondary CuO phase reduces the overall structural quality of the layers and virtually no substitutional incorporation of Cu2+ in ZnO could be evidenced. At low oxygen pressures, a significant fraction of metallic Co and Cu forming nanometer-sized superparamagnetic precipitates of a Co/Cu alloy can be evidenced which are embedded in a ZnO host matrix.

  1. Properties of reactively sputtered oxygenated cadmium sulfide (CdS:O) and their impact on CdTe solar cell performance

    SciTech Connect

    Meysing, Daniel M. Wolden, Colin A.; Griffith, Michelle M.; Mahabaduge, Hasitha; Pankow, Joel; Reese, Matthew O.; Burst, James M.; Rance, William L.; Barnes, Teresa M.

    2015-03-15

    Oxygenated cadmium sulfide (CdS:O) is commonly used as the n-type window layer in high-performance CdTe heterojunction solar cells. This layer is deposited by reactive sputtering, but the optimal amount of oxygen in the sputtering ambient is highly dependent on the specific system and process employed. In this work, the intrinsic properties of CdS:O were measured as a function of the oxygen content (0%–10%) in the sputtering ambient and correlated to device performance with the goal of better defining optimal CdS:O properties for CdTe solar cells. Optimal performance was found using CdS:O films that contained ∼40 at. % oxygen as measured by Rutherford backscattering spectrometry. X-ray photoelectron spectroscopy confirmed these results and showed that oxygen is incorporated primarily as oxygenated sulfur compounds (SO{sub x}). Device efficiency improved from 10.5% using CdS to >14% with CdS:O due largely to increases in short-circuit current density as well as a modest improvement in open-circuit voltage. The transparency of the CdS:O films was well correlated with observed improvements in blue quantum efficiency with increasing oxygen content. The optical bandgap of as-deposited CdS:O was identified as a simple metric for process optimization and transfer, with 2.8 eV being ideal for the device architecture employed.

  2. Combined optical emission and resonant absorption diagnostics of an Ar-O2-Ce-reactive magnetron sputtering discharge

    NASA Astrophysics Data System (ADS)

    El Mel, A. A.; Ershov, S.; Britun, N.; Ricard, A.; Konstantinidis, S.; Snyders, R.

    2015-01-01

    We report the results on combined optical characterization of Ar-O2-Ce magnetron sputtering discharges by optical emission and resonant absorption spectroscopy. In this study, a DC magnetron sputtering system equipped with a movable planar magnetron source with a Ce target is used. The intensities of Ar, O, and Ce emission lines, as well as the absolute densities of Ar metastable and Ce ground state atoms are analyzed as a function of the distance from the magnetron target, applied DC power, O2 content, etc. The absolute number density of the Arm is found to decrease exponentially as a function of the target-to-substrate distance. The rate of this decrease is dependent on the sputtering regime, which should be due to the different collisional quenching rates of Arm by O2 molecules at different oxygen contents. Quantitatively, the absolute number density of Arm is found to be equal to ≈ 3 × 108 cm- 3 in the metallic, and ≈ 5 × 107 cm- 3 in the oxidized regime of sputtering, whereas Ce ground state densities at the similar conditions are found to be few times lower. The absolute densities of species are consistent with the corresponding deposition rates, which decrease sharply during the transition from metallic to poisoned sputtering regime.

  3. Growth of residual stress-free ZnO films on SiO2/Si substrate at room temperature for MEMS devices

    NASA Astrophysics Data System (ADS)

    Singh, Jitendra; Ranwa, Sapana; Akhtar, Jamil; Kumar, Mahesh

    2015-06-01

    ZnO thick Stress relaxed films were deposited by reactive magnetron sputtering on 2"-wafer of SiO2/Si at room temperature. The residual stress of ZnO films was measured by measuring the curvature of wafer using laser scanning method and found in the range of 0.18 x 109 to 11.28 x 109 dyne/cm2 with compressive in nature. Sputter pressure changes the deposition rates, which strongly affects the residual stress and surface morphologies of ZnO films. The crystalline wurtzite structure of ZnO films were confirmed by X-ray diffraction and a shift in (0002) diffraction peak of ZnO towards lower 2θ angle was observed with increasing the compressive stress in the films. The band gap of ZnO films shows a red shift from ˜3.275 eV to ˜3.23 eV as compressive stress is increased, unlike the stress for III-nitride materials. A relationship between stress and band gap of ZnO was derived and proposed. The stress-free growth of piezoelectric films is very important for functional devices applications.

  4. Growth of residual stress-free ZnO films on SiO{sub 2}/Si substrate at room temperature for MEMS devices

    SciTech Connect

    Singh, Jitendra; Akhtar, Jamil; Ranwa, Sapana; Kumar, Mahesh

    2015-06-15

    ZnO thick Stress relaxed films were deposited by reactive magnetron sputtering on 2”-wafer of SiO{sub 2}/Si at room temperature. The residual stress of ZnO films was measured by measuring the curvature of wafer using laser scanning method and found in the range of 0.18 x 10{sup 9} to 11.28 x 10{sup 9} dyne/cm{sup 2} with compressive in nature. Sputter pressure changes the deposition rates, which strongly affects the residual stress and surface morphologies of ZnO films. The crystalline wurtzite structure of ZnO films were confirmed by X-ray diffraction and a shift in (0002) diffraction peak of ZnO towards lower 2θ angle was observed with increasing the compressive stress in the films. The band gap of ZnO films shows a red shift from ∼3.275 eV to ∼3.23 eV as compressive stress is increased, unlike the stress for III-nitride materials. A relationship between stress and band gap of ZnO was derived and proposed. The stress-free growth of piezoelectric films is very important for functional devices applications.

  5. Electrical properties of Mg x Zn1- x O thin films deposited by using RF magnetron co-sputtering with ZnO and Mg0.3Zn0.7O targets

    NASA Astrophysics Data System (ADS)

    Yue, Li Li; Yang, Yi Da; Kim, Hong Seung; Jang, Nak Won; Yun, Young

    2016-03-01

    We successfully deposited hexagonal wurtzite Mg x Zn1- x O (0 ≤ x ≤ 0.18) films on Si substrates by using RF magnetron co-sputtering with ZnO and Mg0.3Zn0.7O targets. The Mg content was varied by controlling the RF power of the Mg0.3Zn0.7O target while the RF power of the ZnO target was fixed at 100 W. The electrical properties of the Mg x Zn1- x O films were investigated by using a transmission line model (TLM) with Ti/Au electrode and Hall effect measurements. The X-ray diffraction (XRD) results demonstrate that some Zn atoms can be replaced by Mg atoms in the Mg x Zn1- x O films. As the Mg content was increased from 0 at.% to 18 at.%, the resistivity of Mg x Zn1- x O films increased and the carrier concentration decreased from 1.17 × 1019 cm-3 to 1.17 × 1017 cm-3, which indicates a decrease in the number of oxygen vacancies. Meanwhile, the Hall mobility increased to 15.3 cm2/Vs. The electrical properties of Mg x Zn1- x O films were tuned by using the Mg content.

  6. Titanium Aluminum Nitride Films Deposited by AC Reactive Magnetron Sputtering: Study of Positioning Effect in an Inverted Cylindrical Magnetron Sputtering System

    NASA Astrophysics Data System (ADS)

    Vandross, George Clinton, II

    TiAlN films were deposited on glass substrates by AC magnetron sputtering at 2 kW with constant Argon and Nitrogen gas flow rates to study the effects of positioning on the deposited films. The deposition system used was an ICM-10 IsoFlux cylindrical magnetron sputtering chamber. The samples were placed in different positions and tilts with respect to the location of the Titanium and Aluminum targets in the chamber. It was found that with change in position and application of tilts, deposited films acquired different physical and chemical properties. It is believed that the differences in these properties were caused by to the change in the incident angle of bombardment of the samples, and the change in surface areas of the samples presented to the targets at each location. As related to the physical traits of the samples, analysis using Scanning Electron Microscopy of the samples displayed variations in the topography, where differences in grain density could be noted as well as structure formations. The chemical properties were also noted to be affected by the variation of tilt and position applied to the sample. X-ray Diffraction Spectroscopy analysis of the samples showed the intensity of the TiAlN characteristic peak of the samples to differ from sample to sample. Results from the XRD analysis of this work showed a 157% and 176% increase in peak intensity of the 0° tilt sample of the Bottom Plate from the 45° tilt sample and 60° tilt sample respectively of the same plate. The results from the XRD analysis of this work also showed a 74% and 151% increase of the peak intensity for the 0° tilt sample of the Middle Plate when compared to the 45° tilt sample and 60° tilt sample respectively of the same plate. Whereas results for this work showed a 54% and 41% decrease in peak intensity of the 0° tilt sample of the Top Plate from the 45° tilt sample and 60° tilt sample respectively of the same plate. Energy Dispersive X-ray Spectroscopy was also performed

  7. Compositional, morphological and mechanical investigations of monolayer type coatings obtained by standard and reactive magnetron sputtering from Ti, TiB2 and WC

    NASA Astrophysics Data System (ADS)

    Jinga, V.; Mateescu, A. O.; Cristea, D.; Mateescu, G.; Burducea, I.; Ionescu, C.; Crăciun, L. S.; Ghiuţă, I.; Samoilă, C.; Ursuţiu, D.; Munteanu, D.

    2015-12-01

    The purpose of this work was to study new composite coatings that would have wear resistant properties. The coatings were obtained by standard and reactive simultaneous magnetron sputtering from three targets (Ti, TiB2, WC) with or without N2 as reactive gas. The chemical composition of the coatings was investigated by Rutherford backscattering spectrometry, while the morphological features were evaluated by atomic force microscopy. Some of the mechanical properties of the coatings, such as hardness and Young's modulus, were investigated by nanoindentation, while the adherence to the substrate was investigated by scratch tests. The wear resistance and friction coefficients were evaluated using a pin-on-disk tribometer. The films are hard (Hit between 20 and 22 GPa) and show promising results concerning their wear resistance, especially if the films would be paired with an appropriate substrate material.

  8. Reactive magnetron sputtering of highly (001)-textured WS2-x films: Influence of Ne+, Ar+ and Xe+ ion bombardment on the film growth

    NASA Astrophysics Data System (ADS)

    Ellmer, K.; Seeger, S.; Sieber, I.; Bohne, W.; Röhrich, J.; Strub, E.; Mientus, R.

    2006-02-01

    Tungsten disulfide WS2 is a layer-type semi-conductor with an energy band gap and an absorption coefficient making it suitable as an absorber for thin film solar cells. In the article [1] WS2-x films were pre-pared by reactive magnetron sputtering from a metallic tungsten target in Ar-H2S atmospheres.The cover figure shows in situ energy-dispersive X-ray diffraction patterns for films deposited at different substrate potentials, i.e. for deposition conditions with ion assistance at different ion energies. These spectra and the corresponding SEM photographs of the film morphology show the strong influence of the ion energy on the film growth. The crystallographic struc-ture of WS2-x is shown between the two SEM pictures.The first author, Klaus Ellmer, is working at the Hahn-Meitner-Institut Berlin, Dept. of Solar Energy Research. His research fields are thin film deposition by reactive magnetron sputtering for solar cells, plasma characterization, in situ energy-dispersive X-ray diffraction and electronic transport in transpar-ent conductive oxides.

  9. Preparation of hydrogenated diamond-like carbon films by reactive Ar/CH4 high power impulse magnetron sputtering with negative pulse voltage

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2015-09-01

    High power impulse magnetron sputtering (HiPIMS) has been attracted, because sputtered target species are highly ionized. High densities of active species such as radical ions and neutral radicals can be also achieved owing to high density reactive HiPIMS plasmas. We investigate properties of hydrogenated diamond-like carbon films prepared by reactive HiPIMS of Ar/CH4 gas mixture. The properties of the films strongly depend on the plasma compositions and the kinetic energy of the carbon-containing ions which can enter into the films. The film preparation is performed at an average power of 60 W and a repetition frequency of 110 Hz, changing CH4 fraction up to 15%. Total pressure ranges between 0.3 and 2 Pa. The maximum of instantaneous power is about 20-25 kW, and the magnitude of the current is 36 A. A negative pulse voltage is applied to the substrates for about 10 μs after the target voltage changed from about -600 V to 0 V. The structural properties are characterized by Raman spectroscopy and nano-indentation method. Film hardness strongly depends on the magnitude of negative pulse voltage. By adjusting the magnitude of negative voltage, the film hardness ranges between about 10 and 22 GPa. This work is partially supported by JSPS KAKENHI Grant Number 26420230.

  10. Spectroscopic ellipsometry and x-ray photoelectron spectroscopy of La{sub 2}O{sub 3} thin films deposited by reactive magnetron sputtering

    SciTech Connect

    Atuchin, V. V.; Kalinkin, A. V.; Kochubey, V. A.; Kruchinin, V. N.; Vemuri, R. S.; Ramana, C. V.

    2011-03-15

    Lanthanum oxide (La{sub 2}O{sub 3}) films were grown by the reactive dc magnetron sputtering and studied their structural, chemical and optical parameters. La{sub 2}O{sub 3} films were deposited onto Si substrates by sputtering La-metal in a reactive gas (Ar+O{sub 2}) mixture at a substrate temperature of 200 deg. C Reflection high-energy electron diffraction measurements confirm the amorphous state of La{sub 2}O{sub 3} films. Chemical analysis of the top-surface layers evaluated with x-ray photoelectron spectroscopy indicates the presence of a layer modified by hydroxylation due to interaction with atmosphere. Optical parameters of a-La{sub 2}O{sub 3} were determined with spectroscopic ellipsometry (SE). There is no optical absorption over spectral range {lambda}=250-1100 nm. Dispersion of refractive index of a-La{sub 2}O{sub 3} was defined by fitting of SE parameters over {lambda}=250-1100 nm.

  11. Reactive sputter deposition of alumina films on magnesium alloy by double cathode glow-discharge plasma technique

    SciTech Connect

    Zhou Chenghou; Xu Jiang; Jiang Shuyun

    2010-02-15

    In order to overcome the problem of the corrosion resistance of AZ31 magnesium alloy, the nanocrystalline Al{sub 2}O{sub 3} film was deposited on AZ31 magnesium alloy by double cathode glow-discharge plasma technique. The microstructure, chemical composition and elemental chemical state of the sputter-deposited nanocrystalline Al{sub 2}O{sub 3} film were analyzed by means of scanning electron microscopy equipped with an energy dispersive spectroscope, X-ray diffraction), transmission electron microscope and X-ray photoelectron spectroscopy. The results indicated that the sputter-deposited nanocrystalline Al{sub 2}O{sub 3} film consisted of single {theta}-Al{sub 2}O{sub 3} phase with average grain size about 60 nm. The hardness and the elastic modulus of the as-deposited nanocrystalline Al{sub 2}O{sub 3} film were about 17.21 GPa and 217 GPa measured by nanoindentation instrument, respectively. The corrosion behavior of the sputter-deposited nanocrystalline Al{sub 2}O{sub 3} film in 3.5%NaCl solution was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. The amount of porosity for the sputter-deposited nanocrystalline Al{sub 2}O{sub 3} film calculated by two electrochemical methods was equal to 0.0086% and 0.168%, respectively. The sputter-deposited nanocrystalline Al{sub 2}O{sub 3} film exhibited excellent corrosion resistance, which was attributed to its dense enough structure to prevent magnesium alloy from corrosion in aggressive solutions.

  12. Growth of Homoepitaxial ZnO Semiconducting Films

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, C.-H.; Lehoczky, S. L.; Harris, M. T.; George, M. A.; McCarty, P.

    1999-01-01

    As a high temperature wide-band-gap (3.3 eV at room temperature) semiconductor, ZnO has been used for many applications such as wave-guides, solar cells, and surface acoustic wave devices, Since ZnO has a 60 meV excitonic binding energy that makes it possible to produce excitonic lasing at room temperature, a recent surge of interest is to synthesize ZnO films for UV/blue/green laser diodes. These applications require films with a smooth surface, good crystal quality, and low defect density. Thus, homoepitaxial film growth is the best choice. Homoepitaxial films have been studied in terms of morphology, crystal structure, and electrical and optical properties. ZnO single crystal substrates grown by the hydrothermal method are mechanically polished and annealed in air for four hours before the films are deposited. The annealing temperature-dependence on ZnO substrate morphology and electrical properties is investigated. Films are synthesized by off-axis reactive sputtering deposition. This produces films that have very smooth surfaces with roughness less than or equal to 5 nm on a 5 microns x 5 microns area. The full width at half maximum of film theta rocking curves measured by the x-ray diffraction is slightly larger than that of the crystal substrate. Films are also characterized by measuring resistivity, optical transmittance, and photoluminescence. The properties of ZnO films grown on (0001) ZnO and (0001) sapphire substrates will also be compared and discussed.

  13. Emission intensity of the λ = 1.54 μm line in ZnO films grown by magnetron sputtering, diffusion doped with Ce, Yb, Er

    SciTech Connect

    Mezdrogina, M. M. Eremenko, M. V.; Smirnov, A. N.; Petrov, V. N.; Terukov, E. I.

    2015-08-15

    The effect of the Er{sup 3+}-ion excitation type on the photoluminescence spectra of crystalline ZnO(ZnO〈Ce, Yb, Er〉) films is determined in the cases of resonant (λ = 532 nm, Er{sup 3+}-ion transition from {sup 4}S{sub 3/2}, {sup 2}H{sub 11/2} levels to {sup 4}I{sub 15/2}) and non-resonant (λ = 325 nm, in the region near the ZnO band-edge emission) excitation. It is shown that resonant excitation gives rise to lines with various emission intensities, characteristic of the Er{sup 3+}-ion intracenter 4f transition with λ = 1535 nm when doping crystalline ZnO films with three rare-earth ions (REIs, Ce, Yb, Er) or with two impurities (Ce, Er) or (Er, Yb), independently of the measurement temperature (T = 83 and 300 K). The doping of crystalline ZnO films with rare-earth impurities (Ce, Yb, Er) leads to the efficient transfer of energy to REIs, a consequence of which is the intense emission of an Er{sup 3+} ion in the IR spectral region at λ{sub max} = 1535 nm. The kick-out diffusion mechanism is used upon the sequential introduction of impurities into semiconductor matrices and during the postgrowth annealing of the ZnO films under study. The crystalline ZnO films doped with Ce, Yb, Er also exhibit intense emission in the visible spectral region at room temperature, which makes them promising materials for optoelectronics.

  14. A cost-effective growth of SiO(x) thin films by reactive sputtering: photoluminescence tuning.

    PubMed

    Pappas, S D; Grammatikopoulos, S; Poulopoulos, P; Kapaklis, V; Delimitis, A; Trachylis, D; Politis, C

    2011-04-01

    We present a new cost-effective method to produce substoichiometric SiO2 thin films by means of a simple sputter-coater operated at a base pressure of 1 x 10(-3) mbar. During sputtering air is introduced through a fine valve so that the sputtering gas is a mixture of air/Ar. High-resolution electron microscopy shows the formation of amorphous SiO(x) thin films for the as-deposited samples. The index x approaches 1 when the ratio of the partial pressure of air/Ar tends to 0.1. On the other hand, pure silica is formed when the ratio of the partial pressure of air/Ar approaches 0.5. The films in the as-deposited state show intense green-yellow photoluminescence. This fades away with short annealing under air at 950 degrees C. If on the other hand, prolonged annealing is performed under Argon atmosphere at 1000 degrees C, red-infrared photoluminescence is recorded due to the formation of Si nanocrystals embedded in SiO2. This simple method could be suitable for the production of thin SiO(x) films with embedded nanocrystals for optoelectronic or photovoltaic applications. PMID:21776754

  15. Photocatalytic activities of wet oxidation synthesized ZnO and ZnO-TiO2 thick porous films

    NASA Astrophysics Data System (ADS)

    Chen, Ruiqun; Han, Jie; Yan, Xiaodong; Zou, Chongwen; Bian, Jiming; Alyamani, Ahmed; Gao, Wei

    2011-05-01

    Highly porous zinc oxide (ZnO) film was produced by using reactive magnetron sputtering zinc target followed by wet oxidation. Titanium dioxide (TiO2) was mixed to the porous films by using either TiO2 target magnetron sputter deposition or sol-spin method. The film thickness could reach 50 μm with uniform porosity. On the sputtering prepared ZnO-TiO2 film surface, fine nanorods with small anatase TiO2 nano-clusters on the tips were observed by SEM and TEM, and the titanium (Ti) composition was determined by XPS as 0.37%. The sol-spin treatment could increase the Ti composition to 4.9%, with reduced pore size compared to the untreated ZnO porous film. Photoluminescence measurements showed that the Ti containing porous film has strong ultraviolet-visible light emission. In the photo-catalysis testing, ZnO and ZnO-TiO2 have similar photo-catalysis activity under 365 nm UV irradiation, but under visible light, the photocatalysis activities of ZnO-TiO2 films were twice higher than that of ZnO porous film, implying promising applications of this porous oxide composite for industrial and dairy farm wastewater treatment.

  16. Assessing the performance and longevity of Nb, Pt, Ta, Ti, Zr, and ZrO₂-sputtered Havar foils for the high-power production of reactive [18F]F by proton irradiation of [18O]H2O.

    PubMed

    Gagnon, K; Wilson, J S; Sant, E; Backhouse, C J; McQuarrie, S A

    2011-10-01

    As water-soluble ionic contaminants, which arise following proton irradiation of [18O]H2O have been associated with decreased [18F]FDG yields, the minimization of these contaminants is an asset in improving the [18F]F reactivity. To this end, we have previously demonstrated that the use of Nb-sputtered Havar foils results in decreased radionuclidic and chemical impurities in proton irradiated [18O]H2O, improved [18F]FDG yields, and improved [18F]FDG yield consistency when compared with non-sputtered Havar. Resulting from the highly reactive chemical microenvironment within the target however, this niobium layer is observed to degrade over time. To find a material that displays increased longevity with regards to maintaining high [18F]F reactivity, this project extensively investigated and compared Havar foils sputtered with Nb, Pt, Ta, Ti, Zr and ZrO₂. Of the materials investigated, the results of this study suggest that Ta-sputtered Havar foil is the preferred choice. For similar integrated currents (~1,000,000 μA min), when comparing the Ta-sputtered Havar with Nb-sputtered Havar we observed: (i) greater than an order of magnitude decrease in radionuclidic impurities, (ii) a 6.4 percent increase (p=0.0025) in the average TracerLab MX [18F]FDG yield, and (iii) an overall improvement in the FDG yield consistency. Excellent performance of the Ta-sputtered foil was maintained throughout its ~1,500,000 μA min lifetime. PMID:21782460

  17. Study on the microstructure, soft magnetic and high frequency properties of obliquely sputtered [Fe65Co35/ZnO]50 multilayer thin films

    NASA Astrophysics Data System (ADS)

    Yao, Dongsheng; Li, Wenchun; Sun, Yunbin; Wu, Hongye; Lu, Yi; Zhao, Jianjun; Feng, Liefeng; Liu, Xiaohong; Zhou, Xueyun

    2016-01-01

    The effect of ZnO layer thickness t on the structure, static magnetic properties and high frequency properties is systemically studied for [Fe65Co35/ZnO(t)]50 multilayer films. The gradually increasing crystallinity of ZnO layer with increasing t is observed in the XRD patterns. The VSM measurements show good soft magnetic properties are obtained in these multilayer films, even though the ZnO layer is thick (up to 3.6 nm). For the typical sample with t=3.6 nm, an obvious in-plane anisotropy field and comparatively small coercivity are achieved, and high electric resistivity up to 12.6 mΩ cm is obtained. The measurement of permeability spectra indicates that the multilayers have an invariable ferromagnetic resonance frequency fr about 4.0 GHz; however, the initial permeability μi can be adjusted from 48 to 136 by decreasing t from 3.6 nm to 1.0 nm. The phenomenon that fr is almost invariable is the result of the decreasing saturation magnetization 4πMs and the increasing dynamic anisotropy field Hk-dyn with increasing t. For our samples, the real part (μ'2G) of complex permeability at f=2.0 GHz remains a high value beyond 90, while the imaginary part (μ"2G) keeps a low value below 1.55, indicating that these multilayer films are promising for application in high frequency range.

  18. Effect of W-Ti target composition on the surface chemistry and electronic structure of WO3-TiO2 films made by reactive sputtering

    NASA Astrophysics Data System (ADS)

    Vargas, M.; Lopez, D. M.; Murphy, N. R.; Grant, J. T.; Ramana, C. V.

    2015-10-01

    Tungsten-titanium (W-Ti) mixed oxide thin films were fabricated using reactive sputtering of W-Ti alloy targets with Ti content ranging from 0 to 30 wt%. The effect of target composition on film structure, surface/interface chemistry and chemical valence state of the W and Ti cations was investigated in detail. All films were amorphous in nature as confirmed by X-ray diffraction analyses. For growth times of 1 h, the thicknesses of the W-Ti-O films decreased significantly from 150 to 35 nm with increasing Ti content in the target, confirming that the oxide film growth behavior is dependent on the sputter-target composition. The chemistry and composition of the films probed using X-ray photoelectron spectroscopy (XPS) confirms the existence of W and Ti in their highest oxidation states of 6+ and 4+, respectively. Quantification of binding energy shifts for W and Ti core-level transitions confirms the formation of WO3-TiO2 composite oxide films. Depth profiles confirm and validate film uniformity, as well as film thickness differences and variable oxidation behavior of W and Ti in the films.

  19. Effect of Substrate Bias Voltage on the Physical Properties of Zirconium Nitride (ZrN) Films Deposited by Mid Frequency Reactive Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Kavitha, A.; Kannan, R.; Loganathan, S.

    2014-05-01

    Present work involves the preparation of Zirconium Nitride thin films on stainless steel (SS) (304L grade) substrate by reactive cylindrical magnetron sputtering method. The X-ray diffraction (XRD) profile of the ZrN thin films prepared with different bias voltage conforms face centered cubic structure with preferred orientation along the (111) plane at lower bias voltage (100 V) and at higher bias voltage (300 V) the preferred orientation shifted to (220) plane. The influences of bias voltage on the thickness and microhardness ZrN thin films have been studied. ZrN thin film sputtered with 300 V bias voltage shows the maximum reflectance of 90% at a wavelength of 1000 nm. The coated substrates have been found to exhibit improved corrosion resistance compared to the SS plate. The root mean square surface roughness and surface morphology were investigated from 3D atomic force microscope (AFM) images and scanning electron microscope (SEM), which indicate smooth and uniform surface pattern without any pin holes.

  20. Characterization of thin MoO3 films formed by RF and DC-magnetron reactive sputtering for gas sensor applications

    NASA Astrophysics Data System (ADS)

    Yordanov, R.; Boyadjiev, S.; Georgieva, V.; Vergov, L.

    2014-05-01

    The present work discusses a technology for deposition and characterization of thin molybdenum oxide (MoOx, MoO3) films studied for gas sensor applications. The samples were produced by reactive radio-frequency (RF) and direct current (DC) magnetron sputtering. The composition and microstructure of the films were studied by XPS, XRD and Raman spectroscopy, the morphology, using high resolution SEM. The research was focused on the sensing properties of the sputtered thin MoO3 films. Highly sensitive gas sensors were implemented by depositing films of various thicknesses on quartz resonators. Making use of the quartz crystal microbalance (QCM) method, these sensors were capable of detecting changes in the molecular range. Prototype QCM structures with thin MoO3 films were tested for sensitivity to NH3 and NO2. Even in as-deposited state and without heating the substrates, these films showed good sensitivity. Moreover, no additional thermal treatment is necessary, which makes the production of such QCM gas sensors simple and cost-effective, as it is fully compatible with the technology for producing the initial resonator. The films are sensitive at room temperature and can register concentrations as low as 50 ppm. The sorption is fully reversible, the films are stable and capable of long-term measurements.

  1. Effect of O{sub 2} flow ratio on the microstructure and stress of room temperature reactively sputtered RuO{sub x} thin films

    SciTech Connect

    Shi Junxia; Huang Feng; Weaver, Mark L.; Klein, Tonya M.

    2005-05-01

    RuO{sub x} thin films were deposited at room temperature by reactive radio frequency magnetron-sputtering using Ar/O{sub 2} discharges of varying O{sub 2} flow ratio (f{sub O{sub 2}}) over the range 10%-50% and were characterized using x-ray diffraction, x-ray reflectivity, x-ray photoelectron spectroscopy, resistivity, and stress-temperature measurements. With the increase of f{sub O{sub 2}}, the film texture changed from (110) to (101). Films deposited with f{sub O{sub 2}}>25% were determined stoichiometric. The residual stresses in as-deposited films were all compressive and increased with addition of O{sub 2}, except for the film sputtered at f{sub O{sub 2}}=20% which was in biaxial tension. The film deposited at f{sub O{sub 2}}=30% had a low resistivity value of 68 {mu}{omega} cm and near zero stress (<50 MPa tensile) after a thermal cycle in air up to 500 deg. C which is promising for use in microdevices.

  2. Growth of (Sr,La)-(Ta,Ti)-O-N perovskite oxide and oxynitride films by radio frequency magnetron sputtering: Influence of the reactive atmosphere on the film structure

    NASA Astrophysics Data System (ADS)

    Le Paven, C.; Le Gendre, L.; Benzerga, R.; Cheviré, F.; Tessier, F.; Jacq, S.; Traoré-Mantion, S.; Sharaiha, A.

    2015-03-01

    In the search for new dielectric and ferroelectric compounds, we were interested in the perovskite (Sr1-xLax)2(Ta1-xTix)2O7 solid solution with ferroelectric end members Sr2Ta2O7 (TCurie=-107 °C) and La2Ti2O7 (TCurie=1461 °C). In order to achieve a Curie temperature close to room temperature, the formulation with x=0.01 was chosen and synthetized as thin films by reactive radio-frequency magnetron sputtering. In oxygen rich plasma, a (Sr0.99La0.01)2(Ta0.99Ti0.01)2O7 film is deposited, characterized by a band-gap Eg=4.75 eV and an (1 1 0) epitaxial growth on (0 0 1)MgO substrate. The use of nitrogen rich plasma allows to synthesize (Sr0.99La0.01)(Ta0.99Ti0.01)O2N oxynitride films, with band gap Eg~2.10 eV and a polycrystalline, textured or epitaxial growth on (0 0 1)MgO substrate. Nitrogen-substoichiometric oxynitride films with larger lattice cells are produced for low dinitrogen percentages in the sputtering plasma.

  3. Influence of surface defects in ZnO thin films on its biosensing response characteristic

    SciTech Connect

    Saha, Shibu; Gupta, Vinay

    2011-09-15

    Highly c-axis oriented zinc oxide (ZnO) thin films deposited by rf magnetron sputtering under varying processing pressure (20-50 mT) in a reactive gas mixture of argon and oxygen were studied for biosensing application. The as-deposited ZnO thin films were in a state of compressive stress having defects related to interstitial Zn and antisite oxygen. Glucose oxidase has been chosen as the model enzyme in the present study and was immobilized on the surface of ZnO thin films deposited on indium tin oxide coated Corning Glass substrate. The studies reveal a correlation between the biosensing characteristic and the presence of defects in the ZnO films. The ZnO films deposited under high pressure (50 mT) are found to be more sensitive for biosensing application due to availability of more surface area for effective immobilization of biomolecules and exhibits a suitable microenvironment with good electron transfer characteristic. The obtained results highlight the importance of desired microstate besides availability of suitable native defects in the ZnO thin film for exhibiting enhanced biosensing response.

  4. Research Update: Reactively sputtered nanometer-thin ZrN film as a diffusion barrier between Al and boron layers for radiation detector applications

    SciTech Connect

    Golshani, Negin Mohammadi, V.; Schellevis, H.; Beenakker, C. I. M.; Ishihara, R.

    2014-10-01

    In this paper, optimization of the process flow for PureB detectors is investigated. Diffusion barrier layers between a boron layer and the aluminum interconnect can be used to enhance the performance and visual appearance of radiation detectors. Few nanometers-thin Zirconium Nitride (ZrN) layer deposited by reactive sputtering in a mixture of Ar/N{sub 2}, is identified as a reliable diffusion barrier with better fabrication process compatibility than others. The barrier properties of this layer have been tested for different boron layers deposited at low and high temperatures with extensive optical microscopy analyses, electron beam induced current, SEM, and electrical measurements. This study demonstrated that spiking behavior of pure Al on Si can be prevented by the thin ZrN layer thus improving the performance of the radiation detectors fabricated using boron layer.

  5. Investigation of structural, optical and electrical properties of (Ti,Nb)Ox thin films deposited by high energy reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Mazur, Michal; Kaczmarek, Danuta; Prociow, Eugeniusz; Domaradzki, Jaroslaw; Wojcieszak, Damian; Bocheński, Jakub

    2014-09-01

    In this work the results of investigations of the titanium-niobium oxides thin films have been reported. The thin films were manufactured with the aid of a modified reactive magnetron sputtering process. The aim of the research was the analysis of structural, optical and electrical properties of the deposited thin films. Additionally, the influence of post-process annealing on the properties of studied coatings has been presented. The as-deposited coatings were amorphous, while annealing at 873 K caused a structural change to the mixture of TiO2 anatase-rutile phases. The prepared thin films exhibited good transparency with transmission level of ca. 50 % and low resistivity varying from 2 Ωcm to 5×10-2 Ωcm, depending on the time and temperature of annealing. What is worth to emphasize, the sign of Seebeck coefficient changed after the annealing process from the electron to hole type electrical conduction.

  6. Investigation of structural, optical and electrical properties of (Ti,Nb)Ox thin films deposited by high energy reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Mazur, Michal; Kaczmarek, Danuta; Prociow, Eugeniusz; Domaradzki, Jaroslaw; Wojcieszak, Damian; Bocheński, Jakub

    2014-06-01

    In this work the results of investigations of the titanium-niobium oxides thin films have been reported. The thin films were manufactured with the aid of a modified reactive magnetron sputtering process. The aim of the research was the analysis of structural, optical and electrical properties of the deposited thin films. Additionally, the influence of post-process annealing on the properties of studied coatings has been presented. The as-deposited coatings were amorphous, while annealing at 873 K caused a structural change to the mixture of TiO2 anatase-rutile phases. The prepared thin films exhibited good transparency with transmission level of ca. 50 % and low resistivity varying from 2 Ωcm to 5×10-2 Ωcm, depending on the time and temperature of annealing. What is worth to emphasize, the sign of Seebeck coefficient changed after the annealing process from the electron to hole type electrical conduction.

  7. TiO2 patterns with wide photo-induced wettability change by a combination of reactive sputtering process and surface modification in a microfluidic channel

    NASA Astrophysics Data System (ADS)

    Kobayashi, Taizo; Konishi, Satoshi

    2015-11-01

    This paper reports the formation of TiO2 patterns with a wide range of photo-induced wettability switching from high hydrophobic to superhydrophilic states for on-chip liquid manipulation. TiO2 thin films with rough surface morphology were formed by a combination of optimised reactive sputtering and CF4 plasma etching. Octadecylphosphonic acid self-assembled monolayer (ODP-SAM) surface modification was applied to the surface-roughened TiO2 thin films in order to obtain a highly hydrophobic surface initially. Photocatalytic decomposition of ODP-SAM on the surface-roughened TiO2 by ultraviolet (UV) irradiation caused a wetting transition from the Cassie-Baxter state to the Wenzel state. Switching of the flow direction into branch channels was also demonstrated by utilising the photoresponsive wettability of the surface-modified TiO2 patterns on a fluidic chip.

  8. Correlation between optical characterization of the plasma in reactive magnetron sputtering deposition of Zr N on SS 316L and surface and mechanical properties of the deposited films

    NASA Astrophysics Data System (ADS)

    Fragiel, A.; Machorro, R.; Muñoz-Saldaña, J.; Salinas, J.; Cota, L.

    2008-05-01

    Optical and surface spectroscopies as well as nanoindentation techniques have been used to study ZrN coatings on 316L stainless steel obtained by DC-reactive magnetron sputtering. The deposit process was carried out using initial and working pressures of 10 -6 Torr and 10 -3 Torr, respectively. The experimental set-up for optical spectra acquisition was designed for the study in situ of the plasma in the deposition chamber. Auger spectroscopy, SEM and X-ray diffraction were used to characterize the coatings. Nanoindentation tests were carried out to measure the mechanical properties of the coating. Plasma characterization revealed the presence of CN molecules and Cr ions in the plasma. Surface spectroscopy results showed that ZrN, Zr 3N 4 and ZrC coexist in the coating. These results allowed the understanding of the mechanical behavior of the coatings, demonstrating the importance of the plasma characterization as a tool for tailoring the properties of hard coatings.

  9. Stress-induced VO{sub 2} films with M2 monoclinic phase stable at room temperature grown by inductively coupled plasma-assisted reactive sputtering

    SciTech Connect

    Okimura, Kunio; Watanabe, Tomo; Sakai, Joe

    2012-04-01

    We report on growth of VO{sub 2} films with M2 monoclinic phase stable at room temperature under atmospheric pressure. The films were grown on quartz glass and Si substrates by using an inductively coupled plasma-assisted reactive sputtering method. XRD-sin{sup 2}{Psi} measurements revealed that the films with M2 phase are under compressive stress in contrast to tensile stress of films with M1 phase. Scanning electron microscopy observations revealed characteristic crystal grain aspects with formation of periodical twin structure of M2 phase. Structural phase transition from M2 to tetragonal phases, accompanied by a resistance change, was confirmed to occur as the temperature rises. Growth of VO{sub 2} films composed of M2 phase crystalline is of strong interest for clarifying nature of Mott transition of strongly correlated materials.

  10. Semiconducting ZnSn{sub x}Ge{sub 1−x}N{sub 2} alloys prepared by reactive radio-frequency sputtering

    SciTech Connect

    Shing, Amanda M.; Coronel, Naomi C.; Lewis, Nathan S.; Atwater, Harry A.

    2015-07-01

    We report on the fabrication and structural and optoelectronic characterization of II-IV-nitride ZnSn{sub x}Ge{sub 1−x}N{sub 2} thin-films. Three-target reactive radio-frequency sputtering was used to synthesize non-degenerately doped semiconducting alloys having <10% atomic composition (x = 0.025) of tin. These low-Sn alloys followed the structural and optoelectronic trends of the alloy series. Samples exhibited semiconducting properties, including optical band gaps and increasing in resistivities with temperature. Resistivity vs. temperature measurements indicated that low-Sn alloys were non-degenerately doped, whereas alloys with higher Sn content were degenerately doped. These films show potential for ZnSn{sub x}Ge{sub 1−x}N{sub 2} as tunable semiconductor absorbers for possible use in photovoltaics, light-emitting diodes, or optical sensors.

  11. Preparation of nitrogen-substituted TiO2 thin film photocatalysts by the radio frequency magnetron sputtering deposition method and their photocatalytic reactivity under visible light irradiation.

    PubMed

    Kitano, Masaaki; Funatsu, Keisho; Matsuoka, Masaya; Ueshima, Michio; Anpo, Masakazu

    2006-12-21

    Nitrogen-substituted TiO2 (N-TiO2) thin film photocatalysts have been prepared by a radio frequency magnetron sputtering (RF-MS) deposition method using a N2/Ar mixture sputtering gas. The effect of the concentration of substituted nitrogen on the characteristics of the N-TiO2 thin films was investigated by UV-vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. The absorption band of the N-TiO2 thin film was found to shift smoothly to visible light regions up to 550 nm, its extent depending on the concentration of nitrogen substituted within the TiO2 lattice in a range of 2.0-16.5%. The N-TiO2 thin film photocatalyst with a nitrogen concentration of 6.0% exhibited the highest reactivity for the photocatalytic oxidation of 2-propanol diluted in water even under visible (lambda > or = 450 nm) or solar light irradiation. Moreover, N-TiO2 thin film photocatalysts prepared on conducting glass electrodes showed anodic photocurrents attributed to the photooxidation of water under visible light, its extent depending on wavelengths up to 550 nm. The absorbed photon to current conversion efficiencies reached 25.2% and 22.4% under UV (lambda = 360 nm) and visible light (lambda = 420 nm), respectively. UV-vis and photoelectrochemical investigations also confirmed that these thin films remain thermodynamically and mechanically stable even under heat treatment at 673 K. In addition, XPS and XRD studies revealed that a significantly high substitution of the lattice O atoms of the TiO2 with the N atoms plays a crucial role in the band gap narrowing of the TiO2 thin films, enabling them to absorb and operate under visible light irradiation as a highly reactive, effective photocatalyst. PMID:17165971

  12. Effects of substrate temperature, substrate orientation, and energetic atomic collisions on the structure of GaN films grown by reactive sputtering

    SciTech Connect

    Schiaber, Ziani S.; Lisboa-Filho, Paulo N.; Silva, José H. D. da; Leite, Douglas M. G.; Bortoleto, José R. R.

    2013-11-14

    The combined effects of substrate temperature, substrate orientation, and energetic particle impingement on the structure of GaN films grown by reactive radio-frequency magnetron sputtering are investigated. Monte-Carlo based simulations are employed to analyze the energies of the species generated in the plasma and colliding with the growing surface. Polycrystalline films grown at temperatures ranging from 500 to 1000 °C clearly showed a dependence of orientation texture and surface morphology on substrate orientation (c- and a-plane sapphire) in which the (0001) GaN planes were parallel to the substrate surface. A large increase in interplanar spacing associated with the increase in both a- and c-parameters of the hexagonal lattice and a redshift of the optical bandgap were observed at substrate temperatures higher than 600 °C. The results showed that the tensile stresses produced during the film's growth in high-temperature deposition ranges were much larger than the expected compressive stresses caused by the difference in the thermal expansion coefficients of the film and substrate in the cool-down process after the film growth. The best films were deposited at 500 °C, 30 W and 600 °C, 45 W, which corresponds to conditions where the out diffusion from the film is low. Under these conditions the benefits of the temperature increase because of the decrease in defect density are greater than the problems caused by the strongly strained lattice that occurr at higher temperatures. The results are useful to the analysis of the growth conditions of GaN films by reactive sputtering.

  13. Effect of RF power on the optical, electrical, mechanical and structural properties of sputtering Ga-doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Tien, Chuen-Lin; Yu, Kuo-Chang; Tsai, Tsung-Yo; Liu, Ming-Chung

    2015-11-01

    We present the influences of radio-frequency (RF) power on the optical, electrical, mechanical, and structural properties of Ga-doped zinc oxide (GZO) thin films by RF magnetron sputtering at room temperature. GZO thin films were grown on unheated glass and silicon substrates using radio-frequency (RF) magnetron sputtering method with different RF powers (from 60 W to 160 W). The optical properties of the GZO thin film were determined by a UV-vis spectrophotometer. The residual stress in GZO films were measured by a home-made Twyman-Green interferometer with the fast Fourier transform (FFT) method. The surface roughness of GZO films were measured by a microscopic interferometry. The microstructure, composition and crystal orientation of the GZO films were determined by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). This paper revealed that the optical, electrical, mechanical, and structural properties of GZO thin film are subject to the RF power. For the optical spectrum measurement, an average optical transmittance in the visible region of the spectra of 85% was obtained. For the characteristic measurements, all the GZO thin films deposited by RF magnetron sputtering have compressive stress at different RF powers. A minimum residual stress of 0.24 GPa is found at the RF power of 140 W. A four-point probe method was used to measure the resistivity of the GZO thin films with different powers, the results indicate that the resistivity increases with increasing of RF power. In addition, the root-mean-square (RMS) surface roughness of GZO thin films slightly increases as the RF power is increasing. We have also compared the results with the relevant literatures.

  14. Amorphous indium-tin-zinc oxide films deposited by magnetron sputtering with various reactive gases: Spatial distribution of thin film transistor performance

    SciTech Connect

    Jia, Junjun; Torigoshi, Yoshifumi; Shigesato, Yuzo; Kawashima, Emi; Utsuno, Futoshi; Yano, Koki

    2015-01-12

    This work presents the spatial distribution of electrical characteristics of amorphous indium-tin-zinc oxide film (a-ITZO), and how they depend on the magnetron sputtering conditions using O{sub 2}, H{sub 2}O, and N{sub 2}O as the reactive gases. Experimental results show that the electrical properties of the N{sub 2}O incorporated a-ITZO film has a weak dependence on the deposition location, which cannot be explained by the bombardment effect of high energy particles, and may be attributed to the difference in the spatial distribution of both the amount and the activity of the reactive gas reaching the substrate surface. The measurement for the performance of a-ITZO thin film transistor (TFT) also suggests that the electrical performance and device uniformity of a-ITZO TFTs can be improved significantly by the N{sub 2}O introduction into the deposition process, where the field mobility reach to 30.8 cm{sup 2} V{sup –1} s{sup –1}, which is approximately two times higher than that of the amorphous indium-gallium-zinc oxide TFT.

  15. Morphology and structure evolution of Cu(In,Ga)S{sub 2} films deposited by reactive magnetron co-sputtering with electron cyclotron resonance plasma assistance

    SciTech Connect

    Nie, Man Ellmer, Klaus

    2014-02-28

    Cu(In,Ga)S{sub 2} (CIGS) films were deposited on Mo coated soda lime glass substrates using an electron cyclotron resonance plasma enhanced one-step reactive magnetron co-sputtering process (ECR-RMS). The crystalline quality and the morphology of the Cu(In,Ga)S{sub 2} films were investigated by X-ray diffraction, atomic force microscopy, scanning electron microscopy, and X-ray fluorescence. We also compared these CIGS films with films previously prepared without ECR assistance and find that the crystallinity of the CIGS films is correlated with the roughness evolution during deposition. Atomic force microscopy was used to measure the surface topography and to derive one-dimensional power spectral densities (1DPSD). All 1DPSD spectra of CIGS films exhibit no characteristic peak which is typical for the scaling of a self-affine surface. The growth exponent β, characterizing the roughness R{sub q} evolution during the film growth as R{sub q} ∼ d{sup β}, changes with film thickness. The root-mean-square roughness at low temperatures increases only slightly with a growth exponent β = 0.013 in the initial growth stage, while R{sub q} increases with a much higher exponent β = 0.584 when the film thickness is larger than about 270 nm. Additionally, we found that the H{sub 2}S content of the sputtering atmosphere and the Cu- to-(In + Ga) ratio has a strong influence of the morphology of the CIGS films in this one-step ECR-RMS process.

  16. Effects of Substrate Bias on the Hardness and Resistivity of Reactively Sputtered TaN and TiN Thin Films

    NASA Astrophysics Data System (ADS)

    Lu, Junqing; Arshi, Nishat

    2016-06-01

    TaN and TiN films are being widely used as conductive layers in electronic devices or protective coatings on metal surfaces. Among various deposition methods, reactive magnetron sputtering is preferred partly due to its ability to control the energy of the depositing ions by applying different substrate bias voltages. In this study, TaN and TiN films were deposited on Si/SiO2 substrates by using direct current magnetron sputtering technique with 370 W target power at 1.9 mTorr and under different substrate biases. The effects of the substrate bias on both the resistivity and the hardness of the deposited TaN and TiN films were investigated. The phase and composition of the deposited films were investigated by x-ray diffraction, the resistivity was measured by a four-point probe, and the hardness was obtained by nano-indentation. For TaN films, the use of substrate bias not only increased the hardness but also increased the resistivity. Moreover, the formation of the Ta3N5 phase at the -300 V substrate bias significantly increased the TaN film resistivity. For TiN films, the optimum resistivity (minimum) of 19.5 µΩ-cm and the hardness (maximum) of 31.5 GPa were achieved at the -100 V substrate bias. Since the phase changes occurred in both the TaN and the TiN films at higher substrate biases and these phase changes negatively affected the resistivity or hardness property of the films, the substrate bias should not significantly exceed -100 V.

  17. Combinatorial Reactive Sputtering of In2S3 as an Alternative Contact Layer for Thin Film Solar Cells.

    PubMed

    Siol, Sebastian; Dhakal, Tara P; Gudavalli, Ganesh S; Rajbhandari, Pravakar P; DeHart, Clay; Baranowski, Lauryn L; Zakutayev, Andriy

    2016-06-01

    High-throughput computational and experimental techniques have been used in the past to accelerate the discovery of new promising solar cell materials. An important part of the development of novel thin film solar cell technologies, that is still considered a bottleneck for both theory and experiment, is the search for alternative interfacial contact (buffer) layers. The research and development of contact materials is difficult due to the inherent complexity that arises from its interactions at the interface with the absorber. A promising alternative to the commonly used CdS buffer layer in thin film solar cells that contain absorbers with lower electron affinity can be found in β-In2S3. However, the synthesis conditions for the sputter deposition of this material are not well-established. Here, In2S3 is investigated as a solar cell contact material utilizing a high-throughput combinatorial screening of the temperature-flux parameter space, followed by a number of spatially resolved characterization techniques. It is demonstrated that, by tuning the sulfur partial pressure, phase pure β-In2S3 could be deposited using a broad range of substrate temperatures between 500 °C and ambient temperature. Combinatorial photovoltaic device libraries with Al/ZnO/In2S3/Cu2ZnSnS4/Mo/SiO2 structure were built at optimal processing conditions to investigate the feasibility of the sputtered In2S3 buffer layers and of an accelerated optimization of the device structure. The performance of the resulting In2S3/Cu2ZnSnS4 photovoltaic devices is on par with CdS/Cu2ZnSnS4 reference solar cells with similar values for short circuit currents and open circuit voltages, despite the overall quite low efficiency of the devices (∼2%). Overall, these results demonstrate how a high-throughput experimental approach can be used to accelerate the development of contact materials and facilitate the optimization of thin film solar cell devices. PMID:27173477

  18. Characterization of CuAlO2 Thin Films Prepared on Sapphire Substrates by Reactive Sputtering and Annealing

    NASA Astrophysics Data System (ADS)

    Tsuboi, Nozomu; Moriya, Tomohiro; Kobayashi, Satoshi; Shimizu, Hidehiko; Kato, Keizo; Kaneko, Futao

    2008-01-01

    As-deposited films were prepared on sapphire substrates at 500-680 °C by alternately sputtering Cu and Al targets in Ar-diluted O2 gas atmosphere. The composition of the as-deposited films corresponded to that of the slightly oxygen-rich region of the CuO-CuAl2O4-Al2O3 system. The films as-deposited at 500 °C had an amorphous structure, while the films as-deposited at 680 °C had CuAl2O4 phase but no CuAlO2 phase. Annealing at 1050 °C in nitrogen flow caused a reduction in the molar fraction of oxygen, i.e., the composition of the annealed films with [Cu]/[Al] ≈1 corresponded to CuAlO2. The annealed films were predominated by the CuAlO2 phase. The preferential orientation of the films toward the c-axis normal to the substrate surface is due to the small lattice mismatch between the rhombohedral [010] of delafossite-type CuAlO2 and the hexagonal [1100] of the sapphire substrate. The annealed films had an absorption edge corresponding to the energy gap of CuAlO2 and exhibited p-type conductivity.

  19. Influence of substrate bias on practical adhesion, toughness, and roughness of reactive dc-sputtered zirconium nitride films

    NASA Astrophysics Data System (ADS)

    Chen, Cheng-Shi; Liu, Chuan-Pu; Yang, Heng-Ghieh; Tsao, C.-Y. A.

    2004-09-01

    The ZrN films were grown on Si (100) substrates using dc magnetron sputtering where the substrate bias was varied from -45 to 50 V. In this article, the film/substrate practical adhesion of the ZrN films were measured by scratch testing while the hardness, elastic modulus, and fracture toughness were measured by nanoindentation. The structures and morphologies of the ZrN films were analyzed using scanning electron microscopy, atomic force microscopy, and x-ray diffraction. The results indicate that the introduction of either negative or positive bias results in the degradation of the practical adhesion properties, while the films under zero bias exhibit the best adhesion. In addition, positive bias results in the increase in both the hardness and elastic modulus, while negative bias enhances the hardness and toughness of the ZrN thin films. The mechanical properties are greatly influenced by substrate bias and can be correlated to microstructure variations. The detailed mechanisms accounted for these phenomena are discussed.

  20. Adherence of sputtered titanium carbides

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Wheeler, D. R.

    1979-01-01

    Sputtered coatings of the refractory metal carbides are of great interest for applications where hard wear-resistant materials are desired. The usefulness of sputtered refractory carbides is often limited, in practice, by spalling or interfacial separation. In this work improvements in the adherence of refractory carbides on iron, nickel and titanium based alloys were obtained by using oxidation, reactive sputtering or sputtered interlayers to alter the coating-substrate interfacial region. X-ray photoelectron spectroscopy and argon ion etching were used to characterize the interfacial regions, and an attempt was made to correlate adherence as measured in wear tests with the chemical nature of the interface.

  1. [Effects of Temperature on the Preparation of Al/Zn3N2 Thin Films Using Magnetron Reactive Sputtering].

    PubMed

    Feng, Jun-qin; Chen, Jun-fang

    2015-08-01

    The effects of substrate temperature on the plasma active species were investigated by plasma optical emission spectroscopy. With increasing substrate temperature, the characteristic spectroscopy intensity of the first positive series of N2* (B(3)Πg-->A(3)Σu(+)), the second positive N2* (C(3)Πu-->B(3)Πg), the first negative series N2(+)* (B(2)Σu(+)-->X(2)Σg(+)) and Zn* are increased. Due to the substrate temperature, each ion kinetic energy is increased and the collision ionization intensified in the chamber. That leading to plasma ion density increase. These phenomenons's show that the substrate temperature raises in a certain range was conducive to zinc nitride thin films growth. Zn3N2 thin films were prepared on Al films using ion sources-assisted magnetron sputtering deposition method. The degree of crystalline of the films was examined with X-ray diffraction (XRD). The results show that has a dominant peak located at 34.359° in room temperature, which was corresponding to the (321) plane of cubic anti-bixbyite zinc nitride structure (JCPDS Card No35-0762). When the substrate temperature was 100 °C, in addition to the (321) reflection, more diffraction peaks appeared corresponding to the (222), (400) and (600) planes, which were located at 31.756°, 36.620° and 56.612° respectively. When the substrate temperature was 200 °C, in addition to the (321), (222), (400) and (600) reflection, more new diffraction peaks also appeared corresponding to the (411), (332), (431) and (622) planes, which were located at 39.070, 43.179°, 47.004° and 62.561° respectively. These results show the film crystalline increased gradually with raise the substrate temperature. XP-1 profilometer were used to analyze the thickness of the Zn3N2 films. The Zn3N2 films deposited on Al films in mixture gas plasma had a deposition rate of 2.0, 2.2, and 2.7 nm · min(-1). These results indicate that the deposition rate was gradually enhanced as substrate temperature increased

  2. Photoelectrochemical properties of N/C-codoped TiO2 film electrodes prepared by reactive DC magnetron sputtering.

    PubMed

    Wu, Kee-Rong; Yeh, Chung-Wei; Hung, Chung-Hsuang; Chung, Chih-Yuan; Cheng, Li-Hsun

    2010-02-01

    This paper aims to characterize the photoelectrochemical properties of the visible-light enabling titanium dioxide (TiO2) film electrodes prepared by codoping nitrogen (N) and a presputtered carbon film (C-film) onto indium tin oxide (ITO) glass substrates using a direct current (DC) magnetron sputtering technique. To improve its photoelectrochemical properties, different amount of C-doping sources, 2 h and 4 h C-film, are chose to prepare the N/C-codoped TiO2 film electrodes. Under visible-light (420 < lambda < 610 nm) illumination, a remarkable photocurrent density of 22 microA/cm2 is obtained for the N/C-TiO2 film electrode prepared with a 4 h C-film (NC(4)-T) at an applied potential of +1.2 V versus SCE. Under ultraviolet (lambda approximately 365 nm) illumination, the NC(4)-T film electrode also exhibits the highest photocurrent density of 0.23 mA/cm2 among all samples tested. A more negative flat band potential of NC(4)-T film electrode is attributed to the synergistic effect of N/C codoping. The XRD spectrum of the NC(4)-T film electrode shows mainly the well-crystallized anatase TiO2 phase and an extremely intense (211) plane. Thus, photoelectrochemical activity of the NC(4)-T film electrode can be ascribed to the well-crystallized columnar crystals with pores at its grain boundary, open surface morphology, which are revealed by SEM and TEM images, and a more negative flat band potential. The visible-light induced activity is mostly enhanced as a result of the synergistic effects of N/C-codoping into the TiO2 crystals. A potential application to photocatalytic splitting of water for hydrogen evolution using solar light is practically possible. PMID:20352756

  3. Influence of working gas pressure on structure and properties of WO3 films reactively deposited by rf magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Takahashi, T.; Tanabe, J.; Yamada, N.; Nakabayashi, H.

    2003-07-01

    Tungsten trioxide (WO3) films with thickness of 0.9-6.7 μm have been deposited on glass-slide substrates, using rf magnetron sputtering in an atmosphere of mixture 80% Ar and 20% O2. The as-deposited films had a dark metallic color, like the W target, at a working gas pressure PW of 1 mTorr. Yellow films resulted at a PW of 3 mTorr. With a further increase of PW, the film color changed to pale yellow. From the x-ray diffraction patterns, the as-deposited films were polycrystalline crystallizing in the monoclinic crystal structure with high c-axis orientation perpendicular to the film plane. The optical transmittance of the films deposited at a PW of 1 mTorr is nearly zero. However, the transmittance of the films deposited at other PW are larger than 70% in the wavelength, λ, ranging from 500 to 900 nm. With decreasing λ to 400 nm, the transmittance decreases steeply to zero. The λ at this absorption edge is longer than that in TiO2 and comes in the visible region. The surface morphology of the films depends on PW. This different morphology may be attributed to the effect of the substrate heating by plasma emission because of the high plasma density at higher PW. The morphology of the films may also depend on the crystallinity of the WO3 films. As PW increased, the surfaces of the films became rougher but the grain sizes of the films did not always become larger. The WO3 films deposited in this study may be used for the underlayer of TiO2 photocatalyst.

  4. Low-temperature film growth of the oxides of zinc, aluminum, and vanadium (and related systems, oxides of gold and germanium, nitrides of aluminum and tungsten) by reactive sputter deposition. Final report, 1 July 1984-31 December 1987

    SciTech Connect

    Aita, C.R.

    1988-02-01

    The research involved investigation of process-parameter growth environment film property relationships for various binary oxide and nitride films grown on unheated substrates by reactive sputter deposition using an elemental target. In-situ optical-emission spectroscopy and glow-discharge mass spectrometry were used to determine gas-phase species in the plasma volume. A battery of techniques were used to characterize (post-deposition) film crystallography, chemistry, microstructure, electrical resistivity, and optical behavior.

  5. Preparation of diamond-like carbon films using reactive Ar/CH4 high power impulse magnetron sputtering system with negative pulse voltage source for substrate

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2016-04-01

    Diamond-like carbon films were prepared using a reactive Ar/CH4 high-power impulse magnetron sputtering system with a negative pulse voltage source for the substrate, changing the CH4 fraction up to 15% in the total pressure range from 0.3 to 2 Pa. The magnitude of the negative pulse voltage for the substrate was also varied up to about 500 V. The hardness of films monotonically increased with increasing magnitude of the negative pulse voltage. The films with hardnesses between 16.5 and 23 GPa were prepared at total pressures less than 0.5 Pa and CH4 fractions less than 10% by applying an appropriate negative pulse voltage of 300-400 V. In X-ray photoelectron spectroscopy, the area ratio C-C sp3/(C-C sp2 + C-C sp3) in the C 1s core level was higher than 30% at pressures less than 0.5 Pa and CH4 fractions less than 15%. On the other hand, the films with hardnesses between 5 and 10 GPa were prepared with a relatively high growth rate at the partial pressures of CH4 higher than 0.1 Pa. However, the observation of the photoluminescence background in Raman spectroscopy indicated a relatively high hydrogen content.

  6. Microstructural evolution and Poisson ratio of epitaxial ScN grown on TiN(001)/MgO(001) by ultrahigh vacuum reactive magnetron sputter deposition

    NASA Astrophysics Data System (ADS)

    Gall, D.; Petrov, I.; Desjardins, P.; Greene, J. E.

    1999-11-01

    ScN layers, 60-80 nm thick, were grown at 800 °C on 220-nm-thick epitaxial TiN(001) buffer layers on MgO(001) by ultrahigh vacuum reactive magnetron sputter deposition in pure N2 discharges. The films are stoichiometric with N/Sc ratios, determined by Rutherford backscattering spectroscopy and x-ray photoelectron spectroscopy, of 1.00±0.02. Plan-view and cross-sectional transmission electron microscopy analyses showed that the films are single crystals which appear defect free up to a critical thickness of ≃15 nm, above which an array of nanopipes form with their tubular axis along the film growth direction and extending to the free surface. The nanopipes are rectangular in cross section with areas of ≃1.5×5 nm2 and are self-organized along <100>, directions with an average separation of ≃40 nm. Their formation is the result of periodic kinetic surface roughening which leads to atomic self-shadowing and, under limited adatom mobility conditions, to deep cusps which are the origin of the nanopipes. The ScN layers are nearly relaxed, as determined from x-ray diffraction θ-2θ scans in both reflection and transmission, with only a small residual compressive strain due to differential thermal contraction. The Poisson ratio of ScN was found to be 0.20±0.04, in good agreement with ab initio calculations.

  7. High performance mid-temperature selective absorber based on titanium oxides cermet deposited by direct current reactive sputtering of a single titanium target

    NASA Astrophysics Data System (ADS)

    Tang, Lu; Cao, Feng; Li, Yang; Bao, Jiming; Ren, Zhifeng

    2016-01-01

    This article reports the design and fabrication of a new double cermet-based low-mid temperature solar selective absorber based on TiOx cermet layers, which were deposited with a single Ti target by varying O2 partial pressure in sputtering chamber as reactive gas. High metal volume fraction cermet 1 and low metal volume fraction cermet 2 were deposited with O2 partial pressure of 0.15 mTorr and 0.25 mTorr, respectively, with direct current power density of 6.58 W cm-2. The complex refractive indices from ellipsometry were used to design solar selective absorber. The reflectance, thermal stability, and morphology were studied in absorbers on Cu and stainless steel. The effect of TiO2 and SiO2 as anti-reflective coating layers was investigated. The absorber on Cu substrate has high absorptance of 90.8% and low emittance of 4.9% (100 °C), and changed to 96.0% and 6.6%, respectively, after annealing at 300 °C for 4 days.

  8. Multi-functional reactively-sputtered copper oxide electrodes for supercapacitor and electro-catalyst in direct methanol fuel cell applications

    NASA Astrophysics Data System (ADS)

    Pawar, Sambhaji M.; Kim, Jongmin; Inamdar, Akbar I.; Woo, Hyeonseok; Jo, Yongcheol; Pawar, Bharati S.; Cho, Sangeun; Kim, Hyungsang; Im, Hyunsik

    2016-02-01

    This work reports on the concurrent electrochemical energy storage and conversion characteristics of granular copper oxide electrode films prepared using reactive radio-frequency magnetron sputtering at room temperature under different oxygen environments. The obtained films are characterized in terms of their structural, morphological, and compositional properties. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope studies reveal that granular, single-phase Cu2O and CuO can be obtained by controlling the oxygen flow rate. The electrochemical energy storage properties of the films are investigated by carrying out cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy tests. The electrochemical analysis reveals that the Cu2O and CuO electrodes have high specific capacitances of 215 and 272 F/g in 6 M KOH solution with a capacity retention of about 80% and 85% after 3000 cycles, respectively. Cyclic voltammetry and chronoamperometry are used to study the electrochemical energy conversion properties of the films via methanol electro-oxidation. The results show that the Cu2O and CuO electrodes are electro-catalytically active and highly stable.

  9. Comparative study of properties between a-GeC:H and a-SiC:H films prepared by radio-frequency reactive sputtering in methane

    NASA Astrophysics Data System (ADS)

    Saito, N.; Yamaguchi, T.; Nakaaki, I.

    1995-09-01

    Hydrogenated amorphous germanium-carbon (a-GeC:H) and silicon-carbon (a-SiC:H) films were deposited by reactive magnetron sputtering of Ge and Si targets in a methane argon gas mixture. The effect of rf power on the structural, optical, and electrical properties of the films was investigated. The carbon content in a-SiC:H films is larger than in a-GeC:H for the same deposition condition, and it decreases with increasing rf power. The intensity of the carbon-related bonds, the optical band gap, and the activation energy of dc conductivity of both films decreases with decreasing carbon content. The temperature dependence of dc conductivity of a-SiC:H exhibits activated-type conduction, whereas hopping conduction is predominant in a-GeC:H. Hydrogen concentration and H bonding ratio are examined, indicating that the termination of the dangling bond by hydrogen is more effective in a a-SiC:H films than a-GeC:H films.

  10. Effect of substrate roughness and working pressure on photocatalyst of N-doped TiOx films prepared by reactive sputtering with air

    NASA Astrophysics Data System (ADS)

    Lee, Seon-Hong; Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N.

    2015-01-01

    N-doped TiOx films on the glass substrate were prepared by radio-frequency (RF) magnetron reactive sputtering of Ti target in a mixed gas of argon and dry air. The effect of substrate roughness and working pressure on the physical properties and the photocatalytic properties of the N-doped TiOx films was investigated. The surface roughness of glass substrate has little influence on the film properties such as produced phases, lattice parameters, introduced nitrogen contents, and atomic bonding configurations, but significant influence on the surface roughness of film resulting in the variation of the photocatalytic ability. The working pressure has little influence on the produced phases and the atomic bonding configurations, but significant influence on the atomic concentration of the N-doped TiOx film, resulting in the large variation of optical, structural, and photocatalytic properties. It is suggested that the high photocatalysis of N-doped TiOx film requires a certain range of the N doping concentration which shows the interstitial complex N doping states in TiO2.

  11. Effect of annealing treatment on the photocatalytic activity of TiO2 thin films deposited by dc reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Arias, L. M. Franco; Arias Duran, A.; Cardona, D.; Camps, E.; Gómez, M. E.; Zambrano, G.

    2015-07-01

    Titanium dioxide (TiO2) thin films have been deposited by DC reactive magnetron sputtering on silicon and quartz substrates with different Ar/O2 ratios in the gas mixture. Substrate temperature was kept constant at 400 °C during the deposition process, and the TiO2 thin films were later annealed at 700 °C for 3 h. The effect of the Ar/O2 ratio in the gas flow and the annealing treatment on the phase composition, deposition rate, crystallinity, surface morphology and the resulting photocatalytic properties were investigated. For photocatalytic measurements, the variation of the concentration of the methylene blue (MB) dye under UV irradiation was followed by a change in the intensity of the characteristic MB band in the UV- Vis transmittance spectra. We report here that the as-grown TiO2 films showed only the anatase phase, whereas after annealing, the samples exhibited both the anatase and rutile phases in proportions that varied with the Ar/O2 ratio in the mixture of gases used during growth. In particular, the annealed TiO2 thin film deposited at a 50/50 ratio of Ar/O2, composed of both anatase (80%) and rutile phases (20%), exhibited the highest photocatalytic activity (30% of MB degradation) compared with the samples without annealing and composed of only the anatase phase.

  12. Multi-functional reactively-sputtered copper oxide electrodes for supercapacitor and electro-catalyst in direct methanol fuel cell applications.

    PubMed

    Pawar, Sambhaji M; Kim, Jongmin; Inamdar, Akbar I; Woo, Hyeonseok; Jo, Yongcheol; Pawar, Bharati S; Cho, Sangeun; Kim, Hyungsang; Im, Hyunsik

    2016-01-01

    This work reports on the concurrent electrochemical energy storage and conversion characteristics of granular copper oxide electrode films prepared using reactive radio-frequency magnetron sputtering at room temperature under different oxygen environments. The obtained films are characterized in terms of their structural, morphological, and compositional properties. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope studies reveal that granular, single-phase Cu2O and CuO can be obtained by controlling the oxygen flow rate. The electrochemical energy storage properties of the films are investigated by carrying out cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy tests. The electrochemical analysis reveals that the Cu2O and CuO electrodes have high specific capacitances of 215 and 272 F/g in 6 M KOH solution with a capacity retention of about 80% and 85% after 3000 cycles, respectively. Cyclic voltammetry and chronoamperometry are used to study the electrochemical energy conversion properties of the films via methanol electro-oxidation. The results show that the Cu2O and CuO electrodes are electro-catalytically active and highly stable. PMID:26888077

  13. Cupric and cuprous oxide by reactive ion beam sputter deposition and the photosensing properties of cupric oxide metal-semiconductor-metal Schottky photodiodes

    NASA Astrophysics Data System (ADS)

    Hong, Min-Jyun; Lin, Yong-Chen; Chao, Liang-Chiun; Lin, Pao-Hung; Huang, Bohr-Ran

    2015-08-01

    Cupric (CuO) and cuprous (Cu2O) oxide thin films have been deposited by reactive ion beam sputter deposition at 400 °C with an Ar:O2 ratio from 2:1 to 12:1. With an Ar:O2 ratio of 2:1, single phase polycrystalline CuO thin films were obtained. Decreasing oxygen flow rate results in CuO + Cu2O and Cu2O + Cu mixed thin films. As Ar:O2 ratio reaches 12:1, Cu2O nanorods with diameter of 250 nm and length longer than 1 μm were found across the sample. Single phase CuO thin film exhibits an indirect band gap of 1.3 eV with a smooth surface morphology. CuO metal-semiconductor-metal (MSM) Schottky photodiodes (PD) were fabricated by depositing Cu interdigitated electrodes on CuO thin films. Photosensing properties of the CuO PD were characterized from 350 to 1300 nm and a maximum responsivity of 43 mA/W was found at λ = 700 nm. The MSM PD is RC limited with a decay time constant less than 1 μs.

  14. Effects of radio frequency power on the chemical bonding, optical and mechanical properties for radio frequency reactive sputtered germanium carbide films

    NASA Astrophysics Data System (ADS)

    Hu, C. Q.; Xu, L.; Tian, H. W.; Jin, Z. S.; Lv, X. Y.; Zheng, W. T.

    2006-12-01

    Germanium carbide (Ge1-xCx) films have been prepared by radio frequency (RF) reactive sputtering of a pure Ge(111) target in a CH4/Ar mixture discharge, and their composition, chemical bonding, optical and mechanical properties have been investigated as a function of RF power. The relationship between the chemical bonding and the optical and mechanical properties of the Ge1-xCx films has been explored. The results show that the refractive index of Ge1-xCx films increases from 1.9 to 3.2 and the optical gap decreases from 1.9 to 1.0 eV as RF power increases from 80 to 250 W, which is due to an increase in the germanium content with increasing RF power. Also, it is found that the hardness of Ge1-xCx films increases with increasing RF power, which can be attributed to an increase in the fraction of sp3 Ge-C bonds at the expense of the sp2 C-C bonds in the Ge1-xCx films.

  15. Multi-functional reactively-sputtered copper oxide electrodes for supercapacitor and electro-catalyst in direct methanol fuel cell applications

    PubMed Central

    Pawar, Sambhaji M.; Kim, Jongmin; Inamdar, Akbar I.; Woo, Hyeonseok; Jo, Yongcheol; Pawar, Bharati S.; Cho, Sangeun; Kim, Hyungsang; Im, Hyunsik

    2016-01-01

    This work reports on the concurrent electrochemical energy storage and conversion characteristics of granular copper oxide electrode films prepared using reactive radio-frequency magnetron sputtering at room temperature under different oxygen environments. The obtained films are characterized in terms of their structural, morphological, and compositional properties. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope studies reveal that granular, single-phase Cu2O and CuO can be obtained by controlling the oxygen flow rate. The electrochemical energy storage properties of the films are investigated by carrying out cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy tests. The electrochemical analysis reveals that the Cu2O and CuO electrodes have high specific capacitances of 215 and 272 F/g in 6 M KOH solution with a capacity retention of about 80% and 85% after 3000 cycles, respectively. Cyclic voltammetry and chronoamperometry are used to study the electrochemical energy conversion properties of the films via methanol electro-oxidation. The results show that the Cu2O and CuO electrodes are electro-catalytically active and highly stable. PMID:26888077

  16. Influence of film thickness on the morphological and electrical properties of epitaxial TiC films deposited by reactive magnetron sputtering on MgO substrates

    NASA Astrophysics Data System (ADS)

    Zoita, N. C.; Braic, V.; Danila, M.; Vlaicu, A. M.; Logofatu, C.; Grigorescu, C. E. A.; Braic, M.

    2014-03-01

    Epitaxial TiC films were deposited on MgO (001) by DC magnetron sputtering in a reactive atmosphere of Ar and CH4 at 800 °C. The films elemental composition and chemical bonding was investigated by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy. The crystallographic structure, investigated by X-ray diffraction, exhibited an increased degree of (001) orientation with the film thickness, with a cube-on-cube epitaxial relationship with the substrate. The films morphology and electrical properties were determined by atomic force microscopy (AFM) and Hall measurements in Van der Pauw geometry. The influences of the film thickness (57-545 nm) on the morphological and electrical properties were investigated. The thinnest film presented the lowest resistivity, ~160 μΩ cm, showing an atomically flat surface, while higher values were obtained for the thicker films, explained by their different morphology dominated by low aspect ratio nanoislands/nanocolumns.

  17. Effect of Aluminum concentration on structural and optical properties of DC reactive magnetron sputtered Zinc Aluminum Oxide thin films for transparent electrode applications

    NASA Astrophysics Data System (ADS)

    Kumar, B. Rajesh; Subba Rao, T.

    2012-11-01

    Zinc Aluminum Oxide(ZAO) thin films were deposited on glass substrates by DC reactive magnetron sputtering in an Ar+O2 gas mixture using commercial available Zn metal (99.99% purity) and Al (99.99% purity) targets of 2 inch diameter and 4 mm thickness. The films were characterized and the effect of aluminum (Al) concentration (2 at %-6 at %) on the structural and optical properties was studied. The average crystallite size obtained from Scherer formula is in the range of 32-44nm. Microstructural analysis using Scanning Electron Microscope (SEM) supplemented with EDS is carried out to find the grain size as well as to find the composition elemental data of prepared thin films. Optical study is performed to calculate the extinction coefficient (k), absorption coefficient (a), optical band gap (Eg) using transmission spectra obtained using UV-VIS-NIR spectrophotometer. There was widening of optical band gap with increasing aluminum concentration. ZAO film with low resistivity 3.2 × 10-4 cm and high transmittance of 80% is obtained for 3at% doped Al which is crucial for optoelectronic applications.

  18. Influence of Substrate Temperature on Structural Properties and Deposition Rate of AlN Thin Film Deposited by Reactive Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Jin, Hao; Feng, Bin; Dong, Shurong; Zhou, Changjian; Zhou, Jian; Yang, Yi; Ren, Tianling; Luo, Jikui; Wang, Demiao

    2012-07-01

    Aluminum nitride (AlN) thin films with c-axis preferred orientation have been prepared by reactive direct-current (DC) magnetron sputtering. The degree of preferred crystal orientation, the cross-sectional structure, and the surface morphology of AlN thin films grown on Si (100) substrates at various substrate temperatures from 60°C to 520°C have been investigated by x-ray diffraction, scanning electron microscopy, and atomic force microscopy. Results show that the substrate temperature has a significant effect on the structural properties, such as the degree of c-axis preferred orientation, the full-width at half-maximum (FWHM) of the rocking curve, the surface morphology, and the cross-sectional structure as well as the deposition rate of the AlN thin films. The optimal substrate temperature is 430°C, with corresponding root-mean-square surface roughness ( R rms) of 1.97 nm, FWHM of AlN (002) diffraction of 2.259°, and deposition rate of 20.86 nm/min. The mechanisms behind these phenomena are discussed. Finally, film bulk acoustic resonators based on AlN films were fabricated; the corresponding typical electromechanical coupling coefficient ( k {t/2}) is 5.1% with series and parallel frequencies of 2.37 GHz and 2.42 GHz, respectively.

  19. Surface fluorination of rutile-TiO2 thin films deposited by reactive sputtering for accelerating response of optically driven capillary effect

    NASA Astrophysics Data System (ADS)

    Kobayashi, Taizo; Maeda, Hironobu; Konishi, Satoshi

    2016-06-01

    We report the acceleration of photoresponsive wettability switching by applying surface fluorination to rutile-TiO2 thin films deposited by reactive sputtering. Photoresponsive wettability switchable surfaces can be applied to optically driven liquid manipulation to enable the elimination of the electrical wiring and pneumatic tubing from fluidic systems. In this work, surface fluorination using CF4 plasma treatment is applied to rutile-TiO2 thin films, which exhibit a wider switching range of wettability than that of anatase-TiO2 thin films. Fluorine termination of TiO2 thin films increases the surface acidity and enhances its photocatalytic performance. TiO2 thin films with and without surface fluorination respectively exhibited the transition of contact angles ranging from 73.7 to 12.3°, and from 70.2 to 32° under UV irradiation for 15 min. Liquid introduction into a microchannel is also demonstrated, utilizing the developed TiO2 surface, which can generate a negative capillary pressure difference under ultraviolet light irradiation.

  20. Elastic constants, Poisson ratios, and the elastic anisotropy of VN(001), (011), and (111) epitaxial layers grown by reactive magnetron sputter deposition

    NASA Astrophysics Data System (ADS)

    Mei, A. B.; Wilson, R. B.; Li, D.; Cahill, David G.; Rockett, A.; Birch, J.; Hultman, L.; Greene, J. E.; Petrov, I.

    2014-06-01

    Elastic constants are determined for single-crystal stoichiometric NaCl-structure VN(001), VN(011), and VN(111) epitaxial layers grown by magnetically unbalanced reactive magnetron sputter deposition on 001-, 011-, and 111-oriented MgO substrates at 430 °C. The relaxed lattice parameter ao = 0.4134 ± 0.0004 nm, obtained from high-resolution reciprocal space maps, and the mass density ρ = 6.1 g/cm3, determined from the combination of Rutherford backscattering spectroscopy and film thickness measurements, of the VN layers are both in good agreement with reported values for bulk crystals. Sub-picosecond ultrasonic optical pump/probe techniques are used to generate and detect VN longitudinal sound waves with measured velocities v001 = 9.8 ± 0.3, v011 = 9.1 ± 0.3, and v111 = 9.1 ± 0.3 km/s. The VN c11 elastic constant is determined from the sound wave velocity measurements as 585 ± 30 GPa; the c44 elastic constant, 126 ± 3 GPa, is obtained from surface acoustic wave measurements. From the combination of c11, c44, vhkl, and ρ we obtain the VN c12 elastic constant 178 ± 33 GPa, the VN elastic anisotropy A = 0.62, the isotropic Poisson ratio ν = 0.29, and the anisotropic Poisson ratios ν001 = 0.23, ν011 = 0.30, and ν111 = 0.29.

  1. Breakdown field enhancement of Si-based MOS capacitor by post-deposition annealing of the reactive sputtered ZrOxNy gate oxide

    NASA Astrophysics Data System (ADS)

    Chew, Chun Chet; Goh, Kian Heng; Gorji, Mohammad Saleh; Tan, Chee Ghuan; Ramesh, S.; Wong, Yew Hoong

    2016-02-01

    Zirconium oxynitride (ZrOxNy) thin films were deposited on silicon (100) substrates by radio frequency-reactive magnetron sputtering in an argon-oxygen-nitrogen atmosphere. Post-deposition annealing (PDA) process was performed in argon ambient at various annealing temperatures (500, 600, 700 and 800 °C) for 15 min. Metal-oxide-semiconductor capacitors were then fabricated with aluminum as the gate electrode. The effects of PDA process on the thin film's structural and electrical properties of the samples were investigated. The structural properties of the deposited films have been evaluated by atomic force microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. On the other hand, the electrical characterization of the film was conducted by current-voltage analysis. The Raman results revealed that (600-800 °C) annealed samples comprised of crystalline multiphase films (t-ZrO2, fcc-ZrN and bcc γ-Zr2ON2). Interfacial layer consisted of Zr-Si-O, Si-O-N and Si-O phase was formed for all investigated samples, and interfacial layer growth was suppressed when annealed at lower temperatures (500 °C). Electrical result revealed that the sample annealed at a relatively low temperature of 500 °C has demonstrated the highest breakdown field which was attributed to the low surface roughness, the low interface trap and the highly amorphous multiphase film.

  2. Titanium oxynitride films for a bipolar plate of polymer electrolyte membrane fuel cell prepared by inductively coupled plasma assisted reactive sputtering

    NASA Astrophysics Data System (ADS)

    Kim, S. Y.; Han, D. H.; Kim, J. N.; Lee, J. J.

    Titanium oxynitride (TiN xO y) films are investigated for application as a bipolar plate coating material in a polymer electrolyte membrane fuel cell (PEMFC). TiN xO y films with various amounts of oxygen are deposited on stainless-steel substrates by inductively coupled plasma (ICP) assisted reactive sputtering by changing the oxygen gas flow rate. The interfacial contact resistance (ICR) and the corrosion resistance of the TiN xO y films are measured under PEMFC simulated conditions. When the amount of oxygen in the TiN xO y film is approximately <12 at.% (O 2 flow rate ≤0.2 sccm), the corrosion resistance is enhanced considerably, whereas the interfacial contact resistance does not change. The corrosion current density decreases from 8 × 10 -6 A cm -2 for the TiN-coated sample to 2.7 × 10 -6 A cm -2 at 0.6 V vs. SCE as a result of oxygen incorporation in the TiN film. The ICR value remains at 2.5 mΩ cm 2 at 150 N cm -2. When a small amount of oxygen is added to the TiN film, it is postulated that the oxygen atoms locate at the column and grain boundaries, and thus prevent corrosive media from penetrating into the substrate while not deteriorating the electrical property of the film.

  3. Understanding of gas phase deposition of reactive magnetron sputtered TiO2 thin films and its correlation with bactericidal efficiency

    NASA Astrophysics Data System (ADS)

    Panda, A. B.; Mahapatra, S. K.; Barhai, P. K.; Das, A. K.; Banerjee, I.

    2012-10-01

    Nanostructured TiO2 thin films were deposited using RF reactive magnetron sputtering at different O2 flow rates (20, 30, 50 and 60 sccm) and constant RF power of 200 W. In situ investigation of the nucleation and growth of the films was made by Optical Emission Spectroscopy (OES). The nano amorphous nature as revealed from X-ray diffraction (XRD) of the as deposited films and abundance of the Ti3+ surface oxidation states and surface hydroxyl group (OH-) in the films deposited at 50 sccm as determined from X-ray photo electron spectroscopy (XPS) was explained on the basis of emission spectra studies. The increase in band gap and decrease in particle size with O2 flow rate was observed from transmission spectra of UV-vis spectroscopy. Photoinduced hydrophilicity has been studied using Optical Contact Angle (OCA) measurement. The post irradiated films showed improved hydrophilicity. The bactericidal efficiency of these films was investigated taking Escherichia coli as model bacteria. The films deposited at 50 sccm shows better bactericidal activity as revealed from the optical density (OD) measurement. The qualitative analysis of the bactericidal efficiency was depicted from Scanning Electron Microscope images. A correlation between bactericidal efficiency and the deposited film has been established and explained on the basis of nucleation growth, band gap and hydrophilicity of the films.

  4. Effect of film thickness on structural and mechanical properties of AlCrN nanocompoite thin films deposited by reactive DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Prakash, Ravi; Kaur, Davinder

    2016-05-01

    In this study, the influence of film thickness on the structural, surface morphology and mechanical properties of Aluminum chromium nitride (AlCrN) thin films has been successfully investigated. The AlCrN thin films were deposited on silicon (100) substrate using dc magnetron reactive co-sputtering at substrate temperature 400° C. The structural, surface morphology and mechanical properties were studied using X-ray diffraction, field-emission scanning electron microscopy and nanoindentation techniques respectively. The thickness of these thin films was controlled by varying the deposition time therefore increase in deposition time led to increase in film thickness. X-ray diffraction pattern of AlCrN thin films with different deposition time shows the presence of (100) and (200) orientations. The crystallite size varies in the range from 12.5 nm to 36.3 nm with the film thickness due to surface energy minimization with the higher film thickness. The hardness pattern of these AlCrN thin films follows Hall-Petch relation. The highest hardness 23.08 Gpa and young modulus 215.31 Gpa were achieved at lowest grain size of 12.5 nm.

  5. Transmission photocathodes based on stainless steel mesh and quartz glass coated with N-doped DLC thin films prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Balalykin, N. I.; Huran, J.; Nozdrin, M. A.; Feshchenko, A. A.; Kobzev, A. P.; Arbet, J.

    2016-03-01

    The influence was investigated of N-doped diamond-like carbon (DLC) films properties on the quantum efficiency of a prepared transmission photocathode. N-doped DLC thin films were deposited on a silicon substrate, a stainless steel mesh and quartz glass (coated with 5 nm thick Cr adhesion film) by reactive magnetron sputtering using a carbon target and gas mixture Ar, 90%N2+10%H2. The elements' concentration in the films was determined by RBS and ERD. The quantum efficiency was calculated from the measured laser energy and the measured cathode charge. For the study of the vectorial photoelectric effect, the quartz type photocathode was irradiated by intensive laser pulses to form pin-holes in the DLC film. The quantum efficiency (QE), calculated at a laser energy of 0.4 mJ, rose as the nitrogen concentration in the DLC films was increased and rose dramatically after the micron-size perforation in the quartz type photocathodes.

  6. Preparation of p-type NiO films by reactive sputtering and their application to CdTe solar cells

    NASA Astrophysics Data System (ADS)

    Ishikawa, Ryousuke; Furuya, Yasuaki; Araki, Ryouichi; Nomoto, Takahiro; Ogawa, Yohei; Hosono, Aikyo; Okamoto, Tamotsu; Tsuboi, Nozomu

    2016-02-01

    Transparent p-type NiO films were prepared by reactive sputtering using the facing-target system under Ar-diluted O2 gas at Tsub of 30 and 200 °C. The increasing intensity of dominant X-ray diffraction (XRD) peaks indicates improvements in the crystallinity of NiO films upon Cu doping. In spite of the crystallographic and optical changes after Cu-doping, the electrical properties of Cu-doped NiO films were slightly improved. Upon Ag-doping at 30 °C under low O2 concentration, on the other hand, the intensity of the dominant (111) XRD peaks was suppressed and p-type conductivity increased from ˜10-3 to ˜10-1 S cm-1. Finally, our Ag-doped NiO films were applied as the back contact of CdTe solar cells. CdTe solar cells with a glass/ITO/CdS/CdTe/NiO structure exhibited an efficiency of 6.4%, suggesting the high potential of using p-type NiO for the back-contact film in thin-film solar cells.

  7. Indium doped ZnO films prepared by RF magnetron sputtering: effect of substrate temperature on the strain-induced band gap.

    PubMed

    Daniel, Georgi P; Kumar, David Devraj; Justinvictor, V B; Nair, Prabitha B; Joy, K; Koshy, Peter; Thomas, P V

    2012-03-01

    Indium doped zinc oxide (InZnO) thin films were deposited onto corning glass substrates by RF magnetron sputtering. The dependence of crystal structure, surface morphology, optical properties and electrical conductivity on substrate temperature was investigated using XRD, AFM, UV-vis Spectrophotometer, Fluorescence Spectrophotometer and four-point probe. The films were prepared at different substrate temperatures viz, room temperature (RT), 473 K and 673 K at RF power 200 W. All the films showed preferred orientation along (002) direction. Crystallite size increased from 14 to 19 nm as the substrate temperature was increased to 473 K. With increase in substrate temperature the crystallites did not show any further growth. AFM analysis showed that the rms roughness value decreased from 60 nm to 23 nm when the substrate temperature was increased to 673 K. Optical measurements revealed maximum band gap and minimum refractive index for the film prepared at 473 K. A strong correlation between the band gap variation and the strain developed at different substrate temperatures is established. PMID:22755081

  8. Evaluation of the optoelectronic properties and corrosion behavior of Al2O3-doped ZnO films prepared by dc pulsed magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Zubizarreta, C.; Berasategui, E. G.; Bayón, R.; Escobar Galindo, R.; Barros, R.; Gaspar, D.; Nunes, D.; Calmeiro, T.; Martins, R.; Fortunato, E.; Barriga, J.

    2014-12-01

    The main requirements for transparent conducting oxide (TCO) films acting as electrodes are a high transmission rate in the visible spectral region and low resistivity. However, in many cases, tolerance to temperature and humidity exposure is also an important requirement to be fulfilled by the TCOs to assure proper operation and durability. Besides improving current encapsulation methods, the corrosion resistance of the developed TCOs must also be enhanced to warrant the performance of optoelectronic devices. In this paper the performance of aluminum-doped zinc oxide (AZO) films deposited by pulsed dc magnetron sputtering has been studied. Structure, optical transmittance/reflectance, electrical properties (resistivity, carrier concentration and mobility) and corrosion resistance of the developed coatings have been analyzed as a function of the doping of the target and the coating thickness. Films grown from a 2.0 wt% Al2O3 target with a thickness of approximately 1 µm showed a very low resistivity of 6.54  ×  10-4 Ωcm and a high optical transmittance in the visible range of 84%. Corrosion studies of the developed samples have shown very low corrosion currents (nanoamperes), very high corrosion resistances (in the order of 107 Ω) and very high electrochemical stability, indicating no tendency for electrochemical corrosion degradation.

  9. Transparent conductive Nb-doped TiO2 films deposited by reactive dc sputtering using Ti-Nb alloy target, precisely controlled in the transition region using impedance feedback system

    NASA Astrophysics Data System (ADS)

    Oka, Nobuto; Sanno, Yuta; Jia, Junjun; Nakamura, Shin-ichi; Shigesato, Yuzo

    2014-05-01

    In this study, a stable reactive sputtering process using a Ti-Nb alloy target was achieved by applying a plasma impedance feedback system. High-quality transparent conductive Nb-doped TiO2 (Nb:TiO2) films were fabricated with high reproducibility. The films were deposited on unheated substrate and subsequently annealed at 873 K under vacuum conditions (below 6.0 × 10-4 Pa) for 1 h. During reactive sputtering, the feedback system precisely controlled the oxidation of the target surface in the so-called transition region. The post-annealing process yielded polycrystalline Nb:TiO2 films whose lattice defects decreased with increasing Nb concentration. An extremely low resistivity (7.2 × 10-4 Ω cm) was achieved for Nb:TiO2 film with 60-70% transmittance in the visible region. The reactive sputtering using Ti-Nb alloys is considered to be a strong candidate for industrial-scale thin-film deposition. Furthermore, it can also control the metal-oxygen stoichiometry of Nb:TiO2 films precisely to achieve desirable properties for each industrial application.

  10. Optimizing TaO{sub x} memristor performance and consistency within the reactive sputtering “forbidden region”

    SciTech Connect

    Lohn, Andrew J.; Stevens, James E.; Mickel, Patrick R.; Marinella, Matthew J.

    2013-08-05

    Standard deposition processes for depositing ReRAM oxides utilize mass flow of reactive gas to control stoichiometry and have difficulty depositing a precisely defined sub-stoichiometry within a “forbidden region” where film properties are discontinuous with mass flow. We show that by maintaining partial pressure within this discontinuous “forbidden region,” instead of by maintaining mass flow, we can optimize tantalum oxide device properties and reduce or eliminate the electroforming step. We also show that defining the partial pressure set point as a fraction of the “forbidden region” instead of as an absolute value can be used to improve wafer-to-wafer consistency with minimal recalibration efforts.

  11. Epitaxy of Pb(Zr, Ti)O3 films on Ir/YSZ/Si under conditions of cathode sputtering: The effect of reactive gas composition

    NASA Astrophysics Data System (ADS)

    Beshenkov, V. G.; Burlakov, A. A.; Znamenskii, A. G.; Marchenko, V. A.

    2014-08-01

    The peculiarities of the growth of PZT films on heteroepitaxial Ir/YSZ/Si structures under conditions of cathode radio-frequency sputtering of a ceramic target in argon-oxygen mixtures have been studied. It is shown that sputtering in a gas mixture with a high partial pressure of oxygen results in crystallization of the PZT films in a metastable pyrochlore structure, while sputtering in argon or the use of argon in the initial phase of the sputtering yields PZT films with an equilibrium perovskite structure.

  12. Growth and characterization of Li-doped ZnO thin films on nanocrystalline diamond substrates

    NASA Astrophysics Data System (ADS)

    Huang, Jian; Xia, Yiben; Wang, Linjun; Xu, Jinyong; Hu, Guang; Zhu, Xuefeng; Shi, Weimin

    2008-02-01

    Nanocrystalline diamond(NCD) films with a mean surface roughness of 23.8 nm were grown on silicon substrates in a hot filament chemical vapor deposition(HFCVD) system. Then, Zn 1-xLi xO (x=0, 0.05, 0.10, 0.15) films were deposited on these NCD films by radio-frequency(RF) reactive magnetron sputtering method. When x was 0.1, the Li-doped ZnO film had a larger resistivity more than 10 8Ω•cm obtained from Hall effect measurement. All the Zn 1-xLi xO films had a strong c-axis orientation structure determined by X-ray diffraction (XRD). The above results suggested that the Li-doped ZnO film/NCD structure prepared in this work was attractive for the application of high frequency surface acoustic wave (SAW) devices.

  13. Fabrication of ZnO photonic crystals by nanosphere lithography using inductively coupled-plasma reactive ion etching with CH{sub 4}/H{sub 2}/Ar plasma on the ZnO/GaN heterojunction light emitting diodes

    SciTech Connect

    Chen, Shr-Jia; Chang, Chun-Ming; Kao, Jiann-Shiun; Chen, Fu-Rong; Tsai, Chuen-Horng

    2010-07-15

    This article reports fabrication of n-ZnO photonic crystal/p-GaN light emitting diode (LED) by nanosphere lithography to further booster the light efficiency. In this article, the fabrication of ZnO photonic crystals is carried out by nanosphere lithography using inductively coupled plasma reactive ion etching with CH{sub 4}/H{sub 2}/Ar plasma on the n-ZnO/p-GaN heterojunction LEDs. The CH{sub 4}/H{sub 2}/Ar mixed gas gives high etching rate of n-ZnO film, which yields a better surface morphology and results less plasma-induced damages of the n-ZnO film. Optimal ZnO lattice parameters of 200 nm and air fill factor from 0.35 to 0.65 were obtained from fitting the spectrum of n-ZnO/p-GaN LED using a MATLAB code. In this article, we will show our recent result that a ZnO photonic crystal cylinder has been fabricated using polystyrene nanosphere mask with lattice parameter of 200 nm and radius of hole around 70 nm. Surface morphology of ZnO photonic crystal was examined by scanning electron microscope.

  14. Homoepitaxial ZnO Film Growth

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, C-H; Lehoczky, S. L.; Harris, M. T.; Callahan, M. J.; McCarty, P.; George, M. A.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    ZnO films have high potential for many applications, such as surface acoustic wave filters, UV detectors, and light emitting devices due to its structural, electrical, and optical properties. High quality epitaxial films are required for these applications. The Al2O3 substrate is commonly used for ZnO heteroepitaxial growth. Recently, high quality ZnO single crystals are available for grow homoepitaxial films. Epitaxial ZnO films were grown on the two polar surfaces (O-face and Zn-face) of (0001) ZnO single crystal substrates using off-axis magnetron sputtering deposition. As a comparison, films were also deposited on (0001) Al2O3 substrates. It was found that the two polar ZnO surfaces have different photoluminescence (PL) spectrum, surface structure and morphology, which strongly influence the epitaxial film growth. The morphology and structure of homoepitaxial films grown on the ZnO substrates were different from heteroepitaxial films grown on the Al2O3. An interesting result shows that high temperature annealing of ZnO single crystals will improve the surface structure on the O-face surface rather than the opposite surface. The measurements of PL, low-angle incident x-ray diffraction, and atomic force microscopy of ZnO films indicate that the O-terminated surface is better for ZnO epitaxial film growth.

  15. Structural and compositional evolutions of InxAl1-xN core-shell nanorods grown on Si(111) substrates by reactive magnetron sputter epitaxy.

    PubMed

    Serban, Elena Alexandra; Åke Persson, Per Ola; Poenaru, Iuliana; Junaid, Muhammad; Hultman, Lars; Birch, Jens; Hsiao, Ching-Lien

    2015-05-29

    Catalystless growth of InxAl(1-x)N core-shell nanorods have been realized by reactive magnetron sputter epitaxy onto Si(111) substrates. The samples were characterized by scanning electron microscopy, x-ray diffraction, scanning transmission electron microscopy, and energy dispersive x-ray spectroscopy. The composition and morphology of InxAl(1-x)N nanorods are found to be strongly influenced by the growth temperature. At lower temperatures, the grown materials form well-separated and uniform core-shell nanorods with high In-content cores, while a deposition at higher temperature leads to the formation of an Al-rich InxAl(1-x)N film with vertical domains of low In-content as a result of merging Al-rich shells. The thickness and In content of the cores (domains) increase with decreasing growth temperature. The growth of the InxAl(1-x)N is traced to the initial stage, showing that the formation of the core-shell nanostructures starts very close to the interface. Phase separation due to spinodal decomposition is suggested as the origin of the resultant structures. Moreover, the in-plane crystallographic relationship of the nanorods and substrate was modified from a fiber textured to an epitaxial growth with an epitaxial relationship of InxAl(1-x)N[0001]//Si[111] and InxAl(1-x)N[1120]//Si[110 by removing the native SiOx layer from the substrate. PMID:25944838

  16. Epitaxial Bi3Fe5O12(001) films grown by pulsed laser deposition and reactive ion beam sputtering techniques

    NASA Astrophysics Data System (ADS)

    Adachi, N.; Denysenkov, V. P.; Khartsev, S. I.; Grishin, A. M.; Okuda, T.

    2000-09-01

    We report on processing and comparative characterization of epitaxial Bi3Fe5O12 (BIG) films grown onto Gd3(ScGa)5O12[GSGG,(001)] single crystal using pulsed laser deposition (PLD) and reactive ion beam sputtering (RIBS) techniques. A very high deposition rate of about 0.8 μm/h has been achieved in the PLD process. Comprehensive x-ray diffraction analyses reveal epitaxial quality both of the films: they are single phase, exclusively (001) oriented, the full width at half maximum of the rocking curve of (004) Bragg reflection is 0.06 deg for PLD and 0.05 deg for RIBS film, strongly in-plane textured with cube-on-cube film-to-substrate epitaxial relationship. Saturation magnetization 4πMs and Faraday rotation at 635 nm were found to be 1400 Gs and -7.8 deg/μm in PLD-BIG, and 1200 Gs and -6.9 deg/μm in RIBS-BIG. Ferromagnetic resonance (FMR) measurements performed at 9.25 GHz yielded the gyromagnetic ratio γ=1.797×107l/s Oe, 1.826×107 l/s Oe; the constants of uniaxial magnetic anisotropy were Ku*=-8.66×104erg/cm3, -8.60×104 erg/cm3; the cubic magnetic anisotropy K1=-2.7×103 erg/cm3,-3.8×103 erg/cm3; and the FMR linewidth ΔH=25 and 34 Oe for PLD and RIBS films correspondingly. High Faraday rotation, low microwave loss, and low coercive field ⩽40 Oe of BIG/GSGG(001) films promise their use in integrated magneto-optic applications.

  17. Large modification in insulator-metal transition of VO2 films grown on Al2O3 (001) by high energy ion irradiation in biased reactive sputtering

    NASA Astrophysics Data System (ADS)

    Azhan, Nurul Hanis; Okimura, Kunio; Ohtsubo, Yoshiyuki; Kimura, Shin-ichi; Zaghrioui, Mustapha; Sakai, Joe

    2016-02-01

    High energy ion irradiation in biased reactive sputtering enabled significant modification of insulator-metal transition (IMT) properties of VO2 films grown on Al2O3 (001). Even at a high biasing voltage with mean ion energy of around 325 eV induced by the rf substrate biasing power of 40 W, VO2 film revealed low IMT temperature (TIMT) at 309 K (36 °C) together with nearly two orders magnitude of resistance change. Raman measurements from -193 °C evidenced that the monoclinic VO2 lattice begins to transform to rutile-tetragonal lattice near room temperature. Raman spectra showed the in-plane compressive stress in biased VO2 films, which results in shortening of V-V distance along a-axis of monoclinic structure, aM-axis (cR-axis) and thus lowering the TIMT. In respect to that matter, significant effects in shortening the in-plane axis were observed through transmission electron microscopy observations. V2p3/2 spectra from XPS measurements suggested that high energy ion irradiation also induced oxygen vacancies and resulted for an early transition onset and rather broader transition properties. Earlier band gap closing against the temperature in VO2 film with higher biasing power was also probed by ultraviolet photoelectron spectroscopy. Present results with significant modification of IMT behavior of films deposited at high-energy ion irradiation with TIMT near the room temperature could be a newly and effective approach to both exploring mechanisms of IMT and further applications of this material, due to the fixed deposition conditions and rather thicker VO2 films.

  18. Structural and compositional evolutions of InxAl1-xN core-shell nanorods grown on Si(111) substrates by reactive magnetron sputter epitaxy

    NASA Astrophysics Data System (ADS)

    Serban, Elena Alexandra; Åke Persson, Per Ola; Poenaru, Iuliana; Junaid, Muhammad; Hultman, Lars; Birch, Jens; Hsiao, Ching-Lien

    2015-05-01

    Catalystless growth of InxAl1-xN core-shell nanorods have been realized by reactive magnetron sputter epitaxy onto Si(111) substrates. The samples were characterized by scanning electron microscopy, x-ray diffraction, scanning transmission electron microscopy, and energy dispersive x-ray spectroscopy. The composition and morphology of InxAl1-xN nanorods are found to be strongly influenced by the growth temperature. At lower temperatures, the grown materials form well-separated and uniform core-shell nanorods with high In-content cores, while a deposition at higher temperature leads to the formation of an Al-rich InxAl1-xN film with vertical domains of low In-content as a result of merging Al-rich shells. The thickness and In content of the cores (domains) increase with decreasing growth temperature. The growth of the InxAl1-xN is traced to the initial stage, showing that the formation of the core-shell nanostructures starts very close to the interface. Phase separation due to spinodal decomposition is suggested as the origin of the resultant structures. Moreover, the in-plane crystallographic relationship of the nanorods and substrate was modified from a fiber textured to an epitaxial growth with an epitaxial relationship of InxAl1-xN[0001]//Si[111] and InxAl1-xN[11\\bar{2}0]//Si[1\\bar{1}0] by removing the native SiOx layer from the substrate.

  19. The effect of increasing V content on the structure, mechanical properties and oxidation resistance of Ti-Si-V-N films deposited by DC reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Fernandes, F.; Loureiro, A.; Polcar, T.; Cavaleiro, A.

    2014-01-01

    In the last years, vanadium rich films have been introduced as possible candidates for self-lubrication at high temperatures, based on the formation of V2O5 oxide. The aim of this investigation was to study the effect of V additions on the structure, mechanical properties and oxidation resistance of Ti-Si-V-N coatings deposited by DC reactive magnetron sputtering. The results achieved for TiSiVN films were compared and discussed in relation to TiN and TiSiN films prepared as reference. All coatings presented a fcc NaCl-type structure. A shift of the diffraction peaks to higher angles with increasing Si and V contents suggested the formation of a substitutional solid solution in TiN phase. Hardness and Young's modulus of the coatings were similar regardless on V content. The onset of oxidation of the films decreased significantly to 500 °C when V was added into the films; this behaviour was independent of the Si and V contents. The thermogravimetric isothermal curves of TiSiVN coatings oxidized at temperatures below the melting point of α-V2O5 (∼685 °C) showed two stages: at an early stage, the weight increase over time is linear, whilst, in the second stage, a parabolic evolution can be fitted to the experimental data. At higher temperatures only a parabolic evolution was fitted. α-V2O5 was the main phase detected at the oxidized surface of the coatings. Reduction of α-V2O5 to β-V2O5 phase occurred for temperatures above its melting point.

  20. Mechanical, tribological, and electrochemical behavior of Cr 1- xAl xN coatings deposited by r.f. reactive magnetron co-sputtering method

    NASA Astrophysics Data System (ADS)

    Sanchéz, J. E.; Sanchéz, O. M.; Ipaz, L.; Aperador, W.; Caicedo, J. C.; Amaya, C.; Landaverde, M. A. Hernández; Beltran, F. Espinoza; Muñoz-Saldaña, J.; Zambrano, G.

    2010-02-01

    Chromium aluminum nitride (Cr 1- xAl xN) coatings were deposited onto AISI H13 steel and silicon substrates by r.f. reactive magnetron co-sputtering in (Ar/N 2) gas mixture from chromium and aluminum targets. Properties of deposited Cr 1- xAl xN coatings such as compositional, structural, morphological, electrochemical, mechanical and tribological, were investigated as functions of aluminum content. X-ray diffraction patterns of Cr 1- xAl xN coatings with different atomic concentrations of aluminum (0.51 < x < 0.69) showed the presence and evolution of (1 1 1), (2 0 0), and (1 0 2) crystallographic orientations associated to the Cr 1- xAl xN cubic and w-AlN phases, respectively. The rate of corrosion of the steel coated with Cr 1- xAl xN varied with the applied power; however, always being clearly lower when compared to the uncoated substrate. The behavior of the protective effect of the Cr 1- xAl xN coatings is based on the substitution of Cr for Al, when the power applied to the aluminum target increases. The mechanical properties were also sensitive to the power applied, leading to a maximum in hardness and a reduced elastic modulus of 30 and 303 GPa at 350 W and a monotonic decrease to 11 and 212 GPa at 450 W, respectively. Finally, the friction coefficient measured by pin-on disk revealed values between 0.45 and 0.70 in humid atmosphere.

  1. Effect of oxygen incorporation on structural and properties of Ti-Si-N nanocomposite coatings deposited by reactive unbalanced magnetron sputtering

    SciTech Connect

    Ding, X.Z.; Zeng, X.T.; Liu, Y.C.; Zhao, L.R.

    2006-07-15

    Ti-Si-N-O nanocomposite coatings with different contents of oxygen were deposited by a combined dc/rf reactive unbalanced magnetron sputtering process in an Ar+N{sub 2}+O{sub 2} mixture atmosphere. The composition, structure, mechanical, and tribological properties of the as-deposited coatings were analyzed by energy dispersive analysis of x-rays, x-ray diffraction (XRD), nanoindentation, and pin-on-disk tribometer experiments, respectively. It was found that in the range of lower oxygen content with atomic ratio of O/N{<=}0.72, the tribological properties of the Ti-Si-N-O coatings are evidently improved, in comparison with the coating without oxygen incorporation. At O/N=0.72, the friction coefficient and wear rate of the as-deposited coatings are reduced to 20% and 45%, respectively. Meanwhile, however, their hardness was not reduced, but, on the contrary, slightly increased. With increasing oxygen content further to O/N{>=}0.72, coating hardness decreased significantly. The friction coefficient of the as-deposited coatings decreased monotonously with the increase of oxygen content in the whole composition range investigated. The wear rate of the coatings exhibited a minimum value at around O/N=0.72. In the lower range of O/N, wear rate decreased significantly due to the lubricant effect of oxygen incorporation, while in the higher range of O/N, wear rate increased gradually due to the weakening of coating hardness. XRD patterns revealed that the as-deposited coatings were mainly crystallized in cubic TiN phase, accompanied with minority of rutile structure titania in the case of higher oxygen incorporation.

  2. Relationship between the physical and structural properties of Nb{sub z}Si{sub y}N{sub x} thin films deposited by dc reactive magnetron sputtering

    SciTech Connect

    Sanjines, R.; Benkahoul, M.; Sandu, C.S.; Schmid, P.E.; Levy, F.

    2005-12-15

    The optical and electrical properties of Nb{sub z}Si{sub y}N{sub x} thin films deposited by dc reactive magnetron sputtering have been investigated as a function of the Si content (C{sub Si}). Optical properties were studied by both specular reflectivity and spectroscopic ellipsometry. Electrical resistivity was measured by the van der Pauw method at room temperature and as a function of the temperature down to 10 K. Both the optical and electrical properties of Nb{sub z}Si{sub y}N{sub x} films are closely related with the chemical composition and microstructure evolution caused by Si addition. For C{sub Si} up to 4 at. % the Si atoms are soluble in the lattice of the NbN crystallites. In this compositional regime, the optical and electrical properties show little dependence on the Si content. Between 4 and 7 at. % the surplus of Si atoms segregates at the grain boundaries, builds an insulating SiN{sub x} layer, and originates important modifications in the optical and electrical properties of these films. Further increase of C{sub Si} leads to the formation of nanocomposite structures. The electrical properties of these films are well described by the grain-boundary scattering model with low probability for electrons to cross the grain boundary. The appearance of the intragranular-insulating SiN{sub x} layer and the reduction of the grain size are noticed in the dielectric function mainly as a strong damping of the plasma oscillation.

  3. Effects of substrate bias on the preferred orientation, phase transition and mechanical properties for NbN films grown by direct current reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wen, M.; Hu, C. Q.; Wang, C.; An, T.; Su, Y. D.; Meng, Q. N.; Zheng, W. T.

    2008-07-01

    NbN films are deposited using direct current reactive magnetron sputtering in discharge of a mixture of N2 and Ar gas, and the effects of substrate bias (Vb) on the preferred orientation, phase transition, and mechanical properties for NbN films are explored by x-ray diffraction, selective area electron diffraction, and nanoindentation measurements. It is found that Vb has a significant influence on the stress in NbN films, leading to a pronounced change in the preferred orientation, phase structure, and hardness. As the substrate is at voltage floating, the stress is tensile. In contrast, as negative Vb is applied, the stress becomes compressive, and increases with increasing the absolute value of negative Vb. It is observed that a phase transition from δ (face-centered cubic) to δ' (hexagonal) for NbN films occurs as Vb is in the range of -80to-120V, which can be attributed to a decrease in the strain energy for NbN films. In order to explore the relationship between the stress and phase transition as well as preferred orientation, density-functional theory based on first principles is used to calculate the elastic constants and shear modulus for NbN with a structure of δ or δ'. The calculated results show that the shear modulus for δ'-NbN is larger than that for δ-NbN, whereas the bulk modulus for δ'-NbN is almost equal to that for δ-NbN, resulting in a difference in hardness for δ- or δ'-NbN single crystal.

  4. Impact of solar UV radiation on toxicity of ZnO nanoparticles through photocatalytic reactive oxygen species (ROS) generation and photo-induced dissolution

    EPA Science Inventory

    The present study investigated the impact of solar UV radiation on ZnO nanoparticle toxicity through photocatalytic ROS generation and photo-induced dissolution. Toxicity of ZnO nanoparticles to Daphnia magna was examined under laboratory light versus simulated solar UV radiatio...

  5. Evaluation of transverse piezoelectric coefficient of ZnO thin films deposited on different flexible substrates: a comparative study on the vibration sensing performance.

    PubMed

    Joshi, Sudeep; Nayak, Manjunatha M; Rajanna, K

    2014-05-28

    We report on the systematic comparative study of highly c-axis oriented and crystalline piezoelectric ZnO thin films deposited on four different flexible substrates for vibration sensing application. The flexible substrates employed for present experimental study were namely a metal alloy (Phynox), metal (aluminum), polyimide (Kapton), and polyester (Mylar). ZnO thin films were deposited by an RF reactive magnetron sputtering technique. ZnO thin films of similar thicknesses of 700 ± 30 nm were deposited on four different flexible substrates to have proper comparative studies. The crystallinity, surface morphology, chemical composition, and roughness of ZnO thin films were evaluated by respective material characterization techniques. The transverse piezoelectric coefficient (d31) value for assessing the piezoelectric property of ZnO thin films on different flexible substrates was measured by a four-point bending method. ZnO thin films deposited on Phynox alloy substrate showed relatively better material characterization results and a higher piezoelectric d31 coefficient value as compared to ZnO films on metal and polymer substrates. In order to experimentally verify the above observations, vibration sensing studies were performed. As expected, the ZnO thin film deposited on Phynox alloy substrate showed better vibration sensing performance. It has generated the highest peak to peak output voltage amplitude of 256 mV as compared to that of aluminum (224 mV), Kapton (144 mV), and Mylar (46 mV). Therefore, metal alloy flexible substrate proves to be a more suitable, advantageous, and versatile choice for integrating ZnO thin films as compared to metal and polymer flexible substrates for vibration sensing applications. The present experimental study is extremely important and helpful for the selection of a suitable flexible substrate for various applications in the field of sensor and actuator technology. PMID:24773266

  6. A comparative study of CdS:F and CdS:O thin films deposited by reactive RF-sputtering technique for window layer application in solar cells

    NASA Astrophysics Data System (ADS)

    Hernández-Rodríguez, E.; Loeza-Poot, M.; Riech, I.; Rejón, V.; Peña, J. L.

    2015-06-01

    In this work, we report our results on the study of CdS thin films doped with fluorine (CdS:F) and oxygen (CdS:O) prepared by the RF-sputtering technique with CHF3 and O2 as reactive gases, respectively. XPS and XRD measurements showed that CdS:F is composed of CdS and CdF2 compounds, while CdS:O is composed of CdS, CdSO4, CdSO3 and CdO2. Both CdS:F and CdS:O samples are highly oriented along the (0 0 2) plane, but with less crystallinity than CdS film. Scanning electron microscopy images showed that the morphology is changed due to the presence of reactive gases. The optical transmittance in the short wavelength range (λ  <  500 nm) is improved in doped films, as higher values were achieved in CdS:O samples. By increasing the reactive gas concentration during the sputtering, the bandgap of CdS:O films is increased, while for CdS:F films it slightly decreases; in both kinds of samples, the refractive index is decreased and all doped films have higher electrical resistivity than CdS.

  7. Preparation of CuSbS2 Thin Films by Co-Sputtering and Solar Cell Devices with Band Gap-Adjustable n-Type InGaN as a Substitute of ZnO

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Liang; Kuo, Dong-Hau; Tuan, Thi Tran Anh

    2016-01-01

    CuSbS2 films were fabricated by co-sputtering with the (Cu + Sb2S3) target at powers of 50 W, 55 W, and 60 W and a Cu target at 2 W under the deposition temperature of 300°C for 2 h, followed by annealing at 350-450°C for 1 h under a Sb2S3 compensation disc to avoid the sulfur deficiency. The (Cu + Sb2S3) cermet target with the composition of Cu:Sb2S3 = 2:1 was formed by hot pressing. The effects of processing conditions on the growth behavior, microstructural characteristics, and electrical properties of CuSbS2 films were investigated. X-ray diffractometry showed that the films prepared by the (Cu + Sb2S3) target at 50 W and 55 W were single phases. The peaks located at 28.4°, 28.7°, and 29.9° were contributed from the (111), (410), and (301) diffraction peaks, respectively. The film prepared with the (Cu + Sb2S3) target at 60 W was Cu rich and had a high electrical conductivity of 180 S cm-1. The 55 W-deposited film was Cu stoichiometric and had low electrical conductivity of 0.05 S cm-1. The 50 W-deposited film with electrical conductivity of 0.24 S cm-1 was good for use as a solar cell device. The solar cell devices made of the p-CuSbS2/ n-ZnO system had an efficiency of 0.16%, while it was 0.76% for the p-CuSbS2/ n-In0.3Ga0.7N system with the InGaN made by reactive sputtering at 200°C instead of metal-organic chemical vapor deposition above 750°C. This replacement with InGaN for a solar cell device has led to a 4.75-fold increase in efficiency.

  8. A reactive magnetron sputtering route for attaining a controlled core-rim phase partitioning in Cu2O/CuO thin films with resistive switching potential

    NASA Astrophysics Data System (ADS)

    Ogwu, A. A.; Darma, T. H.

    2013-05-01

    The achievement of a reproducible and controlled deposition of partitioned Cu2O/CuO thin films by techniques compatible with ULSI processing like reactive magnetron sputtering has been reported as an outstanding challenge in the literature. This phase partitioning underlies their performance as reversible resistive memory switching devices in advanced microelectronic applications of the future. They are currently fabricated by thermal oxidation and chemical methods. We have used a combination of an understanding from plasma chemistry, thermo-kinetics of ions, and rf power variation during deposition to successfully identify a processing window for preparing partitioned Cu2O/CuO films. The production of a core rich Cu2O and surface rich Cu2O/CuO mixture necessary for oxygen migration during resistive switching is confirmed by XRD peaks, Fourier transform infra red Cu (I)-O vibrational modes, XPS Cu 2P3/2 and O 1S peak fitting, and a comparison of satellite peak ratio's in Cu 2P3/2 fitted peaks. We are proposing based on the findings reported in this paper that an XPS satellite peak intensity(Is) to main peak intensity ratio (Im) ≤ 0.45 as an indicator of a core rich Cu2O and surface rich Cu2O/CuO formation in our prepared films. CuO is solely responsible for the satellite peaks. This is explained on the basis that plasma dissociation of oxygen will be limited to the predominant formation of Cu2O under certain plasma deposition conditions we have identified in this paper, which also results in a core-rim phase partitioning. The deposited films also followed a Volmer-Weber columnar growth mode, which could facilitate oxygen vacancy migration and conductive filaments at the columnar interfaces. This is further confirmed by optical transmittance and band-gap measurements using spectrophotometry. This development is expected to impact on the early adoption of copper oxide based resistive memory electronic switching devices in advanced electronic devices of the future

  9. Influence of vanadium incorporation on the microstructure, mechanical and tribological properties of Nb–V–Si–N films deposited by reactive magnetron sputtering

    SciTech Connect

    Ju, Hongbo; Xu, Junhua

    2015-09-15

    Composite Nb–V–Si–N films with various V contents (3.7–13.2 at.%) were deposited by reactive magnetron sputtering and the effects of V content on the microstructure, mechanical and tribological properties of Nb–V–Si–N films were investigated. The results revealed that a three-phase structure, consisting of face-centered cubic (fcc) Nb–V–Si–N, hexagonal close-packed (hcp) Nb–V–Si–N and amorphous Si{sub 3}N{sub 4}, co-exists in the Nb–V–Si–N films and the cubic phase is dominant. The hardness and critical load (L{sub c}) of Nb–V–Si–N films initially increased gradually and reached a summit, then decreased with the increasing V content in the films and the maximum values were 35 GPa and 9.8 N, respectively, at 6.4 at.% V. The combination of V into Nb–Si–N film led to the fracture toughness linearly increasing from 1.11 MPa·m{sup 1/2} at 3.7 at.% V to 1.67 MPa·m{sup 1/2} at 13.2 at.% V. At room temperature (RT), the average friction coefficient decreased from 0.80 at 3.7 at.% V to 0.55 at 13.2 at.% V for the Nb–V–Si–N films. The wear rate of Nb–V–Si–N films initially decreased and then increased after reaching a minimum value of about 6.35 × 10{sup −} {sup 7} mm{sup 3}/N·mm at 6.4 at.% V. As the rise of testing temperature from 200 °C to 600 °C, the average friction coefficient of Nb–V–Si–N films decreased with the increase of the testing temperature regardless of V content. However, the wear rate gradually increased for all films. The average friction coefficient and wear rate at RT and elevated temperatures were mainly influenced by the vanadium oxides with weakly bonded lattice planes. - Highlight: • Fcc-Nb–V–Si–N, hcp-Nb–V–Si–N and amorphous Si{sub 3}N{sub 4} co-existed in the films. • The amount of Si{sub 3}N{sub 4} decreased with increasing V content in the films. • Hardness of Nb–V–Si–N film (6.4 at.%) reached a maximum value of 35 GPa. • Addition of V led to the

  10. Growth of fullerene-like carbon nitride thin solid films by reactive magnetron sputtering; role of low-energy ion irradiation in determining microstructure and mechanical properties

    NASA Astrophysics Data System (ADS)

    Neidhardt, J.; Czigány, Zs.; Brunell, I. F.; Hultman, L.

    2003-03-01

    Fullerene-like (FL) carbon nitride (CNx) films were deposited on Si (100) substrates by dc reactive, unbalanced, magnetron sputtering in a N2/Ar mixture from a high-purity pyrolythic graphite cathode in a dual-magnetron system with coupled magnetic fields. The N2 fraction in the discharge gas (0%-100%) and substrate bias (-25 V; -40 V) was varied, while the total pressure (0.4 Pa) and substrate temperature (450 °C) was kept constant. The coupled configuration of the magnetrons resulted in a reduced ion flux density, leading to a much lower average energy per incorporated particle, due to a less focused plasma as compared to a single magnetron. This enabled the evolution of a pronounced FL microstructure. The nitrogen concentration in the films saturated rapidly at 14-18 at. %, as determined by elastic recoil analysis, with a minor dependence on the discharge conditions. No correlations were detected between the photoelectron N1s core level spectra and the different microstructures, as observed by high-resolution electron microscopy. A variety of distinct FL structures were obtained, ranging from structures with elongated and aligned nitrogen-containing graphitic sheets to disordered structures, however, not exclusively linked to the total N concentration in the films. The microstructure evolution has rather to be seen as in equilibrium between the two competing processes of adsorption and desorption of nitrogen-containing species at the substrate. This balance is shifted by the energy and number of arriving species as well as by the substrate temperature. The most exceptional structure, for lower N2 fractions, consists of well-aligned, multi-layered circular features (nano-onions) with an inner diameter of approximately 0.7 nm and successive shells at a distance of ˜0.35 nm up to a diameter of 5 nm. It is shown that the intrinsic stress formation is closely linked with the evolution and accommodation of the heavily bent fullerene-like sheets. The FL CNx

  11. Surface Engineering of ZnO Thin Film for High Efficiency Planar Perovskite Solar Cells

    NASA Astrophysics Data System (ADS)

    Tseng, Zong-Liang; Chiang, Chien-Hung; Wu, Chun-Guey

    2015-09-01

    Sputtering made ZnO thin film was used as an electron-transport layer in a regular planar perovskite solar cell based on high quality CH3NH3PbI3 absorber prepared with a two-step spin-coating. An efficiency up to 15.9% under AM 1.5G irradiation is achieved for the cell based on ZnO film fabricated under Ar working gas. The atmosphere of the sputtering chamber can tune the surface electronic properties (band structure) of the resulting ZnO thin film and therefore the photovoltaic performance of the corresponding perovskite solar cell. Precise surface engineering of ZnO thin film was found to be one of the key steps to fabricate ZnO based regular planar perovskite solar cell with high power conversion efficiency. Sputtering method is proved to be one of the excellent techniques to prepare ZnO thin film with controllable properties.

  12. Sputter target

    DOEpatents

    Gates, Willard G.; Hale, Gerald J.

    1980-01-01

    The disclosure relates to an improved sputter target for use in the deposition of hard coatings. An exemplary target is given wherein titanium diboride is brazed to a tantalum backing plate using a gold-palladium-nickel braze alloy.

  13. Fabrication of a ZnO Pyroelectric Sensor

    PubMed Central

    Hsiao, Chun-Ching; Huang, Kuo-Yi; Hu, Yuh-Chung

    2008-01-01

    This paper proposes a two-step radio frequency (RF) sputtering process to form a ZnO film for pyroelectric sensors. It is shown that the two-step sputtering process with a lower power step followed by a higher power step can significantly improve the voltage responsivity of the ZnO pyroelectric sensor. The improvement is attributed mainly to the formation of ZnO film with a strongly preferred orientation towards the c-axis. Furthermore, a nickel film deposited onto the uncovered parts of the ZnO film can effectively improve the voltage responsivity at higher modulating frequencies since the nickel film can enhance the incident energy absorption of the ZnO layer.

  14. Effect of SiN x diffusion barrier thickness on the structural properties and photocatalytic activity of TiO2 films obtained by sol-gel dip coating and reactive magnetron sputtering.

    PubMed

    Ghazzal, Mohamed Nawfal; Aubry, Eric; Chaoui, Nouari; Robert, Didier

    2015-01-01

    We investigate the effect of the thickness of the silicon nitride (SiN x ) diffusion barrier on the structural and photocatalytic efficiency of TiO2 films obtained with different processes. We show that the structural and photocatalytic efficiency of TiO2 films produced using soft chemistry (sol-gel) and physical methods (reactive sputtering) are affected differentially by the intercalating SiN x diffusion barrier. Increasing the thickness of the SiN x diffusion barrier induced a gradual decrease of the crystallite size of TiO2 films obtained by the sol-gel process. However, TiO2 obtained using the reactive sputtering method showed no dependence on the thickness of the SiN x barrier diffusion. The SiN x barrier diffusion showed a beneficial effect on the photocatalytic efficiency of TiO2 films regardless of the synthesis method used. The proposed mechanism leading to the improvement in the photocatalytic efficiency of the TiO2 films obtained by each process was discussed. PMID:26665074

  15. Effect of SiNx diffusion barrier thickness on the structural properties and photocatalytic activity of TiO2 films obtained by sol–gel dip coating and reactive magnetron sputtering

    PubMed Central

    Aubry, Eric; Chaoui, Nouari; Robert, Didier

    2015-01-01

    Summary We investigate the effect of the thickness of the silicon nitride (SiNx) diffusion barrier on the structural and photocatalytic efficiency of TiO2 films obtained with different processes. We show that the structural and photocatalytic efficiency of TiO2 films produced using soft chemistry (sol–gel) and physical methods (reactive sputtering) are affected differentially by the intercalating SiNx diffusion barrier. Increasing the thickness of the SiNx diffusion barrier induced a gradual decrease of the crystallite size of TiO2 films obtained by the sol–gel process. However, TiO2 obtained using the reactive sputtering method showed no dependence on the thickness of the SiNx barrier diffusion. The SiNx barrier diffusion showed a beneficial effect on the photocatalytic efficiency of TiO2 films regardless of the synthesis method used. The proposed mechanism leading to the improvement in the photocatalytic efficiency of the TiO2 films obtained by each process was discussed. PMID:26665074

  16. Epitaxial Growth of V2O3 Thin Films on c-Plane Al2O3 in Reactive Sputtering and Its Transformation to VO2 Films by Post Annealing

    NASA Astrophysics Data System (ADS)

    Okimura, Kunio; Suzuki, Yasushi

    2011-06-01

    Epitaxial growth of thin vanadium sesquioxide (V2O3) films on c-plane sapphire (c-Al2O3) substrates was achieved with reactive magnetron sputtering under restricted oxygen flow. Even with a film thickness of approximately 12 nm, highly c-axis textured growth of corundum V2O3 was realized because of the smaller mismatch of V2O3 against corundum Al2O3. Post annealing in O2 atmosphere for as-grown V2O3 films caused phase transformation to oxidized crystalline phases. At a moderate annealing temperature of 450 °C, the V2O3 thin films transformed to VO2 films, which show a resistivity change of over three orders of magnitude. The X-ray photoelectron spectroscopy spectra for the annealed VO2 film showed a single charge state of V4+, indicating a homogeneous crystalline structure, in contrast to the inhomogeneous feature with mixed charge states of V in addition to V3+ for as-grown V2O3 film. This method is promising to prepare thin VO2 films with metal-insulator transition in productive reactive sputtering and to examine crystalline phase transformation mechanisms, including phase coexistence.

  17. Structural and electrical properties of ZnO films deposited with low-temperature facing targets magnetron sputtering (FTS) system with changes in H2 and O2 flow rate.

    PubMed

    Kim, Hye Ran; Jin, Su Bong; Wen, Long; Choi, Yoon Seok; Choi, In Sik; Han, Jeon Geon

    2013-11-01

    ZnO has been studied as a strong candidate for high-quality TCO in accordance with increasing demand to replace ITO. The origin of n-doping in ZnO is not clearly understood, but recently, the H2 effect has received attention due to the role it plays in O-rich and O-poor conditions. In spite of recent rapid developments, controlling the electrical conductivity of ZnO has remained a major challenge. To control the electrical conductivity of ZnO, this study was performed using an FTS system with H2 and O2 addition at low processing temperature. The structural and electrical properties of ZnO thin films deposited at various H2 and O2 flow rates were investigated using XRD and a sheet resistance meter. In response to changes in H2 and O2 flow rates, the crystallization and related grain size of the ZnO films were somewhat changed. The sheet resistance increased from approximately 10(-1) to approximately 10(4) M ohm/sq. when the O2 flow rate was increased, and the resistance decreased from approximately 10(-1) to approximately 10(-4) M ohm/sq. when the H2 flow rate was increased. The increase of sheet resistance with O2 flow rates could be explained by decrease of oxygen vacancies. The decrease of sheet resistance with H2 flow rates could be explained by increase of the electrons from interstitial hydrogen atoms. The plasma characteristics were analyzed using optical emission spectroscopy (OES). But, the overall spectrum did not change with the H2 and O2 gas flow rates. So, the dramatic changes in the electrical properties of ZnO thin films could be considered to be a result of changes in chemical composition of the thin films rather than the plasma status. PMID:24245326

  18. A MEMS based acetone sensor incorporating ZnO nanowires synthesized by wet oxidation of Zn film

    NASA Astrophysics Data System (ADS)

    Behera, Bhagaban; Chandra, Sudhir

    2015-01-01

    In this work, we report a simple and efficient method for synthesis of ZnO nanowires by thermal oxidation of Zn film and their integration with MEMS technologies to fabricate a sensor for acetone vapour detection. ZnO nanowires were prepared by thermal oxidation of sputter deposited Zn film. The nanostructured ZnO was characterized by x-ray diffraction, a scanning electron microscope and room temperature photoluminescence measurements. The ZnO nanowires synthesis process was integrated with MEMS technologies to obtain a sensor for volatile organic compounds, incorporating an on-chip Ni microheater and an interdigited electrode structure. To reduce the heat loss from the on-chip microheater, the sensor was made on a thin silicon diaphragm obtained via a modified reactive ion etching process. This resulted in considerable power saving during sensor operation. For this, a three-mask process was used. The performance of the microheater was simulated on COMSOL and validated experimentally. The sensor has been tested for acetone vapour sensing and the operating parameters were optimized. The sensor has the ability to detect acetone vapour at 5 parts per million (ppm) concentrations when operated at 100 °C. The sensor consumed only 36 mW power and showed a high-sensitivity value of 26.3% for 100 ppm of acetone vapour.

  19. Investigations of rapid thermal annealing induced structural evolution of ZnO: Ge nanocomposite thin films via GISAXS

    NASA Astrophysics Data System (ADS)

    Ceylan, Abdullah; Ozcan, Yusuf; Orujalipoor, Ilghar; Huang, Yen-Chih; Jeng, U.-Ser; Ide, Semra

    2016-06-01

    In this work, we present in depth structural investigations of nanocomposite ZnO: Ge thin films by utilizing a state of the art grazing incidence small angle x-ray spectroscopy (GISAXS) technique. The samples have been deposited by sequential r.f. and d.c. sputtering of ZnO and Ge thin film layers, respectively, on single crystal Si(100) substrates. Transformation of Ge layers into Ge nanoparticles (Ge-np) has been initiated by ex-situ rapid thermal annealing of asprepared thin film samples at 600 °C for 30, 60, and 90 s under forming gas atmosphere. A special attention has been paid on the effects of reactive and nonreactive growth of ZnO layers on the structural evolution of Ge-np. GISAXS analyses have been performed via cylindrical and spherical form factor calculations for different nanostructure types. Variations of the size, shape, and distributions of both ZnO and Ge nanostructures have been determined. It has been realized that GISAXS results are not only remarkably consistent with the electron microscopy observations but also provide additional information on the large scale size and shape distribution of the nanostructured components.

  20. Inverse I-V Injection Characteristics of ZnO Nanoparticle-Based Diodes.

    PubMed

    Mundt, Paul; Vogel, Stefan; Bonrad, Klaus; von Seggern, Heinz

    2016-08-10

    Simple Al/ZnO(NP)/Au diodes produced by spin coating of ZnO nanoparticle dispersions (ZnO(NP)) on Al/Al2O3 and Au substrates and subsequent Au deposition have been investigated to understand electron injection properties of more complex devices, incorporating ZnO(NP) as injection layer. Inverse I-V characteristics have been observed compared to conventional Al/ZnO(SP)/Au diodes produced by reactive ion sputtering of ZnO. SEM micrographs reveal that the void-containing contact of ZnO(NP) with the bottom Al electrode and the rough morphology of the top Au electrode are likely to be responsible for the observed injection and ejection probabilities of electrons. A simple tunneling model, incorporating the voids, explains the strongly reduced injection currents from Al whereas the top electrode fabricated by vapor deposition of Au onto the nanoparticle topology adopts the inverse ZnO(NP) morphology leading to enlarged injection areas combined with Au-tip landscapes. These tips in contrast to the smooth sputtered ZnO(SP) lead to electric field enhancement and strongly increased injection of electrons in reverse direction. The injected charge piles up at the barrier generated by voids between ZnO(NP) and the bottom electrode forcing a change in the barrier shape and therefore allowing for higher ejection rates. Both effects in combination explain the inverse I-V characteristic of nanoparticle based diodes. PMID:27443793

  1. Ion mass spectrometry investigations of the discharge during reactive high power pulsed and direct current magnetron sputtering of carbon in Ar and Ar/N{sub 2}

    SciTech Connect

    Schmidt, S.; Greczynski, G.; Jensen, J.; Hultman, L.; Czigany, Zs.

    2012-07-01

    Ion mass spectrometry was used to investigate discharges formed during high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a graphite target in Ar and Ar/N{sub 2} ambient. Ion energy distribution functions (IEDFs) were recorded in time-averaged and time-resolved mode for Ar{sup +}, C{sup +}, N{sub 2}{sup +}, N{sup +}, and C{sub x}N{sub y}{sup +} ions. An increase of N{sub 2} in the sputter gas (keeping the deposition pressure, pulse width, pulse frequency, and pulse energy constant) results for the HiPIMS discharge in a significant increase in C{sup +}, N{sup +}, and CN{sup +} ion energies. Ar{sup +}, N{sub 2}{sup +}, and C{sub 2}N{sup +} ion energies, in turn, did not considerably vary with the changes in working gas composition. The HiPIMS process showed higher ion energies and fluxes, particularly for C{sup +} ions, compared to DCMS. The time evolution of the plasma species was analyzed for HiPIMS and revealed the sequential arrival of working gas ions, ions ejected from the target, and later during the pulse-on time molecular ions, in particular CN{sup +} and C{sub 2}N{sup +}. The formation of fullerene-like structured CN{sub x} thin films for both modes of magnetron sputtering is explained by ion mass-spectrometry results and demonstrated by transmission electron microscopy as well as diffraction.

  2. Investigation of Li-doped ferroelectric and piezoelectric ZnO films by electric force microscopy and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Ni, H. Q.; Lu, Y. F.; Liu, Z. Y.; Qiu, H.; Wang, W. J.; Ren, Z. M.; Chow, S. K.; Jie, Y. X.

    2001-08-01

    We have grown Li-doped ZnO films on silicon (100) using the rf planar magnetron sputtering method. The surface charges induced piezoelectrically by defect and by polarization can be observed by electric force microscopy. The Li-doped ZnO films have been proven to be ferroelectric. The Raman spectra of ZnO and Li-doped ZnO films have been measured.

  3. Stress evolution during growth of GaN (0001)/Al2O3(0001) by reactive dc magnetron sputter epitaxy

    NASA Astrophysics Data System (ADS)

    Junaid, M.; Sandström, P.; Palisaitis, J.; Darakchieva, V.; Hsiao, C.-L.; Persson, P. O. Å.; Hultman, L.; Birch, J.

    2014-04-01

    We study the real time stress evolution, by in situ curvature measurements, during magnetron sputter epitaxy of GaN (0 0 0 1) epilayers at different growth temperatures, directly on Al2O3(0 0 0 1) substrates. The epilayers are grown by sputtering from a liquid Ga target in a mixed N2/Ar discharge. For 600 °C, a tensile biaxial stress evolution is observed, while for 700 °C and 800 °C, compressive stress evolutions are observed. Structural characterization by cross-sectional transmission electron microscopy, and atomic force microscopy, revealed that films grew at 700 °C and 800 °C in a layer-by-layer mode while a growth temperature of 600 °C led to an island growth mode. High resolution x-ray diffraction data showed that edge and screw threading dislocation densities decreased with increasing growth temperature, with a total density of 5.5 × 1010 cm-2 at 800 °C. The observed stress evolution and growth modes are explained by a high surface mobility during magnetron sputter epitaxy at 700-800 °C. Other possible reasons for the different stress evolutions are also discussed.

  4. The influence of Atomic Oxygen on the Figure of Merit of Indium Tin Oxide thin Films grown by reactive Dual Ion Beam Sputtering

    NASA Astrophysics Data System (ADS)

    Geerts, Wilhelmus; Simpson, Nelson; Woodall, Allen; Compton, Maclyn

    2014-03-01

    Indium Tin Oxide (ITO) is a transparent conducting oxide that is used in flat panel displays and optoelectronics. Highly conductive and transparent ITO films are normally produced by heating the substrate to 300 Celsius during deposition excluding plastics to be used as a substrate material. We investigated whether high quality ITO films can be sputtered at room temperature using atomic instead of molecular oxygen. The films were deposited by dual ion beam sputtering (DIBS). During deposition the substrate was exposed to a molecular or an atomic oxygen flux. Microscope glass slides and silicon wafers were used as substrates. A 29 nm thick SIO2 buffer layer was used. Optical properties were measured with a M2000 Woollam variable angle spectroscopic ellipsometer. Electrical properties were measured by linear four point probe using a Jandel 4pp setup employing silicon carbide electrodes, high input resistance, and Keithley low bias current buffer amplifiers. The figure of merit (FOM), i.e. the ratio of the conductivity and the average optical absorption coefficient (400-800 nm), was calculated from the optical and electric properties and appeared to be 1.2 to 5 times higher for the samples sputtered with atomic oxygen. The largest value obtained for the FOM was 0.08 reciprocal Ohms. The authors would like to thank the Research Corporation for Financial Support.

  5. Optical properties of Li-doped ZnO films

    NASA Astrophysics Data System (ADS)

    Valentini, Antonio; Quaranta, Fabio; Vasanelli, Lorenzo; Piccolo, R.

    1991-03-01

    The difficulty to achieve a refractive index matching between active substrate and active layer grown on, is one of the main problem in integrated optical devices based on gallium arsenide, because of its high refractive index value. One possible solution could be an active layer whose refractive index is variable during the grown. Zinc oxide is a very interesting material because of its electro-optic and acousto- optic properties. It has a low cost and can be prepared by a variety of techniques. In this paper deposition of lithium doped zinc oxide films by reactive sputtering has been investigated in order to study the dependence of optical properties on lithium content and deposition parameters. A ZnO:Li target was used. The film depositions were performed varying the oxygen content in sputtering gas. For comparison undoped ZnO films were also prepared. We have performed optical and electrical measurement on films relating the results to Li contents and O/Zn ratio obtained by nuclear reaction and Rutherford backscattering measurements respectively. The film analysis has shown that dopant concentration is mainly controlled by gas mixture. The optical properties are dependent on deposition conditions. Optical waveguides have been prepared and characterized. The results are presented and discussed.

  6. Role of ZnO thin film in the vertically aligned growth of ZnO nanorods by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Son, Nguyen Thanh; Noh, Jin-Seo; Park, Sungho

    2016-08-01

    The effect of ZnO thin film on the growth of ZnO nanorods was investigated. ZnO thin films were sputter-deposited on Si substrate with varying the thickness. ZnO nanorods were grown on the thin film using a chemical bath deposition (CBD) method at 90 °C. The ZnO thin films showed granular structure and vertical roughness on the surface, which facilitated the vertical growth of ZnO nanorods. The average grain size and the surface roughness of ZnO film increased with an increase in film thickness, and this led to the increase in both the average diameter and the average length of vertically grown ZnO nanorods. In particular, it was found that the average diameter of ZnO nanorods was very close to the average grain size of ZnO thin film, confirming the role of ZnO film as a seed layer for the vertical growth of ZnO nanorods. The CBD growth on ZnO seed layers may provide a facile route to engineering vertically aligned ZnO nanorod arrays.

  7. Physical deoxygenation of graphene oxide paper surface and facile in situ synthesis of graphene based ZnO films

    SciTech Connect

    Ding, Jijun; Wang, Minqiang Zhang, Xiangyu; Ran, Chenxin; Shao, Jinyou; Ding, Yucheng

    2014-12-08

    In-situ sputtering ZnO films on graphene oxide (GO) paper are used to fabricate graphene based ZnO films. Crystal structure and surface chemical states are investigated. Results indicated that GO paper can be effectively deoxygenated by in-situ sputtering ZnO on them without adding any reducing agent. Based on the principle of radio frequency magnetron sputtering, we propose that during magnetron sputtering process, plasma streams contain large numbers of electrons. These electrons not only collide with argon atoms to produce secondary electrons but also they are accelerated to bombard the substrates (GO paper) resulting in effective deoxygenation of oxygen-containing functional groups. In-situ sputtering ZnO films on GO paper provide an approach to design graphene-semiconductor nanocomposites.

  8. Electronic-grade GaN(0001)/Al{sub 2}O{sub 3}(0001) grown by reactive DC-magnetron sputter epitaxy using a liquid Ga target

    SciTech Connect

    Junaid, M.; Hsiao, C.-L.; Palisaitis, J.; Jensen, J.; Persson, P. O. A.; Hultman, L.; Birch, J.

    2011-04-04

    Electronic-grade GaN (0001) epilayers have been grown directly on Al{sub 2}O{sub 3} (0001) substrates by reactive direct-current-magnetron sputter epitaxy (MSE) using a liquid Ga sputtering target in an Ar/N{sub 2} atmosphere. The as-grown GaN epitaxial films exhibit low threading dislocation density on the order of {<=}10{sup 10} cm{sup -2} determined by transmission electron microscopy and modified Williamson-Hall plot. X-ray rocking curve shows narrow full-width at half maximum (FWHM) of 1054 arc sec of the 0002 reflection. A sharp 4 K photoluminescence peak at 3.474 eV with a FWHM of 6.3 meV is attributed to intrinsic GaN band edge emission. The high structural and optical qualities indicate that MSE-grown GaN epilayers can be used for fabricating high-performance devices without the need of any buffer layer.

  9. Anatase TiO₂ films with dominant {001} facets fabricated by direct-current reactive magnetron sputtering at room temperature: oxygen defects and enhanced visible-light photocatalytic behaviors.

    PubMed

    Zheng, Jian-Yun; Bao, Shan-Hu; Guo, Yu; Jin, Ping

    2014-04-23

    A TiO2 film with dominant anatase {001} facets is directly prepared by direct-current reactive magnetron sputtering at room temperature without using morphology-controlling agents. The formation mechanism of anatase TiO2 films with dominant {001} facets is explained by the competition between thermodynamics and ion impinging in the deposition process. The crystalline TiO2 film shows a superior photocatalytic efficiency for the degradation of Rhodamine B under UV-visible (λ > 250 nm) lights. Furthermore, a comparable photodegradation of Rhodamine B is also found on the TiO2 film surface by using visible (λ > 420 nm) lights. During film growth, the surface bombarded by high energy of ions yields plenty of oxygen defects, which can enhance the photocatalytic activity of the films irradiated under visible light. PMID:24720367

  10. Structural, chemical and nanomechanical investigations of SiC/polymeric a-C:H films deposited by reactive RF unbalanced magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Tomastik, C.; Lackner, J. M.; Pauschitz, A.; Roy, M.

    2016-03-01

    Amorphous carbon (or diamond-like carbon, DLC) films have shown a number of important properties usable for a wide range of applications for very thin coatings with low friction and good wear resistance. DLC films alloyed with (semi-)metals show some improved properties and can be deposited by various methods. Among those, the widely used magnetron sputtering of carbon targets is known to increase the number of defects in the films. Therefore, in this paper an alternative approach of depositing silicon-carbide-containing polymeric hydrogenated DLC films using unbalanced magnetron sputtering was investigated. The influence of the C2H2 precursor concentration in the deposition chamber on the chemical and structural properties of the deposited films was investigated by Raman spectroscopy, X-ray photoelectron spectroscopy and elastic recoil detection analysis. Roughness, mechanical properties and scratch response of the films were evaluated with the help of atomic force microscopy and nanoindentation. The Raman spectra revealed a strong correlation of the film structure with the C2H2 concentration during deposition. A higher C2H2 flow rate results in an increase in SiC content and decrease in hydrogen content in the film. This in turn increases hardness and elastic modulus and decreases the ratio H/E and H3/E2. The highest scratch resistance is exhibited by the film with the highest hardness, and the film having the highest overall sp3 bond content shows the highest elastic recovery during scratching.

  11. Lifetime dependence of nitrided carbon stripper foils on sputter angle during N+ ion beam sputtering

    NASA Astrophysics Data System (ADS)

    Sugai, I.; Oyaizu, M.; Takeda, Y.; Kawakami, H.; Kawasaki, K.; Hattori, T.; Kadono, T.

    2015-09-01

    We fabricated high-lifetime thin nitride carbon stripper (NCS) foils with high nitrogen contents using ion-beam sputtering with reactive nitrogen gas and investigated the dependence of their lifetimes on the sputter angle. The nitrogen in carbon foils plays a critical role in determining their lifetime. Therefore, in order to investigate the effects of the nitrogen level in NCS foils on foil lifetime, we measured the sputtering yield for different sputter angles at a sputtering voltage of 10 kV while using carbon-based targets. We also measured the nitrogen-to-carbon thickness ratios of the foils using Rutherford backscattering spectrometry. The foils made at a sputter angle of 15° using a glassy amorphous carbon target exhibited an average increase of 200-fold in lifetime when compared to commercially available foils.

  12. Photoluminescence of as-grown and thermal annealed SiO{sub x}/Si-nanocrystals heterolayers grown by reactive rf sputtering

    SciTech Connect

    Mota-Pineda, E.; Melendez-Lira, M.; Zapata-Torres, M.; Angel, P. del; Perez-Centeno, A.; Santana-Aranda, M. A.; Jimenez-Sandoval, S.

    2010-11-15

    SiO{sub x}/Si-nanocrystals (Si NCs) heterolayers were fabricated employing a rf magnetron sputtering system. The synthesis process, through modification of the oxygen partial pressure of the plasma, promotes the synthesis of stoichiometric SiO{sub 2} layers and affect the Si NCs layer giving place to SiO{sub x}/Si NCs (1.64

  13. Dynamics of reactive high-power impulse magnetron sputtering discharge studied by time- and space-resolved optical emission spectroscopy and fast imaging

    SciTech Connect

    Hala, M.; Viau, N.; Zabeida, O.; Klemberg-Sapieha, J. E.; Martinu, L.

    2010-02-15

    Time- and space-resolved optical emission spectroscopy and fast imaging were used for the investigation of the plasma dynamics of high-power impulse magnetron sputtering discharges. 200 {mu}s pulses with a 50 Hz repetition frequency were applied to a Cr target in Ar, N{sub 2}, and N{sub 2}/Ar mixtures and in a pressure range from 0.7 to 2.66 Pa. The power density peaked at 2.2-6 kW cm{sup -2}. Evidence of dominating self-sputtering was found for all investigated conditions. Up to four different discharge phases within each pulse were identified: (i) the ignition phase, (ii) the high-current metal-dominated phase, (iii) the transient phase, and (iv) the low-current gas-dominated phase. The emission of working gas excited by fast electrons penetrating the space in-between the electrodes during the ignition phase spread far outwards from the target at a speed of 24 km s{sup -1} in 1.3 Pa of Ar and at 7.5 km s{sup -1} in 1.3 Pa of N{sub 2}. The dense metal plasma created next to the target propagated in the reactor at a speed ranging from 0.7 to 3.5 km s{sup -1}, depending on the working gas composition and the pressure. In fact, it increased with higher N{sub 2} concentration and lower pressure. The form of the propagating plasma wave changed from a hemispherical shape in Ar, to a droplike shape extending far from the target in N{sub 2}. An important N{sub 2} emission rise in the latter case was detected during the transition at the end of the metal-dominated phase.

  14. Corrosion Behaviour of Sputtered Alumina Thin Films

    NASA Astrophysics Data System (ADS)

    Reddy, I. Neelakanta; Dey, Arjun; Sridhara, N.; Anoop, S.; Bera, Parthasarathi; Rani, R. Uma; Anandan, Chinnasamy; Sharma, Anand Kumar

    2015-10-01

    Corrosion studies of sputtered alumina thin films grown on stainless steel (SS) 304 were carried out by linear polarization and electrochemical impedance spectroscopy. Noticeable changes were not observed in morphology and surface roughness of films after carrying out the corrosion test. Corrosion current density (icorr) of alumina coated SS decreased up to 10-10 A cm-2 while icorr value in the range of 10-5-10-6 A cm-2 was observed for bare SS. The direct sputtered film showed superior corrosion resistance behaviour than the reactive sputtered film. This might be attributed to the difference in thickness of the films sputtered by direct and reactive methods. The electronic structure of deposited alumina films was studied both before and after corrosion test by X-ray photoelectron spectroscopy technique which also confirmed no structural changes of alumina film after exposing it to corrosive environment.

  15. Optical and electrical characterization of aluminium doped ZnO layers

    NASA Astrophysics Data System (ADS)

    Major, C.; Nemeth, A.; Radnoczi, G.; Czigany, Zs.; Fried, M.; Labadi, Z.; Barsony, I.

    2009-08-01

    Al doped ZnO (ZAO) thin films (with Al-doping levels 2 at.%) were deposited at different deposition parameters on silicon substrate by reactive magnetron sputtering for solar cell contacts, and samples were investigated by transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS) and spectroscopic ellipsometry (SE). Specific resistances were measured by the well known 4-pin method. Well visible columnar structure and in most cases voided other regions were observed at the grain boundaries by TEM. EELS measurements were carried out to characterize the grain boundaries, and the results show spacing voids between columnar grains at samples with high specific resistance, while no spacing voids were observed at highly conductive samples. SE measurements were evaluated by using the analytical expression suggested by Yoshikawa and Adachi [H. Yoshikawa, S. Adachi, Japanese Journal of Applied Physics 36 (1997) 6237], and the results show correlation between specific resistance and band gap energy and direct exciton strength parameter.

  16. Identification of acceptor states in Li-doped p-type ZnO thin films

    NASA Astrophysics Data System (ADS)

    Zeng, Y. J.; Ye, Z. Z.; Lu, J. G.; Xu, W. Z.; Zhu, L. P.; Zhao, B. H.; Limpijumnong, Sukit

    2006-07-01

    We investigate photoluminescence from reproducible Li-doped p-type ZnO thin films prepared by dc reactive magnetron sputtering. The LiZn acceptor state, with an energy level located at 150meV above the valence band maximum, is identified from free-to-neutral-acceptor transitions. Another deeper acceptor state located at 250meV emerges with the increased Li concentration. A broad emission centered at 2.96eV is attributed to a donor-acceptor pair recombination involving zinc vacancy. In addition, two chemical bonding states of Li, evident in x-ray photoelectron spectroscopy, are probably associated with the two acceptor states observed.

  17. Substrate Preparations in Epitaxial ZnO Film Growth

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, C.-H.; Lehoczky, S. L.; Harris, M. T.; Callahan, M. J.; George, M. A.

    2000-01-01

    Epitaxial ZnO films were grown on the two polar surfaces (O-face and Zn-face) of (0001) ZnO single crystal substrates using off-axis magnetron sputtering deposition. Annealing-temperature dependence of ZnO substrates was studied. ZnO films grown on sapphire substrates have also been investigated for comparison purposes and the annealing temperature of A1203 substrates is 1000 C. Substrates and films were characterized using photoluminescence (PL) spectrum, x-ray diffraction, atomic force microscope, energy dispersive spectrum, and electric transport measurements. It has been found that the ZnO film properties were different when films were grown on the two polarity surfaces of ZnO substrates and the A1203 substrates. An interesting result shows that high temperature annealing of ZnO single crystals will improve the surface structure on the O-face surface rather than the opposite surface. The measurements of homoepitaxial ZnO films indicate that the O-terminated surface is better for ZnO epitaxial film growth.

  18. Room temperature surface passivation of silicon for screen printed c-Si solar cells by HiTUS reactive sputter deposition

    NASA Astrophysics Data System (ADS)

    Kaminski, P. M.; Bass, K.; Claudio, G.; Walls, J. M.

    2014-05-01

    The dielectric coatings used on silicon solar cells serve a dual purpose: a surface passivation layer and as an antireflection coating. Silicon nitride films were deposited by sputtering, using a HiTUS technology, on crystalline silicon wafers. Films were deposited without substrate heating, which simplifies the deposition process, from a polycrystalline silicon target in a mixed ambient of argon, nitrogen and hydrogen gasses. After the deposition, the minority carrier lifetime, refractive index and deposition rate were measured. Photo conductance decay measurements show that the minority carrier lifetime increased up to 26 μs on a 40 Ω/□ doped 1 Ω cm p-type <1 0 0> Cz-Si pseudo square wafer (compared to 1 μs measured for bare wafer) and up to 984 μs for a double-side polished 3 Ω cm Cz-Si wafer (from ˜70 μs measured for uncoated wafer). Spectroscopic ellipsometry measurements showed that the refractive index of the deposited films was 2.05 at λ = 632.8 nm; deposition rate was measured at 22.4 nm/min. The films were used to prepare screen-printed c-Si solar cells. The resultant cells showed an efficiency of 15.14% with silicon nitride films grown without the use of silane or substrate heating.

  19. Electrochromic behavior of W(x)Si(y)O(z) thin films prepared by reactive magnetron sputtering at normal and glancing angles.

    PubMed

    Gil-Rostra, Jorge; Cano, Manuel; Pedrosa, José M; Ferrer, Francisco Javier; García-García, Francisco; Yubero, Francisco; González-Elipe, Agustín R

    2012-02-01

    This work reports the synthesis at room temperature of transparent and colored W(x)Si(y)O(z) thin films by magnetron sputtering (MS) from a single cathode. The films were characterized by a large set of techniques including X-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectrometry (RBS), Fourier transform infrared (FT-IR), and Raman spectroscopies. Their optical properties were determined by the analysis of the transmission and reflection spectra. It was found that both the relative amount of tungsten in the W-Si MS target and the ratio O(2)/Ar in the plasma gas were critical parameters to control the blue coloration of the films. The long-term stability of the color, attributed to the formation of a high concentration of W(5+) and W(4+) species, has been related with the formation of W-O-Si bond linkages in an amorphous network. At normal geometry (i.e., substrate surface parallel to the target) the films were rather compact, whereas they were very porous and had less tungsten content when deposited in a glancing angle configuration. In this case, they presented outstanding electrochromic properties characterized by a fast response, a high coloration, a complete reversibility after more than one thousand cycles and a relatively very low refractive index in the bleached state. PMID:22208156

  20. Sputtering and ion plating

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The proceedings of a conference on sputtering and ion plating are presented. Subjects discussed are: (1) concepts and applications of ion plating, (2) sputtering for deposition of solid film lubricants, (3) commercial ion plating equipment, (4) industrial potential for ion plating and sputtering, and (5) fundamentals of RF and DC sputtering.

  1. Growth, structural and optoelectronic properties tuning of nitrogen-doped ZnO thin films synthesized by means of reactive pulsed laser deposition

    SciTech Connect

    Naouar, M.; Ka, I.; Gaidi, M.; Alawadhi, H.; Bessais, B.; Khakani, M.A.El

    2014-09-15

    Highlights: • PLD technique has been used to elaborate N doped ZnO. • A maximum incorporation of 0.7 at.% has been achieved at a pressure of 25 mTorr. • Increasing the N{sub 2} pressure decreases the nitrogen content with the creation of more defects. • Optical transmission and PL spectra have confirmed the band gap narrowing. - Abstract: Pulsed laser deposition has been successfully used to achieve in-situ nitrogen doping of zinc oxide thin films at a temperature as low as 300 °C. Nitrogen-doped zinc oxide (ZnO:N) thin films with a maximum nitrogen content of 0.7 at.% were obtained by varying the nitrogen background pressure in the range of 0–150 mTorr. The ZnO:N thin films were found to present hexagonal crystalline structure with dense and smooth surface. X-ray photoelectron spectroscopy analysis confirms the effective incorporation of nitrogen into ZnO thin films. Optical transmission together with room temperature photoluminescence measurements show that the band gap of the ZnO:N films shifts from 3.3 eV to 3.1 eV as nitrogen concentration varies in the range of 0.2–0.7 at.%. The narrower band gap is obtained at an optimal nitrogen concentration of 0.22 at.%. This band gap narrowing is found to be caused by both nitrogen incorporation and nitrogen-induced defects in the ZnO:N films.

  2. Carrier mobility of highly transparent conductive Al-doped ZnO polycrystalline films deposited by radio-frequency, direct-current, and radio-frequency-superimposed direct-current magnetron sputtering: Grain boundary effect and scattering in the grain bulk

    NASA Astrophysics Data System (ADS)

    Nomoto, Junichi; Makino, Hisao; Yamamoto, Tetsuya

    2015-01-01

    The effects of using radio-frequency (RF)-superimposed direct-current (DC) magnetron sputtering deposition on the structural, electrical, and optical properties of aluminum-doped ZnO (AZO)-based highly transparent conducting oxide films have been examined. AZO films were deposited on heated non-alkaline glass substrates (200 °C) using ZnO:Al2O3 (2 wt. % Al2O3) ceramic oxide targets with the total power varied from 150 to 300 W, and at various RF to DC power ratios, AZO films deposited by a mixed approach with the RF to the total power ratio of 0.14 showed the lowest resistivity of 2.47 × 10-4 Ω cm with the highest carrier concentration of 6.88 × 1020 cm-3 and the highest Hall mobility (μH) of 36.8 cm2/Vs together with the maximum value of an average transmittance in the visible spectral range from 400 to 700 nm. From the analysis of optical data based on the simple Drude model combined with the Tauc-Lorentz model and the results of Hall effect measurements, the optical mobility (μopt) was determined. A comparison of μopt with μH clarified the effects of the mixed approach not only on the reduction of the grain boundary contribution to the carrier transport but also on retaining high carrier mobility of in-grains for the AZO films.

  3. Magnetron sputtering source

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.; Grabner, R.F.; Ramsey, P.B.

    1994-08-02

    A magnetron sputtering source for sputtering coating substrates includes a high thermal conductivity electrically insulating ceramic and magnetically attached sputter target which can eliminate vacuum sealing and direct fluid cooling of the cathode assembly. The magnetron sputtering source design results in greater compactness, improved operating characteristics, greater versatility, and low fabrication cost. The design easily retrofits most sputtering apparatuses and provides for safe, easy, and cost effective target replacement, installation, and removal. 12 figs.

  4. Magnetron sputtering source

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.; Grabner, R. Fred; Ramsey, Philip B.

    1994-01-01

    A magnetron sputtering source for sputtering coating substrates includes a high thermal conductivity electrically insulating ceramic and magnetically attached sputter target which can eliminate vacuum sealing and direct fluid cooling of the cathode assembly. The magnetron sputtering source design results in greater compactness, improved operating characteristics, greater versatility, and low fabrication cost. The design easily retrofits most sputtering apparatuses and provides for safe, easy, and cost effective target replacement, installation, and removal.

  5. Ambient-Temperature Sputtering Of Composite Oxide Films

    NASA Technical Reports Server (NTRS)

    Thakoor, Sarita

    1992-01-01

    Technique for deposition of homogeneous films of multicomponent oxides on substrates at ambient temperature based on sequential sputter deposition of individual metal components, as alternating ultra-thin layers, from multiple targets. Substrates rotated over sputtering targets of lead, zirconium, and titanium. Dc-magnetron sputtering of constituent metals in reactive ambient of argon and oxygen leads to formation of the respective metal oxides intermixed on extremely fine scale in desired composition. Compatible with low-temperature microelectronic processing.

  6. Preparation and characteristics of vanadium oxide thin films by controlling the sputtering voltage

    NASA Astrophysics Data System (ADS)

    Wei, Xiongbang; Li, Shibin; Gou, Jun; Dong, Xiang; Yang, Xiaohui; Li, Weizhi; Wang, Tao; Wu, Zhiming; Jiang, Yadong; Chen, Zhi

    2014-06-01

    Influence of sputtering voltage on the deposition process and characteristics of vanadium oxide thin films prepared by reactive DC magnetron sputtering is investigated. The target surface cleaning is controlled by adjusting the sputtering voltage. During the sputtering process, the sputtering voltage increases faster with larger O2 gas flow rate. The sputtering voltage is easy to be stable with larger sputtering voltage. The measured sputtering voltage is correlated to the ion induced secondary electron emission (ISEE) coefficient of the target material. The ISEE coefficient of the oxidized vanadium target surface is lower than the ISEE coefficient of the vanadium metal. The semiconductor to metal (S-M) phase transition temperature decreases with the sputtering voltage, leading to the lower the corresponding temperature of the maximum temperature coefficient of resistance (TCR). By this way, O/V ratio, R, and TCR of VOx films can be controlled by adjusting the sputtering voltage.

  7. Fiber texturing in nano-crystalline TiO2 thin films deposited at 150 °C by dc-reactive sputtering on fiber-textured [0 0 0 1] ZnO : Al substrates

    NASA Astrophysics Data System (ADS)

    Pellegrino, Giovanna; Bongiorno, Corrado; Ravesi, Sebastiano; Alberti, Alessandra

    2012-09-01

    TiO2 thin films were deposited at an effective surface temperature of 150 °C by dc-reactive magnetron sputtering on ZnO : Al oriented substrates having a fiber texture along the [0 0 0 1] axis, and studied by transmission electron microscopy and x-ray diffraction analyses. The substrate texturing was used to tailor the TiO2 structure in such a way that a porous matrix made of anatase nano-grains (10 nm in diameter) is formed instead of an amorphous layer (as observed at 150 °C on glass). Additionally, we demonstrate that, by adding an ex situ 200 °C annealing, the anatase domains also gain a fiber texture with the axes aligned to that of the substrate. The TiO2/AZO structural coupling is expected to play a crucial role for the carrier transport through the interface as required in dye-sensitized solar cells. Moreover, the low temperatures used render the process compatible with commonly used plastics substrates.

  8. Epitaxial growth of In{sub x}Ga{sub 1-x}N alloy films on sapphire and silicon by reactive co-sputtering of GaAs and indium

    SciTech Connect

    Mohan, Shyam Major, S. S.; Srinivasa, R. S.

    2015-06-24

    In{sub x}Ga{sub 1-x}N alloy films (0.2reactive co-sputtering of GaAs and indium with 100% nitrogen at a substrate temperature of 600 °C. X-ray diffraction studies show the formation of completely c-axis oriented, single phase alloy films over the studied range of composition. The crystallite size along the growth direction and surface morphology of alloy films, particularly those with higher indium fraction exhibit substantial improvement on Si (100) substrate, compared to the c-cut sapphire substrate. The electrical resistivity decreases monotonously with increase in indium fraction and the alloy films on Si (100) show substantially higher mobility, compared to those on sapphire. These features are attributed to superior crystallinity of alloy films on Si (100), which possibly arise from the formation of interfacial hexagonal α-Si{sub 3}N{sub 4}, owing to the interaction of nitrogen plasma with Si surface.

  9. Light-modulated resistive switching memory behavior in ZnO/BaTiO3/ZnO multilayer

    NASA Astrophysics Data System (ADS)

    Wei, Lujun; Sun, Bai; Zhao, Wenxi; Li, Hongwei; Jia, Xiangjiang; Wu, Jianhong; Chen, Peng

    2016-05-01

    Nanoscale structure ZnO/BaTiO3/ZnO multilayer was fabricated on silicon (Si) substrate by RF magnetron sputtering system. The light-modulated resistive switching characteristics in ZnO/BaTiO3/ZnO devices were observed. The light-modulated resistive switching shows good repeatability at room temperature.

  10. Electrochromism in sputtered WO{sub 3} thin films

    SciTech Connect

    Batchelor, R.A.; Burdis, M.S.; Siddle, J.R.

    1996-03-01

    There are large variations in the properties of WO{sub 3} sputtered under different conditions and two samples sputtered from an oxide target and reactively sputtered from a metal target were compared in detail. The thin film sputtered from an oxide target was found to color and bleach rapidly in 1 M LiClO{sub 4} in propylene carbonate, while the thin film reactively sputtered from a metal target could be colored deeply, but bleached only slowly. By calculating the rate of change of optical density during cyclic voltammetry, it was possible to directly compare the coloration response with the current/voltage behavior of the electrodes. In both cases at least two lithium insertion reactions appear to occur. The distinction between the two reactions was especially clear in the sample sputtered from a metal target, in which an insertion of high electrochromic efficiency occurred up to Li{sub 0.2}WO{sub 3} and then an insertion of considerably lower electrochromic efficiency up to Li{sub 0.5}WO{sub 3}. Although a small amount of coloration and bleaching continued to occur after switching the reactively sputtered sample to open circuit during the coloration and bleaching cycles; transmission change was largely halted by disconnecting the external current supply. The slow end to the bleach of the reactively sputtered sample corresponded to a reaction of high electrochromic efficiency.

  11. Nanocomposite Ti/hydrocarbon plasma polymer films from reactive magnetron sputtering as growth support for osteoblast-like and endothelial cells.

    PubMed

    Grinevich, Andrey; Bacakova, Lucie; Choukourov, Andrei; Boldyryeva, Hanna; Pihosh, Yuriy; Slavinska, Danka; Noskova, Lenka; Skuciova, Maria; Lisa, Vera; Biederman, Hynek

    2009-03-15

    Nanocomposite Ti/hydrocarbon plasma polymer (Ti/ppCH) films were deposited by DC magnetron sputtering of titanium target in n-hexane, argon, or a mixture of these two gases. The resultant films were heterogeneous, with inorganic regions of nanometer scale distributed within a plasma polymer matrix. The titanium content was controlled by adjusting the argon/n-hexane ratio in the working gas. In the pure n-hexane atmosphere, the Ti concentration was found to be below 1 at %, whereas in pure argon it reached 20 at %, as measured by Rutherford backscattering spectroscopy and elastic recoil detection analysis (RBS/ERDA). A high level of titanium oxidation is detected with TiO(2), substoichiometric titania, and titanium carbide, composing an inorganic phase of the composite films. In addition, high hydrogen content is detected in films rich with titanium. Ti-deficient and Ti-rich films proved equally good substrates for adhesion and growth of cultured human osteoblast-like MG 63 cells. In these cells, the population densities on days 1, 3, and 7 after seeding, spreading area on day 1, formation of talin-containing focal adhesion plaques as well as concentrations of talin and osteocalcin (per mg of protein) were comparable to the values obtained in cells on the reference cell culture materials, represented by microscopic glass coverslips or a polystyrene dish. An interesting finding was made when the Ti/ppCH films were seeded with calf pulmonary artery endothelial cells of the line CPAE. The cell population densities, the spreading area and also the concentration of von Willebrand factor, a marker of endothelial cell maturation, were significantly higher on Ti-rich than on Ti-deficient films. On Ti-rich films, these parameters were also higher or similar in comparison with the reference cell culture materials. Thus, both types of films could be used for coating bone implants, of which the Ti-rich film remains effective in enhancing the endothelialization of blood

  12. Zinc Oxide Thin Films Fabricated with Direct Current Magnetron Sputtering Deposition Technique

    SciTech Connect

    Hoon, Jian-Wei; Chan, Kah-Yoong; Krishnasamy, Jegenathan; Tou, Teck-Yong

    2011-03-30

    Zinc oxide (ZnO) is a very promising material for emerging large area electronic applications including thin-film sensors, transistors and solar cells. We fabricated ZnO thin films by employing direct current (DC) magnetron sputtering deposition technique. ZnO films with different thicknesses ranging from 100 nm to 1020 nm were deposited on silicon (Si) substrate. The deposition pressure was varied from 12 mTorr to 25 mTorr. The influences of the film thickness and the deposition pressure on structural properties of the ZnO films were investigated using Mahr surface profilometer and atomic force microscopy (AFM). The experimental results reveal that the film thickness and the deposition pressure play significant role in the structural formation of the deposited ZnO thin films. ZnO films deposited on Si substrates are promising for variety of thin-film sensor applications.

  13. Annihilation of Leishmania by daylight responsive ZnO nanoparticles: a temporal relationship of reactive oxygen species-induced lipid and protein oxidation

    PubMed Central

    Nadhman, Akhtar; Khan, Malik Ihsanullah; Nazir, Samina; Khan, Momin; Shahnaz, Gul; Raza, Abida; Shams, Dilawar Farhan; Yasinzai, Masoom

    2016-01-01

    Lipid and protein oxidation are well-known manifestations of free radical activity and oxidative stress. The current study investigated extermination of Leishmania tropica promastigotes induced by lipid and protein oxidation with reactive oxygen species produced by PEGylated metal-based nanoparticles. The synthesized photodynamic therapy-based doped and nondoped zinc oxide nanoparticles were activated in daylight that produced reactive oxygen species in the immediate environment. Lipid and protein oxidation did not occur in dark. The major lipid peroxidation derivatives comprised of conjugated dienes, lipid hydroperoxides, and malondialdehyde whereas water, ethane, methanol, and ethanol were found as the end products. Proteins were oxidized to carbonyls, hydroperoxides, and thiol degrading products. Interestingly, lipid hydroperoxides were produced by more than twofold of the protein hydroperoxides, indicating higher degradation of lipids compared to proteins. The in vitro evidence represented a significant contribution of the involvement of both lipid and protein oxidation in the annihilated antipromastigote effect of nanoparticles. PMID:27330288

  14. Improved adhesion of sputtered refractory carbides to metal substrates

    NASA Technical Reports Server (NTRS)

    Wheeler, D. R.; Brainard, W. A.

    1980-01-01

    Sputtered coatings of the refractory metal carbides are of great interest for applications where hard wear-resistant materials are desired. The usefulness of sputtered refractory carbides is often limited in practice by spalling or interfacial separation. In this work improvements in the adherence of refractory carbides on iron, nickel and titanium base alloys were obtained by using oxidation, reactive sputtering or sputtered interlayers to alter the coating-substrate interfacial region. X-ray photoelectron spectroscopy and argon ion etching were used to characterize the interfacial regions, and an attempt was made to correlate adherence as measured in wear tests with the chemical nature of the interface.

  15. Transparent conductive Al-doped ZnO thin films grown at room temperature

    SciTech Connect

    Wang Yuping; Lu Jianguo; Bie Xun; Gong Li; Li Xiang; Song Da; Zhao Xuyang; Ye Wenyi; Ye Zhizhen

    2011-05-15

    Aluminum-doped ZnO (ZnO:Al, AZO) thin films were prepared on glass substrates by dc reactive magnetron sputtering from a Zn-Al alloy target at room temperature. The effects of the Ar-to-O{sub 2} partial pressure ratios on the structural, electrical, and optical properties of AZO films were studied in detail. AZO films grown using 100:4 to 100:8 Ar-to-O{sub 2} ratio result in acceptable quality films with c-axis orientated crystals, uniform grains, 10{sup -3} {Omega} cm resistivity, greater than 10{sup 20} cm{sup -3} electron concentration, and high transmittance, 90%, in the visible region. The lowest resistivity of 4.11x10{sup -3} {Omega} cm was obtained under the Ar-to-O{sub 2} partial pressure ratio of 100:4. A relatively strong UV emission at {approx}3.26 eV was observed in the room-temperature photoluminescence spectrum. X-ray photoelectron spectroscopy analysis confirmed that Al was introduced into ZnO and substitutes for Zn and doped the film n-type.

  16. Microstructural and optical properties of nanocrystalline ZnO deposited onto vertically aligned carbon nanotubes by physical vapor deposition

    SciTech Connect

    Borkar, Tushar; Chang, Won Seok; Hwang, Jun Yeon; Shepherd, Nigel D.; Banerjee, Rajarshi

    2012-10-15

    Nanocrystalline ZnO films with thicknesses of 5 nm, 10 nm, 20 nm, and 50 nm were deposited via magnetron sputtering onto the surface of vertically aligned multi-walled carbon nanotubes (MWCNTs). The ZnO/CNTs heterostructures were characterized by scanning electron microscopy, high resolution transmission electron microscopy, and X-ray diffraction studies. No structural degradation of the CNTs was observed and photoluminescence (PL) measurements of the nanostructured ZnO layers show that the optical properties of these films are typical of ZnO deposited at low temperatures. The results indicate that magnetron sputtering is a viable technique for growing heterostructures and depositing functional layers onto CNTs.

  17. A comparative study of ultraviolet photoconductivity relaxation in zinc oxide (ZnO) thin films deposited by different techniques

    SciTech Connect

    Yadav, Harish Kumar; Gupta, Vinay

    2012-05-15

    Photoresponse characteristics of ZnO thin films deposited by three different techniques namely rf diode sputtering, rf magnetron sputtering, and electrophoretic deposition has been investigated in the metal-semiconductor-metal (MSM) configuration. A significant variation in the crystallinity, surface morphology, and photoresponse characteristics of ZnO thin film with change in growth kinetics suggest that the presence of defect centers and their density govern the photodetector relaxation properties. A relatively low density of traps compared to the true quantum yield is found very crucial for the realization of practical ZnO thin film based ultraviolet (UV) photodetector.

  18. Merits and Demerits of Transparent Conducting Magnetron Sputtered ZnO:Al, ITO and SnO2:F Thin Films for Solar Cell Applications

    NASA Astrophysics Data System (ADS)

    Das, Rajesh; Das, Himadri Sekhar

    2016-06-01

    Transparent conducting ZnO:Al and indium tin oxide (ITO) thin films were deposited by magnetron sputtering under reactive environment. Both the transparent conducting oxide (TCO) films were exposed intentionally in hydrogen environment at 350 °C calcinations temperature to study the post treated TCO film's opto-electronic, structural as well as surface morphological properties. Electrical resistivity of both ZnO:Al, ITO and SnO2:F films are comparable (order of 10-4 Ω-cm), lowest sheet resistance are 8.5, 3.7 and 4.6 Ω/sq respectively and slightly improved after hydrogen exposure at 350 °C. Optical transmittance and internal texture of hydrogen environment exposed ZnO films remains invariant, but in case of ITO, SnO2:F films optical transmittance deteriorated drastically. Hexagonal wurtzite structure with (002) c-axis orientation is observed for pre- and post-hydrogen exposed ZnO films whereas internal texture as well as crystallographic orientation of ITO and SnO2:F films have significantly changed. Surface grains of ITO films have been significantly enhanced, but no such variations are observed in ZnO surface morphology. ZnO:Al and ITO films show unique plasmonic properties in near infrared transmittance due to free carrier generation in conduction band. Based on surface features/morphology, haze factor and internal texture light scattering mechanism is modeled.

  19. Single-phase polycrystalline Ti(1-x)W(x)N alloys (0 less than or equal to x less than or equal to 0.7)grown by UHV reactive magnetron sputtering: Microstructure and physical properties

    NASA Astrophysics Data System (ADS)

    Moser, J. H.; Tian, F.; Haller, O.; Bergstrom, D. B.; Petrov, I.; Greene, J. E.; Wiemer, C.

    1994-12-01

    Single-phase 300 nm thick B1-NaCl structure polycrystalline Ti(1-x)W(x)N alloys, with compositions extending from TiN to Ti(0.3)W(0.7)N, have been grown at 500 C on amorphous SiO2 by ultra-high vacuum reactive magnetron sputtering from Ti and W targets in 10 mTorr N2 discharges. The anion-to-cation ratio ranged from slightly overstoichiometric (1 less than N/(Ti+W) less than or equal to 1.1) in TiN-rich alloys to understoichiometric in WN-rich alloys with N/(Ti+W)=0.9 at x=0.7. The relaxed alloy lattice constant a(sub 0) initially increased with increasing W and then decreased below the stoichiometric TiN value, a(sub TiN)=0.42416 nm, for understoichiometric (i.e. N deficient) alloys with x greater than 0.5. Plan-view and cross-sectional transmission electron microscopy showed that the films exhibited a columnar microstructure, with typical column diameters of 20-25 nm, and a preferred orientation which changed from strong (111) in TiN-rich alloys to strong (002) in WN-rich alloys. The normalized room-temperature resistivity increased linearly at a rate drho/rho(sub TiN) dx=2.5 with increasing WN concentration x due to a combination of alloy, boundary, and free-surface scattering. All of the above results as a function of film composition are directly related to differences in the intensity of low-energy particle irradiation (primarily backscattered N) during film growth.

  20. Self-focused ZnO transducers for ultrasonic biomicroscopy

    PubMed Central

    Cannata, J. M.; Williams, J. A.; Zhou, Q. F.; Sun, L.; Shung, K. K.; Yu, H.; Kim, E. S.

    2008-01-01

    A simple fabrication technique was developed to produce high frequency (100 MHz) self-focused single element transducers with sputtered zinc oxide (ZnO) crystal films. This technique requires the sputtering of a ZnO film directly onto a curved backing substrate. Transducers were fabricated by sputtering an 18 μm thick ZnO layer on 2 mm diameter aluminum rods with ends shaped and polished to produce a 2 mm focus or f-number equal to one. The aluminum rod served a dual purpose as the backing layer and positive electrode for the resultant transducers. A 4 μm Parylene matching layer was deposited on the transducers after housing and interconnect. This matching layer was used to protect the substrate and condition the transfer of acoustic energy between the ZnO film and the load medium. The pulse-echo response for a representative transducer was centered at 101 MHz with a -6 dB bandwidth of 49%. The measured two way insertion loss was 44 dB. A tungsten wire phantom and an adult zebrafish eye were imaged to show the capability of these transducers. PMID:18596925

  1. Self-focused ZnO transducers for ultrasonic biomicroscopy

    SciTech Connect

    Cannata, J. M.; Williams, J. A.; Zhou, Q. F.; Sun, L.; Shung, K. K.; Yu, H.; Kim, E. S.

    2008-04-15

    A simple fabrication technique was developed to produce high frequency (100 MHz) self-focused single element transducers with sputtered zinc oxide (ZnO) crystal films. This technique requires the sputtering of a ZnO film directly onto a curved backing substrate. Transducers were fabricated by sputtering an 18 {mu}m thick ZnO layer on 2 mm diameter aluminum rods with ends shaped and polished to produce a 2 mm focus or f-number equal to one. The aluminum rod served a dual purpose as the backing layer and positive electrode for the resultant transducers. A 4 {mu}m Parylene matching layer was deposited on the transducers after housing and interconnect. This matching layer was used to protect the substrate and condition the transfer of acoustic energy between the ZnO film and the load medium. The pulse-echo response for a representative transducer was centered at 101 MHz with a -6 dB bandwidth of 49%. The measured two way insertion loss was 44 dB. A tungsten wire phantom and an adult zebrafish eye were imaged to show the capability of these transducers.

  2. The nitridation of ZnO nanowires

    PubMed Central

    2012-01-01

    ZnO nanowires (NWs) with diameters of 50 to 250 nm and lengths of several micrometres have been grown by reactive vapour transport via the reaction of Zn with oxygen on 1 nm Au/Si(001) at 550°C under an inert flow of Ar. These exhibited clear peaks in the X-ray diffraction corresponding to the hexagonal wurtzite crystal structure of ZnO and a photoluminescence spectrum with a peak at 3.3 eV corresponding to band edge emission close to 3.2 eV determined from the abrupt onset in the absorption-transmission through ZnO NWs grown on 0.5 nm Au/quartz. We find that the post growth nitridation of ZnO NWs under a steady flow of NH3 at temperatures ≤600°C promotes the formation of a ZnO/Zn3N2 core-shell structure as suggested by the suppression of the peaks related to ZnO and the emergence of new ones corresponding to the cubic crystal structure of Zn3N2 while maintaining their integrity. Higher temperatures lead to the complete elimination of the ZnO NWs. We discuss the effect of nitridation time, flow of NH3, ramp rate and hydrogen on the conversion and propose a mechanism for the nitridation. PMID:22397754

  3. Comparison of the Sputter Rates of Oxide Films Relative to the Sputter Rate of SiO2

    SciTech Connect

    Baer, Donald R.; Engelhard, Mark H.; Lea, Alan S.; Nachimuthu, Ponnusamy; Droubay, Timothy C.; Kim, J.; Lee, B.; Mathews, C.; Opila, R. L.; Saraf, Laxmikant V.; Stickle, William F.; Wallace, Robert; Wright, B. S.

    2010-09-02

    Because of the increasing technological importance of oxide films for a variety of applications, there is a growing interest in knowing the sputter rates for a wide variety of oxides. To support needs of users of the Environmental Molecular Sciences Laboratory (EMSL) User facility as well as our research programs, we have made a series of measurements of the sputter rates for oxide films that have been grown by oxygen plasma assisted molecular beam epitaxy (OPA-MBE), pulsed laser deposition (PLD), Atomic Layer Deposition (ALD), electrochemical oxidation, or sputter deposition. The sputter rates for these oxide films were determined in comparison to the sputter rates for thermally grown SiO2, a common sputter rate reference material. The film thicknesses and densities of these films were usually measured using x-ray reflectivity (XRR). These samples were mounted in an x-ray photoelectron spectroscopy (XPS) system or an Auger electron spectrometer for sputtering measurements using argon ion sputtering. Although the primary objective was to determine relative sputter rates at a fixed angle, the measurements were also used to determine: i) the angle dependence of the relative sputter rates; ii) the energy dependence of the relative sputter rates; and iii) the extent of ion beam reduction for the various oxides. Materials examined include: SiO2 (reference films), Al2O3, CeO2, Cr2O3, Fe2O3, HfO2, ITO (In-Sn-oxide) Ta2O5, TiO2 (anatase and rutile) and ZnO. We find that the sputter rates for the oxides can vary up to a factor of two (usually slower) from that observed for SiO2. The ratios of sputter rates to SiO2 appear to be relatively independent of ion beam energy for the range of 1kV to 4 kV and for incident angles of less than 50º. As expected, the ion beam reduction of the oxides varies with the sputter angle. These studies demonstrate that we can usually obtain sputter rate reproducibility better than 5% for similar oxide films.

  4. Structural and optical properties of zinc oxide film using RF-sputtering technique

    SciTech Connect

    Hashim, A. J.; Jaafar, M. S.; Ghazai, Alaa J.

    2012-11-27

    This paper reports the fabrication of zinc oxide (ZnO) film using RF-sputtering technique. Determination of the structural properties using High Resolution X-ray Diffraction (HRXRD) confirmed that ZnO film deposited on silicon (Si) substrate has a high quality. This result is in line with the Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) which were used to image the morphology of the film, in which a rough surface was demonstrated. Photoluminescence (PL) emission is included to study the optical properties of ZnO film that shows two PL peak in the UV region at 371 nm and in visible region at 530 nm respectively.

  5. Influence of homo buffer layer thickness on the quality of ZnO epilayers.

    PubMed

    Eid, E A; Fouda, A N

    2015-10-01

    ZnO buffer layers with different thicknesses were deposited on a-plane sapphire substrates at 300 °C. ZnO epilayers were grown on ZnO buffers at 600 °C by radio-frequency magnetron sputtering and vacuum annealed at 900 °C for an hour. Influence of nucleation layer thickness on the structural and quality of ZnO thin films was investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), and Raman spectroscopy. The best ZnO film quality was obtained with the ZnO buffer layer of 45 nm thick which provided the smoothest surface with RMS value of 0.3 nm. X-ray diffraction measurements reveal that the films have a single phase wurtzite structure with (0001) preferred crystal orientation. As evident from narrow FWHM of ZnO (0002) rocking curve, ZnO buffer can serve as a good template for the growth of high-quality ZnO films with little tilt. In addition, the micro-Raman scattering measurements at room temperature revealed the existence of Raman active phonon modes of ZnO; A1(TO), A1(LO) and E2(high). The latter two modes were not observed in thin buffer layer beside the dis-appearance of E2(low) mode in all films. PMID:25950638

  6. Characterization of Flexible CIGS Thin Film Solar Cells or Stainless Steel with Intrinsic ZnO Diffusion Barriers.

    PubMed

    Kim, Chae-Woong; Kim, Hye Jin; Kim, Jin Hyeok; Jeong, Chaehwan

    2016-05-01

    ZnO diffusion barrier layer was deposited by RF magnetron sputtering by using the same method as intrinsic ZnO layer. The CIGS solar cells were fabricated on stainless steel substrate. The 50-200 nm thin ZnO diffusion barriers effectively reduced the diffusion of Fe and Cr, from stainless steel substrates into the CIGS absorbers. The CIGS solar cells with ZnO diffusion barriers increased the J(sc) and FF, which resulted in an increase of cell efficiency from 5.9% up to 9.06%. PMID:27483885

  7. Synthesis, characterization and photocatalytic activity of PVP stabilized ZnO and modified ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Bandekar, Gauri; Rajurkar, N. S.; Mulla, I. S.; Mulik, U. P.; Amalnerkar, D. P.; Adhyapak, P. V.

    2013-01-01

    In the present study, ZnO nanostructures have been successfully synthesized by hydrothermal, sonochemical and precipitation methods using polyvinyl pyrrolidone (PVP) as the capping agent. The ZnO nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-Visible spectroscopy and photoluminescence (PL) techniques. The XRD results revealed the hexagonal wurtzite structure of the ZnO nanostructures for all the samples. Furthermore, the morphology of the ZnO particles was obtained from FESEM micrographs. Particles prepared by hydrothermal method were found to be rice grain shaped and that prepared by precipitation and sonochemical methods were spherical shaped. Sunlight driven photocatalytic degradation of methylene blue (MB) was studied for ZnO nanostructures synthesized by various methods. The ZnO nanostructures were further decorated with Ag nanoparticles to enhance its dye degradation efficiency. The Ag decorated ZnO nanoparticles exhibited a higher degradation rate as compared to pure ZnO nanoparticles which was independent of pH. Since this process of dye degradation relies on the degradation of dye due to oxidation by highly reactive hydroxyl radicals, there are many factors which affect the efficiency of this process. Hence a study was conducted on the effect of various parameters on ZnO viz amount of catalyst, reaction pH and concentration of MB dye.

  8. Characterization of ZnO Thin Films Prepared by Thermal Oxidation of Zn

    NASA Astrophysics Data System (ADS)

    Bouanane, I.; Kabir, A.; Boulainine, D.; Zerkout, S.; Schmerber, G.; Boudjema, B.

    2016-07-01

    Zinc oxide thin films were prepared by thermal oxidation of zinc films at a temperature of 500°C for 2 h. The Zn films were deposited onto glass substrates by magnetron RF sputtering. The sputtering time varied from 2.5 min to 15 min. The physico-chemical characterization of the ZnO films was carried out depending on the Zn sputtering time. According to x-ray diffraction, ZnO films were polycrystalline and the Zn-ZnO phase transformation was direct. The mean transmittance of the ZnO films was around 80% and the band gap increased from 3.15 eV to 3.35 eV. Photoluminescence spectra show ultraviolet, visible, and infrared emission bands. The increase of the UV emission band was correlated with the improvement of the crystalline quality of the ZnO films. The concentration of native defects was found to decrease with increasing Zn sputtering time. The decrease of the electrical resistivity as a function of Zn sputtering time was linked to extrinsic hydrogen-related defects.

  9. Characterization of ZnO Thin Films Prepared by Thermal Oxidation of Zn

    NASA Astrophysics Data System (ADS)

    Bouanane, I.; Kabir, A.; Boulainine, D.; Zerkout, S.; Schmerber, G.; Boudjema, B.

    2016-04-01

    Zinc oxide thin films were prepared by thermal oxidation of zinc films at a temperature of 500°C for 2 h. The Zn films were deposited onto glass substrates by magnetron RF sputtering. The sputtering time varied from 2.5 min to 15 min. The physico-chemical characterization of the ZnO films was carried out depending on the Zn sputtering time. According to x-ray diffraction, ZnO films were polycrystalline and the Zn-ZnO phase transformation was direct. The mean transmittance of the ZnO films was around 80% and the band gap increased from 3.15 eV to 3.35 eV. Photoluminescence spectra show ultraviolet, visible, and infrared emission bands. The increase of the UV emission band was correlated with the improvement of the crystalline quality of the ZnO films. The concentration of native defects was found to decrease with increasing Zn sputtering time. The decrease of the electrical resistivity as a function of Zn sputtering time was linked to extrinsic hydrogen-related defects.

  10. Surface Engineering of ZnO Thin Film for High Efficiency Planar Perovskite Solar Cells

    PubMed Central

    Tseng, Zong-Liang; Chiang, Chien-Hung; Wu, Chun-Guey

    2015-01-01

    Sputtering made ZnO thin film was used as an electron-transport layer in a regular planar perovskite solar cell based on high quality CH3NH3PbI3 absorber prepared with a two-step spin-coating. An efficiency up to 15.9% under AM 1.5G irradiation is achieved for the cell based on ZnO film fabricated under Ar working gas. The atmosphere of the sputtering chamber can tune the surface electronic properties (band structure) of the resulting ZnO thin film and therefore the photovoltaic performance of the corresponding perovskite solar cell. Precise surface engineering of ZnO thin film was found to be one of the key steps to fabricate ZnO based regular planar perovskite solar cell with high power conversion efficiency. Sputtering method is proved to be one of the excellent techniques to prepare ZnO thin film with controllable properties. PMID:26411577

  11. Surface Engineering of ZnO Thin Film for High Efficiency Planar Perovskite Solar Cells.

    PubMed

    Tseng, Zong-Liang; Chiang, Chien-Hung; Wu, Chun-Guey

    2015-01-01

    Sputtering made ZnO thin film was used as an electron-transport layer in a regular planar perovskite solar cell based on high quality CH3NH3PbI3 absorber prepared with a two-step spin-coating. An efficiency up to 15.9% under AM 1.5G irradiation is achieved for the cell based on ZnO film fabricated under Ar working gas. The atmosphere of the sputtering chamber can tune the surface electronic properties (band structure) of the resulting ZnO thin film and therefore the photovoltaic performance of the corresponding perovskite solar cell. Precise surface engineering of ZnO thin film was found to be one of the key steps to fabricate ZnO based regular planar perovskite solar cell with high power conversion efficiency. Sputtering method is proved to be one of the excellent techniques to prepare ZnO thin film with controllable properties. PMID:26411577

  12. Solar system sputtering

    NASA Technical Reports Server (NTRS)

    Tombrello, T. A.

    1982-01-01

    The sites and materials involved in solar system sputtering of planetary surfaces are reviewed, together with existing models for the processes of sputtering. Attention is given to the interaction of the solar wind with planetary atmospheres in terms of the role played by the solar wind in affecting the He-4 budget in the Venus atmosphere, and the erosion and differentiation of the Mars atmosphere by solar wind sputtering. The study is extended to the production of isotopic fractionation and anomalies in interplanetary grains by irradiation, and to erosion effects on planetary satellites with frozen volatile surfaces, such as with Io, Europa, and Ganymede. Further measurements are recommended of the molecular form of the ejected material, the yields and energy spectra of the sputtered products, the iosotopic fractionation sputtering causes, and the possibility of electronic sputtering enhancement with materials such as silicates.

  13. A reactive magnetron sputtering route for attaining a controlled core-rim phase partitioning in Cu{sub 2}O/CuO thin films with resistive switching potential

    SciTech Connect

    Ogwu, A. A.; Darma, T. H.

    2013-05-14

    The achievement of a reproducible and controlled deposition of partitioned Cu{sub 2}O/CuO thin films by techniques compatible with ULSI processing like reactive magnetron sputtering has been reported as an outstanding challenge in the literature. This phase partitioning underlies their performance as reversible resistive memory switching devices in advanced microelectronic applications of the future. They are currently fabricated by thermal oxidation and chemical methods. We have used a combination of an understanding from plasma chemistry, thermo-kinetics of ions, and rf power variation during deposition to successfully identify a processing window for preparing partitioned Cu{sub 2}O/CuO films. The production of a core rich Cu{sub 2}O and surface rich Cu{sub 2}O/CuO mixture necessary for oxygen migration during resistive switching is confirmed by XRD peaks, Fourier transform infra red Cu (I)-O vibrational modes, XPS Cu 2P{sub 3/2} and O 1S peak fitting, and a comparison of satellite peak ratio's in Cu 2P{sub 3/2} fitted peaks. We are proposing based on the findings reported in this paper that an XPS satellite peak intensity(I{sub s}) to main peak intensity ratio (I{sub m}) {<=} 0.45 as an indicator of a core rich Cu{sub 2}O and surface rich Cu{sub 2}O/CuO formation in our prepared films. CuO is solely responsible for the satellite peaks. This is explained on the basis that plasma dissociation of oxygen will be limited to the predominant formation of Cu{sub 2}O under certain plasma deposition conditions we have identified in this paper, which also results in a core-rim phase partitioning. The deposited films also followed a Volmer-Weber columnar growth mode, which could facilitate oxygen vacancy migration and conductive filaments at the columnar interfaces. This is further confirmed by optical transmittance and band-gap measurements using spectrophotometry. This development is expected to impact on the early adoption of copper oxide based resistive memory

  14. Investigation of Reactively Sputtered Titanium Oxide Memristors

    NASA Astrophysics Data System (ADS)

    Olin-Ammentorp, Wilkie

    Over the previous decade, flash memory has made massive gains in storage density and market share. However, due to fundamental scaling limits being reached, a replacement memory device must be found. Resistive random access memory (RRAM) is a leading candidate to replace flash memory as a storage-class memory. RRAM is a broad classification of devices, all of which share the commonality that their information is stored in the resistance of a material. These devices are often described as being memristive. The objective of the study performed was to develop a process for fabricating microelectronic structures to investigate the memristive behavior of materials. The first approach taken was to explore a self-aligned fabrication process that relies on angular deposition of electrodes to create crossbar structures. These structures consist of a bottom electrode, the material being characterized, and a top electrode. Issues related to access to contacts were encountered while using the self-aligned process, and it was refined into an improved process. This process used conventional lithography and patterning techniques to replace the angular self-aligned deposition. The improved process successfully demonstrated memristive switching of a titanium oxide film, with on/off ratios of 4.25E5 at 1 V observed. Set voltages of 3 V were used to switch the memristors into a low-resistance state. Large variations in resistances between devices were observed, and are commonly encountered in memristors at microscales due to stochastic nature of filament formation. Further work using shaped electrodes to improve characteristics has been proposed, and a shaping etch which could be applied towards this goal was demonstrated.

  15. Ion beam sputter etching

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.

    1986-01-01

    An ion beam etching process which forms extremely high aspect ratio surface microstructures using thin sputter masks is utilized in the fabrication of integrated circuits. A carbon rich sputter mask together with unmasked portions of a substrate is bombarded with inert gas ions while simultaneous carbon deposition occurs. The arrival of the carbon deposit is adjusted to enable the sputter mask to have a near zero or even slightly positive increase in thickness with time while the unmasked portions have a high net sputter etch rate.

  16. Magnetron discharge sputtering for fabrication of nanogradient optical coatings

    NASA Astrophysics Data System (ADS)

    Volpian, O. D.; Kuzmichev, A. I.; Ermakov, G. F.; Krikunov, A. I.; Obod, Yu A.; Silin, N. V.; Shkatula, S. V.

    2015-11-01

    The technology of the middle frequency pulse reactive magnetron sputtering for fabrication of nanogradient optical coatings with smooth variation of refractive index was developed and studied. The technology is based on programmable motion of a substrate over two magnetrons with targets of different materials. The feature of the deposition process is a constant composition of reactive gas medium and an invariable magnetron operation mode. To realize this technology, an automatic computer-controlled sputtering system additionally comprising a gas discharge activator of reactive gas (oxygen) and an in situ optical monitor- spectrovisor has been built. The dielectric oxide-based nanogradient coatings of photon-barrier type were successfully fabricated. The obtained results confirm the high potential of the middle frequency pulse reactive magnetron sputtering of silicon and metal targets for fabrication of nanogradient dielectric optical coatings with excellent properties.

  17. Effect of ZnO Nanostructured Thin Films on Pseudomonas Putida Cell Division

    NASA Astrophysics Data System (ADS)

    Ivanova, I.; Lukanov, A.; Angelov, O.; Popova, R.; Nichev, H.; Mikli, V.; Dimova-Malinovska, Doriana; Dushkin, C.

    In this report we study the interaction between the bacteria Pseudomonas putida and nanostructured ZnO and ZnO:H thin films prepared by magnetron sputtering of a ZnO target. The nanostructured ZnO and ZnO:H thin films possess some biological-active properties when in contact with bacteria. Our experimental data show that these films have no destructive effect on the cell division of Pseudomonas putida in poor liquid medium and can be applied in biosensor devices.

  18. Comparison of the sputter rates of oxide films relative to the sputter rate of SiO{sub 2}

    SciTech Connect

    Baer, D. R.; Engelhard, M. H.; Lea, A. S.; Nachimuthu, P.; Droubay, T. C.; Kim, J.; Lee, B.; Mathews, C.; Opila, R. L.; Saraf, L. V.; Stickle, W. F.; Wallace, R. M.; Wright, B. S.

    2010-09-15

    There is a growing interest in knowing the sputter rates for a wide variety of oxides because of their increasing technological importance in many different applications. To support the needs of users of the Environmental Molecular Sciences Laboratory, a national scientific user facility, as well as our research programs, the authors made a series of measurements of the sputter rates from oxide films that have been grown by oxygen plasma-assisted molecular beam epitaxy, pulsed laser deposition, atomic layer deposition, electrochemical oxidation, or sputter deposition. The sputter rates for these oxide films were determined in comparison with those from thermally grown SiO{sub 2}, a common reference material for sputter rate determination. The film thicknesses and densities for most of these oxide films were measured using x-ray reflectivity. These oxide films were mounted in an x-ray photoelectron or Auger electron spectrometer for sputter rate measurements using argon ion sputtering. Although the primary objective of this work was to determine relative sputter rates at a fixed angle, the measurements also examined (i) the angle dependence of the relative sputter rates, (ii) the energy dependence of the relative sputter rates, and (iii) the extent of ion beam induced reduction for some oxides. Oxide films examined include SiO{sub 2}, Al{sub 2}O{sub 3}, CeO{sub 2}, Cr{sub 2}O{sub 3}, Fe{sub 2}O{sub 3}, HfO{sub 2}, In-Sn oxide, Ta{sub 2}O{sub 5}, TiO{sub 2} (anatase, rutile, and amorphous), and ZnO. The authors found that the sputter rates for the oxides can vary up to a factor of 2 (usually lower) from that observed for SiO{sub 2}. The ratios of sputter rates relative to those of SiO{sub 2} appear to be relatively independent of ion beam energy in the range of 1-4 kV and for incident angles <50 deg. As expected, the extent of ion beam induced reduction of the oxides varies with the sputter angle.

  19. Investigation of thin ZnO layers in view of laser desorption-ionization

    NASA Astrophysics Data System (ADS)

    Grechnikov, A. A.; Georgieva, V. B.; Alimpiev, S. S.; Borodkov, A. S.; Nikiforov, S. M.; Simanovsky, Ya O.; Dimova-Malinovska, D.; Angelov, O. I.

    2010-04-01

    Thin zinc oxide films (ZnO) were developed as a matrix-free platform for surface assisted laser desorption-ionization (SALDI) time-of-flight mass spectrometry. The ZnO films were deposited by RF magnetron sputtering of ZnO ceramic targets in Ar atmospheres on monocrystalline silicon. The generation under UV (355 nm) laser irradiation of positive ions of atenolol, reserpine and gramicidin S from the ZnO layers deposited was studied. All analytes tested were detected as protonated molecules with no or very structure-specific fragmentation. The mass spectra obtained showed low levels of chemical background noise. All ZnO films studied exhibited high stability and good reproducibility. The detection limits for test analytes are in the 10 femtomol range.

  20. Effect of Corrosion by Diluted HCL Solution on the Zno:. AL Texture

    NASA Astrophysics Data System (ADS)

    Shi, Mingji; Wang, Ping; Chen, Lanli

    2012-08-01

    High quality textured ZnO: Al electrode can improve the energy conversion efficiency of silicon based thin film solar cells. ZnO: Al films were deposited under 200W. Different textured surfaces were got when etching ZnO: Al films with diluted HCl solutions of 0.5% for different times. The transmission spectrum, square resistance and atomic force microscopy (AFM) images of the samples were measured. The dependence of corrosion time on the resistivity, transmittance and surface texture of the samples were studied. With the increasing of the corrosion time, the resistivity increased, the transmittance decreased, the root-mean-square roughness first increases, then decreases. High quality textured ZnO: Al electrode was obtained when etching the ZnO: Al film deposited under 200W of sputtering power with diluted HCl solution of 0.5%.