Optical properties of aluminum-doped zinc oxide films deposited by direct-current pulse magnetron reactive sputtering

NASA Astrophysics Data System (ADS)

Gao, Xiao-Yong; Chen, Chao; Zhang, Sa

2014-03-01

A series of <103>-oriented aluminum-doped zinc oxide (AZO) films were deposited on glass substrates via direct-current pulse magnetron reactive sputtering at different O2-to-Ar gas flow ratios (GFRs). The optical properties of the films were characterized using the fitted optical constants in the general oscillator model (which contains two Psemi-Tri oscillators) through the use of measured ellipsometric parameters. The refractive index dispersion data below the interband absorption edge were analyzed using a single-oscillator model. The fitted optical energy gap obtained using the single-oscillator model clearly shows a blue shift, followed by a red shift, as the GFR increases from 0.9/18 to 2.1/18. This shift can be attributed to the change in the free electron concentration of the film, which is closely related to the film stress. In addition, the fitted β value indicates that the AZO film falls under the ionic class. The photoluminescence spectrum indicates a photoluminescence mechanism of the direct and wide energy gap semiconductor.

Preliminary Experiment of Non-Inductive Plasma Current Startup in SUNIST Spherical Tokamak

NASA Astrophysics Data System (ADS)

He, Yexi; Zhang, Liang; Xie, Lifeng; Tang, Yi; Yang, Xuanzong; Feng, Chunhua; Fu, Hongjun

2006-01-01

The non-inductive plasma current startup is an important motivation in SUNIST spherical tokamak. In the recent experiment, the magnetron microwave system of 100 kW and 2.45 GHz has been used to the ECR plasma current startup. Besides the toroidal field, a vertical field was applied to generate preliminary toroidal plasma current without the action of the central solenoid. As the evidence of plasma current startup with the effect of vertical field drift, the direction of plasma current is changed when the direction of vertical field changes during the ECR plasma current startup discharge. We also observed a maximum plasma current by scanning vertical field in both directions. Additionally, we used electrode discharge to assist the ECR plasma current startup.

Electrochemical characteristics of amorphous carbon nanorod synthesized by radio frequency magnetron sputtering

NASA Astrophysics Data System (ADS)

Chang, Hsin-Yueh; Huang, Yung-Jui; Chang, Hsuan-Chen; Su, Wei-Jhih; Shih, Yi-Ting; Chen, John L.; Honda, Shin-ichi; Huang, Ying-Sheng; Lee, Kuei-Yi

2015-01-01

Amorphous carbon nanorods (CNRs) were deposited directly using radio frequency magnetron sputtering. The synthesized CNR electrochemical properties were investigated using graphene as the current collector for an electric double layer capacitor. The CNRs were vertically aligned to the graphene to achieve higher specific surface area. The capacitor performance was characterized using electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge testing in 1 M KOH electrolyte at 30°C, 40°C, 50°C, and 60°C. The CNR specific capacitance was observed to increase with increasing measurement temperature and could reach up to 830 F/g at 60°C. Even after extensive measurements, the CNR electrode maintained good adhesion to the graphene current collector thereby suggesting electrode material stability.

Satellite Power System (SPS) magnetron tube assessment study

NASA Technical Reports Server (NTRS)

Brown, W. C.

1981-01-01

The data base was extended with respect to the magnetron directional amplifier and its operating parameters that are pertinent to its application in the solar power satellite. On the basis of the resulting extended data base the design of a magnetron was outlined that would meet the requirements of the SPS application and a technology program was designed that would result in its development. The proposed magnetron design for the SPS is a close scale of the microwave oven magnetron, and resembles it closely physically and electrically.

Electrical characteristics of thin Ta2O5 films deposited by reactive pulsed direct-current magnetron sputtering

NASA Astrophysics Data System (ADS)

Kim, J.-Y.; Nielsen, M. C.; Rymaszewski, E. J.; Lu, T.-M.

2000-02-01

Room temperature deposition of tantalum oxide films on metallized silicon substrates was investigated by reactive pulsed magnetron sputtering of Ta in an Ar/O2 ambient. The dielectric constant of the tantalum oxide ranged from 19 to 31 depending on the oxygen percentage [P(%)=PO2/(PO2+PAr)] used during sputtering. The leakage current density was less than 10 nA/cm2 at 0.5 MV/cm electric field and the dielectric breakdown field was greater than 3.8 MV/cm for P=60%. A charge storage as high as 3.3 μF/cm2 was achieved for 70-Å-thick film. Pulse frequency variation (from 20 to 200 kHz) did not give a significant effect in the electrical properties (dielectric constant or leakage current density) of the Ta2O5 films.

Resonant interaction of the electron beam with a synchronous wave in controlled magnetrons for high-current superconducting accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazakevich, G.; Johnson, R.; Lebedev, V.

A simplified analytical model of the resonant interaction of the beam of Larmor electrons drifting in the crossed constant fields of a magnetron with a synchronous wave providing a phase grouping of the drifting charge was developed to optimize the parameters of an rf resonant injected signal driving the magnetrons for management of phase and power of rf sources with a rate required for superconducting high-current accelerators. The model, which considers the impact of the rf resonant signal injected into the magnetron on the operation of the injection-locked tube, substantiates the recently developed method of fast power control of magnetronsmore » in the range up to 10 dB at the highest generation efficiency, with low noise, precise stability of the carrier frequency, and the possibility of wideband phase control. Experiments with continuous wave 2.45 GHz, 1 kW microwave oven magnetrons have verified the correspondence of the behavior of these tubes to the analytical model. A proof of the principle of the novel method of power control in magnetrons, based on the developed model, was demonstrated in the experiments. The method is attractive for high-current superconducting rf accelerators. This study also discusses vector methods of power control with the rates required for superconducting accelerators, the impact of the rf resonant signal injected into the magnetron on the rate of phase control of the injection-locked tubes, and a conceptual scheme of the magnetron transmitter with highest efficiency for high-current accelerators.« less

Resonant interaction of the electron beam with a synchronous wave in controlled magnetrons for high-current superconducting accelerators

DOE PAGES

Kazakevich, G.; Johnson, R.; Lebedev, V.; ...

2018-06-14

A simplified analytical model of the resonant interaction of the beam of Larmor electrons drifting in the crossed constant fields of a magnetron with a synchronous wave providing a phase grouping of the drifting charge was developed to optimize the parameters of an rf resonant injected signal driving the magnetrons for management of phase and power of rf sources with a rate required for superconducting high-current accelerators. The model, which considers the impact of the rf resonant signal injected into the magnetron on the operation of the injection-locked tube, substantiates the recently developed method of fast power control of magnetronsmore » in the range up to 10 dB at the highest generation efficiency, with low noise, precise stability of the carrier frequency, and the possibility of wideband phase control. Experiments with continuous wave 2.45 GHz, 1 kW microwave oven magnetrons have verified the correspondence of the behavior of these tubes to the analytical model. A proof of the principle of the novel method of power control in magnetrons, based on the developed model, was demonstrated in the experiments. The method is attractive for high-current superconducting rf accelerators. This study also discusses vector methods of power control with the rates required for superconducting accelerators, the impact of the rf resonant signal injected into the magnetron on the rate of phase control of the injection-locked tubes, and a conceptual scheme of the magnetron transmitter with highest efficiency for high-current accelerators.« less

RP and RQA Analysis for Floating Potential Fluctuations in a DC Magnetron Sputtering Plasma

NASA Astrophysics Data System (ADS)

Sabavath, Gopikishan; Banerjee, I.; Mahapatra, S. K.

2016-04-01

The nonlinear dynamics of a direct current magnetron sputtering plasma is visualized using recurrence plot (RP) technique. RP comprises the recurrence quantification analysis (RQA) which is an efficient method to observe critical regime transitions in dynamics. Further, RQA provides insight information about the system’s behavior. We observed the floating potential fluctuations of the plasma as a function of discharge voltage by using Langmuir probe. The system exhibits quasi-periodic-chaotic-quasi-periodic-chaotic transitions. These transitions are quantified from determinism, Lmax, and entropy of RQA. Statistical investigations like kurtosis and skewness also studied for these transitions which are in well agreement with RQA results.

Localized traveling ionization zones and their importance for the high power impulse magnetron sputtering process

NASA Astrophysics Data System (ADS)

Maszl, Christian

2016-09-01

High power impulse magnetron sputtering (HiPIMS) is a technique to deposit thin films with superior quality. A high ionization degree up to 90% and the natural occurence of high energetic metal ions are the reason why HiPIMS exceeds direct current magnetron sputtering in terms of coating quality. On the other hand HiPIMS suffers from a reduced efficiency, especially if metal films are produced. Therefore, a lot of research is done by experimentalists and theoreticians to clarify the transport mechanisms from target to substrate and to identify the energy source of the energetic metal ions. Magnetron plasmas are prone to a wide range of wave phenomena and instabilities. Especially, during HiPIMS at elevated power/current densities, symmetry breaks and self-organization in the plasma torus are observed. In this scenario localized travelling ionization zones with certain quasi-mode numbers are present which are commonly referred to as spokes. Because of their high rotation speed compared to typical process times of minutes their importance for thin film deposition was underestimated at first. Recent investigations show that spokes have a strong impact on particle transport, are probably the source of the high energetic metal ions and are therefore the essence of HiPIMS plasmas. In this contribution we will describe the current understanding of spokes, discuss implications for thin film synthesis and highlight open questions. This project is supported by the DFG (German Science Foundation) within the framework of the Coordinated Research Center SFB-TR 87 and the Research Department ``Plasmas with Complex Interactions'' at Ruhr-University Bochum.

Effect of assistant rf field on phase composition of iron nitride film prepared by magnetron sputtering process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, W.L.; Zheng, F.; Fei, W.D.

2006-01-15

Fe-N thin films were fabricated using a direct current magnetron sputtering process assisted by a radio-frequency (rf) field. The effect of the rf field on the phase composition of the films was investigated. The results indicate that with the assistance of the rf field, various kinds of iron nitrides can be obtained in the films, including {alpha}{sup '}-Fe-N, {alpha}{sup ''}-Fe{sub 16}N{sub 2}, {xi}-Fe{sub 2}N, {epsilon}-Fe{sub 3}N, and {gamma}{sup ''}-FeN with ZnS structure. It was found that the rf field greatly benefits the formation of iron nitrides in the Fe-N films.

Characteristic of Nano-Cu Film Prepared by Energy Filtrating Magnetron Sputtering Technique and Its Optical Property

NASA Astrophysics Data System (ADS)

Wang, Zhaoyong; Hu, Xing; Yao, Ning

2015-03-01

At the optimized deposition parameters, Cu film was deposited by the direct current magnetron sputtering (DMS) technique and the energy filtrating magnetron sputtering (EFMS) technique. The nano-structure was charactered by x-ray diffraction. The surface morphology of the film was observed by atomic force microscopy. The optical properties of the film were measured by spectroscopic ellipsometry. The refractive index, extinction coefficient and the thickness of the film were obtained by the fitted spectroscopic ellipsometry data using the Drude-Lorentz oscillator optical model. Results suggested that a Cu film with different properties was fabricated by the EFMS technique. The film containing smaller particles is denser and the surface is smoother. The average transmission coefficient, the refractive index and the extinction coefficients are higher than those of the Cu film deposited by the DMS technique. The average transmission coefficient (400-800 nm) is more than three times higher. The refractive index and extinction coefficient (at 550 nm) are more than 36% and 14% higher, respectively.

Low temperature fabrication of VO x thin films for uncooled IR detectors by direct current reactive magnetron sputtering method

NASA Astrophysics Data System (ADS)

Dai, Jun; Wang, Xingzhi; He, Shaowei; Huang, Ying; Yi, Xinjian

2008-03-01

Vanadium oxide films have been fabricated on Si3N4-film-coated silicon substrates by direct current reactive magnetron sputtering method. Conditions of deposition are optimized making use of parameters such as sputtering time, dc power, oxygen partial pressure and substrate temperature. X-ray diffraction indicates that the film is a mixture of VO2, V2O3, and V3O5. Four-probe measurement shows that the VOx thin film owns high temperature coefficient of resistance (TCR ∼-2.05%/°C) and suitable square resistance 18.40 kΩ/□ (measured at 25 °C), indicating it is a well candidate material for uncooled IR detectors. In addition, IR absorption in the wavelength of 2-16 μm has been characterized. It is worth noting that the films are sputtered at a relatively low temperature of 210 °C in a controlled Ar/O2 atmosphere. Compared to traditional craft, this method needs no post-anneal at high temperature (400-500 °C).

Experimental radiation cooled magnetrons for space

NASA Astrophysics Data System (ADS)

Brown, W. C.; Pollock, M.

The heat disposal problem that occurs in the microwave generator of the Solar Power Satellite when it converts dc power from solar photovoltaic arrays into microwave power for transmission to earth is examined. A theoretical study is made of the radiation cooling of a magnetron directional amplifier, and some experimental data obtained from the QKH 2244 magnetron are presented. This instrument is an unpackaged microwave oven magnetron to which an anodized aluminum radiator has been attached and whose magnetic field is supplied by special samarium cobalt magnets.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Högberg, Hans, E-mail: hans.hogberg@liu.se; Tengdelius, Lina; Eriksson, Fredrik

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{submore » 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.« less

Real-Time Terahertz Imaging Using a Quantum Cascade Laser and Uncooled Microbolometer Focal Plane Array

DTIC Science & Technology

2008-06-01

reverse magnetron ” design (in which the polarity of the magnetron elements are reversed—such that the cathode constitutes the outer ring; the anode ...included as inset frames within Fig. 20. The dual nature of this figure (reporting both voltage and intensity vs. bias current) is useful in that it...tuned micro- magnetrons [60]-[61]. Conventional magnetrons (such as those used to generate microwaves) have physical dimensions which are excessively

Magnetic properties of in-plane oriented barium hexaferrite thin films prepared by direct current magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xiaozhi; Yue, Zhenxing, E-mail: yuezhx@mail.tsinghua.edu.cn; Meng, Siqin

2014-12-28

In-plane c-axis oriented Ba-hexaferrite (BaM) thin films were prepared on a-plane (112{sup ¯}0) sapphire (Al{sub 2}O{sub 3}) substrates by DC magnetron sputtering followed by ex-situ annealing. The DC magnetron sputtering was demonstrated to have obvious advantages over the traditionally used RF magnetron sputtering in sputtering rate and operation simplicity. The sputtering power had a remarkable influence on the Ba/Fe ratio, the hematite secondary phase, and the grain morphology of the as-prepared BaM films. Under 80 W of sputtering power, in-plane c-axis highly oriented BaM films were obtained. These films had strong magnetic anisotropy with high hysteresis loop squareness (M{sub r}/M{sub s}more » of 0.96) along the in-plane easy axis and low M{sub r}/M{sub s} of 0.03 along the in-plane hard axis. X-ray diffraction patterns and pole figures revealed that the oriented BaM films grew via an epitaxy-like growth process with the crystallographic relationship BaM (101{sup ¯}0)//α-Fe{sub 2}O{sub 3}(112{sup ¯}0)//Al{sub 2}O{sub 3}(112{sup ¯}0)« less

Phase Grouping of Larmor Electrons by a Synchronous Wave in Controlled Magnetrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazakevich, G.; Johnson, R.; Lebedev, V.

A simplified analytical model based on the charge drift approximation has been developed. It considers the resonant interaction of the synchronous wave with the flow of Larmor electrons in a magnetron. The model predicts stable coherent generation of the tube above and below the threshold of self-excitation. This occurs if the magnetron is driven by a sufficient resonant injected signal (up to -10 dB). The model substantiates precise stability, high efficiency and low noise at the range of the magnetron power control over 10 dB by variation of the magnetron current. The model and the verifying experiments with 2.45 GHz,more » 1 kW magnetrons are discussed.« less

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

NASA Astrophysics Data System (ADS)

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

1988-06-01

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.

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.

An efficient magnetron transmitter for superconducting accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazakevich, G.; Lebedev, V.; Yakovlev, V.

A concept of a highly-efficient high-power magnetron transmitter allowing wide-band phase and the mid-frequency power control at the frequency of the locking signal is proposed. The proposal is aimed for powering Superconducting RF (SRF) cavities of intensity-frontier accelerators. The transmitter is intended to operate with phase and amplitude control feedback loops allowing suppression of microphonics and beam loading in the SRF cavities. The concept utilizes injectionlocked magnetrons controlled in phase by the locking signal supplied by a feedback system. The injection-locking signal pre-excites the magnetron and allows its operation below the critical voltage. This realizes control of the magnetron powermore » in a wide range by control of the magnetron current. Pre-excitation of the magnetron by the locking signal provides an output power range up to 10 dB. Experimental studies were carried out with 2.45 GHz, 1 kW, CW magnetrons. They demonstrated stable operation of the magnetrons and power control at a low noise level. In conclusion, an analysis of the kinetics of the drifting charge in the drift approximation substantiates the concept and the experimental results.« less

An efficient magnetron transmitter for superconducting accelerators

DOE PAGES

Kazakevich, G.; Lebedev, V.; Yakovlev, V.; ...

2016-09-22

A concept of a highly-efficient high-power magnetron transmitter allowing wide-band phase and the mid-frequency power control at the frequency of the locking signal is proposed. The proposal is aimed for powering Superconducting RF (SRF) cavities of intensity-frontier accelerators. The transmitter is intended to operate with phase and amplitude control feedback loops allowing suppression of microphonics and beam loading in the SRF cavities. The concept utilizes injectionlocked magnetrons controlled in phase by the locking signal supplied by a feedback system. The injection-locking signal pre-excites the magnetron and allows its operation below the critical voltage. This realizes control of the magnetron powermore » in a wide range by control of the magnetron current. Pre-excitation of the magnetron by the locking signal provides an output power range up to 10 dB. Experimental studies were carried out with 2.45 GHz, 1 kW, CW magnetrons. They demonstrated stable operation of the magnetrons and power control at a low noise level. In conclusion, an analysis of the kinetics of the drifting charge in the drift approximation substantiates the concept and the experimental results.« less

The Magnetron Method for the Determination of e/m for Electrons: Revisited

ERIC Educational Resources Information Center

Azooz, A. A.

2007-01-01

Additional information concerning the energy distribution function of electrons in a magnetron diode valve can be extracted. This distribution function is a manifestation of the effect of space charge at the anode. The electron energy distribution function in the magnetron is obtained from studying the variation of the anode current with the…

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.

A cookbook for building a high-current dimpled H – magnetron source for accelerators

DOE PAGES

Bollinger, Daniel S.; Karns, Patrick R.; Tan, Cheng -Yang

2015-10-30

A high-current (>50 mA) dimpled H – magnetron source has been built at Fermilab for supplying H – beam to the entire accelerator complex. Despite many decades of expertise with slit H – magnetron sources at Fermilab, we were faced with many challenges from the dimpled H – magnetron source, which needed to be overcome in order to make it operational. Dimpled H – sources for high-energy physics are not new: Brookhaven National Laboratory has operated a dimpled H- source for more than two decades. However, the transference of that experience to Fermilab took about two years because a cookbookmore » for building this type of source did not exist and seemingly innocuous or undocumented choices had a huge impact on the success or failure for this type of source. Moreover, it is the goal of this paper to document the reasons for these choices and to present a cookbook for building and operating dimpled H – magnetron sources.« less

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.

Recent operation of the FNAL magnetron H- ion source

NASA Astrophysics Data System (ADS)

Karns, P. R.; Bollinger, D. S.; Sosa, A.

2017-08-01

This paper will detail changes in the operational paradigm of the Fermi National Accelerator Laboratory (FNAL) magnetron H- ion source due to upgrades in the accelerator system. Prior to November of 2012 the H- ions for High Energy Physics (HEP) experiments were extracted at ˜18 keV vertically downward into a 90 degree bending magnet and accelerated through a Cockcroft-Walton accelerating column to 750 keV. Following the upgrade in the fall of 2012 the H- ions are now directly extracted from a magnetron at 35 keV and accelerated to 750 keV by a Radio Frequency Quadrupole (RFQ). This change in extraction energy as well as the orientation of the ion source required not only a redesign of the ion source, but an updated understanding of its operation at these new values. Discussed in detail are the changes to the ion source timing, arc discharge current, hydrogen gas pressure, and cesium delivery system that were needed to maintain consistent operation at >99% uptime for HEP, with an increased ion source lifetime of over 9 months.

The characteristics of a new negative metal ion beam source and its applications

NASA Astrophysics Data System (ADS)

Paik, Namwoong

2001-10-01

Numerous efforts at energetic thin film deposition processes using ion beams have been made to meet the demands of today's thin film industry. As one of these efforts, a new Magnetron Sputter Negative Ion Source (MSNIS) was developed. In this study, the development and the characterization of the MSNIS were investigated. Amorphous carbon films were used as a sample coating medium to evaluate the ion beam energy effect. A review of energetic Physical Vapor Deposition (PVD) techniques is presented in Chapter 1. The energetic PVD methods can be classified into two major categories: the indirect ion beam method Ion Beam Assisted Deposition (IBAD), and the direct ion beam method-Direct Ion Beam Deposition (DIBD). In this chapter, currently available DIBD processes such as Cathodic Arc, Laser Ablation, Ionized Physical Vapor Deposition (I-PVD) and Magnetron Sputter Negative Ion Source (MSNIS) are individually reviewed. The design and construction of the MSNIS is presented in chapter 2. The MSNIS is a hybrid of the conventional magnetron sputter configuration and the cesium surface ionizer. The negative sputtered ions are produced directly from the sputter target by surface ionization. In chapter 3, the ion beam and plasma characteristics of an 8″ diameter MSNIS are investigated using a retarding field analyzer and a cylindrical Langmuir Probe. The measured electron temperature is approximately 2-5 eV, while the plasma density and plasma potential were of the order of 10 11-1012 cm3 and 5-20 V, respectively, depending on the pressure and power. In chapter 4, in order to evaluate the effect of the ion beam on the resultant films, amorphous carbon films were deposited under various conditions. The structure of carbon films was investigated using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The result suggests the fraction of spa bonding is more than 70% in some samples prepared by MSNIS while magnetron sputtered samples showed less than 30%. (Abstract shortened by UMI.)

The structure and properties of pulsed dc magnetron sputtered nanocrystalline TiN films for electrodes of alkali metal thermal-to-electric conversion systems.

PubMed

Chun, Sung-Yong

2013-03-01

Titanium nitride films used as an important electrode material for the design of alkali metal thermal-to-electric conversion (AMTEC) system have been prepared using dc (direct current) and asymmetric-bipolar pulsed dc magnetron sputtering. The pulse frequency and the duty cycle were varied from 5 to 50 kHz and 50 to 95%, respectively. The deposition rate, grain size and resistivity of pulsed dc sputtered films were decreased when the pulse frequency increased, while the nano hardness of titanium nitride films increased. We present in detail coatings (e.g., deposition rate, grain size, prefer-orientation, resistivity and hardness). Our studies show that titanium nitride coatings with superior properties can be prepared using asymmetric-bipolar pulsed dc sputtering.

A hybrid electron cyclotron resonance metal ion source with integrated sputter magnetron for the production of an intense Al{sup +} ion beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weichsel, T., E-mail: tim.weichsel@fep.fraunhofer.de; Hartung, U.; Kopte, T.

2015-09-15

A metal ion source prototype has been developed: a combination of magnetron sputter technology with 2.45 GHz electron cyclotron resonance (ECR) ion source technology—a so called magnetron ECR ion source (MECRIS). An integrated ring-shaped sputter magnetron with an Al target is acting as a powerful metal atom supply in order to produce an intense current of singly charged metal ions. Preliminary experiments show that an Al{sup +} ion current with a density of 167 μA/cm{sup 2} is extracted from the source at an acceleration voltage of 27 kV. Spatially resolved double Langmuir probe measurements and optical emission spectroscopy were usedmore » to study the plasma states of the ion source: sputter magnetron, ECR, and MECRIS plasma. Electron density and temperature as well as Al atom density were determined as a function of microwave and sputter magnetron power. The effect of ECR heating is strongly pronounced in the center of the source. There the electron density is increased by one order of magnitude from 6 × 10{sup 9} cm{sup −3} to 6 × 10{sup 10} cm{sup −3} and the electron temperature is enhanced from about 5 eV to 12 eV, when the ECR plasma is ignited to the magnetron plasma. Operating the magnetron at constant power, it was observed that its discharge current is raised from 1.8 A to 4.8 A, when the ECR discharge was superimposed with a microwave power of 2 kW. At the same time, the discharge voltage decreased from about 560 V to 210 V, clearly indicating a higher plasma density of the MECRIS mode. The optical emission spectrum of the MECRIS plasma is dominated by lines of excited Al atoms and shows a significant contribution of lines arising from singly ionized Al. Plasma emission photography with a CCD camera was used to prove probe measurements and to identify separated plasma emission zones originating from the ECR and magnetron discharge.« less

Discharge current modes of high power impulse magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Zhongzhen, E-mail: wuzz@pkusz.edu.cn; Xiao, Shu; Ma, Zhengyong

2015-09-15

Based on the production and disappearance of ions and electrons in the high power impulse magnetron sputtering plasma near the target, the expression of the discharge current is derived. Depending on the slope, six possible modes are deduced for the discharge current and the feasibility of each mode is discussed. The discharge parameters and target properties are simplified into the discharge voltage, sputtering yield, and ionization energy which mainly affect the discharge plasma. The relationship between these factors and the discharge current modes is also investigated.

On Both Spatial And Velocity Distribution Of Sputtered Particles In Magnetron Discharge

NASA Astrophysics Data System (ADS)

Vitelaru, C.; Pohoata, V.; Tiron, V.; Costin, C.; Popa, G.

2012-12-01

The kinetics of the sputtered atoms from the metallic target as well as the time-space distribution of the argon metastable atoms have been investigated for DC and high power pulse magnetron discharge by means of Tunable Diode - Laser Absorption Spectroscopy (TD-LAS) and Tunable Diode - Laser Induced Fluorescence (TD-LIF). The discharge was operated in argon (5-30 mTorr) with two different targets, tungsten and aluminum, for pulses of 1 to 20 μs, at frequencies of 0.2 to 1 kHz. Peak current intensity of ~100 A has been attained at cathode peak voltage of ~1 kV. The mean velocity distribution functions and particle fluxes of the sputtered metal atoms, in parallel and perpendicular direction to the target, have been obtained and compared for DC and pulse mode.

The target material influence on the current pulse during high power pulsed magnetron sputtering

NASA Astrophysics Data System (ADS)

Moens, Filip; Konstantinidis, Stéphanos; Depla, Diederik

2017-10-01

The current-time characteristic during high power pulsed magnetron sputtering is measured under identical conditions for seventeen different target materials. Based on physical processes such as gas rarefaction, ion-induced electron emission, and electron impact ionization, two test parameters were derived that significantly correlate with specific features of the current-time characteristic: i) the peak current is correlated to the momentum transfer between the sputtered material and the argon gas, ii) while the observed current plateau after the peak is connected to the metal ionization rate.

Highly conductive ultrathin Co films by high-power impulse magnetron sputtering

NASA Astrophysics Data System (ADS)

Jablonka, L.; Riekehr, L.; Zhang, Z.; Zhang, S.-L.; Kubart, T.

2018-01-01

Ultrathin Co films deposited on SiO2 with conductivities exceeding that of Cu are demonstrated. Ionized deposition implemented by high-power impulse magnetron sputtering (HiPIMS) is shown to result in smooth films with large grains and low resistivities, namely, 14 µΩ cm at a thickness of 40 nm, which is close to the bulk value of Co. Even at a thickness of only 6 nm, a resistivity of 35 µΩ cm is obtained. The improved film quality is attributed to a higher nucleation density in the Co-ion dominated plasma in HiPIMS. In particular, the pulsed nature of the Co flux as well as shallow ion implantation of Co into SiO2 can increase the nucleation density. Adatom diffusion is further enhanced in the ionized process, resulting in a dense microstructure. These results are in contrast to Co deposited by conventional direct current magnetron sputtering where the conductivity is reduced due to smaller grains, voids, rougher interfaces, and Ar incorporation. The resistivity of the HiPIMS films is shown to be in accordance with models by Mayadas-Shatzkes and Sondheimer which consider grain-boundary and surface-scattering.

The n-type conduction of indium-doped Cu{sub 2}O thin films fabricated by direct current magnetron co-sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Xing-Min; Su, Xiao-Qiang; Ye, Fan, E-mail: yefan@szu.edu.cn

2015-08-24

Indium-doped Cu{sub 2}O thin films were fabricated on K9 glass substrates by direct current magnetron co-sputtering in an atmosphere of Ar and O{sub 2}. Metallic copper and indium disks were used as the targets. X-ray diffraction showed that the diffraction peaks could only be indexed to simple cubic Cu{sub 2}O, with no other phases detected. Indium atoms exist as In{sup 3+} in Cu{sub 2}O. Ultraviolet-visible spectroscopy showed that the transmittance of the samples was relatively high and that indium doping increased the optical band gaps. The Hall effect measurement showed that the samples were n-type semiconductors at room temperature. Themore » Seebeck effect test showed that the films were n-type semiconductors near or over room temperature (<400 K), changing to p-type at relatively high temperatures. The conduction by the samples in the temperature range of the n-type was due to thermal band conduction and the donor energy level was estimated to be 620.2–713.8 meV below the conduction band. The theoretical calculation showed that indium doping can raise the Fermi energy level of Cu{sub 2}O and, therefore, lead to n-type conduction.« less

RF priming of a long pulse relativistic magnetron

NASA Astrophysics Data System (ADS)

White, William Michael

Rapid startup, increased pulsewidth and mode locking of magnetrons have been demonstrated experimentally on a relativistic magnetron by radio frequency (RF) priming. Experiments utilize a -300 kV, 2-8 kA, 300-500 ns electron beam to drive a Titan 6-vane relativistic magnetron (˜100 MW output power). The RF priming source is a 100 kW pulsed magnetron operating at 1.27-1.32 GHz. Tuning stubs were utilized in the Titan structure to adjust the operating frequency of the relativistic magnetron pi-mode upward by 30%. The tuning was guided by simulation in the MAGIC 3D code and experimental cold tests including a mapping of the azimuthal electric field inside the relativistic magnetron structure. The most successful tuning geometry was that of a standard anode resonant structure, but RF priming experiments were performed on a rising-sun structure as well. The Time Frequency Analysis (TFA) program was used to directly observe the effects of RF priming on the relativistic magnetron. RF priming was successful in decreasing mode competition by suppressing the generation of the 2pi/3-mode power by 41%. RF priming experiments were also successful in increasing microwave pulsewidth by 12% and decreasing microwave output delay by 22%. These improvements were observed while operating in a priming regime not satisfying Adler's Relation. Overall, the improvements made to the performance of the relativistic magnetron were modest because of the low priming power available (50-250 kW).

Magnetron sputtering for the production of EUV mask blanks

NASA Astrophysics Data System (ADS)

Kearney, Patrick; Ngai, Tat; Karumuri, Anil; Yum, Jung; Lee, Hojune; Gilmer, David; Vo, Tuan; Goodwin, Frank

2015-03-01

Ion Beam Deposition (IBD) has been the primary technique used to deposit EUV mask blanks since 1995 when it was discovered it could produce multilayers with few defects. Since that time the IBD technique has been extensively studied and improved and is finally approaching usable defectivities. But in the intervening years, the defectivity of magnetron sputtering has been greatly improved. This paper evaluates the suitability of a modern magnetron tool to produce EUV mask blanks and the ability to support HVM production. In particular we show that the reflectivity and uniformity of these tools are superior to current generation IBD tools, and that the magnetron tools can produce EUV films with defect densities comparable to recent best IBD tool performance. Magnetron tools also offer many advantages in manufacturability and tool throughput; however, challenges remain, including transitioning the magnetron tools from the wafer to mask formats. While work continues on quantifying the capability of magnetron sputtering to meet the mask blank demands of the industry, for the most part the remaining challenges do not require any fundamental improvements to existing technology. Based on the recent results and the data presented in this paper there is a clear indication that magnetron deposition should be considered for the future of EUV mask blank production.

Plasma emission spectroscopy and its relation to the refractive index of silicon nitride thin films deposited by reactive magnetron sputtering

NASA Astrophysics Data System (ADS)

Sanginés, R.; Abundiz-Cisneros, N.; Hernández Utrera, O.; Diliegros-Godines, C.; Machorro-Mejía, R.

2018-03-01

In this work, we present a thorough study on the relation between the plasma emission and the change of the silicon nitride thin films refractive index. Thin films were grown by reactive magnetron direct current sputtering technique and deposited onto silicon wafers at different fluxes of Ar and N2 and at different working pressures. This procedure, at certain deposition parameters, produced poor quality films, i.e. films with refractive index other than pure Si3N4 films. The emission of the plasma was interrogated in real time by means of optical emission spectroscopy (OES) observing at the vicinity of the trget location. In addition, optical properties of the films were measured by in situ ellipsometric-spectroscopy and then correlated with OES observations. Changes in the film refractive index could be deduced from changes in plasma emission applying a principal component analysis.

Structural-dependent thermal conductivity of aluminium nitride produced by reactive direct current magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belkerk, B. E.; Soussou, A.; Carette, M.

This Letter reports the thermal conductivity of aluminium nitride (AlN) thin-films deposited by reactive DC magnetron sputtering on single-crystal silicon substrates (100) with varying plasma and magnetic conditions achieving different crystalline qualities. The thermal conductivity of the films was measured at room temperature with the transient hot-strip technique for film thicknesses ranging from 100 nm to 4000 nm. The thermal conductivity was found to increase with the thickness depending on the synthesis conditions and film microstructure. The conductivity in the bulk region of the films, so-called intrinsic conductivity, and the boundary resistance were in the range [120-210] W m{sup -1}more » K{sup -1} and [2-30 Multiplication-Sign 10{sup -9}] K m{sup 2} W{sup -1}, respectively, in good agreement with microstructures analysed by x-ray diffraction, high-resolution-scanning-electron-microscopy, and transmission-electron-microscopy.« less

Characterization of polycrystalline nickel cobaltite nanostructures prepared by DC plasma magnetron co-sputtering for gas sensing applications

NASA Astrophysics Data System (ADS)

Hammadi, Oday A.; Naji, Noor E.

2018-03-01

In this work, a gas sensor is fabricated from polycrystalline nickel cobaltite nano films deposited on transparent substrates by closed-field unbalanced dual-magnetrons (CFUBDM) co-sputtering technique. Two targets of nickel and cobalt are mounted on the cathode of discharge system and co-sputtered by direct current (DC) argon discharge plasma in presence of oxygen as a reactive gas. The total gas pressure is 0.5 mbar and the mixing ratio of Ar:O2 gases is 5:1. The characterization measurements performed on the prepared films show that their transmittance increases with the incident wavelength, the polycrystalline structure includes 5 crystallographic planes, the average particle size is about 35 nm, the electrical conductivity is linearly increasing with increasing temperature, and the activation energy is about 0.41 eV. These films show high sensitivity to ethanol vapor.

Development of High Power Vacuum Tubes for Accelerators and Plasma Heating

NASA Astrophysics Data System (ADS)

Srivastava, Vishnu

2012-11-01

High pulsed power magnetrons and klystrons for medical and industrial accelerators, and high CW power klystrons and gyrotrons for plasma heating in tokamak, are being developed at CEERI. S-band 2.0MW pulsed tunable magnetrons of centre frequency 2856MHz and 2998 MHz were developed, and S-band 2.6MW pulsed tunable magnetron is being developed for medical LINAC, and 3MW pulsed tunable magnetron is being developed for industrial accelerator. S-band (2856MHz), 5MW pulsed klystron was developed for particle accelerator, and S-band 6MW pulsed klystron is under development for 10MeV industrial accelerator. 350MHz, 100kW (CW) klystron is being developed for proton accelerator, and C-band 250kW (CW) klystron is being developed for plasma heating. 42GHz, 200kW (CW/Long pulse) gyrotron is under development for plasma heating. Plasma filled tubes are also being developed for switching. 25kV/1kA and 40kV/3kA thyratrons were developed for high voltage high current switching in pulse modulators for magnetrons and klystrons. 25kV/3kA Pseudospark switch of current rise time of 1kA/|a-sec and pulse repetition rate of 500Hz is being developed. Plasma assisted high power microwave device is also being investigated.

Tribological and structural properties of titanium nitride and titanium aluminum nitride coatings deposited with modulated pulsed power magnetron sputtering

NASA Astrophysics Data System (ADS)

Ward, Logan

The demand for economical high-performance materials has brought attention to the development of advanced coatings. Recent advances in high power magnetron sputtering (HPPMS) have shown to improve tribological properties of coatings. These coatings offer increased wear and oxidation resistance, which may facilitate the use of more economical materials in harsh applications. This study demonstrates the use of novel forms of HPPMS, namely modulated pulsed-power magnetron sputtering (MPPMS) and deep oscillation magnetron sputtering (DOMS), for depositing TiN and Ti1-xAlxN tribological coatings on commonly used alloys, such as Ti-6Al-4V and Inconel 718. Both technologies have been shown to offer unique plasma characteristics in the physical vapor deposition (PVD) process. High power pulses lead to a high degree of ionization compared to traditional direct-current magnetron sputtering (DCMS) and pulsed magnetron sputtering (PMS). Such a high degree of ionization was previously only achievable by cathodic arc deposition (CAD); however, CAD can lead to increased macroparticles that are unfavorable in high friction and corrosive environments. MPPMS, DOMS, and other HPPMS techniques offer unique plasma characteristics and have been shown to produce coatings with refined grain structure, improved density, hardness, adhesion, and wear resistance. Using DOMS and MPPMS, TiN and Ti1-xAlxN coatings were deposited using PMS to compare microstructures and tribological performance. For Ti1-xAlxN, two sputtering target compositions, Ti 0.5Al0.5 and Ti0.3Al0.7, were used to evaluate the effects of MPPMS on the coating's composition and tribological properties. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize microstructure and crystallographic texture. Several tribological properties were evaluated including: wear rate, coefficient of friction, adhesion, and nanohardness. Results show that substrate material can have a significant effect on adhesion and the mechanical response between the coating and substrate. Depending on deposition parameters and the selected material MPPMS and DOMS are promising alternatives to DCMS, PMS, and CAD.

Effect of residual gas on structural, electrical and mechanical properties of niobium films deposited by magnetron sputtering deposition

NASA Astrophysics Data System (ADS)

Wang, Lanruo; Zhong, Yuan; Li, Jinjin; Cao, Wenhui; Zhong, Qing; Wang, Xueshen; Li, Xu

2018-04-01

Magnetron sputtering is an important method in the superconducting thin films deposition. The residual gas inside the vacuum chamber will directly affect the quality of the superconducting films. In this paper, niobium films are deposited by magnetron sputtering under different chamber residual gas conditions. The influence of baking and sputtering process on residual gas are studied as well. Surface morphology, electrical and mechanical properties of the films are analysed. The residual gas analysis result before the sputtering process could be regarded as a reference condition to achieve high quality superconducting thin films.

Deposition and characterization of TiAlSiN nanocomposite coatings prepared by reactive pulsed direct current unbalanced magnetron sputtering

NASA Astrophysics Data System (ADS)

Barshilia, Harish C.; Ghosh, Moumita; Shashidhara; Ramakrishna, Raja; Rajam, K. S.

2010-08-01

This work reports the performance of high speed steel drill bits coated with TiAlSiN nanocomposite coating at different Si contents (5.5-8.1 at.%) prepared using a four-cathode reactive pulsed direct current unbalanced magnetron sputtering system. The surface morphology of the as-deposited coatings was characterized using field emission scanning electron microscopy. The crystallographic structure, chemical composition and bonding structure were evaluated using X-ray diffraction, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, respectively. The corrosion behavior, mechanical properties and thermal stability of TiAlSiN nanocomposite coatings were also studied using potentiodynamic polarization, nanoindentation and Raman spectroscopy, respectively. The TiAlSiN coating thickness was approximately 2.5-2.9 μm. These coatings exhibited a maximum hardness of 38 GPa at a silicon content of approximately 6.9 at.% and were stable in air up to 850 °C. For the performance evaluation, the TiAlSiN coated drills were tested under accelerated machining conditions by drilling a 12 mm thick 304 stainless steel plate. Under dry conditions the uncoated drill bits failed after drilling 50 holes, whereas, TiAlSiN coated drill bits (Si = 5.5 at.%) drilled 714 holes before failure. Results indicated that for TiAlSiN coated drill bits the tool life increased by a factor of more than 14.

Fabrication and characterization of He-charged ODS-FeCrNi films deposited by a radio-frequency plasma magnetron sputtering technique

NASA Astrophysics Data System (ADS)

Song, Liang; Wang, Xianping; Wang, Le; Zhang, Ying; Liu, Wang; Jiang, Weibing; Zhang, Tao; Fang, Qianfeng; Liu, Changsong

2017-04-01

He-charged oxide dispersion strengthened (ODS) FeCrNi films were prepared by a radio-frequency (RF) plasma magnetron sputtering method in a He and Ar mixed atmosphere at 150 °C. As a comparison, He-charged FeCrNi films were also fabricated at the same conditions through direct current (DC) plasma magnetron sputtering. The doping of He atoms and Y2O3 in the FeCrNi films was realized by the high backscattered rate of He ions and Y2O3/FeCrNi composite target sputtering method, respectively. Inductive coupled plasma (ICP) and x-ray photoelectron spectroscopy (XPS) analysis confirmed the existence of Y2O3 in FeCrNi films, and Y2O3 content hardly changed with sputtering He/Ar ratio. Cross-sectional scanning electron microscopy (SEM) shows that the FeCrNi films were composed of dense columnar nanocrystallines and the thickness of the films was obviously dependent on He/Ar ratio. Nanoindentation measurements revealed that the FeCrNi films fabricated through DC/RF plasma magnetron sputtering methods exhibited similar hardness values at each He/Ar ratio, while the dispersion of Y2O3 apparently increased the hardness of the films. Elastic recoil detection (ERD) showed that DC/RF magnetron sputtered FeCrNi films contained similar He amounts (˜17 at.%). Compared with the minimal change of He level with depth in DC-sputtered films, the He amount decreases gradually in depth in the RF-sputtered films. The Y2O3-doped FeCrNi films were shown to exhibit much smaller amounts of He owing to the lower backscattering possibility of Y2O3 and the inhibition effect of nano-sized Y2O3 particles on the He element.

Neutral gas rotation in magnetron discharge

NASA Astrophysics Data System (ADS)

Pal, A. F.; Ryabinkin, A. N.; Serov, A. O.; Filippov, A. V.

2014-12-01

We have experimentally established the existence and determined the velocity of motion of the neutral component of plasma in a planar magnetron discharge, which takes place in the direction of drift of the charged plasma component in crossed electric and magnetic ( E × B) fields. For this purpose, we have studied the propagation of a small gaseous additive over the plasma ring of dc magnetron discharge in the diffusion regime. The obtained temporal dependences of the intensity of atomic emission spectra of the additive in various regions of the plasma ring are compared to the results of numerical solution of the diffusion equation for the experimental conditions studied.

Performance characterization of a solenoid-type gas valve for the H- magnetron source at FNAL

NASA Astrophysics Data System (ADS)

Sosa, A.; Bollinger, D. S.; Karns, P. R.

2017-08-01

The magnetron-style H- ion sources currently in operation at Fermilab use piezoelectric gas valves to function. This kind of gas valve is sensitive to small changes in ambient temperature, which affect the stability and performance of the ion source. This motivates the need to find an alternative way of feeding H2 gas into the source. A solenoid-type gas valve has been characterized in a dedicated off-line test stand to assess the feasibility of its use in the operational ion sources. H- ion beams have been extracted at 35 keV using this valve. In this study, the performance of the solenoid gas valve has been characterized measuring the beam current output of the magnetron source with respect to the voltage and pulse width of the signal applied to the gas valve.

Investigation of high power impulse magnetron sputtering (HIPIMS) discharge using fast ICCD camera

NASA Astrophysics Data System (ADS)

Hecimovic, Ante

2012-10-01

High power impulse magnetron sputtering (HIPIMS) combines impulse glow discharges at power levels up to the MW range with conventional magnetron cathodes to achieve a highly ionised sputtered flux. The dynamics of the HIPIMS discharge was investigated using fast Intensified Charge Coupled Device (ICCD) camera. In the first experiment the HIPIMS plasma was recorded from the side with goal to analyse the plasma intensity using Abel inversion to obtain the emissivity maps of the plasma species. Resulting emissivity maps provide the information on the spatial distribution of Ar and sputtered material and evolution of the plasma chemistry above the cathode. In the second experiment the plasma emission was recorded with camera facing the target. The images show that the HIPIMS plasma develops drift wave type instabilities characterized by well defined regions of high and low plasma emissivity along the racetrack of the magnetron. The instabilities cause periodic shifts in the floating potential. The structures rotate in ExB direction at velocities of 10 kms-1 and frequencies up to 200 kHz. The high emissivity regions comprise Ar and metal ion emission with strong Ar and metal neutral emission depletion. A detailed analysis of the temporal evolution of the saturated instabilities using four consequently triggered fast ICCD cameras is presented. Furthermore working gas pressure and discharge current variation showed that the shape and the speed of the instability strongly depend on the working gas and target material combination. In order to better understand the mechanism of the instability, different optical interference band pass filters (of metal and gas atom, and ion lines) were used to observe the spatial distribution of each species within the instability.

Recirculating planar magnetrons: simulations and experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Franzi, Matthew; Gilgenbach, Ronald; French, David

2011-07-01

The Recirculating Planar Magnetron (RPM) is a novel crossed-field device whose geometry is expected to reduce thermal load, enhance current yield as well as ease the geometric limitations in scaling to high RF frequencies as compared to the conventional cylindrical magnetrons. The RPM has two different adaptations: A. Axial B field and radial E field; B. Radial B field and axial E field. The preliminary configuration (A) to be used in experiments at the University of Michigan consists of two parallel planar sections which join on either end by cylindrical regions to form a concentric extruded ellipse. Similar to conventionalmore » magnetrons, a voltage across the AK gap in conjunction with an axial magnetic field provides the electrons with an ExB drift. The device is named RPM because the drifting electrons recirculate from one planar region to the other. The drifting electrons interact with the resonantly tuned slow wave structure on the anode causing spoke formation. These electron spokes drive a RF electric field in the cavities from which RF power may be extracted to Waveguides. The RPM may be designed in either a conventional configuration with the anode on the outside, for simplified extraction, or as an inverted magnetron with the anode at the inner conductor, for fast start-up. Currently, experiments at the Pulsed Power and Microwave Laboratory at the University of Michigan are in the setup and design phase. A conventional RPM with planar cavities is to be installed on the Michigan Electron Long Beam Accelerator (MELBA) and is anticipated to operate at -200kV, 0.2T with a beam current of 1-10 kA at 1GHz. The conventional RPM consists of 12 identical planar cavities, 6 on each planar side, with simulated quality factor of 20.« less

Formation of pyrite (FeS{sub 2}) thin films by thermal sulfurization of dc magnetron sputtered iron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soukup, R. J.; Prabukanthan, P.; Ianno, N. J.

2011-01-15

Iron films deposited by direct current magnetron sputtering onto glass substrates were converted into FeS{sub 2} films by thermal sulfurization. Experiments were carried out to optimize the sulfurization process, and the formation of FeS{sub 2} thin films was investigated under different annealing temperatures and times. High quality FeS{sub 2} films were fabricated using this process, and single phase pyrite films were obtained after sulfurization in a sulfur and nitrogen atmosphere at 450 deg. C for 1 h. Film crystallinity and phase identification were determined by using x-ray diffraction. The cubic phase pyrite films prepared were p-type, and scanning electron microscopymore » studies exhibited a homogeneous surface of pyrite. The authors have found that the best Ohmic contact for their pyrite thin films, using inexpensive metals, was Ni. The following were chosen for the study: Al, Mo, Fe, and Ni, and the one that led to the lowest resistance, 333 {Omega}, was Ni.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 atmore » 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.« less

Performance Characterization of a Solenoid-type Gas Valve for the H- Magnetron Source at FNAL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sosa, A.; Bollinger, D. S.; Karns, P. R.

2016-09-06

The magnetron-style H- ion sources currently in operation at Fermilab use piezoelectric gas valves to function. This kind of gas valve is sensitive to small changes in ambient temperature, which affect the stability and performance of the ion source. This motivates the need to find an alternative way of feeding H2 gas into the source. A solenoid-type gas valve has been characterized in a dedicated off-line test stand to assess the feasibility of its use in the operational ion sources. H- ion beams have been extracted at 35 keV using this valve. In this study, the performance of the solenoidmore » gas valve has been characterized measuring the beam current output of the magnetron source with respect to the voltage and pulse width of the signal applied to the gas valve.« less

Magnetron cathodes in plasma electrode Pockels cells

DOEpatents

Rhodes, M.A.

1995-04-25

Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal. 5 figs.

Magnetron cathodes in plasma electrode pockels cells

DOEpatents

Rhodes, Mark A.

1995-01-01

Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating. pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal.

Combined experimental and theoretical description of direct current magnetron sputtering of Al by Ar and Ar/N2 plasma

NASA Astrophysics Data System (ADS)

Trieschmann, Jan; Ries, Stefan; Bibinov, Nikita; Awakowicz, Peter; Mráz, Stanislav; Schneider, Jochen M.; Mussenbrock, Thomas

2018-05-01

Direct current magnetron sputtering of Al by Ar and Ar/N2 low pressure plasmas was characterized by experimental and theoretical means in a unified consideration. Experimentally, the plasmas were analyzed by optical emission spectroscopy, while the film deposition rate was determined by weight measurements and laser optical microscopy, and the film composition by energy dispersive x-ray spectroscopy. Theoretically, a global particle and power balance model was used to estimate the electron temperature T e and the electron density n e of the plasma at constant discharge power. In addition, the sputtering process and the transport of the sputtered atoms were described using Monte Carlo models—TRIDYN and dsmcFoam, respectively. Initially, the non-reactive situation is characterized based on deposition experiment results, which are in agreement with predictions from simulations. Subsequently, a similar study is presented for the reactive case. The influence of the N2 addition is found to be twofold, in terms of (i) the target and substrate surface conditions (e.g., sputtering, secondary electron emission, particle sticking) and (ii) the volumetric changes of the plasma density n e governing the ion flux to the surfaces (e.g., due to additional energy conversion channels). It is shown that a combined experimental/simulation approach reveals a physically coherent and, in particular, quantitative understanding of the properties (e.g., electron density and temperature, target surface nitrogen content, sputtered Al density, deposited mass) involved in the deposition process.

Photoreduction of CO{sub 2} by TiO{sub 2} nanocomposites synthesized through reactive direct current magnetron sputter deposition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, L.; Graham, M. E.; Li, G.

The photoreduction of CO{sub 2} into methane provides a carbon-neutral energy alternative to fossil fuels, but its feasibility requires improvements in the photo-efficiency of materials tailored to this reaction. We hypothesize that mixed phase TiO{sub 2} nano-materials with high interfacial densities are extremely active photocatalysts well suited to solar fuel production by reducing CO{sub 2} to methane and shifting to visible light response. Mixed phase TiO{sub 2} films were synthesized by direct current (DC) magnetron sputtering and characterized by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Bundles of anatase-rutile nano-columns havingmore » high densities of two kinds of interfaces (those among the bundles and those between the columns) are fabricated. Films sputtered at a low deposition angle showed the highest methane yield, compared to TiO{sub 2} fabricated under other sputtering conditions and commercial standard Degussa P25 under UV irradiation. The yield of methane could be significantly increased ({approx} 12% CO{sub 2} conversion) by increasing the CO{sub 2} to water ratio and temperature (< 100 C) as a combined effect. These films also displayed a light response strongly shifted into the visible range. This is explained by the creation of non-stoichiometric titania films having unique features that we can potentially tailor to the solar energy applications.« less

Bias current dependence of resistivity in Co0.4Fe0.4B0.2 ultrathin film prepared by RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Mandal, Snehal; Mazumdar, Dipak; Das, I.

2018-04-01

Ultrathin film of Co0.4Fe0.4B0.2 was prepared on p-type Si (100) substrate by RF magnetron sputtering. X-Ray Reflectivity and Atomic Force Microscopy measurements were performed to estimate the thickness and surface roughness of the film. Electrical transport measurements were performed by four-probe method in a current-in-plane (CIP) geometry. Presence of non-linearity in the current-voltage (I-V) characteristics was observed at higher current range. The electrical resistivity was found to change by several orders of magnitude (105) by changing the bias current from nano-ampere (nA) to milli-ampere (mA) range. This bias current dependence of the resistivity has been explained by different transport mechanisms.

Precision vector control of a superconducting RF cavity driven by an injection locked magnetron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chase, Brian; Pasquinelli, Ralph; Cullerton, Ed

The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons [1]. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs - compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRFmore » cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.« less

Precision vector control of a superconducting RF cavity driven by an injection locked magnetron

DOE PAGES

Chase, Brian; Pasquinelli, Ralph; Cullerton, Ed; ...

2015-03-01

The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons [1]. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs - compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRFmore » cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.« less

Waveguide-Mode Terahertz Free Electron Lasers Driven by Magnetron-Based Microtrons

NASA Astrophysics Data System (ADS)

Jeong, Young Uk; Miginsky, Sergey; Gudkov, Boris; Lee, Kitae; Mun, Jungho; Shim, Gyu Il; Bae, Sangyoon; Kim, Hyun Woo; Jang, Kyu-Ha; Park, Sunjeong; Park, Seong Hee; Vinokurov, Nikolay

2016-04-01

We have developed small-sized terahertz free-electron lasers by using low-cost and compact microtrons combining with magnetrons as high-power RF sources. We could stabilize the bunch repetition rate by optimizing a modulator for the magnetron and by coupling the magnetron with an accelerating cavity in the microtron. By developing high-performance undulators and low-loss waveguide-mode resonators having small cross-sectional areas, we could strengthen the interaction between the electron beam and the THz wave inside the FEL resonators to achieve lasing even with low-current electron beams from the microtron. We used a parallel-plate waveguide in a planar electromagnet undulator for our first THz FEL. We try to reduce the size of the FEL resonator by combining a dielectric-coated circular waveguide and a variable-period helical undulator to realize a table-top THz FEL for applying it to the security inspection on airports.

Improved Magnetron Stability and Reduced Noise in Efficient Transmitters for Superconducting Accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazakevich, G.; Johnson, R.; Lebedev, V.

State of the art high-current superconducting accelerators require efficient RF sources with a fast dynamic phase and power control. This allows for compensation of the phase and amplitude deviations of the accelerating voltage in the Superconducting RF (SRF) cavities caused by microphonics, etc. Efficient magnetron transmitters with fast phase and power control are attractive RF sources for this application. They are more cost effective than traditional RF sources such as klystrons, IOTs and solid-state amplifiers used with large scale accelerator projects. However, unlike traditional RF sources, controlled magnetrons operate as forced oscillators. Study of the impact of the controlling signalmore » on magnetron stability, noise and efficiency is therefore important. This paper discusses experiments with 2.45 GHz, 1 kW tubes and verifies our analytical model which is based on the charge drift approximation.« less

High-efficiency solar cells fabricated from direct-current magnetron sputtered n-indium tin oxide onto p-InP grown by atmospheric pressure metalorganic vapor phase epitaxy

NASA Technical Reports Server (NTRS)

Li, X.; Wanlass, M. W.; Gessert, T. A.; Emery, K. A.; Coutts, T. J.

1989-01-01

An attempt is made to improve device efficiencies by depositing indium tin oxide onto epitaxially grown p-InP on p(+)-InP substrates. This leads to a reduction in the device series resistance, high-quality reproducible surfaces, and an improvement in the transport properties of the base layer. Moreover, many of the facets associated with badly characterized bulk liquid encapsulated Czochralski substrates used in previous investigations are removed in this way.

Dusty waves and vortices in rf magnetron discharge plasma

NASA Astrophysics Data System (ADS)

Filippov, A. V.; Pal, A. F.; Ryabinkin, A. N.; Serov, A. O.; Shugaev, F. V.

2018-01-01

The appearance and subsequent growth of metallic particles in plasma of planar rf magnetron sputter were observed. The origin of the particles is sputtering of the rf electrode by ion flux from the plasma. In some regions of formed dust cloud the particles were involved in the horizontal or vertical circular movement. The horizontal rotation along the sputtered track in the cyclotron drift direction was observed close to the main magnetron plasma. The torus-shaped dust vortex ring engirdled the secondary plasma of the discharge at height of a few centimeters over the electrode. Close to this region particle density waves propagated through the cloud. The possible role of discharge plasma azimuthal inhomogeneity and gas dynamics effects in the forming the observed structures was considered.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Majzoobi, A.; Joshi, R. P., E-mail: ravi.joshi@ttu.edu; Neuber, A. A.

Particle-in-cell simulations are performed to analyze the efficiency, output power and leakage currents in a 12-Cavity, 12-Cathode rising-sun magnetron with diffraction output (MDO). The central goal is to conduct a parameter study of a rising-sun magnetron that comprehensively incorporates performance enhancing features such as transparent cathodes, axial extraction, the use of endcaps, and cathode extensions. Our optimum results demonstrate peak output power of about 2.1 GW, with efficiencies of ∼70% and low leakage currents at a magnetic field of 0.45 Tesla, a 400 kV bias with a single endcap, for a range of cathode extensions between 3 and 6 centimeters.

Biocompatibility and Surface Properties of TiO2 Thin Films Deposited by DC Magnetron Sputtering

PubMed Central

López-Huerta, Francisco; Cervantes, Blanca; González, Octavio; Hernández-Torres, Julián; García-González, Leandro; Vega, Rosario; Herrera-May, Agustín L.; Soto, Enrique

2014-01-01

We present the study of the biocompatibility and surface properties of titanium dioxide (TiO2) thin films deposited by direct current magnetron sputtering. These films are deposited on a quartz substrate at room temperature and annealed with different temperatures (100, 300, 500, 800 and 1100 °C). The biocompatibility of the TiO2 thin films is analyzed using primary cultures of dorsal root ganglion (DRG) of Wistar rats, whose neurons are incubated on the TiO2 thin films and on a control substrate during 18 to 24 h. These neurons are activated by electrical stimuli and its ionic currents and action potential activity recorded. Through X-ray diffraction (XRD), the surface of TiO2 thin films showed a good quality, homogeneity and roughness. The XRD results showed the anatase to rutile phase transition in TiO2 thin films at temperatures between 500 and 1100 °C. This phase had a grain size from 15 to 38 nm, which allowed a suitable structural and crystal phase stability of the TiO2 thin films for low and high temperature. The biocompatibility experiments of these films indicated that they were appropriated for culture of living neurons which displayed normal electrical behavior. PMID:28788667

Properties of Diamond-Like Carbon Films Synthesized by Dual-Target Unbalanced Magnetron Sputtering

NASA Astrophysics Data System (ADS)

Liu, Cui; Li, Guo-Qing; Gou, Wei; Mu, Zong-Xin; Zhang, Cheng-Wu

2004-11-01

Smooth, dense and uniform diamond-like carbon films (DLC films) for industrial applications have successfully been prepared by dual-target unbalanced magnetron sputtering and the DLC characteristics of the films are confirmed by Raman spectra. It is found that the sputtering current of target plays an important role in the DLC film deposition. Deposition rate of 3.5 μm/h is obtained by using the sputtering current of 30 A. The friction coefficient of the films is 0.2-0.225 measured by using a pin-on-disc microtribometer. The structure of the films tends to have a growth of sp3 bonds content at high sputtering current. The compressive residual stress in the films increases with the increasing sputtering current of the target.

Studies on Magnetron Sputtered ZnO-Ag Films: Adhesion Activity of S. aureus

NASA Astrophysics Data System (ADS)

Geetha, S. R.; Dhivya, P.; Raj, P. Deepak; Sridharan, M.; Princy, S. Adline

Zinc oxide (ZnO) thin films have been deposited onto thoroughly cleaned stainless steel (AISI SS 304) substrates by reactive direct current (dc) magnetron sputtering and the films were doped with silver (Ag). The prepared thin films were analyzed using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM) to investigate the structural and morphological properties. The thickness values of the films were in the range of 194 to 256nm. XRD results revealed that the films were crystalline with preferred (002) orientation. Grain size values of pure ZnO films were found to be 19.82-23.72nm. On introducing Ag into ZnO film, the micro-structural properties varied. Adhesion test was carried out with Staphylococcus aureus (S. aureus) in order to know the adherence property of the deposited films. Colony formation units (CFU) were counted manually and bacterial adhesion inhibition (BAI) was calculated. We observed a decrease in the CFU on doping Ag in the ZnO films. BAI of the film deposited at - 100 V substrate bias was found to be increased on Ag doping from 69 to 88%.

Comparative measurements of plasma potential with ball-pen and Langmuir probe in low-temperature magnetized plasma

NASA Astrophysics Data System (ADS)

Zanáška, M.; Adámek, J.; Peterka, M.; Kudrna, P.; Tichý, M.

2015-03-01

The ball-pen probe (BPP) is used for direct plasma potential measurements in magnetized plasma. The probe can adjust the ratio of the electron and ion saturation currents Isat-/Isat+ to be close to one and therefore its I-V characteristic becomes nearly symmetric. If this is achieved, the floating potential of the BPP is close to the plasma potential. Because of its rather simple construction, it offers an attractive probe for measurements in magnetized plasma. Comparative measurements of plasma potential by BPPs of different dimensions as well as one Langmuir probe (LP) in an argon discharge plasma of a cylindrical magnetron were performed at various experimental conditions. An additional comparison by an emissive probe was also performed. All these types of probes provide similar values of plasma potential in a wide range of plasma parameters. Our results for three different BPP dimensions indicate that the BPP can be operated in a cylindrical magnetron DC argon discharge if the value of the ratio of the magnetic field and neutral gas pressure, B/p, is greater than approximately 10 mT/Pa.

Electrical Conductivity and Barrier Properties of Lithium Niobate Thin Films

NASA Astrophysics Data System (ADS)

Gudkov, S. I.; Baklanova, K. D.; Kamenshchikov, M. V.; Solnyshkin, A. V.; Belov, A. N.

2018-04-01

The thin-film structures made of LiNbO3 and obtained via laser ablation and magnetron sputtering are studied with volt-farad and volt-ampere characteristics. A potential barrier on the Si-LiNbO3 interface was found for both types of the films with the capacitance-voltage characteristics. The current-voltage characteristics showed that there are several conduction mechanisms in the structures studied. The Poole-Frenkel effect and the currents limited by a space charge mainly contribute to the electrical conductivity in the LiNbO3 film produced with the laser ablation method. The currents limited by a space charge contribute to the main mechanism in the film heterostructure obtained with the magnetron sputtering method.

Stacking fault related luminescence in GaN nanorods.

PubMed

Forsberg, M; Serban, A; Poenaru, I; Hsiao, C-L; Junaid, M; Birch, J; Pozina, G

2015-09-04

Optical and structural properties are presented for GaN nanorods (NRs) grown in the [0001] direction on Si(111) substrates by direct-current reactive magnetron sputter epitaxy. Transmission electron microscopy (TEM) reveals clusters of dense stacking faults (SFs) regularly distributed along the c-axis. A strong emission line at ∼3.42 eV associated with the basal-plane SFs has been observed in luminescence spectra. The optical signature of SFs is stable up to room temperatures with the activation energy of ∼20 meV. Temperature-dependent time-resolved photoluminescence properties suggest that the recombination mechanism of the 3.42 eV emission can be understood in terms of multiple quantum wells self-organized along the growth axis of NRs.

Solid state RF power: The route to 1W per euro cent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heid, Oliver

2013-04-19

In most particle accelerators RF power is a decisive design constraint due to high costs and relative inflexibility of current electron beam based RF sources, i.e. Klystrons, Magnetrons, Tetrodes etc. At VHF/UHF frequencies the transition to solid state devices promises to fundamentally change the situation. Recent progress brings 1 Watt per Euro cent installed cost within reach. We present a Silicon Carbide semiconductor solution utilising the Solid State Direct Drive technology at unprecedented efficiency, power levels and power densities. The proposed solution allows retrofitting of existing RF accelerators and opens the route to novel particle accelerator concepts.

Langmuir Probe Measurements in a Grid-Assisted Magnetron Sputtering System

NASA Astrophysics Data System (ADS)

Sagás, Julio César; Pessoa, Rodrigo Sávio; Maciel, Homero Santiago

2018-02-01

The grid-assisted magnetron sputtering is a variation of the magnetron sputtering commonly used for thin film deposition. In this work, Langmuir probe measurements were performed in such a system by using the grid under two basic and practical electrical conditions, i.e., floating and grounded. The results show that grounding the grid leads to an enhancement of the plasma confinement and to increases in both floating and plasma potential, as inferred from the probe characteristics. The grounded grid drains electrons from the plasma, acting as an auxiliary anode and reducing the plasma diffusion toward the chamber walls. For the same discharge current, the improved confinement results in a lower electron temperature when compared to floating condition, although the electron densities are comparable in both cases.

Characterization of graded TiC layers deposited by HiPIMS method

NASA Astrophysics Data System (ADS)

Bohovicova, Jana; Bonova, Lucia; Halanda, Juraj; Ivan, Jozef; Mesko, Marcel; Advanced Technologies Research Institute Team; Institute of Electronic; Photonic Team

2016-09-01

An advanced yet recent development of sputter technique is high power impulse magnetron sputtering (HiPIMS), in which short, energetic pulses are applied to the target, leading to a formation of an ultra-dense plasma in front of the cathode, that provide a high degree of ionization of sputtered material, and consequently enable to control the energy and the direction of the deposition flux. This gives a possibility to alter composition and microstructure in a controlled manner, enables the optimization of TiC for tribological applications. The aim of this work is to link physical phenomena in transient HiPIMS discharges to microstructural and compositional properties of graded TiC thin films. It was found that Ti bottom layer is contamination free. Compared to the direct current magnetron sputtering films, we observed an element specific reduction of impurities measured by ERDA by a factor 3 for N, 4 for H and by a factor of 20 for O. The high purity of Ti layer is partly explained by gas rarefaction and the cleaning effect of the bombarding ions. Graphitization degree of carbon top layer was elucidated by Raman spectroscopy. The compositional effects are correlated with differences in the film microstructure revealed by SEM, XRD and TEM analysis. This work was supported by VEGA, Project No. 1/0503/15 and APVV, Project No. 15-0168.

Polarization of stacking fault related luminescence in GaN nanorods

NASA Astrophysics Data System (ADS)

Pozina, G.; Forsberg, M.; Serban, E. A.; Hsiao, C.-L.; Junaid, M.; Birch, J.; Kaliteevski, M. A.

2017-01-01

Linear polarization properties of light emission are presented for GaN nanorods (NRs) grown along [0001] direction on Si(111) substrates by direct-current magnetron sputter epitaxy. The near band gap photoluminescence (PL) measured at low temperature for a single NR demonstrated an excitonic line at ˜3.48 eV and the stacking faults (SFs) related transition at ˜3.43 eV. The SF related emission is linear polarized in direction perpendicular to the NR growth axis in contrast to a non-polarized excitonic PL. The results are explained in the frame of the model describing basal plane SFs as polymorphic heterostructure of type II, where anisotropy of chemical bonds at the interfaces between zinc blende and wurtzite GaN subjected to in-built electric field is responsible for linear polarization parallel to the interface planes.

Overview of recent studies and design changes for the FNAL magnetron ion source

NASA Astrophysics Data System (ADS)

Bollinger, D. S.; Sosa, A.

2017-08-01

This paper presents several studies and design changes that will eventually be implemented to the Fermi National Accelerator Laboratory (FNAL) magnetron ion source. The topics include tungsten cathode insert, solenoid gas valves, current controlled arc pulser, cesium boiler redesign, gas mixtures of hydrogen and nitrogen, and duty factor reduction. The studies were performed on the FNAL test stand described in [1], with the aim to improve source lifetime, stability, and reducing the amount of tuning needed.

High performance thin film transistor with ZnO channel layer deposited by DC magnetron sputtering.

PubMed

Moon, Yeon-Keon; Moon, Dae-Yong; Lee, Sang-Ho; Jeong, Chang-Oh; Park, Jong-Wan

2008-09-01

Research in large area electronics, especially for low-temperature plastic substrates, focuses commonly on limitations of the semiconductor in thin film transistors (TFTs), in particular its low mobility. ZnO is an emerging example of a semiconductor material for TFTs that can have high mobility, while a-Si and organic semiconductors have low mobility (<1 cm2/Vs). ZnO-based TFTs have achieved high mobility, along with low-voltage operation low off-state current, and low gate leakage current. In general, ZnO thin films for the channel layer of TFTs are deposited with RF magnetron sputtering methods. On the other hand, we studied ZnO thin films deposited with DC magnetron sputtering for the channel layer of TFTs. After analyzing the basic physical and chemical properties of ZnO thin films, we fabricated a TFT-unit cell using ZnO thin films for the channel layer. The field effect mobility (micro(sat)) of 1.8 cm2/Vs and threshold voltage (Vth) of -0.7 V were obtained.

Simulation and Experimental Studies of a 2.45GHz Magnetron Source for an SRF Cavity with Field Amplitude and Phase Controls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Haipeng; Plawski, Tomasz E.; Rimmer, Robert A.

2016-06-01

Phase lock to an SRF cavity by using injection signal through output waveguide of a magnetron has been demonstrated [1, 3]. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using MATLAB/Simulink simulations [2]. Based on these, we are planning to use an FPGA based digital LLRF system, which allows applying various types of control algorithms in order to achieve the required accelerating field stability. Since the 1497 MHz magnetron is still in the design stage, the proof of principle measurements of a commercial 2450 MHz magnetron are carried out to characterize the anode I-V curve,more » output power (the tube electronic efficiency), frequency dependence on the anode current (frequency pushing) and the Rieke diagram (frequency pulling by the reactive load). Based on early Simulink simulation, experimental data and extension of the Adler equation governing injection phase stability by Chen’s model, the specification of the new LLRF control chassis for both 2450 and 1497MHz systems are presented in this paper.« less

Effect of thickness on surface morphology, optical and humidity sensing properties of RF magnetron sputtered CCTO thin films

NASA Astrophysics Data System (ADS)

Ahmadipour, Mohsen; Ain, Mohd Fadzil; Ahmad, Zainal Arifin

2016-11-01

In this study, calcium copper titanate (CCTO) thin films were deposited on ITO substrates successfully by radio frequency (RF) magnetron sputtering method in argon atmosphere. The CCTO thin films present a polycrystalline, uniform and porous structure. The surface morphology, optical and humidity sensing properties of the synthesized CCTO thin films have been studied by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), UV-vis spectrophotometer and current-voltage (I-V) analysis. XRD and AFM confirmed that the intensity of peaks and pore size of CCTO thin films were enhanced by increasing the thin films. Tauc plot method was adopted to estimate the optical band gaps. The surface structure and energy band gaps of the deposited films were affected by film thickness. Energy band gap of the layers were 3.76 eV, 3.68 eV and 3.5 eV for 200 nm, 400 nm, and 600 nm CCTO thin films layer, respectively. The humidity sensing properties were measured by using direct current (DC) analysis method. The response times were 12 s, 22 s, and 35 s while the recovery times were 500 s, 600 s, and 650 s for 200 nm, 400 nm, and 600 nm CCTO thin films, respectively at humidity range of 30-90% relative humidity (RH).

Improvement of corrosion protection property of Mg-alloy by DLC and Si-DLC coatings with PBII technique and multi-target DC-RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Masami, Ikeyama; Setsuo, Nakao; Tsutomu, Sonoda; Junho, Choi

2009-05-01

Magnesium alloys have been considered as one of the most promising light weight materials with potential applications for automobile and aircraft components. Their poor corrosion resistance, however, has to date prevented wider usage. Diamond-like carbon (DLC) and silicon-incorporated DLC (Si-DLC) coatings are known to provide a high degree of corrosion protection, and hold accordingly promise for enhancing the corrosion resistance of the magnesium alloys. In this work we have studied the effect of coating conditions of DLC coatings as well as Si incorporation into coating on corrosion resistance, deposited onto AZ91 magnesium alloy substrates by plasma based ion implantation (PBII). The influences of a Ti interlayer beneath the DLC, Si-DLC and Ti incorporated DLC (Ti-DLC) coatings fabricated by multi-target direct-current radio-frequency (DC-RF) magnetron sputtering were also examined on both the adhesion strength and corrosion resistance of the materials. We have also examined the effect of the Si content in the Si-DLC coatings made by magnetron sputtering on the alloys' corrosion resistance. The results of potentiodynamic polarization measurements demonstrate that Si-DLC coating deposited by PBII exhibits the highest corrosion resistance in an aqueous 0.05 M NaCl solution. Although Ti layer is helpful in increasing adhesion between DLC coating and AZ91 substrate, it also influences adversely corrosion protection. The ozone treatment of the magnesium alloy's surface before the formation of coatings has been found to improve both adhesion strength and corrosion resistance.

Effects of substrate heating and vacuum annealing on optical and electrical properties of alumina-doped ZnO films deposited by DC magnetron sputtering

NASA Astrophysics Data System (ADS)

Tang, Chien-Jen; Wang, Chun-Yuan; Jaing, Cheng-Chung

2011-10-01

Alumina-doped zinc oxide (AZO) films have wide range of applications in optical and optoelectronic devices. AZO films have advantage in high transparency, high stability to hydrogen plasma and low cost to alternative ITO film. AZO film was prepared by direct-current (DC) magnetron sputtering from ceramic ZnO:Al2O3 target. The AZO films were compared in two different conditions. The first is substrate heating process, in which AZO film was deposited by different substrate temperature, room temperature, 150 °C and 250 °C. The second is vacuum annealing process, in which AZO film with deposited at room temperature have been annealed at 250 °C and 450 °C in vacuum. The optical properties, electrical properties, grain size and surface structure properties of the films were studied by UV-VIS-NIR spectrophotometer, Hall effect measurement equipment, x-ray diffraction, and scanning electron microscopy. The resistivity, carrier mobility, carrier concentration, and grain size of AZO films were 1.92×10-3 Ω-cm, 6.38 cm2/Vs, 5.08×1020 #/cm3, and 31.48 nm respectively, in vacuum annealing of 450 °C. The resistivity, carrier mobility, carrier concentration, and grain size of AZO films were 8.72×10-4 Ω-cm, 6.32 cm2/Vs, 1.13×1021 #/cm3, and 31.56 nm, respectively, when substrate temperature was at 250 °C. Substrate heating process is better than vacuum annealed process for AZO film deposited by DC Magnetron Sputtering.

Sputter deposition of MgxAlyOz thin films in a dual-magnetron device: a multi-species Monte Carlo model

NASA Astrophysics Data System (ADS)

Yusupov, M.; Saraiva, M.; Depla, D.; Bogaerts, A.

2012-07-01

A multi-species Monte Carlo (MC) model, combined with an analytical surface model, has been developed in order to investigate the general plasma processes occurring during the sputter deposition of complex oxide films in a dual-magnetron sputter deposition system. The important plasma species, such as electrons, Ar+ ions, fast Ar atoms and sputtered metal atoms (i.e. Mg and Al atoms) are described with the so-called multi-species MC model, whereas the deposition of MgxAlyOz films is treated by an analytical surface model. Target-substrate distances for both magnetrons in the dual-magnetron setup are varied for the purpose of growing stoichiometric complex oxide thin films. The metal atoms are sputtered from pure metallic targets, whereas the oxygen flux is only directed toward the substrate and is high enough to obtain fully oxidized thin films but low enough to avoid target poisoning. The calculations correspond to typical experimental conditions applied to grow these complex oxide films. In this paper, some calculation results are shown, such as the densities of various plasma species, their fluxes toward the targets and substrate, the deposition rates, as well as the film stoichiometry. Moreover, some results of the combined model are compared with experimental observations. Note that this is the first complete model, which can be applied for large and complicated magnetron reactor geometries, such as dual-magnetron configurations. With this model, we are able to describe all important plasma species as well as the deposition process. It can also be used to predict film stoichiometries of complex oxide films on the substrate.

Achieving High Current Density of Perovskite Solar Cells by Modulating the Dominated Facets of Room-Temperature DC Magnetron Sputtered TiO2 Electron Extraction Layer.

PubMed

Huang, Aibin; Lei, Lei; Zhu, Jingting; Yu, Yu; Liu, Yan; Yang, Songwang; Bao, Shanhu; Cao, Xun; Jin, Ping

2017-01-25

The short circuit current density of perovskite solar cell (PSC) was boosted by modulating the dominated plane facets of TiO 2 electron transport layer (ETL). Under optimized condition, TiO 2 with dominant {001} facets showed (i) low incident light loss, (ii) highly smooth surface and excellent wettability for precursor solution, (iii) efficient electron extraction, and (iv) high conductivity in perovskite photovoltaic application. A current density of 24.19 mA cm -2 was achieved as a value near the maximum limit. The power conversion efficiency was improved to 17.25%, which was the record value of PSCs with DC magnetron sputtered carrier transport layer. What is more, the room-temperature process had a great significance for the cost reduction and flexible application of PSCs.

Effect of nitrogen doping on the structural, optical and electrical properties of indium tin oxide films prepared by magnetron sputtering for gallium nitride light emitting diodes

NASA Astrophysics Data System (ADS)

Tian, Lifei; Cheng, Guoan; Wang, Hougong; Wu, Yulong; Zheng, Ruiting; Ding, Peijun

2017-01-01

The indium tin oxide (ITO) films are prepared by the direct current magnetron sputtering technology with an ITO target in a mixture of argon and nitrogen gas at room temperature. The blue transmittance at 455 nm rises from 63% to 83% after nitrogen doping. The resistivity of the ITO film reduces from 4.6 × 10-3 (undoped film) to 5.7 × 10-4 Ω cm (N-doped film). The X-ray photoelectron spectroscopy data imply that the binding energy of the In3d5/2 peak is declined 0.05 eV after nitrogen doping. The high resolution transmission electron microscope images show that the nitrogen loss density of the GaN/ITO interface with N-doped ITO film is smaller than that of the GaN/ITO interface with undoped ITO film. The forward turn-on voltage of gallium nitride light emitting diode reduces by 0.5 V after nitrogen doping. The fabrication of the N-doped ITO film is conducive to modify the N component of the interface between GaN and ITO layer.

Comparative measurements of plasma potential with ball-pen and Langmuir probe in low-temperature magnetized plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zanáška, M.; Kudrna, P.; Tichý, M.

The ball-pen probe (BPP) is used for direct plasma potential measurements in magnetized plasma. The probe can adjust the ratio of the electron and ion saturation currents I{sub sat}{sup −}/I{sub sat}{sup +} to be close to one and therefore its I-V characteristic becomes nearly symmetric. If this is achieved, the floating potential of the BPP is close to the plasma potential. Because of its rather simple construction, it offers an attractive probe for measurements in magnetized plasma. Comparative measurements of plasma potential by BPPs of different dimensions as well as one Langmuir probe (LP) in an argon discharge plasma ofmore » a cylindrical magnetron were performed at various experimental conditions. An additional comparison by an emissive probe was also performed. All these types of probes provide similar values of plasma potential in a wide range of plasma parameters. Our results for three different BPP dimensions indicate that the BPP can be operated in a cylindrical magnetron DC argon discharge if the value of the ratio of the magnetic field and neutral gas pressure, B/p, is greater than approximately 10 mT/Pa.« less

Modeling and experimental studies of a side band power re-injection locked magnetron

NASA Astrophysics Data System (ADS)

Ye, Wen-Jun; Zhang, Yi; Yuan, Ping; Zhu, Hua-Cheng; Huang, Ka-Ma; Yang, Yang

2016-12-01

A side band power re-injection locked (SBPRIL) magnetron is presented in this paper. A tuning stub is placed between the external injection locked (EIL) magnetron and the circulator. Side band power of the EIL magnetron is reflected back to the magnetron. The reflected side band power is reused and pulled back to the central frequency. A phase-locking model is developed from circuit theory to explain the process of reuse of side band power in SBPRIL magnetron. Theoretical analysis proves that the side band power is pulled back to the central frequency of the SBPRIL magnetron, then the amplitude of the RF voltage increases and the phase noise performance is improved. Particle-in-cell (PIC) simulation of a 10-vane continuous wave (CW) magnetron model is presented. Computer simulation predicts that the frequency spectrum’s peak of the SBPRIL magnetron has an increase of 3.25 dB compared with the free running magnetron. The phase noise performance at the side band offset reduces 12.05 dB for the SBPRIL magnetron. Besides, the SBPRIL magnetron experiment is presented. Experimental results show that the spectrum peak rises by 14.29% for SBPRIL magnetron compared with the free running magnetron. The phase noise reduces more than 25 dB at 45-kHz offset compared with the free running magnetron. Project supported by the National Basic Research Program of China (Grant No. 2013CB328902) and the National Natural Science Foundation of China (Grant No. 61501311).

Infrared characteristics of VO2 thin films for smart window and laser protection applications

NASA Astrophysics Data System (ADS)

Huang, Zhangli; Chen, Sihai; Lv, Chaohong; Huang, Ying; Lai, Jianjun

2012-11-01

Vanadium dioxide (VO2) films with a low semiconductor-to-metal transition temperature of 45 °C were fabricated through direct current magnetron sputtering followed by a post-annealing. Atomic force microscopy measurements show that the VO2 grain size is about one hundred of nanometers. Infrared (IR) characteristic is well investigated by applying a He-Ne laser power intensity measurement, and the result reveals that the VO2 film exhibits excellent IR switching property. Furthermore, solar smart window and laser protection experiments demonstrate that the obtained VO2 thin film is a promising material for the application in related fields.

Laser Trimming of CuAlMo Thin-Film Resistors: Effect of Laser Processing Parameters

NASA Astrophysics Data System (ADS)

Birkett, Martin; Penlington, Roger

2012-08-01

This paper reports the effect of varying laser trimming process parameters on the electrical performance of a novel CuAlMo thin-film resistor material. The films were prepared on Al2O3 substrates by direct-current (DC) magnetron sputtering, before being laser trimmed to target resistance value. The effect of varying key laser parameters of power, Q-rate, and bite size on the resistor stability and tolerance accuracy were systematically investigated. By reducing laser power and bite size and balancing this with Q-rate setting, significant improvements in resistor stability and resistor tolerance accuracies of less than ±0.5% were achieved.

Stability of Brillouin flow in planar, conventional, and inverted magnetrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simon, D. H.; Lau, Y. Y.; Greening, G.

2015-08-15

The Brillouin flow is the prevalent flow in crossed-field devices. We systematically study its stability in the conventional, planar, and inverted magnetron geometry. To investigate the intrinsic negative mass effect in Brillouin flow, we consider electrostatic modes in a nonrelativistic, smooth bore magnetron. We found that the Brillouin flow in the inverted magnetron is more unstable than that in a planar magnetron, which in turn is more unstable than that in the conventional magnetron. Thus, oscillations in the inverted magnetron may startup faster than the conventional magnetron. This result is consistent with simulations, and with the negative mass property inmore » the inverted magnetron configuration. Inclusion of relativistic effects and electromagnetic effects does not qualitatively change these conclusions.« less

On the road to self-sputtering in high power impulse magnetron sputtering: particle balance and discharge characteristics

NASA Astrophysics Data System (ADS)

Huo, Chunqing; Lundin, Daniel; Raadu, Michael A.; Anders, André; Tomas Gudmundsson, Jon; Brenning, Nils

2014-04-01

The onset and development of self-sputtering (SS) in a high power impulse magnetron sputtering (HiPIMS) discharge have been studied using a plasma chemical model and a set of experimental data, taken with an aluminum target and argon gas. The model is tailored to duplicate the discharge in which the data are taken. The pulses are long enough to include both an initial transient and a following steady state. The model is used to unravel how the internal discharge physics evolves with pulse power and time, and how it is related to features in the discharge current-voltage-time characteristics such as current densities, maxima, kinks and slopes. The connection between the self-sputter process and the discharge characteristics is quantified and discussed in terms of three parameters: a critical target current density Jcrit based on the maximum refill rate of process (argon) gas above the target, an SS recycling factor ΠSS-recycle, and an approximation \\tilde{\\alpha} of the probabilities of ionization of species that come from the target (both sputtered metal and embedded argon atoms). For low power pulses, discharge voltages UD ⩽ 380 V with peak current densities below ≈ 0.2 A cm-2, the discharge is found to be dominated by process gas sputtering. In these pulses there is an initial current peak in time, associated with partial gas rarefaction, which is followed by a steady-state-like plateau in all parameters similar to direct current magnetron sputtering. In contrast, high power pulses, with UD ⩾ 500 V and peak current densities above JD ≈ 1.6 A cm-2, make a transition to a discharge mode where SS dominates. The transition is found not to be driven by process gas rarefaction which is only about 10% at this time. Maximum gas rarefaction is found later in time and always after the initial peak in the discharge current. With increasing voltage, and pulse power, the discharge can be described as following a route where the role of SS increases in four steps: process gas sputtering, gas-sustained SS, self-sustained SS and SS runaway. At the highest voltage, 1000 V, the discharge is very close to, but does not go into, the SS runaway mode. This absence of runaway is proposed to be connected to an unexpected finding: that twice ionized ions of the target species play almost no role in this discharge, not even at the highest powers. This reduces ionization by secondary-emitted energetic electrons almost to zero in the highest power range of the discharge.

Effect of Annealing Processes on Cu-Zr Alloy Film for Copper Metallization

NASA Astrophysics Data System (ADS)

Wang, Ying; Li, Fu-yin; Tang, Bin-han

2017-12-01

The effect of two different annealing processes on the microstructure and barrier-forming ability of Cu-Zr alloy films has been investigated. Cu-Zr alloy films were deposited directly onto SiO2/Si substrates via direct current magnetron sputtering and subsequently annealed by the vacuum annealing process (VAP) or rapid annealing process under argon atmosphere at temperatures 350°C, 450°C, and 550°C. Then, the microstructure, interface characteristics, and electrical properties of the samples were measured. After annealing, the samples showed a preferential (111) crystal orientation, independent of the annealing process. After two annealing methods, Zr aggregated at the Cu-Zr/SiO2 interface and no serious interdiffusion occurred between Cu and Si. The leakage current measurements revealed that the samples annealed by VAP show a higher reliability. According to the results, the vacuum annealing has better barrier performance than the rapid annealing when used for the fabrication of Cu-based interconnects.

The current-density distribution in a pulsed dc magnetron deposition discharge

NASA Astrophysics Data System (ADS)

Vetushka, Alena; Bradley, James W.

2007-04-01

Using a carefully constructed magnetic probe (a B-dot probe) the spatial and temporal evolution of the perturbation in the magnetic field ΔB in an unbalanced pulsed dc magnetron has been determined. The plasma was run in argon at a pressure of 0.74 Pa and the plasma ions sputtered a pure graphite target. The pulse frequency and duty were set at 100 kHz and 55%, respectively. From the ΔB measurements (measured with magnitudes up to about 0.01 mT) the axial, azimuthal and radial components of the total current density j in the plasma bulk were determined. In the plasma 'on' phase, the axial current density jz has a maximum value of approximately 200 A m-2 above the racetrack region, while high values in the azimuthal current density jΦ are distributed in a region from 1 to 3 cm into the bulk plasma with jΦ exceeding 350 A m-2. In the 'off' phase of the plasma, jz decays almost instantaneously (at least within the 100 ns time-resolution of the ΔB measurements) as the electric field collapses; however, jΦ decays with a characteristic time constant of about 1 µs. This slow decay can be attributed to the presence of decaying Grad-B and curvature drifts, with their rates controlled by the decay in the plasma density. A comparison between axial and azimuthal current densities in the plasma 'on' time, when the plasma is being driven, strongly indicates that classical transport does not operate in the magnetron discharge.

Phase control and fast start-up of a magnetron using modulation of an addressable faceted cathode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Browning, J., E-mail: JimBrowning@BoiseState.edu; Fernandez-Gutierrez, S.; Lin, M. C.

The use of an addressable, faceted cathode has been proposed as a method of modulating current injection in a magnetron to improve performance and control phase. To implement the controllable electron emission, five-sided and ten-sided faceted planar cathodes employing gated field emitters are considered as these emitters could be fabricated on flat substrates. For demonstration, the conformal finite-difference time-domain particle-in-cell simulation, as implemented in VORPAL, has been used to model a ten-cavity, rising sun magnetron using the modulated current sources and benchmarked against a typical continuous current source. For the modulated, ten-sided faceted cathode case, the electrons are injected frommore » three emitter elements on each of the ten facets. Each emitter is turned ON and OFF in sequence at the oscillating frequency with five emitters ON at one time to drive the five electron spokes of the π-mode. The emitter duty cycle is then 1/6th the Radio-Frequency (RF) period. Simulations show a fast start-up time as low as 35 ns for the modulated case compared to 100 ns for the continuous current cases. Analysis of the RF phase using the electron spoke locations and the RF magnetic field components shows that the phase is controlled for the modulated case while it is random, as typical, for the continuous current case. Active phase control during oscillation was demonstrated by shifting the phase of the electron injection 180° after oscillations started. The 180° phase shift time was approximately 25 RF cycles.« less

Anomalous effects in the aluminum oxide sputtering yield

NASA Astrophysics Data System (ADS)

Schelfhout, R.; Strijckmans, K.; Depla, D.

2018-04-01

The sputtering yield of aluminum oxide during reactive magnetron sputtering has been quantified by a new and fast method. The method is based on the meticulous determination of the reactive gas consumption during reactive DC magnetron sputtering and has been deployed to determine the sputtering yield of aluminum oxide. The accuracy of the proposed method is demonstrated by comparing its results to the common weight loss method excluding secondary effects such as redeposition. Both methods exhibit a decrease in sputtering yield with increasing discharge current. This feature of the aluminum oxide sputtering yield is described for the first time. It resembles the discrepancy between published high sputtering yield values determined by low current ion beams and the low deposition rate in the poisoned mode during reactive magnetron sputtering. Moreover, the usefulness of the new method arises from its time-resolved capabilities. The evolution of the alumina sputtering yield can now be measured up to a resolution of seconds. This reveals the complex dynamical behavior of the sputtering yield. A plausible explanation of the observed anomalies seems to originate from the balance between retention and out-diffusion of implanted gas atoms, while other possible causes are commented.

Application of valence-to-core X-ray emission spectroscopy for identification and estimation of amount of carbon covalently bonded to chromium in amorphous Cr-C coatings prepared by magnetron sputtering

NASA Astrophysics Data System (ADS)

Safonov, V. A.; Habazaki, H.; Glatzel, P.; Fishgoit, L. A.; Drozhzhin, O. A.; Lafuerza, S.; Safonova, O. V.

2018-01-01

Cr-C coatings containing different amount of carbon ranging from ∼5 to 50 at.% were prepared by the direct current (DC) magnetron sputtering on a polished substrate of polycrystalline silicon. The thickness of the samples was about 400 nm. We characterized the composition and the structure of the as-received coatings and those annealed at 500 °C by X-ray diffraction (XRD), Energy dispersion X-ray spectroscopy (EDX) and valence-to-core X-ray emission spectroscopy (vtc-XES) methods As follows from XRD measurements, the samples with the carbon content above 35 at.% do not demonstrate any sign of the long-range order and annealing at 500 °C does not change their crystallinity. The vtc-XES curves of the as-prepared and annealed samples can be fitted as a superposition of corresponding spectra of chromium metal and chromium carbide (Cr3C2) phases. After the annealing, the content of carbides in the samples (and, correspondingly, the content of covalently bonded carbon) somewhat increases. This suggests that the as-received coatings contain a certain amount of carbon that is not covalently bonded to chromium (most likely, elemental carbon) and their annealing at 500 °C transforms this carbon into the additional (of the order of 2-5 at.%) amount of chromium carbide compounds. It deserves mentioning that for Cr-C coatings prepared by the electrochemical deposition from Cr(III) electrolytes containing organic compounds we have not observed changes in the vtc-X-ray emission spectra after similar annealing. This suggests that electrochemical deposition method in contrast to magnetron sputtering technique even at low temperatures favors the formation of only covalently bonded carbon.

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.

Effects of nitrogen ion implantation time on tungsten films deposited by DC magnetron sputtering on AISI 410 martensitic stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malau, Viktor, E-mail: malau@ugm.ac.id; Ilman, Mochammad Noer, E-mail: noer-ilman@yahoo.com; Iswanto, Priyo Tri, E-mail: priyatri@yahoo.com

Nitrogen ion implantation time on tungsten thin film deposited on surface of AISI 410 steel has been performed. Tungsten thin film produced by dc magnetron sputtering method was deposited on AISI 410 martensitic stainless steel substrates, and then the nitrogen ions were implanted on tungsten thin film. The objective of this research is to investigate the effects of implantation deposition time on surface roughness, microhardness, specific wear and corrosion rate of nitrogen implanted on tungsten film. Magnetron sputtering process was performed by using plasma gas of argon (Ar) to bombardier tungsten target (W) in a vacuum chamber with a pressuremore » of 7.6 x 10{sup −2} torr, a voltage of 300 V, a sputter current of 80 mA for sputtered time of 10 minutes. Nitrogen implantation on tungsten film was done with an initial pressure of 3x10{sup −6} mbar, a fluence of 2 x 10{sup 17} ions/cm{sup 2}, an energy of 100 keV and implantation deposition times of 0, 20, 30 and 40 minutes. The surface roughness, microhardness, specific wear and corrosion rate of the films were evaluated by surfcorder test, Vickers microhardness test, wear test and potentiostat (galvanostat) test respectively. The results show that the nitrogen ions implanted deposition time on tungsten film can modify the surface roughness, microhardness, specific wear and corrosion rate. The minimum surface roughness, specific wear and corrosion rate can be obtained for implantation time of 20 minutes and the maximum microhardness of the film is 329 VHN (Vickers Hardness Number) for implantation time of 30 minutes. The specific wear and corrosion rate of the film depend directly on the surface roughness.« less

The structure, surface topography and mechanical properties of Si-C-N films fabricated by RF and DC magnetron sputtering

NASA Astrophysics Data System (ADS)

Shi, Zhifeng; Wang, Yingjun; Du, Chang; Huang, Nan; Wang, Lin; Ning, Chengyun

2011-12-01

Silicon carbon nitride thin films were deposited on Co-Cr alloy under varying deposition conditions such as sputtering power and the partial pressure ratio of N2 to Ar by radio frequency and direct current magnetron sputtering techniques. The chemical bonding configurations, surface topography and hardness were characterized by means of X-ray photoelectron spectroscopy, atomic force microscopy and nano-indentation technique. The sputtering power exhibited important influence on the film composition, chemical bonding configurations and surface topography, the electro-negativity had primary effects on chemical bonding configurations at low sputtering power. A progressive densification of the film microstructure occurring with the carbon fraction was increased. The films prepared by RF magnetron sputtering, the relative content of the Si-N bond in the films increased with the sputtering power increased, and Si-C and Si-Si were easily detachable, and C-O, N-N and N-O on the film volatile by ion bombardment which takes place very frequently during the film formation process. With the increase of sputtering power, the films became smoother and with finer particle growth. The hardness varied between 6 GPa and 11.23 GPa depending on the partial pressure ratio of N2 to Ar. The tribological characterization of Co-Cr alloy with Si-C-N coating sliding against UHMWPE counter-surface in fetal bovine serum, shows that the wear resistance of the Si-C-N coated Co-Cr alloy/UHMWPE sliding pair show much favourable improvement over that of uncoated Co-Cr alloy/UHMWPE sliding pair. This study is important for the development of advanced coatings with tailored mechanical and tribological properties.

Pd-catalysts for DFAFC prepared by magnetron sputtering

NASA Astrophysics Data System (ADS)

Bieloshapka, I.; Jiricek, P.; Vorokhta, M.; Tomsik, E.; Rednyk, A.; Perekrestov, R.; Jurek, K.; Ukraintsev, E.; Hruska, K.; Romanyuk, O.; Lesiak, B.

2017-10-01

Samples of a palladium catalyst for direct formic acid fuel cell (DFAFC) applications were prepared on the Elat® carbon cloth by magnetron sputtering. The quantity of Pd was equal to 3.6, 120 and 720 μg/cm2. The samples were tested in a fuel cell for electro-oxidation of formic acid, and were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The XPS measurements revealed a high contribution of PdCx phase formed at the Pd/Elat® surface interface, with carbon concentration in PdCx from x = 9.9-14.6 at.%, resulting from the C substrate and CO residual gases. Oxygen groups, e.g. hydroxyl (-OH), carbonyl (Cdbnd O) and carboxyl (COOH), resulted from the synthesis conditions due to the presence of residual gases, electro-oxidation during the reaction and oxidation in the atmosphere. Because of the formation of CO and CO2 on the catalysts during the reaction, or because of poisoning by impurities containing the -CH3 group, together with the risk of Pd losses due to dissolution in formic acid, there was a negative effect of catalyst degradation on the active area surface. The effect of different loadings of Pd layers led to increasing catalyst efficiency. Current-voltage curves showed that different amounts of catalyst did not increase the DFAFC power to a great extent. One reason for this was the catalyst structure formed on the carbon cloth. AFM and SEM measurements showed a layer-by-layer growth with no significant variations in morphology. The results for electric power recalculated for the Pd loading per 1 mg of catalyst layers in comparison to carbon substrates decorated by Pd nanoparticles showed that there is potential for applying anodes for formic acid fuel cells prepared by magnetron sputtering.

The use of segmented cathodes to determine the spoke current density distribution in high power impulse magnetron sputtering plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poolcharuansin, Phitsanu; The Technological Plasma Research Unit, Department of Physics, Mahasarakham University, Maha Sarakham 44150; Estrin, Francis Lockwood

2015-04-28

The localized target current density associated with quasi-periodic ionization zones (spokes) has been measured in a high power impulse magnetron sputtering (HiPIMS) discharge using an array of azimuthally separated and electrical isolated probes incorporated into a circular aluminum target. For a particular range of operating conditions (pulse energies up to 2.2 J and argon pressures from 0.2 to 1.9 Pa), strong oscillations in the probe current density are seen with amplitudes up to 52% above a base value. These perturbations, identified as spokes, travel around the discharge above the target in the E×B direction. Using phase information from the angularly separated probes,more » the spoke drift speeds, angular frequencies, and mode number have been determined. Generally, at low HiPIMS pulse energies E{sub p} < 0.8 J, spokes appear to be chaotic in nature (with random arrival times), however as E{sub p} increases, coherent spokes are observed with velocities between 6.5 and 10 km s{sup −1} and mode numbers m = 3 or above. At E{sub p} > 1.8 J, the plasma becomes spoke-free. The boundaries between chaotic, coherent, and no-spoke regions are weakly dependent on pressure. During each HiPIMS pulse, the spoke velocities increase by about 50%. Such an observation is explained by considering spoke velocities to be determined by the critical ionization velocity, which changes as the plasma composition changes during the pulse. From the shape of individual current density oscillations, it appears that the leading edge of the spoke is associated with a slow increase in local current density to the target and the rear with a more rapid decrease. The measurements show that the discharge current density associated with individual spokes is broadly spread over a wide region of the target.« less

Reduced atomic shadowing in HiPIMS: Role of the thermalized metal ions

NASA Astrophysics Data System (ADS)

Oliveira, João Carlos; Ferreira, Fábio; Anders, André; Cavaleiro, Albano

2018-03-01

In magnetron sputtering, the ability to tailor film properties depends primarily on the control of the flux of particles impinging on the growing film. Among deposition mechanisms, the shadowing effect leads to the formation of a rough surface and a porous, columnar microstructure. Re-sputtered species may be re-deposited in the valleys of the films surface and thereby contribute to a reduction of roughness and to fill the underdense regions. Both effects are non-local and they directly compete to shape the final properties of the deposited films. Additional control of the bombarding flux can be obtained by ionizing the sputtered flux, because ions can be controlled with respect to their energy and impinging direction, such as in High-Power Impulse Magnetron Sputtering (HiPIMS). In this work, the relation between ionization of the sputtered species and thin film properties is investigated in order to identify the mechanisms which effectively influence the shadowing effect in Deep Oscillation Magnetron Sputtering (DOMS), a variant of HiPIMS. The properties of two Cr films deposited using the same averaged target power by d.c. magnetron sputtering and DOMS have been compared. Additionally, the angle distribution of the Cr species impinging on the substrate was simulated using Monte Carlo-based programs while the energy distribution of the energetic particles bombarding the substrate was evaluated by energy-resolved mass analysis. It was found that the acceleration of the thermalized chromium ions at the substrate sheath in DOMS significantly reduces the high angle component of their impinging angle distribution and, thus, efficiently reduces atomic shadowing. Therefore, a high degree of ionization in HiPIMS results in almost shadowing effect-free film deposition and allows us to deposit dense and compact films without the need of high energy particle bombardment during growth.

Characterization and optimization of the magnetron directional amplifier

NASA Astrophysics Data System (ADS)

Hatfield, Michael Craig

Many applications of microwave wireless power transmission (WPT) are dependent upon a high-powered electronically-steerable phased array composed of many radiating modules. The phase output from the high-gain amplifier in each module must be accurately controlled if the beam is to be properly steered. A highly reliable, rugged, and inexpensive design is essential for making WPT applications practical. A conventional microwave oven magnetron may be combined with a ferrite circulator and other external circuitry to create such a system. By converting it into a two-port amplifier, the magnetron is capable of delivering at least 30 dB of power gain while remaining phase-locked to the input signal over a wide frequency range. The use of the magnetron in this manner is referred to as a MDA (Magnetron Directional Amplifier). The MDA may be integrated with an inexpensive slotted waveguide array (SWA) antenna to form the Electronically-Steerable Phased Array Module (ESPAM). The ESPAM provides a building block approach to creating phased arrays for WPT. The size and shape of the phased array may be tailored to satisfy a diverse range of applications. This study provided an in depth examination into the capabilities of the MDA/ESPAM. The basic behavior of the MDA was already understood, as well as its potential applicability to WPT. The primary objective of this effort was to quantify how well the MDA could perform in this capacity. Subordinate tasks included characterizing the MDA behavior in terms of its system inputs, optimizing its performance, performing sensitivity analyses, and identifying operating limitations. A secondary portion of this study examined the suitability of the ESPAM in satisfying system requirements for the solar power satellite (SPS). Supporting tasks included an analysis of SPS requirements, modeling of the SWA antenna, and the demonstration of a simplified phased array constructed of ESPAM elements. The MDA/ESPAM is well suited for use as an amplifier or an element in a WPT phased array, providing over 75% efficiency and a fractional bandwidth exceeding 1.7% at 2.45 GHz. The results of this effort provide the WPT design engineer with tools to predict the MDA's optimum performance and limitations.

High power microwave source development

NASA Astrophysics Data System (ADS)

Benford, James N.; Miller, Gabriel; Potter, Seth; Ashby, Steve; Smith, Richard R.

1995-05-01

The requirements of this project have been to: (1) improve and expand the sources available in the facility for testing purposes and (2) perform specific tasks under direction of the Defense Nuclear Agency about the applications of high power microwaves (HPM). In this project the HPM application was power beaming. The requirements of this program were met in the following way: (1) We demonstrated that a compact linear induction accelerator can drive HPM sources at repetition rates in excess of 100 HZ at peak microwave powers of a GW. This was done for the relativistic magnetron. Since the conclusion of this contract such specifications have also been demonstrated for the relativistic klystron under Ballistic Missile Defense Organization funding. (2) We demonstrated an L band relativistic magnetron. This device has been used both on our single pulse machines, CAMEL and CAMEL X, and the repetitive system CLIA. (3) We demonstrated that phase locking of sources together in large numbers is a feasible technology and showed the generation of multigigawatt S-band radiation in an array of relativistic magnetrons.

Plasma sputtering robotic device for in-situ thick coatings of long, small diameter vacuum tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hershcovitch, A., E-mail: hershcovitch@bnl.gov; Blaskiewicz, M.; Brennan, J. M.

A novel robotic plasma magnetron mole with a 50 cm long cathode was designed, fabricated, and operated. The reason for this endeavor is to alleviate the problems of unacceptable resistive heating of stainless steel vacuum tubes in the BNL Relativistic Heavy Ion Collider (RHIC). The magnetron mole was successfully operated to copper coat an assembly containing a full-size, stainless steel, cold bore, RHIC magnet tubing connected to two types of RHIC bellows, to which two additional pipes made of RHIC tubing were connected. To increase the cathode lifetime, a movable magnet package was developed, and the thickest possible cathode was made,more » with a rather challenging target to substrate (de facto anode) distance of less than 1.5 cm. Achieving reliable steady state magnetron discharges at such a short cathode to anode gap was rather challenging, when compared to commercial coating equipment, where the target to substrate distance is 10's cm; 6.3 cm is the lowest experimental target to substrate distance found in the literature. Additionally, the magnetron developed during this project provides unique omni-directional uniform coating. The magnetron is mounted on a carriage with spring loaded wheels that successfully crossed bellows and adjusted for variations in vacuum tube diameter, while keeping the magnetron centered. Electrical power and cooling water were fed through a cable bundle. The umbilical cabling system is driven by a motorized spool. Excellent coating adhesion was achieved. Measurements indicated that well-scrubbed copper coating reduced secondary electron yield to 1, i.e., the problem of electron clouds can be eliminated. Room temperature RF resistivity measurement indicated that a 10 μm copper coated stainless steel RHIC tube has a conductivity close to that of pure copper tubing. Excellent coating adhesion was achieved. The device details and experimental results are described.« less

Plasma Sputtering Robotic Device for In-Situ Thick Coatings of Long, Small Diameter Vacuum Tubes

NASA Astrophysics Data System (ADS)

Hershcovitch, Ady

2014-10-01

A novel robotic plasma magnetron mole with a 50 cm long cathode was designed fabricated & operated. Reason for this endeavor is to alleviate the problems of unacceptable ohmic heating of stainless steel vacuum tubes and of electron clouds, due to high secondary electron yield (SEY), in the BNL Relativistic Heavy Ion Collider (RHIC). The magnetron mole was successfully operated to copper coat an assembly containing a full-size, stainless steel, cold bore, RHIC magnet tubing connected to two types of RHIC bellows, to which two additional pipes made of RHIC tubing were connected. To increase cathode lifetime, movable magnet package was developed, and thickest possible cathode was made, with a rather challenging target to substrate (de facto anode) distance of less than 1.5 cm. Achieving reliable steady state magnetron discharges at such a short cathode to anode gap was rather challenging, when compared to commercial coating equipment, where the target to substrate distance is 10's cm; 6.3 cm is the lowest experimental target to substrate distance found in the literature. Additionally, the magnetron developed during this project provides unique omni-directional uniform coating. The magnetron is mounted on a carriage with spring loaded wheels that successfully crossed bellows and adjusted for variations in vacuum tube diameter, while keeping the magnetron centered. Electrical power and cooling water were fed through a cable bundle. The umbilical cabling system is driven by a motorized spool. Excellent coating adhesion was achieved. Measurements indicated that well-scrubbed copper coating reduced SEY to 1, i.e., the problem of electron clouds can be eliminated. Room temperature RF resistivity measurement indicated that 10 μm Cu coated stainless steel RHIC tube has conductivity close to that of pure copper tubing. Excellent coating adhesion was achieved. Device detail and experimental results will be presented. Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH1-886 with the US Department of Energy.

Plasma sputtering robotic device for in-situ thick coatings of long, small diameter vacuum tubesa)

NASA Astrophysics Data System (ADS)

Hershcovitch, A.; Blaskiewicz, M.; Brennan, J. M.; Custer, A.; Dingus, A.; Erickson, M.; Fischer, W.; Jamshidi, N.; Laping, R.; Liaw, C.-J.; Meng, W.; Poole, H. J.; Todd, R.

2015-05-01

A novel robotic plasma magnetron mole with a 50 cm long cathode was designed, fabricated, and operated. The reason for this endeavor is to alleviate the problems of unacceptable resistive heating of stainless steel vacuum tubes in the BNL Relativistic Heavy Ion Collider (RHIC). The magnetron mole was successfully operated to copper coat an assembly containing a full-size, stainless steel, cold bore, RHIC magnet tubing connected to two types of RHIC bellows, to which two additional pipes made of RHIC tubing were connected. To increase the cathode lifetime, a movable magnet package was developed, and the thickest possible cathode was made, with a rather challenging target to substrate (de facto anode) distance of less than 1.5 cm. Achieving reliable steady state magnetron discharges at such a short cathode to anode gap was rather challenging, when compared to commercial coating equipment, where the target to substrate distance is 10's cm; 6.3 cm is the lowest experimental target to substrate distance found in the literature. Additionally, the magnetron developed during this project provides unique omni-directional uniform coating. The magnetron is mounted on a carriage with spring loaded wheels that successfully crossed bellows and adjusted for variations in vacuum tube diameter, while keeping the magnetron centered. Electrical power and cooling water were fed through a cable bundle. The umbilical cabling system is driven by a motorized spool. Excellent coating adhesion was achieved. Measurements indicated that well-scrubbed copper coating reduced secondary electron yield to 1, i.e., the problem of electron clouds can be eliminated. Room temperature RF resistivity measurement indicated that a 10 μm copper coated stainless steel RHIC tube has a conductivity close to that of pure copper tubing. Excellent coating adhesion was achieved. The device details and experimental results are described.

Synthesis and properties of nanocrystalline copper indium oxide thin films deposited by Rf magnetron sputtering.

PubMed

Singh, Mandeep; Singh, V N; Mehta, B R

2008-08-01

Nanocrystalline copper indium oxide (CuInO2) thin films with particle size ranging from 25 nm to 71 nm have been synthesized from a composite target using reactive Rf magnetron sputtering technique. X-ray photoelectron spectroscopy (XPS) combined with glancing angle X-ray diffraction (GAXRD) analysis confirmed the presence of delafossite CuInO2 phase in these films. The optical absorption studies show the presence of two direct band gaps at 3.3 and 4.3 eV, respectively. The resistance versus temperature measurements show thermally activated hopping with activation energy of 0.84 eV to be the conduction mechanism.

Investigation of the optical property and structure of WO3 thin films with different sputtering depositions

NASA Astrophysics Data System (ADS)

Chen, Hsi-Chao; Jan, Der-Jun; Chen, Chien-Han; Huang, Kuo-Ting; Lo, Yen-Ming; Chen, Sheng-Hui

2011-09-01

The purpose of this research was to compare the optical properties and structure of tungsten oxide (WO3) thin films that was deposited by different sputtering depositions. WO3 thin films deposited by two different depositions of direct current (DC) magnetron sputtering and pulsed DC sputtering. A 99.95% WO3 target was used as the starting material for these depositions. These WO3 thin films were deposited on the ITO glass, PET and silicon substrate by different ratios of oxygen and argon. A shadow moiré interferometer would be introduced to measure the residual stress for PET substrate. RF magnetron sputtering had the large residual stress than the other's depositions. A Raman spectrum could exhibit the phase of oxidation of WO3 thin film by different depositions. At the ratio of oxygen and argon was about 1:1, and the WO3 thin films had the best oxidation. However, it was important at the change of the transmittance (ΔT = Tbleached - Tcolored) between the coloring and bleaching for the smart window. Therefore, we also found the WO3 thin films had the large variation of transmittance between the coloring and bleaching at the gas ratios of oxygen and argon of 1:1.

Thickness and surface roughness study of co-sputtered nanostructured alumina/tungsten (Al2O3/W) thin films

NASA Astrophysics Data System (ADS)

Naveen, A.; Krishnamurthy, L.; Shridhar, T. N.

2018-04-01

Tungsten (W) and Alumina (Al2O3) thin films have been developed using co-sputtering technique on SS304, Copper (Cu) and Glass slides using Direct Current magnetron sputtering (DC) and Radio Frequency (RF) magnetron sputtering methods respectively. Central Composite Design (CCD) method approach has been adopted to determine the number of experimental plans for deposition and DC power, RF power and Argon gas flow rate have been input parameters, each at 5 levels for development of thin films. In this research paper, study has been carried out determine the optimized condition of deposition parameters for thickness and surface roughness of the thin films. Thickness and average Surface roughness in terms of nanometer (nm) have been characterized by thickness profilometer and atomic force microscopy respectively. The maximum and minimum average thickness observed to be 445 nm and 130 respectively. The optimum deposition condition for W/Al2O3 thin film growth was determined to be at 1000 watts of DC power and 800 watts of RF power, 20 minutes of deposition time, and almost 300 Standard Cubic Centimeter(SCCM) of Argon gas flow. It was observed that average roughness difference found to be less than one nanometer on SS substrate and one nanometer on copper approximately.

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.

Reactive high power impulse magnetron sputtering

NASA Astrophysics Data System (ADS)

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

2012-10-01

Here we discuss reactive high power impulse magnetron sputtering sputtering (HiPIMS) [1] of Ti target in an Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on both the pulse repetition frequency and discharge voltage. The discharge current increases with decreasing frequency or voltage. This we attribute to an increase in the secondary electron emission yield during the self-sputtering phase of the pulse, as nitride [2] or oxide [3] forms on the target. We also discuss the growth of TiN films on SiO2 at temperatures of 22-600 ^oC. The HiPIMS process produces denser films at lower growth temperature and the surface is much smoother and have a significantly lower resistivity than dc magnetron sputtered films on SiO2 at all growth temperatures due to reduced grain boundary scattering [4].[4pt] [1] J. T. Gudmundsson, N. Brenning, D. Lundin and U. Helmersson, J. Vac. Sci. Technol. A, 30 030801 (2012)[0pt] [2] F. Magnus, O. B. Sveinsson, S. Olafsson and J. T. Gudmundsson, J. Appl. Phys., 110 083306 (2011)[0pt] [3] F. Magnus, T. K. Tryggvason, S. Olafsson and J. T. Gudmundsson, J. Vac. Sci. Technol., submitted 2012[0pt] [4] F. Magnus, A. S. Ingason, S. Olafsson and J. T. Gudmundsson, IEEE Elec. Dev. Lett., accepted 2012

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.

Microwave-driven ultraviolet light sources

DOEpatents

Manos, Dennis M.; Diggs, Jessie; Ametepe, Joseph D.

2002-01-29

A microwave-driven ultraviolet (UV) light source is provided. The light source comprises an over-moded microwave cavity having at least one discharge bulb disposed within the microwave cavity. At least one magnetron probe is coupled directly to the microwave cavity.

High power impulse magnetron sputtering and its applications

NASA Astrophysics Data System (ADS)

Yan, YUAN; Lizhen, YANG; Zhongwei, LIU; Qiang, CHEN

2018-04-01

High power impulse magnetron sputtering (HiPIMS) has attracted a great deal of attention because the sputtered material is highly ionized during the coating process, which has been demonstrated to be advantageous for better quality coating. Therefore, the mechanism of the HiPIMS technique has recently been investigated. In this paper, the current knowledge of HiPIMS is described. We focus on the mechanical properties of the deposited thin film in the latest applications, including hard coatings, adhesion enhancement, tribological performance, and corrosion protection layers. A description of the electrical, optical, photocatalytic, and functional coating applications are presented. The prospects for HiPIMS are also discussed in this work.

Ion energies in high power impulse magnetron sputtering with and without localized ionization zones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yuchen; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720; Tanaka, Koichi

2015-03-23

High speed imaging of high power impulse magnetron sputtering discharges has revealed that ionization is localized in moving ionization zones but localization disappears at high currents for high yield targets. This offers an opportunity to study the effect ionization zones have on ion energies. We measure that ions have generally higher energies when ionization zones are present, supporting the concept that these zones are associated with moving potential humps. We propose that the disappearance of ionization zones is caused by an increased supply of atoms from the target which cools electrons and reduces depletion of atoms to be ionized.

Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition

NASA Astrophysics Data System (ADS)

Tolosa, Maria D. Reyes; Damonte, Laura C.; Brine, Hicham; Bolink, Henk J.; Hernández-Fenollosa, María A.

2013-03-01

Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of them. Additionally, these primary oxide layers prevent direct hole combination when used in optoelectronic devices. Structural and optical characterizations were carried out by scanning electron microscopy, atomic force microscopy, and optical transmission spectroscopy. We show that the properties of the ZnO nanostructured films depend strongly on the type of primary oxide-covered substrate used. Previous studies on different electrodeposition methods for nucleation and growth are considered in the final discussion.

Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition.

PubMed

Tolosa, Maria D Reyes; Damonte, Laura C; Brine, Hicham; Bolink, Henk J; Hernández-Fenollosa, María A

2013-03-23

Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of them. Additionally, these primary oxide layers prevent direct hole combination when used in optoelectronic devices. Structural and optical characterizations were carried out by scanning electron microscopy, atomic force microscopy, and optical transmission spectroscopy. We show that the properties of the ZnO nanostructured films depend strongly on the type of primary oxide-covered substrate used. Previous studies on different electrodeposition methods for nucleation and growth are considered in the final discussion.

Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition

PubMed Central

2013-01-01

Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of them. Additionally, these primary oxide layers prevent direct hole combination when used in optoelectronic devices. Structural and optical characterizations were carried out by scanning electron microscopy, atomic force microscopy, and optical transmission spectroscopy. We show that the properties of the ZnO nanostructured films depend strongly on the type of primary oxide-covered substrate used. Previous studies on different electrodeposition methods for nucleation and growth are considered in the final discussion. PMID:23522332

Methods of Phase and Power Control in Magnetron Transmitters for Superconducting Accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazadevich, G.; Johnson, R.; Neubauer, M.

Various methods of phase and power control in magnetron RF sources of superconducting accelerators intended for ADS-class projects were recently developed and studied with conventional 2.45 GHz, 1 kW, CW magnetrons operating in pulsed and CW regimes. Magnetron transmitters excited by a resonant (injection-locking) phasemodulated signal can provide phase and power control with the rates required for precise stabilization of phase and amplitude of the accelerating field in Superconducting RF (SRF) cavities of the intensity-frontier accelerators. An innovative technique that can significantly increase the magnetron transmitter efficiency at the widerange power control required for superconducting accelerators was developed and verifiedmore » with the 2.45 GHz magnetrons operating in CW and pulsed regimes. High efficiency magnetron transmitters of this type can significantly reduce the capital and operation costs of the ADSclass accelerator projects.« less

Structural investigations in helium charged titanium films using grazing incidence XRD and EXAFS spectroscopy

NASA Astrophysics Data System (ADS)

Wan, Chubin; Zhou, Xiaosong; Wang, Yuting; Li, Shina; Ju, Xin; Peng, Shuming

2014-01-01

The crystal structure and local atomic arrangements surrounding Ti atoms were determined for He-charged hexagonal close-packed (hcp) Ti films and measured at glancing angles by synchrotron radiation X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy, respectively. The charged specimens were prepared by direct current magnetron sputtering with a He/Ar mixture. He atoms with a relatively medium concentration (He/Ti atomic ratio as high as 17 at.%) were incorporated evenly in the deposited films. XRD results showed the changes in the peak intensities in Ti films with different He contents. EXAFS Fourier Transform analysis indicated that the average Ti-Ti distance decreased significantly, and proved the existence of phase transition.

An inverted cylindrical sputter magnetron as metal vapor supply for electron cyclotron resonance ion sources.

PubMed

Weichsel, T; Hartung, U; Kopte, T; Zschornack, G; Kreller, M; Silze, A

2014-05-01

An inverted cylindrical sputter magnetron device has been developed. The magnetron is acting as a metal vapor supply for an electron cyclotron resonance (ECR) ion source. FEM simulation of magnetic flux density was used to ensure that there is no critical interaction between both magnetic fields of magnetron and ECR ion source. Spatially resolved double Langmuir probe and optical emission spectroscopy measurements show an increase in electron density by one order of magnitude from 1 × 10(10) cm(-3) to 1 × 10(11) cm(-3), when the magnetron plasma is exposed to the magnetic mirror field of the ECR ion source. Electron density enhancement is also indicated by magnetron plasma emission photography with a CCD camera. Furthermore, photographs visualize the formation of a localized loss-cone - area, when the magnetron is operated at magnetic mirror field conditions. The inverted cylindrical magnetron supplies a metal atom load rate of R > 1 × 10(18) atoms/s for aluminum, which meets the demand for the production of a milliampere Al(+) ion beam.

RF Priming Experiments and Simulations of Magnetic Priming in Relativistic Magnetrons

NASA Astrophysics Data System (ADS)

White, W. M.; Gilgenbach, R. M.; Jones, M. C.; Neculaes, V. B.; Lau, Y. Y.; Jordan, N.; Pengvanich, P.; Edgar, R.; Hoff, B.; Spencer, T. A.; Price, D.

2004-11-01

We investigate 2 priming techniques in relativistic magnetrons for rapid startup and mode-locking: RF priming experiments with 0.1-1 MW from a 2nd magnetron; Magnetic-priming simulations by azimuthally-varying-axial magnetic field. Experiments utilize MELBA-C with a Titan 6-vane magnetron: V = -300kV, I = 1-10kA, e-beam T = 0.5 μs, microwave power = 100-500 MW, f= 1-1.3 GHz, base vacuum= 8.5 x 10-10 Torr. The AFRL RF priming magnetron is at 0.1-2 MW, 3 μsec, 1.27-1.32 GHz. About 0.2-0.3 MW is injected into 1 of 3 open coupling slots in the relativistic magnetron. Analysis of the relativistic magnetron's microwave output shows a clear effect of RF priming. Simulations of magnetic priming in the pi-mode are run in MAGIC code by imposing N/2 azimuthal-variations in the axial magnetic field of an N-vane magnetron. Faster startup and mode-locking are simulated by rapid-electron spoke formation and excitation of RF fields.

Magnetron sputtering based direct fabrication of three dimensional CdTe hierarchical nanotrees exhibiting stable superhydrophobic property

NASA Astrophysics Data System (ADS)

Luo, Bingwei; Deng, Yuan; Wang, Yao; Shi, Yongming; Cao, Lili; Zhu, Wei

2013-09-01

Three dimensional CdTe hierarchical nanotrees are initially prepared by a simple one-step magnetron sputtering method without any templates or additives. The CdTe hierarchical nanotrees are constructed by the spear-like vertical trunks and horizontal branches with the diameters of about 100 nm at bottom and became cuspidal on the top. The particular nanostructure imparts these materials superhydrophobic property, and this property can be preserved after placing in air for 90 days, and is stable even after the ultraviolet light and X-ray irradiation, respectively. This study provides a simple strategy to achieve superhydrophobic properties for CdTe materials at lower temperature, which opens a new potential for CdTe solar cell with self-cleaning property.

Unprecedented Al supersaturation in single-phase rock salt structure VAlN films by Al+ subplantation

NASA Astrophysics Data System (ADS)

Greczynski, G.; Mráz, S.; Hans, M.; Primetzhofer, D.; Lu, J.; Hultman, L.; Schneider, J. M.

2017-05-01

Modern applications of refractory ceramic thin films, predominantly as wear-protective coatings on cutting tools and on components utilized in automotive engines, require a combination of excellent mechanical properties, thermal stability, and oxidation resistance. Conventional design approaches for transition metal nitride coatings with improved thermal and chemical stability are based on alloying with Al. It is well known that the solubility of Al in NaCl-structure transition metal nitrides is limited. Hence, the great challenge is to increase the Al concentration substantially while avoiding precipitation of the thermodynamically favored wurtzite-AlN phase, which is detrimental to mechanical properties. Here, we use VAlN as a model system to illustrate a new concept for the synthesis of metastable single-phase NaCl-structure thin films with the Al content far beyond solubility limits obtained with conventional plasma processes. This supersaturation is achieved by separating the film-forming species in time and energy domains through synchronization of the 70-μs-long pulsed substrate bias with intense periodic fluxes of energetic Al+ metal ions during reactive hybrid high power impulse magnetron sputtering of the Al target and direct current magnetron sputtering of the V target in the Ar/N2 gas mixture. Hereby, Al is subplanted into the cubic VN grains formed by the continuous flux of low-energy V neutrals. We show that Al subplantation enables an unprecedented 42% increase in metastable Al solubility limit in V1-xAlxN, from x = 0.52 obtained with the conventional method to 0.75. The elastic modulus is 325 ± 5 GPa, in excellent agreement with density functional theory calculations, and approximately 50% higher than for corresponding films grown by dc magnetron sputtering. The extension of the presented strategy to other Al-ion-assisted vapor deposition methods or materials systems is straightforward, which opens up the way for producing supersaturated single-phase functional ceramic alloy thin films combining excellent mechanical properties with high oxidation resistance.

Pulsing frequency induced change in optical constants and dispersion energy parameters of WO3 films grown by pulsed direct current magnetron sputtering

NASA Astrophysics Data System (ADS)

Punitha, K.; Sivakumar, R.; Sanjeeviraja, C.

2014-03-01

In this work, we present the pulsing frequency induced change in the structural, optical, vibrational, and luminescence properties of tungsten oxide (WO3) thin films deposited on microscopic glass and fluorine doped tin oxide (SnO2:F) coated glass substrates by pulsed dc magnetron sputtering technique. The WO3 films deposited on SnO2:F substrate belongs to monoclinic phase. The pulsing frequency has a significant influence on the preferred orientation and crystallinity of WO3 film. The maximum optical transmittance of 85% was observed for the film and the slight shift in transmission threshold towards higher wavelength region with increasing pulsing frequency revealed the systematic reduction in optical energy band gap (3.78 to 3.13 eV) of the films. The refractive index (n) of films are found to decrease (1.832 to 1.333 at 550 nm) with increasing pulsing frequency and the average value of extinction coefficient (k) is in the order of 10-3. It was observed that the dispersion data obeyed the single oscillator of the Wemple-Didomenico model, from which the dispersion energy (Ed) parameters, dielectric constants, plasma frequency, oscillator strength, and oscillator energy (Eo) of WO3 films were calculated and reported for the first time due to variation in pulsing frequency during deposition by pulsed dc magnetron sputtering. The Eo is change between 6.30 and 3.88 eV, while the Ed varies from 25.81 to 7.88 eV, with pulsing frequency. The Raman peak observed at 1095 cm-1 attributes the presence of W-O symmetric stretching vibration. The slight shift in photoluminescence band is attributed to the difference in excitons transition. We have made an attempt to discuss and correlate these results with the light of possible mechanisms underlying the phenomena.

Boron ion beam generation utilizing lanthanum hexaboride cathodes: Comparison of vacuum arc and planar magnetron glow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikolaev, A. G.; Vizir, A. V.; Yushkov, G. Yu., E-mail: gyushkov@mail.ru

Boron ion beams are widely used for semiconductor ion implantation and for surface modification for improving the operating parameters and increasing the lifetime of machine parts and tools. For the latter application, the purity requirements of boron ion beams are not as stringent as for semiconductor technology, and a composite cathode of lanthanum hexaboride may be suitable for the production of boron ions. We have explored the use of two different approaches to boron plasma production: vacuum arc and planar high power impulse magnetron in self-sputtering mode. For the arc discharge, the boron plasma is generated at cathode spots, whereasmore » for the magnetron discharge, the main process is sputtering of cathode material. We present here the results of comparative test experiments for both kinds of discharge, aimed at determining the optimal discharge parameters for maximum yield of boron ions. For both discharges, the extracted ion beam current reaches hundreds of milliamps and the fraction of boron ions in the total extracted ion beam is as high as 80%.« less

An inverted cylindrical sputter magnetron as metal vapor supply for electron cyclotron resonance ion sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weichsel, T., E-mail: tim.weichsel@fep.fraunhofer.de; Hartung, U.; Kopte, T.

2014-05-15

An inverted cylindrical sputter magnetron device has been developed. The magnetron is acting as a metal vapor supply for an electron cyclotron resonance (ECR) ion source. FEM simulation of magnetic flux density was used to ensure that there is no critical interaction between both magnetic fields of magnetron and ECR ion source. Spatially resolved double Langmuir probe and optical emission spectroscopy measurements show an increase in electron density by one order of magnitude from 1 × 10{sup 10} cm{sup −3} to 1 × 10{sup 11} cm{sup −3}, when the magnetron plasma is exposed to the magnetic mirror field of themore » ECR ion source. Electron density enhancement is also indicated by magnetron plasma emission photography with a CCD camera. Furthermore, photographs visualize the formation of a localized loss-cone - area, when the magnetron is operated at magnetic mirror field conditions. The inverted cylindrical magnetron supplies a metal atom load rate of R > 1 × 10{sup 18} atoms/s for aluminum, which meets the demand for the production of a milliampere Al{sup +} ion beam.« less

The Pulsed Cylindrical Magnetron for Deposition

NASA Astrophysics Data System (ADS)

Korenev, Sergey

2012-10-01

The magnetron sputtering deposition of films and coatings broadly uses in microelectronics, material science, environmental applications and etc. The rate of target evaporation and time for deposition of films and coatings depends on magnetic field. These parameters link with efficiency of gas molecules ionization by electrons. The cylindrical magnetrons use for deposition of films and coatings on inside of pipes for different protective films and coatings in oil, chemical, environmental applications. The classical forming of magnetic field by permanent magnets or coils for big and long cylindrical magnetrons is complicated. The new concept of pulsed cylindrical magnetron for high rate deposition of films and coating for big and long pipes is presented in this paper. The proposed cylindrical magnetron has azimuthally pulsed high magnetic field, which allows forming the high ionized plasma and receiving high rate of evaporation material of target (central electrode). The structure of proposed pulsed cylindrical magnetron sputtering system is given. The main requirements to deposition system are presented. The preliminary data for forming of plasma and deposition of Ta films and coatings on the metal pipers are discussed. The comparison of classical and proposed cylindrical magnetrons is given. The analysis of potential applications is considered.

A Two-stage Injection-locked Magnetron for Accelerators with Superconducting Cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazakevich, Grigory; Flanagan, Gene; Johnson, Rolland

2012-05-01

A concept for a two-stage injection-locked CW magnetron intended to drive Superconducting Cavities (SC) for intensity-frontier accelerators has been proposed. The concept considers two magnetrons in which the output power differs by 15-20 dB and the lower power magnetron being frequency-locked from an external source locks the higher power magnetron. The injection-locked two-stage CW magnetron can be used as an RF power source for Fermilab's Project-X to feed separately each of the 1.3 GHz SC of the 8 GeV pulsed linac. We expect output/locking power ratio of about 30-40 dB assuming operation in a pulsed mode with pulse duration ofmore » ~ 8 ms and repetition rate of 10 Hz. The experimental setup of a two-stage magnetron utilising CW, S-band, 1 kW tubes operating at pulse duration of 1-10 ms, and the obtained results are presented and discussed in this paper.« less

Heavy particle transport in sputtering systems

NASA Astrophysics Data System (ADS)

Trieschmann, Jan

2015-09-01

This contribution aims to discuss the theoretical background of heavy particle transport in plasma sputtering systems such as direct current magnetron sputtering (dcMS), high power impulse magnetron sputtering (HiPIMS), or multi frequency capacitively coupled plasmas (MFCCP). Due to inherently low process pressures below one Pa only kinetic simulation models are suitable. In this work a model appropriate for the description of the transport of film forming particles sputtered of a target material has been devised within the frame of the OpenFOAM software (specifically dsmcFoam). The three dimensional model comprises of ejection of sputtered particles into the reactor chamber, their collisional transport through the volume, as well as deposition of the latter onto the surrounding surfaces (i.e. substrates, walls). An angular dependent Thompson energy distribution fitted to results from Monte-Carlo simulations is assumed initially. Binary collisions are treated via the M1 collision model, a modified variable hard sphere (VHS) model. The dynamics of sputtered and background gas species can be resolved self-consistently following the direct simulation Monte-Carlo (DSMC) approach or, whenever possible, simplified based on the test particle method (TPM) with the assumption of a constant, non-stationary background at a given temperature. At the example of an MFCCP research reactor the transport of sputtered aluminum is specifically discussed. For the peculiar configuration and under typical process conditions with argon as process gas the transport of aluminum sputtered of a circular target is shown to be governed by a one dimensional interaction of the imposed and backscattered particle fluxes. The results are analyzed and discussed on the basis of the obtained velocity distribution functions (VDF). This work is supported by the German Research Foundation (DFG) in the frame of the Collaborative Research Centre TRR 87.

C-axis orientated AlN films deposited using deep oscillation magnetron sputtering

NASA Astrophysics Data System (ADS)

Lin, Jianliang; Chistyakov, Roman

2017-02-01

Highly <0001> c-axis orientated aluminum nitride (AlN) films were deposited on silicon (100) substrates by reactive deep oscillation magnetron sputtering (DOMS). No epitaxial favored bond layer and substrate heating were applied for assisting texture growth. The effects of the peak target current density (varied from 0.39 to 0.8 Acm-2) and film thickness (varied from 0.25 to 3.3 μm) on the c-axis orientation, microstructure, residual stress and mechanical properties of the AlN films were investigated by means of X-ray diffraction rocking curve methodology, transmission electron microscopy, optical profilometry, and nanoindentation. All AlN films exhibited a <0001> preferred orientation and compressive residual stresses. At similar film thicknesses, an increase in the peak target current density to 0.53 Acm-2 improved the <0001> orientation. Further increasing the peak target current density to above 0.53 Acm-2 showed limited contribution to the texture development. The study also showed that an increase in the thickness of the AlN films deposited by DOMS improved the c-axis alignment accompanied with a reduction in the residual stress.

Improvements on the stability and operation of a magnetron H - ion source

DOE PAGES

Sosa, A.; Bollinger, D. S.; Karns, P. R.; ...

2017-05-31

The magnetron H - ion sources developed in the 1970s currently in operation at Fermilab provide beam to the rest of the accelerator complex. A series of modifications to these sources have been tested in a dedicated offline test stand with the aim of improving different operational issues. The solenoid type gas valve was tested as an alternative to the piezoelectric gas valve in order to avoid its temperature dependence. A new cesium oven was designed and tested in order to avoid glass pieces that were present with the previous oven, improve thermal insulation and fine tune its temperature. Amore » current-regulated arc modulator was developed to run the ion source at a constant arc current, providing very stable beam outputs during operations. In order to reduce beam noise, the addition of small amounts of N 2 gas was explored, as well as testing different cathode shapes with increasing plasma volume. This study summarizes the studies and modifications done in the source over the last three years with the aim of improving its stability, reliability and overall performance.« less

Improvements on the stability and operation of a magnetron H- ion source

NASA Astrophysics Data System (ADS)

Sosa, A.; Bollinger, D. S.; Karns, P. R.; Tan, C. Y.

2017-05-01

The magnetron H- ion sources developed in the 1970s currently in operation at Fermilab provide beam to the rest of the accelerator complex. A series of modifications to these sources have been tested in a dedicated off-line test stand with the aim of improving different operational issues. The solenoid type gas valve was tested as an alternative to the piezoelectric gas valve in order to avoid its temperature dependence. A new cesium oven was designed and tested in order to avoid glass pieces that were present with the previous oven, improve thermal insulation and fine-tune its temperature. A current-regulated arc modulator was developed to run the ion source at a constant arc current, providing very stable beam outputs during operations. In order to reduce beam noise, the addition of small amounts of N2 gas was explored, as well as testing different cathode shapes with increasing plasma volume. This paper summarizes the studies and modifications done in the source over the past three years with the aim of improving its stability, reliability and overall performance.

Improvements on the stability and operation of a magnetron H - ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sosa, A.; Bollinger, D. S.; Karns, P. R.

The magnetron H - ion sources developed in the 1970s currently in operation at Fermilab provide beam to the rest of the accelerator complex. A series of modifications to these sources have been tested in a dedicated offline test stand with the aim of improving different operational issues. The solenoid type gas valve was tested as an alternative to the piezoelectric gas valve in order to avoid its temperature dependence. A new cesium oven was designed and tested in order to avoid glass pieces that were present with the previous oven, improve thermal insulation and fine tune its temperature. Amore » current-regulated arc modulator was developed to run the ion source at a constant arc current, providing very stable beam outputs during operations. In order to reduce beam noise, the addition of small amounts of N 2 gas was explored, as well as testing different cathode shapes with increasing plasma volume. This study summarizes the studies and modifications done in the source over the last three years with the aim of improving its stability, reliability and overall performance.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goto, Tetsuya; Matsuoka, Takaaki; Ohmi, Tadahiro

Novel magnetron-sputtering equipment, called rotation magnet sputtering (ROT-MS), was developed to overcome various disadvantages of current magnetron-sputtering equipment. Disadvantages include (1) very low target utilization of less than 20%, (2) difficulty in obtaining uniform deposition on the substrate, and (3) charge-up damages and ion-bombardment-induced damages resulting from very high electron temperature (>3 eV) and that the substrate is set at the plasma excitation region. In ROT-MS, a number of moving high-density plasma loops are excited on the target surface by rotating helical magnets, resulting in very high target utilization with uniform target erosion and uniform deposition on the substrate. Thismore » excellent performance can be principally maintained even if equipment size increases for very large-substrate deposition. Because strong horizontal magnetic fields (>0.05 T) are produced within a very limited region just at the target surface, very low electron-temperature plasmas (<2.5 eV for Ar plasma and <1 eV for direct-current-excited Xe plasma) are excited at the very limited region adjacent to the target surface with a combination of grounded plate closely mounted on the strong magnetic field region. Consequently, the authors can establish charge-up damage-free and ion-bombardment-induced damage-free processes. ROT-MS has been applied for thin-film formation of LaB{sub 6}, which is well known as a stable, low-work-function bulk-crystal material for electron emissions. The work function of the LaB{sub 6} film decreased to 2.8 eV due to enhanced (100)-orientation crystallinity and reduced resistivity realized by adjusting the flux of low-energy bombarding ions impinging on the depositing surface, which work very efficiently, improving the performance of the electron emission devices.« less

Axial distribution of plasma fluctuations, plasma parameters, deposition rate and grain size during copper deposition

NASA Astrophysics Data System (ADS)

Gopikishan, S.; Banerjee, I.; Pathak, Anand; Mahapatra, S. K.

2017-08-01

Floating potential fluctuations, plasma parameters and deposition rate have been investigated as a function of axial distance during deposition of copper in direct current (DC) magnetron sputtering system. Fluctuations were analyzed using phase space, power spectra and amplitude bifurcation plots. It has been observed that the fluctuations are modified from chaotic to ordered state with increase in the axial distance from cathode. Plasma parameters such as electron density (ne), electron temperature (Te) and deposition rate (Dr) were measured and correlated with plasma fluctuations. It was found that more the deposition rate, greater the grain size, higher the electron density, higher the electron temperature and more chaotic the oscillations near the cathode. This observation could be helpful to the thin film technology industry to optimize the required film.

Fabrication and performance analysis of 4-sq cm indium tin oxide/InP photovoltaic solar cells

NASA Technical Reports Server (NTRS)

Gessert, T. A.; Li, X.; Phelps, P. W.; Coutts, T. J.; Tzafaras, N.

1991-01-01

Large-area photovoltaic solar cells based on direct current magnetron sputter deposition of indium tin oxide (ITO) into single-crystal p-InP substrates demonstrated both the radiation hardness and high performance necessary for extraterrestrial applications. A small-scale production project was initiated in which approximately 50 ITO/InP cells are being produced. The procedures used in this small-scale production of 4-sq cm ITO/InP cells are presented and discussed. The discussion includes analyses of performance range of all available production cells, and device performance data of the best cells thus far produced. Additionally, processing experience gained from the production of these cells is discussed, indicating other issues that may be encountered when large-scale productions are begun.

Enhanced Tribocorrosion Performance of Cr/GLC Multilayered Films for Marine Protective Application.

PubMed

Li, Lei; Liu, Lin-Lin; Li, Xiaowei; Guo, Peng; Ke, Peiling; Wang, Aiying

2018-04-18

The corrosion and tribology are all closely related to the interface/surface of materials, which are extremely important for the mechanical components used in harsh marine environments. In this work, we fabricated Cr/graphite-like carbon (GLC) multilayered films with different modulation periods on the 316L stainless steels by direct current magnetron sputtering. Tribocorrosion tests in artificial seawater show that the tribocorrosion resistance of the Cr/GLC films is improved as the modulation period decreases from 1000 to 333 nm and then drastically drops with further decreasing to 250 nm. By taking a top-layer thickening strategy for the Cr/GLC film with 250 nm modulation period, the tribocorrosion performance is significantly enhanced. The corresponded mechanisms are discussed in terms of the film structure and electrochemical corrosion behavior.

Detection of gain enhancement in laser-induced fluorescence of rhodamine B lasing dye by silicon dioxide nanostructures-coated cavity

NASA Astrophysics Data System (ADS)

Al-Tameemi, Mohammed N. A.

2018-03-01

In this work, nanostructured silicon dioxide films are deposited by closed-field unbalanced direct-current (DC) reactive magnetron sputtering technique on two sides of quartz cells containing rhodamine B dye dissolved in ethanol with 10‒5 M concentration as a random gain medium. The preparation conditions are optimized to prepare highly pure SiO2 nanostructures with a minimum particle size of about 20 nm. The effect of SiO2 films as external cavity for the random gain medium is determined by the laser-induced fluorescence of this medium, and an increase of about 200% in intensity is observed after the deposition of nanostructured SiO2 thin films on two sides of the dye cell.

Research Progresses and Suggestions of Manufacturing Technologies of Engine Bearing Bushes

NASA Astrophysics Data System (ADS)

Cao, J.; Yin, Z. W.; Li, H. L.; Y Gao, G.

2017-12-01

Bearing bush is a key part of diesel engine, and its performance directly influences the life of whole machine. Several manufacturing technologies of bearing bush such as centrifugal casting, sintering, electroplating and magnetron sputtering have been overviewed. Their bond strength, porosity, production efficient, layer thickness, frictional coefficient and corresponding materials analyzed and compared. Results show that the porosity and oxidation of sintering and centrifugal casting are higher than that of other two methods. However, the production efficiency and coating thickness are better than that of electroplating and magnetron sputtering. Based on above comparisons and discussions, the improvements of all manufacturing technologies are suggested and supersonic cold spraying is suggested. It is proved that cold spraying technology is the best choice in the future with the developing of low frictional materials.

Boron-rich plasma by high power impulse magnetron sputtering of lanthanum hexaboride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oks, Efim M.; Anders, Andre

2012-10-15

Boron-rich plasmas have been obtained using a LaB{sub 6} target in a high power impulse sputtering (HiPIMS) system. The presence of {sup 10}B{sup +}, {sup 11}B{sup +}, Ar{sup 2+}, Ar{sup +}, La{sup 2+}, and La{sup +} and traces of La{sup 3+}, {sup 12}C{sup +}, {sup 14}N{sup +}, and {sup 16}O{sup +} have been detected using an integrated mass and energy spectrometer. Peak currents as low as 20 A were sufficient to obtain plasma dominated by {sup 11}B{sup +} from a 5 cm planar magnetron. The ion energy distribution function for boron exhibits an energetic tail extending over several 10 eV,more » while argon shows a pronounced peak at low energy (some eV). This is in agreement with models that consider sputtering (B, La) and gas supply (from background and 'recycling'). Strong voltage oscillations develop at high current, greatly affecting power dissipation and plasma properties.« less

Bloch equations applied to ion cyclotron resonance spectroscopy: Broadband interconversion between magnetron and cyclotron motion for ion axialization

NASA Astrophysics Data System (ADS)

Guan, Shenheng; Marshall, Alan G.

1993-03-01

Conversion of magnetron motion to cyclotron motion combined with collisional cooling of the cyclotron motion provides an efficient way to reduce the kinetic energy of trapped heavy ions and to reduce their magnetron radii in an ion cyclotron resonance (ICR) ion trap. The coupling of magnetron and cyclotron motion can be realized by azimuthal quadrupolar excitation. Theoretical understanding of the coupling process has until now been based on resonant single-frequency quadrupolar excitation at the combination frequency ωc=ω++ω-, in which ωc is the ion cyclotron orbital frequency in the absence of electrostatic field; and ω+ and ω- are the reduced cyclotron and magnetron frequencies in the presence of an electrostatic trapping potential. In this work, we prove that the magnetron/cyclotron coupling is closely related to a two energy level system whose behavior is described by the well-known Bloch equations. By means of a special transformation, the equations of motion for the coupling may be expressed in Bloch-type equations in spherical coordinates. We show that magnetron-to-cyclotron conversion by single-frequency quadrupolar excitation in ICR is analogous to a 180° pulse in nuclear magnetic resonance (NMR). We go on to show that simultaneous magnetron-to-cyclotron conversion of ions over a finite mass-to-charge ratio range may be produced by quadrupolar frequency-sweep excitation, by analogy to adiabatic rapid passage in magnetic resonance. Axialization by broadband magnetron-to-cyclotron conversion followed by cyclotron cooling is successfully demonstrated experimentally for a crude oil distillate sample.

Method and apparatus for improved high power impulse magnetron sputtering

DOEpatents

Anders, Andre

2013-11-05

A high power impulse magnetron sputtering apparatus and method using a vacuum chamber with a magnetron target and a substrate positioned in the vacuum chamber. A field coil being positioned between the magnetron target and substrate, and a pulsed power supply and/or a coil bias power supply connected to the field coil. The pulsed power supply connected to the field coil, and the pulsed power supply outputting power pulse widths of greater that 100 .mu.s.

Tutorial: Reactive high power impulse magnetron sputtering (R-HiPIMS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anders, André

High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. Furthermore, by applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films.more » Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become “poisoned,” i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron sputtering.« less

Tutorial: Reactive high power impulse magnetron sputtering (R-HiPIMS)

DOE PAGES

Anders, André

2017-03-21

High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. Furthermore, by applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films.more » Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become “poisoned,” i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron sputtering.« less

Tutorial: Reactive high power impulse magnetron sputtering (R-HiPIMS)

NASA Astrophysics Data System (ADS)

Anders, André

2017-05-01

High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. By applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films. Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become "poisoned," i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron sputtering.

Study of a non-equilibrium plasma pinch with application for microwave generation

NASA Astrophysics Data System (ADS)

Al Agry, Ahmad Farouk

The Non-Equilibrium Plasma Pinch (NEPP), also known as the Dense Plasma Focus (DPF) is well known as a source of energetic ions, relativistic electrons and neutrons as well as electromagnetic radiation extending from the infrared to X-ray. In this dissertation, the operation of a 15 kJ, Mather type, NEPP machine is studied in detail. A large number of experiments are carried out to tune the machine parameters for best performance using helium and hydrogen as filling gases. The NEPP machine is modified to be able to extract the copious number of electrons generated at the pinch. A hollow anode with small hole at the flat end, and a mock magnetron without biasing magnetic field are built. The electrons generated at the pinch are very difficult to capture, therefore a novel device is built to capture and transport the electrons from the pinch to the magnetron. The novel cup-rod-needle device successfully serves the purpose to capture and transport electrons to monitor the pinch current. Further, the device has the potential to field emit charges from its needle end acting as a pulsed electron source for other devices such as the magnetron. Diagnostics tools are designed, modeled, built, calibrated, and implemented in the machine to measure the pinch dynamics. A novel, UNLV patented electromagnetic dot sensors are successfully calibrated, and implemented in the machine. A new calibration technique is developed and test stands designed and built to measure the dot's ability to track the impetus signal over its dynamic range starting and ending in the noise region. The patented EM-dot sensor shows superior performance over traditional electromagnetic sensors, such as Rogowski coils. On the other hand, the cup-rod structure, when grounded on the rod side, serves as a diagnostic tool to monitor the pinch current by sampling the actual current, a quantity that has been always very challenging to measure without perturbing the pinch. To the best of our knowledge, this method of measuring the pinch current is unique and has never been done before. Agreement with other models is shown. The operation of the NEPP machine with the hole in the center of the anode and the magnetron connected including the cup-rod structure is examined against the NEPP machine signature with solid anode. Both cases showed excellent agreement. This suggests that the existence of the hole and the diagnostic tool inside the anode have negligible effects on the pinch.

Characterization of Magnetron Sputtered Copper-Nickel Thin Film and Alloys

DTIC Science & Technology

2016-09-01

ARL-TR-7783 ● SEP 2016 US Army Research Laboratory Characterization of Magnetron Sputtered Copper-Nickel Thin Films and Alloys...TR-7783 ● SEP 2016 US Army Research Laboratory Characterization of Magnetron Sputtered Copper-Nickel Thin Films and Alloys by Eugene...

Microstructure of ZnO Thin Films Deposited by High Power Impulse Magnetron Sputtering (Postprint)

DTIC Science & Technology

2015-03-01

AFRL-RX-WP-JA-2015-0185 MICROSTRUCTURE OF ZNO THIN FILMS DEPOSITED BY HIGH POWER IMPULSE MAGNETRON SPUTTERING (POSTPRINT) A. N. Reed...COVERED (From – To) 29 January 2013 – 16 February 2015 4. TITLE AND SUBTITLE MICROSTRUCTURE OF ZNO THIN FILMS DEPOSITED BY HIGH POWER IMPULSE MAGNETRON...ABSTRACT High power impulse magnetron sputtering was used to deposit thin (~100 nm) zinc oxide (ZnO) films from a ceramic ZnO target onto substrates

Negative hydrogen ion sources for accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moehs, D.P.; /Fermilab; Peters, J.

2005-08-01

A variety of H{sup -} ion sources are in use at accelerator laboratories around the world. A list of these ion sources includes surface plasma sources with magnetron, Penning and surface converter geometries as well as magnetic-multipole volume sources with and without cesium. Just as varied is the means of igniting and maintaining magnetically confined plasmas. Hot and cold cathodes, radio frequency, and microwave power are all in use, as well as electron tandem source ignition. The extraction systems of accelerator H{sup -} ion sources are highly specialized utilizing magnetic and electric fields in their low energy beam transport systemsmore » to produce direct current, as well as pulsed and/or chopped beams with a variety of time structures. Within this paper, specific ion sources utilized at accelerator laboratories shall be reviewed along with the physics of surface and volume H{sup -} production in regard to source emittance. Current research trends including aperture modeling, thermal modeling, surface conditioning, and laser diagnostics will also be discussed.« less

Modelling of the reactive sputtering process with non-uniform discharge current density and different temperature conditions

NASA Astrophysics Data System (ADS)

Vašina, P; Hytková, T; Eliáš, M

2009-05-01

The majority of current models of the reactive magnetron sputtering assume a uniform shape of the discharge current density and the same temperature near the target and the substrate. However, in the real experimental set-up, the presence of the magnetic field causes high density plasma to form in front of the cathode in the shape of a toroid. Consequently, the discharge current density is laterally non-uniform. In addition to this, the heating of the background gas by sputtered particles, which is usually referred to as the gas rarefaction, plays an important role. This paper presents an extended model of the reactive magnetron sputtering that assumes the non-uniform discharge current density and which accommodates the gas rarefaction effect. It is devoted mainly to the study of the behaviour of the reactive sputtering rather that to the prediction of the coating properties. Outputs of this model are compared with those that assume uniform discharge current density and uniform temperature profile in the deposition chamber. Particular attention is paid to the modelling of the radial variation of the target composition near transitions from the metallic to the compound mode and vice versa. A study of the target utilization in the metallic and compound mode is performed for two different discharge current density profiles corresponding to typical two pole and multipole magnetics available on the market now. Different shapes of the discharge current density were tested. Finally, hysteresis curves are plotted for various temperature conditions in the reactor.

Crystallization of Sr0.5Ba0.5Nb2O6 Thin Films on LaNiO3 Electrodes by RF Magnetron Reactive Sputtering

NASA Astrophysics Data System (ADS)

Jong, Chao-An; Gan, Jon-Yiew

2000-02-01

Strontium barium niobium (Sr0.5Ba0.5Nb2O6) (SBN) thin films are prepared on conductive-oxide LNO (LaNiO3) electrodes by the rf magnetron sputtering system. Instead of conventional furnace annealing, SBN thin films are crystallized by rapid thermal annealing (RTA) above 700°C for 5 min. The textured SBN films are crystallized with two orientations: one is the (001) or (310) direction, and the other is the (002) or (620) direction. Films compositions measured by the electron spectroscopy of chemical analysis (ESCA) quantitative analysis method show nearly the same stoichiometric ratio as the target. The depth profiles of SBN films and the target are examined by secondary ion mass spectrometer (SIMS). The concentrations of the films are quite uniform. After being heat treated at 800°C for 5 min by RTA, La and Ni diffuse into the SBN film. The diffusion coefficient of La in SBN films is also calculated.

Cathode Priming vs. RF Priming for Relativistic Magnetrons

NASA Astrophysics Data System (ADS)

White, W. M.; Spencer, T. A.; Price, D.

2005-10-01

Magnetron start-oscillation time, pulsewidth and pi-mode locking are experimentally compared for RF priming versus cathode priming on the Michigan-Titan relativistic magnetron (-300 kV, 2-10 kA, 300-500 ns). Cathode priming [1, 2] is an innovative technique first demonstrated experimentally at UM. In this technique, the cathode is fabricated with N/2 emitting strips or N/2-separate cathodes (for an N-cavity magnetron), which generate the desired number of spokes for pi-mode. Cathode priming yields 13% faster startup with more reproducible pi-mode oscillation. Radio Frequency (RF) priming is investigated as the baseline priming technique for magnetrons. The external priming source is a 100kW, 3μs pulsewidth magnetron on loan from AFRL. RF priming reduced startup delay by 15% and increased pulsewidth by 9%. [1] M.C. Jones, V.B. Neculaes, R.M. Gilgenbach, W.M. White, M.R. Lopez, Y.Y. Lau, T.A. Spencer, and D. Price, Rev. Sci. Inst., 75, 2976 (2004) [2] M.C. Jones, Doctoral Dissertation, University of Michigan, 2005

Synthesis and properties of CS x F y thin films deposited by reactive magnetron sputtering in an Ar/SF6 discharge

NASA Astrophysics Data System (ADS)

Lai, Chung-Chuan; Goyenola, Cecilia; Broitman, Esteban; Näslund, Lars-Åke; Högberg, Hans; Hultman, Lars; Gueorguiev, Gueorgui K.; Rosen, Johanna

2017-05-01

A theoretical and experimental study on the growth and properties of a ternary carbon-based material, CS x F y , synthesized from SF6 and C as primary precursors is reported. The synthetic growth concept was applied to model the possible species resulting from the fragmentation of SF6 molecules and the recombination of S-F fragments with atomic C. The possible species were further evaluated for their contribution to the film growth. Corresponding solid CS x F y thin films were deposited by reactive direct current magnetron sputtering from a C target in a mixed Ar/SF6 discharge with different SF6 partial pressures ({{P}\\text{S{{\\text{F}}\\text{6}}}} ). Properties of the films were determined by x-ray photoelectron spectroscopy, x-ray reflectivity, and nanoindentation. A reduced mass density in the CS x F y films is predicted due to incorporation of precursor species with a more pronounced steric effect, which also agrees with the low density values observed for the films. Increased {{P}\\text{S{{\\text{F}}\\text{6}}}} leads to decreasing deposition rate and increasing density, as explained by enhanced fluorination and etching on the deposited surface by a larger concentration of F/F2 species during the growth, as supported by an increment of the F relative content in the films. Mechanical properties indicating superelasticity were obtained from the film with lowest F content, implying a fullerene-like structure in CS x F y compounds.

Growth (AlCrNbSiTiV)N thin films on the interrupted turning and properties using DCMS and HIPIMS system

NASA Astrophysics Data System (ADS)

Chang, Kai-Sheng; Chen, Kuan-Ta; Hsu, Chun-Yao; Hong, Po-Da

2018-05-01

This paper determines the optimal settings in the deposition parameters for (AlCrNbSiTiV)N high-entropy alloy (HEAs) nitride films that are deposited on CBN cutting tools and glass substrates. We use direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HIPIMS), with Ar plasma and N2 reactive gases. Experiments with the grey-Taguchi method are conducted to determine the effect of deposition parameters (deposition time, substrate DC bias, DC power and substrate temperature) on interrupted turning 50CrMo4 steel machining and the films' structural properties. Experimental result shows that the multiple performance characteristics for these (AlCrNbSiTiV)N HEAs film coatings can be improved using the grey-Taguchi method. As can be seen, the coated film is homogeneous, very compact and exhibits perfect adherence to the substrate. The distribution of elements is homogeneous through the depth of the (AlCrNbSiTiV)N film, as measured by an auger electron nanoscope. After interrupted turning with an (AlCrNbSiTiV)N film coated tool, we obtain much longer tool life than when using uncoated tools. The correlation of these results with microstructure analysis and tool life indicates that HIPIMS discharge induced a higher (AlCrNbSiTiV)N film density, a smoother surface structure and a higher hardness surface.

Structural and morphological properties of ITO thin films grown by magnetron sputtering

NASA Astrophysics Data System (ADS)

Ghorannevis, Z.; Akbarnejad, E.; Ghoranneviss, M.

2015-10-01

Physical properties of transparent and conducting indium tin oxide (ITO) thin films grown by radiofrequency (RF) magnetron sputtering are studied systematically by changing deposition time. The X-ray diffraction (XRD) data indicate polycrystalline thin films with grain orientations predominantly along the (2 2 2) and (4 0 0) directions. From atomic force microscopy (AFM) it is found that by increasing the deposition time, the roughness of the film increases. Scanning electron microscopy (SEM) images show a network of a high-porosity interconnected nanoparticles, which approximately have a pore size ranging between 20 and 30 nm. Optical measurements suggest an average transmission of 80 % for the ITO films. Sheet resistances are investigated using four-point probes, which imply that by increasing the film thickness the resistivities of the films decrease to 2.43 × 10-5 Ω cm.

Strong Orientation-Dependent Spin-Orbit Torque in Thin Films of the Antiferromagnet Mn2Au

NASA Astrophysics Data System (ADS)

Zhou, X. F.; Zhang, J.; Li, F.; Chen, X. Z.; Shi, G. Y.; Tan, Y. Z.; Gu, Y. D.; Saleem, M. S.; Wu, H. Q.; Pan, F.; Song, C.

2018-05-01

Antiferromagnets with zero net magnetic moment, strong anti-interference, and ultrafast switching speed are potentially competitive in high-density information storage. The body-centered tetragonal antiferromagnet Mn2Au with opposite-spin sublattices is a unique metallic material for Néel-order spin-orbit-torque (SOT) switching. We investigate the SOT switching in quasiepitaxial (103), (101) and (204) Mn2Au films prepared by a simple magnetron sputtering method. We demonstrate current-induced antiferromagnetic moment switching in all of the prepared Mn2Au films by using a short current pulse at room temperature, whereas differently oriented films exhibit distinguished switching characters. A direction-independent reversible switching is attained in Mn2Au (103) films due to negligible magnetocrystalline anisotropy energy, while for Mn2Au (101) and (204) films, the switching is invertible with the current applied along the in-plane easy axis and its vertical axis, but it becomes attenuated seriously during initial switching circles when the current is applied along the hard axis because of the existence of magnetocrystalline anisotropy energy. Besides the fundamental significance, the strong orientation-dependent SOT switching, which is not realized, irrespective of ferromagnet and antiferromagnet, provides versatility for spintronics.

A Compact, Pi-Mode Extraction Scheme for the Axial B-Field Recirculating Planar Magnetron

DTIC Science & Technology

2012-07-23

Figure 4). Thus, in a planar magnetron, the minimum phase velocity, vph , to stay above cutoff in the rectangular waveguide is ℎ = ...as magnetrons, electrons must be accelerated such that they are in synchronism with the phase velocity, vph , of the electromagnetic wave for an

Influence of ionisation zone motion in high power impulse magnetron sputtering on angular ion flux and NbO x film growth

DOE PAGES

Franz, Robert; Clavero, César; Kolbeck, Jonathan; ...

2016-01-21

Here, the ion energies and fluxes in the high power impulse magnetron sputtering plasma from a Nb target were analysed angularly resolved along the tangential direction of the racetrack. A reactive oxygen-containing atmosphere was used as such discharge conditions are typically employed for the synthesis of thin films. Asymmetries in the flux distribution of the recorded ions as well as their energies and charge states were noticed when varying the angle between mass-energy analyser and target surface. More positively charged ions with higher count rates in the medium energy range of their distributions were detected in +E x B thanmore » in -E x B direction, thus confirming the notion that ionisation zones (also known as spokes or plasma bunches) are associated with moving potential humps. The motion of the recorded negatively charged high-energy oxygen ions was unaffected. NbO x thin films at different angles and positions were synthesised and analysed as to their structure and properties in order to correlate the observed plasma properties to the film growth conditions. The chemical composition and the film thickness varied with changing deposition angle, where the latter, similar to the ion fluxes, was higher in +E x B than in -E x B direction.« less

Phosphorus Doping Effect in a Zinc Oxide Channel Layer to Improve the Performance of Oxide Thin-Film Transistors

NASA Astrophysics Data System (ADS)

Han, Dong-Suk; Moon, Yeon-Keon; Lee, Sih; Kim, Kyung-Taek; Moon, Dae-Yong; Lee, Sang-Ho; Kim, Woong-Sun; Park, Jong-Wan

2012-09-01

In this study, we fabricated phosphorus-doped zinc oxide-based thin-film transistors (TFTs) using direct current (DC) magnetron sputtering at a relatively low temperature of 100°C. To improve the TFT device performance, including field-effect mobility and bias stress stability, phosphorus dopants were employed to suppress the generation of intrinsic defects in the ZnO-based semiconductor. The positive and negative bias stress stabilities were dramatically improved by introducing the phosphorus dopants, which could prevent turn-on voltage ( V ON) shift in the TFTs caused by charge trapping within the active channel layer. The study showed that phosphorus doping in ZnO was an effective method to control the electrical properties of the active channel layers and improve the bias stress stability of oxide-based TFTs.

Structural, electrical, optical and magnetic properties of NiO/ZnO thin films

NASA Astrophysics Data System (ADS)

Sushmitha, V.; Maragatham, V.; Raj, P. Deepak; Sridharan, M.

2018-02-01

Nickel oxide/Zinc oxide (NiO/ZnO) thin films have been deposited onto thoroughly cleaned glass substrates by reactive direct current (DC) magnetron sputtering technique and subsequently annealed at 300 °C for 3 h in vacuum. The NiO/ZnO thin films were then studied for their structural, optical and electrical properties. X-ray diffraction (XRD) pattern of ZnO and NiO showed the diffraction planes corresponding to hexagonal and cubic phase respectively. The optical properties showed that with the increase in the deposition time of NiO the energy band gap varied between 3.1 to 3.24 eV. Hence, by changing the deposition time of NiO the tuning of band gap and conductivity were achieved. The magnetic studies revealed the diamagnetic nature of the NiO/ZnO thin films.

Sputtered deposited nanocrystalline ZnO films: A correlation between electrical, optical and microstructural properties

NASA Astrophysics Data System (ADS)

Lee, J.; Gao, W.; Li, Z.; Hodgson, M.; Metson, J.; Gong, H.; Pal, U.

2005-05-01

Zinc oxide thin films were prepared by dc (direct current) and rf (radio frequency) magnetron sputtering on glass substrates. ZnO films produced by dc sputtering have a high resistance, while the films produced using rf sputtering are significantly more conductive. While the conductive films have a compact nodular surface morphology, the resistive films have a relatively porous surface with columnar structures in cross section. Compared to the dc sputtered films, rf sputtered films have a microstructure with smaller d spacing, lower internal stress, higher band gap energy and higher density. Dependence of conductivity on the deposition technique and the resulting d spacing , stress, density, band gap, film thickness and Al doping are discussed. Correlations between the electrical conductivity, microstructural parameters and optical properties of the films have been made.

Cyclic voltammetry on sputter-deposited films of electrochromic Ni oxide: Power-law decay of the charge density exchange

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, Rui-Tao, E-mail: Ruitao.Wen@angstrom.uu.se; Granqvist, Claes G.; Niklasson, Gunnar A.

2014-10-20

Ni-oxide-based thin films were produced by reactive direct-current magnetron sputtering and were characterized by X-ray diffraction and Rutherford backscattering spectroscopy. Intercalation of Li{sup +} ions was accomplished by cyclic voltammetry (CV) in an electrolyte of LiClO{sub 4} in propylene carbonate, and electrochromism was documented by spectrophotometry. The charge density exchange, and hence the optical modulation span, decayed gradually upon repeated cycling. This phenomenon was accurately described by an empirical power law, which was valid for at least 10{sup 4} cycles when the applied voltage was limited to 4.1 V vs Li/Li{sup +}. Our results allow lifetime assessments for one of themore » essential components in an electrochromic device such as a “smart window” for energy-efficient buildings.« less

Inactivation of bacteria under visible light and in the dark by Cu films. Advantages of Cu-HIPIMS-sputtered films.

PubMed

Ehiasarian, A; Pulgarin, Cesar; Kiwi, John

2012-11-01

The Cu polyester thin-sputtered layers on textile fabrics show an acceptable bacterial inactivation kinetics using sputtering methods. Direct current magnetron sputtering (DCMS) for 40 s of Cu on cotton inactivated Escherichia coli within 30 min under visible light and within 120 min in the dark. For a longer DCMS time of 180 s, the Cu content was 0.294% w/w, but the bacterial inactivation kinetics under light was observed within 30 min, as was the case for the 40-s sputtered sample. This observation suggests that Cu ionic species play a key role in the E. coli inactivation and these species were further identified by X-ray photoelectron spectroscopy (XPS). The 40-s sputtered samples present the highest amount of Cu sites held in exposed positions interacting on the cotton with E. coli. Cu DC magnetron sputtering leads to thin metallic semi-transparent gray-brown Cu coating composed by Cu nanoparticulate in the nanometer range as found by electron microscopy (EM). Cu cotton fabrics were also functionalized by bipolar asymmetric DCMSP. Sputtering by DCMS and DCMSP for longer times lead to darker and more compact Cu films as detected by diffuse reflectance spectroscopy and EM. Cu is deposited on the polyester in the form of Cu(2)O and CuO as quantified by XPS. The redox interfacial reactions during bacterial inactivation involve changes in the Cu oxidation states and in the oxidation intermediates and were followed by XPS. High-power impulse magnetron sputtering (HIPIMS)-sputtered films show a low rugosity indicating that the texture of the Cu nanoparticulate films were smooth. The values of R (q) and R (a) were similar before and after the E. coli inactivation providing evidence for the stability of the HIPIMS-deposited Cu films. The Cu loading percentage required in the Cu films sputtered by HIPIMS to inactivate E. coli was about three times lower compared to DCMS films. This indicates a substantial Cu metal savings within the preparation of antibacterial films.

Pulsing frequency induced change in optical constants and dispersion energy parameters of WO{sub 3} films grown by pulsed direct current magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Punitha, K.; Sivakumar, R., E-mail: krsivakumar1979@yahoo.com; Sanjeeviraja, C.

2014-03-21

In this work, we present the pulsing frequency induced change in the structural, optical, vibrational, and luminescence properties of tungsten oxide (WO{sub 3}) thin films deposited on microscopic glass and fluorine doped tin oxide (SnO{sub 2}:F) coated glass substrates by pulsed dc magnetron sputtering technique. The WO{sub 3} films deposited on SnO{sub 2}:F substrate belongs to monoclinic phase. The pulsing frequency has a significant influence on the preferred orientation and crystallinity of WO{sub 3} film. The maximum optical transmittance of 85% was observed for the film and the slight shift in transmission threshold towards higher wavelength region with increasing pulsingmore » frequency revealed the systematic reduction in optical energy band gap (3.78 to 3.13 eV) of the films. The refractive index (n) of films are found to decrease (1.832 to 1.333 at 550 nm) with increasing pulsing frequency and the average value of extinction coefficient (k) is in the order of 10{sup −3}. It was observed that the dispersion data obeyed the single oscillator of the Wemple-Didomenico model, from which the dispersion energy (E{sub d}) parameters, dielectric constants, plasma frequency, oscillator strength, and oscillator energy (E{sub o}) of WO{sub 3} films were calculated and reported for the first time due to variation in pulsing frequency during deposition by pulsed dc magnetron sputtering. The E{sub o} is change between 6.30 and 3.88 eV, while the E{sub d} varies from 25.81 to 7.88 eV, with pulsing frequency. The Raman peak observed at 1095 cm{sup −1} attributes the presence of W-O symmetric stretching vibration. The slight shift in photoluminescence band is attributed to the difference in excitons transition. We have made an attempt to discuss and correlate these results with the light of possible mechanisms underlying the phenomena.« less

Efficient planar n-i-p type heterojunction flexible perovskite solar cells with sputtered TiO2 electron transporting layers.

PubMed

Mali, Sawanta S; Hong, Chang Kook; Inamdar, A I; Im, Hyunsik; Shim, Sang Eun

2017-03-02

The development of hybrid organo-lead trihalide perovskite solar cells (PSCs) comprising an electron transporting layer (ETL), a perovskite light absorber and a hole transporting layer (HTL) has received significant attention for their potential in efficient PSCs. However, the preparation of a compact and uniform ETL and the formation of a uniform light absorber layer suffer from a high temperature processing treatment and the formation of unwanted perovskite islands, respectively. A low temperature/room temperature processed ETL is one of the best options for the fabrication of flexible PSCs. In the present work, we report the implementation of a room temperature processed compact TiO 2 ETL and the synthesis of extremely uniform flexible planar PSCs based on methylammonium lead mixed halides MAPb(I 1-x Br x ) 3 (x = 0.1) via RF-magnetron sputtering and a toluene dripping treatment, respectively. The compact TiO 2 ETLs with different thicknesses (30 to 100 nm) were directly deposited on a flexible PET coated ITO substrate by varying the RF-sputtering time and used for the fabrication of flexible PSCs. The photovoltaic properties revealed that flexible PSC performance is strongly dependent on the TiO 2 ETL thickness. The open circuit voltage (V OC ) and fill factor (FF) are directly proportional to the TiO 2 ETL thickness while the 50 nm thick TiO 2 ETL shows the highest current density (J SC ) of 20.77 mA cm -2 . Our controlled results reveal that the room temperature RF-magnetron sputtered 50 nm-thick TiO 2 ETL photoelectrode exhibits a power conversion efficiency (PCE) in excess of 15%. The use of room temperature synthesis of the compact TiO 2 ETL by RF magnetron sputtering results in an enhancement of the device performance for cells prepared on flexible substrates. The champion flexible planar PSC based on this architecture exhibited a promising power conversion efficiency as high as 15.88%, featuring a high FF of 0.69 and V OC of 1.108 V with a negligible hysteresis under AM 1.5 G illumination. Furthermore, the mechanical bending stability revealed that the fabricated devices show stable PCE up to 200 bending cycles. The interface properties revealed that the 50 nm thick TiO 2 ETL provides superior charge injection characteristics and low internal resistance. The present work provides a simplistic and reliable approach for the fabrication of highly efficient stable flexible perovskite solar cells.

Device for timing and power level setting for microwave applications

NASA Astrophysics Data System (ADS)

Ursu, M.-P.; Buidoş, T.

2016-08-01

Nowadays, the microwaves are widely used for various technological processes. The microwaves are emitted by magnetrons, which have strict requirements concerning power supplies for anode and filament cathodes, intensity of magnetic field, cooling and electromagnetic shielding. The magnetrons do not tolerate any alteration of their required voltages, currents and magnetic fields, which means that their output microwave power is fixed, so the only way to alter the power level is to use time-division, by turning the magnetron on and off by repetitive time patterns. In order to attain accurate and reproducible results, as well as correct and safe operation of the microwave device, all these requirements must be fulfilled. Safe, correct and reproducible operation of the microwave appliance can be achieved by means of a specially built electronic device, which ensures accurate and reproducible exposure times, interlocking of the commands and automatic switch off when abnormal operating conditions occur. This driving device, designed and realized during the completion of Mr.Ursu's doctoral thesis, consists of a quartz time-base, several programmable frequency and duration dividers, LED displays, sensors and interlocking gates. The active and passive electronic components are placed on custom-made PCB's, designed and made by means of computer-aided applications and machines. The driving commands of the electronic device are delivered to the magnetron power supplies by means of optic zero-passing relays. The inputs of the electronic driving device can sense the status of the microwave appliance. The user is able to enter the total exposure time, the division factor that sets the output power level and, as a novelty, the clock frequency of the time divider.

A novel injection-locked amplitude-modulated magnetron at 1497 MHz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neubauer, Michael; Wang, Haipeng

2015-12-15

Thomas Jefferson National Accelerator Facility (JLab) uses low efficiency klystrons in the CEBAF machine. In the older portion they operate at 30% efficiency with a tube mean time between failure (MTBF) of five to six years. A highly efficient source (>55-60%) must provide a high degree of backwards compatibility, both in size and voltage requirements, to replace the klystron presently used at JLab, while providing energy savings. Muons, Inc. is developing a highly reliable, highly efficient RF source based upon a novel injection-locked amplitude modulated (AM) magnetron with a lower total cost of ownership, >80% efficiency, and MTBF of sixmore » to seven years. The design of the RF source is based upon a single injection-locked magnetron system at 8 kW capable of operating up to 13 kW, using the magnetron magnetic field to achieve the AM required for backwards compatibility to compensate for microphonics and beam loads. A novel injection-locked 1497 MHz 8 kW AM magnetron with a trim magnetic coil was designed and its operation numerically simulated during the Phase I project. The low-level RF system to control the trim field and magnetron anode voltage was designed and modeled for operation at the modulation frequencies of the microphonics. A plan for constructing a prototype magnetron and control system was developed.« less

Structural and tribological properties of CrTiAlN coatings on Mg alloy by closed-field unbalanced magnetron sputtering ion plating

NASA Astrophysics Data System (ADS)

Shi, Yongjing; Long, Siyuan; Yang, Shicai; Pan, Fusheng

2008-09-01

In this paper, a series of multi-layer hard coating system of CrTiAlN has been prepared by closed-field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique in a gas mixture of Ar + N 2. The coatings were deposited onto AZ31 Mg alloy substrates. During deposition step, technological temperature and metallic atom concentration of coatings were controlled by adjusting the currents of different metal magnetron targets. The nitrogen level was varied by using the feedback control of plasma optical emission monitor (OEM). The structural, mechanical and tribological properties of coatings were characterized by means of X-ray photoelectron spectrometry, high-resolution transmission electron microscope, field emission scanning electron microscope (FESEM), micro-hardness tester, and scratch and ball-on-disc tester. The experimental results show that the N atomic concentration increases and the oxide on the top of coatings decreases; furthermore the modulation period and the friction coefficient decrease with the N 2 level increasing. The outstanding mechanical property can be acquired at medium N 2 level, and the CrTiAlN coatings on AZ31 Mg alloy substrates outperform the uncoated M42 high speed steel (HSS) and the uncoated 316 stainless steel (SS).

Investigation of Influence of Gas Ratio on the Electron Temperature in TiN Magnetron Sputtering Deposition System

DTIC Science & Technology

2013-07-01

31st ICPIG, July 14-19, 2013, Granada , Spain Investigation of Influence of Gas Ratio on the Electron Temperature in TiN Magnetron Sputtering...ICPIG) Held in Granada , Spain on 14-19 July 2013 14. ABSTRACT In this work, a nanolayer of titanium nitride which produced by the magnetron

Theory of injection locking and rapid start-up of magnetrons, and effects of manufacturing errors in terahertz traveling wave tubes

NASA Astrophysics Data System (ADS)

Pengvanich, Phongphaeth

In this thesis, several contemporary issues on coherent radiation sources are examined. They include the fast startup and the injection locking of microwave magnetrons, and the effects of random manufacturing errors on phase and small signal gain of terahertz traveling wave amplifiers. In response to the rapid startup and low noise magnetron experiments performed at the University of Michigan that employed periodic azimuthal perturbations in the axial magnetic field, a systematic study of single particle orbits is performed for a crossed electric and periodic magnetic field. A parametric instability in the orbits, which brings a fraction of the electrons from the cathode toward the anode, is discovered. This offers an explanation of the rapid startup observed in the experiments. A phase-locking model has been constructed from circuit theory to qualitatively explain various regimes observed in kilowatt magnetron injection-locking experiments, which were performed at the University of Michigan. These experiments utilize two continuous-wave magnetrons; one functions as an oscillator and the other as a driver. Time and frequency domain solutions are developed from the model, allowing investigations into growth, saturation, and frequency response of the output. The model qualitatively recovers many of the phase-locking frequency characteristics observed in the experiments. Effects of frequency chirp and frequency perturbation on the phase and lockability have also been quantified. Development of traveling wave amplifier operating at terahertz is a subject of current interest. The small circuit size has prompted a statistical analysis of the effects of random fabrication errors on phase and small signal gain of these amplifiers. The small signal theory is treated with a continuum model in which the electron beam is monoenergetic. Circuit perturbations that vary randomly along the beam axis are introduced through the dimensionless Pierce parameters describing the beam-wave velocity mismatch (b), the gain parameter (C), and the cold tube circuit loss ( d). Our study shows that perturbation in b dominates the other two in terms of power gain and phase shift. Extensive data show that standard deviation of the output phase is linearly proportional to standard deviation of the individual perturbations in b, C and d.

Development of an inductively coupled impulse sputtering source for coating deposition

NASA Astrophysics Data System (ADS)

Loch, Daniel Alexander Llewellyn

In recent years, highly ionised pulsed plasma processes have had a great impact on improving the coating performance of various applications, such as for cutting tools and ITO coatings, allowing for a longer service life and improved defect densities. These improvements stem from the higher ionisation degree of the sputtered material in these processes and with this the possibility of controlling the flux of sputtered material, allowing the regulation of the hardness and density of coatings and the ability to sputter onto complex contoured substrates. The development of Inductively Coupled Impulse Sputtering (ICIS) is aimed at the potential of utilising the advantages of highly ionised plasma for the sputtering of ferromagnetic material. In traditional magnetron based sputter processes ferromagnetic materials would shunt the magnetic field of the magnetron, thus reducing the sputter yield and ionisation efficiency. By generating the plasma within a high power pulsed radio frequency (RF) driven coil in front of the cathode, it is possible to remove the need for a magnetron by applying a high voltage pulsed direct current to the cathode attracting argon ions from the plasma to initiate sputtering. This is the first time that ICIS technology has been deployed in a sputter coating system. To study the characteristics of ICIS, current and voltage waveforms have been measured to examine the effect of increasing RF-power. Plasma analysis has been conducted by optical emission spectroscopy to investigate the excitation mechanisms and the emission intensity. These are correlated to the set RF-power by modelling assumptions based on electron collisions. Mass spectroscopy is used to measure the plasma potential and ion energy distribution function. Pure copper, titanium and nickel coatings have been deposited on silicon with high aspect ratio via to measure the deposition rate and characterise the microstructure. For titanium and nickel the emission modelling results are in good agreement with the model expectations showing that electron collisions are the main excitation mechanism. The plasma potential was measured as 20 eV, this is an ideal level for good adatom mobility with reduced lattice defects. All surfaces in the via were coated, perpendicular column growth on the sidewalls indicates a predominantly ionised metal flux to the substrate and the deposition rates agree with the literature value of the sputter yield of the materials. The results of the studies show that ICIS is a viable process for the deposition of magnetic coatings with high ionisation in the plasma.

Effect of thickness on optoelectrical properties of Nb-doped indium tin oxide thin films deposited by RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Li, Shi-na; Ma, Rui-xin; Ma, Chun-hong; Li, Dong-ran; Xiao, Yu-qin; He, Liang-wei; Zhu, Hong-min

2013-05-01

Niobium-doped indium tin oxide (ITO:Nb) thin films are prepared on glass substrates with various film thicknesses by radio frequency (RF) magnetron sputtering from one piece of ceramic target material. The effects of thickness (60-360 nm) on the structural, electrical and optical properties of ITO: Nb films are investigated by means of X-ray diffraction (XRD), ultraviolet (UV)-visible spectroscopy, and electrical measurements. XRD patterns show the highly oriented (400) direction. The lowest resistivity of the films without any heat treatment is 3.1×10-4Ω·cm-1, and the resistivity decreases with the increase of substrate temperature. The highest Hall mobility and carrier concentration are 17.6 N·S and 1.36×1021 cm-3, respectively. Band gap energy of the films depends on substrate temperature, which varies from 3.48 eV to 3.62 eV.

Spectroscopic ellipsometry investigation of the optical properties of graphene oxide dip-coated on magnetron sputtered gold thin films

NASA Astrophysics Data System (ADS)

Politano, Grazia Giuseppina; Vena, Carlo; Desiderio, Giovanni; Versace, Carlo

2018-02-01

Despite intensive investigations on graphene oxide-gold nanocomposites, the interaction of graphene oxide sheets with magnetron sputtered gold thin films has not been studied yet. The optical constants of graphene oxide thin films dip-coated on magnetron sputtered gold thin films were determined by spectroscopic ellipsometry in the [300-1000] wavelength range. Moreover, the morphologic properties of the samples were investigated by SEM analysis. Graphene oxide absorbs mainly in the ultraviolet region, but when it is dip-coated on magnetron sputtered gold thin films, its optical constants show dramatic changes, becoming absorbing in the visible region, with a peak of the extinction coefficient at 3.1 eV. Using magnetron sputtered gold thin films as a substrate for graphene oxide thin films could therefore be the key to enhance graphene oxide optical sheets' properties for several technological applications, preserving their oxygen content and avoiding the reduction process.

NOVEL TECHNIQUE OF POWER CONTROL IN MAGNETRON TRANSMITTERS FOR INTENSE ACCELERATORS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazakevich, G.; Johnson, R.; Neubauer, M.

A novel concept of a high-power magnetron transmitter allowing dynamic phase and power control at the frequency of locking signal is proposed. The transmitter compensating parasitic phase and amplitude modulations inherent in Superconducting RF (SRF) cavities within closed feedback loops is intended for powering of the intensity-frontier superconducting accelerators. The con- cept uses magnetrons driven by a sufficient resonant (in- jection-locking) signal and fed by the voltage which can be below the threshold of self-excitation. This provides an extended range of power control in a single magnetron at highest efficiency minimizing the cost of RF power unit and the operationmore » cost. Proof-of-principle of the proposed concept demonstrated in pulsed and CW regimes with 2.45 GHz, 1kW magnetrons is discussed here. A conceptual scheme of the high-power transmitter allowing the dynamic wide-band phase and y power controls is presented and discussed.« less

An ionization region model of the reactive Ar/O2 high power impulse magnetron sputtering discharge

NASA Astrophysics Data System (ADS)

Gudmundsson, J. T.; Lundin, D.; Brenning, N.; Raadu, M. A.; Huo, Chunqing; Minea, T. M.

2016-12-01

A new reactive ionization region model (R-IRM) is developed to describe the reactive Ar/O2 high power impulse magnetron sputtering (HiPIMS) discharge with a titanium target. It is then applied to study the temporal behavior of the discharge plasma parameters such as electron density, the neutral and ion composition, the ionization fraction of the sputtered vapor, the oxygen dissociation fraction, and the composition of the discharge current. We study and compare the discharge properties when the discharge is operated in the two well established operating modes, the metal mode and the poisoned mode. Experimentally, it is found that in the metal mode the discharge current waveform displays a typical non-reactive evolution, while in the poisoned mode the discharge current waveform becomes distinctly triangular and the current increases significantly. Using the R-IRM we explore the current increase and find that when the discharge is operated in the metal mode Ar+ and Ti+ -ions contribute most significantly (roughly equal amounts) to the discharge current while in the poisoned mode the Ar+ -ions contribute most significantly to the discharge current and the contribution of O+ -ions, Ti+ -ions, and secondary electron emission is much smaller. Furthermore, we find that recycling of atoms coming from the target, that are subsequently ionized, is required for the current generation in both modes of operation. From the R-IRM results it is found that in the metal mode self-sputter recycling dominates and in the poisoned mode working gas recycling dominates. We also show that working gas recycling can lead to very high discharge currents but never to a runaway. It is concluded that the dominating type of recycling determines the discharge current waveform.

Effect of Argon/Oxygen Flow Rate Ratios on DC Magnetron Sputtered Nano Crystalline Zirconium Titanate Thin Films

NASA Astrophysics Data System (ADS)

Rani, D. Jhansi; Kumar, A. GuruSampath; Sarmash, T. Sofi; Chandra Babu Naidu, K.; Maddaiah, M.; Rao, T. Subba

2016-06-01

High transmitting, non absorbent, nano crystalline zirconium titanate (ZT) thin films suitable for anti reflection coatings (ARC) were deposited on to glass substrates by direct current (DC) magnetron reactive sputtering technique, under distinct Argon to Oxygen (Ar/O2) gas flow rate ratios of 31/1, 30/2, 29/3 and 28/4, with a net gas flow (Ar + O2) of 32sccm, at an optimum substrate temperature of 250°C. The influence of the gas mixture ratio on the film properties has been investigated by employing x-ray diffraction (XRD), ultra violet visible (UV-vis) spectroscopy, atomic force microscopy (AFM), energy dispersive x-ray analysis (EDX) and four point probe methods. The films showed a predominant peak at 30.85° with (111) orientation. The crystallite size reduced from 22.94 nm to 13.5 nm and the surface roughness increased from 11.53 nm to 50.58 nm with increase in oxygen content respectively. The films deposited at 31/1 and 30/2 showed almost similar chemical composition. Increased oxygen content results an increase in electrical resistivity from 3.59 × 103 to 2.1 × 106 Ωm. The film deposited at Ar/O2 of 28/4 exhibited higher average optical transmittance of 91%, but its refractive index is higher than that of what is required for ARC. The films deposited at 31/1 and 30/2 of Ar/O2 possess higher transmittance (low absorbance) apart from suitable refractive index. Thus, these films are preferable candidates for ARC.

Comparison of the optical responses of O-poor and O-rich thermochromic VOX films during semiconductor-to-metal transition

NASA Astrophysics Data System (ADS)

Luo, Zhenfei; Wu, Zhiming; Wang, Tao; Xu, Xiangdong; Li, Weizhi; Li, Wei; Jiang, Yadong

2012-09-01

O-poor and O-rich thermochromic vanadium oxide (VOX) nanostructured thin films were prepared by applying reactive direct current magnetron sputtering and post-annealing in oxygen ambient. UV-visible spectrophotometer and spectroscopic ellipsometry were used to investigate the optical properties of films. It was found that, when the O-poor VOX thin film underwent semiconductor-to-metal transition, the values of optical conductivity and extinction coefficient in the visible region increased due to the existence of occupied band-gap states. This noticeable feature, however, was not observed for the O-rich film, which showed a similar optical behavior with the stoichiometric crystalline VO2 films reported in the literatures. Moreover, the O-poor VOX film exhibits consistent variations of transmission values in the visible/near-infrared region when it undergoes semiconductor-to-metal transition.

Smelting Magnesium Metal using a Microwave Pidgeon Method

PubMed Central

Wada, Yuji; Fujii, Satoshi; Suzuki, Eiichi; Maitani, Masato M.; Tsubaki, Shuntaro; Chonan, Satoshi; Fukui, Miho; Inazu, Naomi

2017-01-01

Magnesium (Mg) is a lightweight metal with applications in transportation and sustainable battery technologies, but its current production through ore reduction using the conventional Pidgeon process emits large amounts of CO2 and particulate matter (PM2.5). In this work, a novel Pidgeon process driven by microwaves has been developed to produce Mg metal with less energy consumption and no direct CO2 emission. An antenna structure consisting of dolomite as the Mg source and a ferrosilicon antenna as the reducing material was used to confine microwave energy emitted from a magnetron installed in a microwave oven to produce a practical amount of pure Mg metal. This microwave Pidgeon process with an antenna configuration made it possible to produce Mg with an energy consumption of 58.6 GJ/t, corresponding to a 68.6% reduction when compared to the conventional method. PMID:28401910

Research on optical reflectance and infrared emissivity of TiNx films depending on sputtering pressure

NASA Astrophysics Data System (ADS)

Lu, Linlin; Luo, Fa; Huang, Zhibin; Zhou, Wancheng; Zhu, Dongmei

2018-06-01

TiNx thin films were deposited on glass substrates using direct current reactive magnetron sputtering, and effects of sputtering pressure on optical reflectance and infrared emissivity of TiNx films were studied. The results indicated that sputtering pressure was a key factor to affect the optical reflectance and infrared emissivity of TiNx films in this study. When sputtering pressure varied from 0.3 Pa to 1.2 Pa, an average reflectance of less than 25% in the visible range was obtained for the prepared films. With the working pressure rise, the resistivity of TiNx films went up. Meanwhile, the infrared emissivity of the films increased. As sputtering pressure was 0.3 Pa, the infrared emissivity in the wavelength of 3-5 and 8-14 μm of TiNx film with dark color and low optical reflectance was less than 0.2.

Structural and Magnetic Properties of Sputter-Deposited Polycrystalline Ni-Mn-Ga Ferromagnetic Shape-Memory Thin Films

NASA Astrophysics Data System (ADS)

Vinodh Kumar, S.; Seenithurai, S.; Manivel Raja, M.; Mahendran, M.

2015-10-01

Polycrystalline Ni-Mn-Ga ferromagnetic shape-memory thin films have been deposited on Si (100) substrates using a direct-current magnetron sputtering technique. The microstructure and the temperature dependence of magnetic properties of the films have been investigated by x-ray diffraction, scanning electron microscopy, and thermomagnetic measurements. As-deposited Ni50.2Mn30.6Ga19.2 film showed quasi-amorphous structure with paramagnetic nature at room temperature. When annealed at 873 K, the quasi-amorphous film attained crystallinity and possessed L21 cubic ordering with high magnetic transition temperature. Saturation magnetization and coercivity values for the annealed film were found to be 220 emu/cm3 and 70 Oe, respectively, indicating soft ferromagnetic character with low magnetocrystalline anisotropy. The magnetic transitions of the film deposited at 100 W were above room temperature, making this a potential candidate for use in microelectromechanical system devices.

Superconducting structure with layers of niobium nitride and aluminum nitride

DOEpatents

Murduck, James M.; Lepetre, Yves J.; Schuller, Ivan K.; Ketterson, John B.

1989-01-01

A superconducting structure is formed by depositing alternate layers of aluminum nitride and niobium nitride on a substrate. Deposition methods include dc magnetron reactive sputtering, rf magnetron reactive sputtering, thin-film diffusion, chemical vapor deposition, and ion-beam deposition. Structures have been built with layers of niobium nitride and aluminum nitride having thicknesses in a range of 20 to 350 Angstroms. Best results have been achieved with films of niobium nitride deposited to a thickness of approximately 70 Angstroms and aluminum nitride deposited to a thickness of approximately 20 Angstroms. Such films of niobium nitride separated by a single layer of aluminum nitride are useful in forming Josephson junctions. Structures of 30 or more alternating layers of niobium nitride and aluminum nitride are useful when deposited on fixed substrates or flexible strips to form bulk superconductors for carrying electric current. They are also adaptable as voltage-controlled microwave energy sources.

Magnetron sputtered zinc oxide nanorods as thickness-insensitive cathode interlayer for perovskite planar-heterojunction solar cells.

PubMed

Liang, Lusheng; Huang, Zhifeng; Cai, Longhua; Chen, Weizhong; Wang, Baozeng; Chen, Kaiwu; Bai, Hua; Tian, Qingyong; Fan, Bin

2014-12-10

Suitable electrode interfacial layers are essential to the high performance of perovskite planar heterojunction solar cells. In this letter, we report magnetron sputtered zinc oxide (ZnO) film as the cathode interlayer for methylammonium lead iodide (CH3NH3PbI3) perovskite solar cell. Scanning electron microscopy and X-ray diffraction analysis demonstrate that the sputtered ZnO films consist of c-axis aligned nanorods. The solar cells based on this ZnO cathode interlayer showed high short circuit current and power conversion efficiency. Besides, the performance of the device is insensitive to the thickness of ZnO cathode interlayer. Considering the high reliability and maturity of sputtering technique both in lab and industry, we believe that the sputtered ZnO films are promising cathode interlayers for perovskite solar cells, especially in large-scale production.

Plasma diagnostics of low pressure high power impulse magnetron sputtering assisted by electron cyclotron wave resonance plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stranak, Vitezslav; University of South Bohemia, Institute of Physics and Biophysics, Branisovska 31, 370 05 Ceske Budejovice; Herrendorf, Ann-Pierra

2012-11-01

This paper reports on an investigation of the hybrid pulsed sputtering source based on the combination of electron cyclotron wave resonance (ECWR) inductively coupled plasma and high power impulse magnetron sputtering (HiPIMS) of a Ti target. The plasma source, operated in an Ar atmosphere at a very low pressure of 0.03 Pa, provides plasma where the major fraction of sputtered particles is ionized. It was found that ECWR assistance increases the electron temperature during the HiPIMS pulse. The discharge current and electron density can achieve their stable maximum 10 {mu}s after the onset of the HiPIMS pulse. Further, a highmore » concentration of double charged Ti{sup ++} with energies of up to 160 eV was detected. All of these facts were verified experimentally by time-resolved emission spectroscopy, retarding field analyzer measurement, Langmuir probe, and energy-resolved mass spectrometry.« less

Superconducting structure with layers of niobium nitride and aluminum nitride

DOEpatents

Murduck, J.M.; Lepetre, Y.J.; Schuller, I.K.; Ketterson, J.B.

1989-07-04

A superconducting structure is formed by depositing alternate layers of aluminum nitride and niobium nitride on a substrate. Deposition methods include dc magnetron reactive sputtering, rf magnetron reactive sputtering, thin-film diffusion, chemical vapor deposition, and ion-beam deposition. Structures have been built with layers of niobium nitride and aluminum nitride having thicknesses in a range of 20 to 350 Angstroms. Best results have been achieved with films of niobium nitride deposited to a thickness of approximately 70 Angstroms and aluminum nitride deposited to a thickness of approximately 20 Angstroms. Such films of niobium nitride separated by a single layer of aluminum nitride are useful in forming Josephson junctions. Structures of 30 or more alternating layers of niobium nitride and aluminum nitride are useful when deposited on fixed substrates or flexible strips to form bulk superconductors for carrying electric current. They are also adaptable as voltage-controlled microwave energy sources. 8 figs.

As(III) Removal from Drinking Water by Carbon Nanotube Membranes with Magnetron-Sputtered Copper: Performance and Mechanisms.

PubMed

Luan, Hongyan; Zhang, Quan; Cheng, Guo-An; Huang, Haiou

2018-06-20

Current approaches for functionalizing carbon nanotubes (CNTs) often utilize harsh chemical conditions, and the resulting harmful wastes can cause various environmental and health concerns. In this study, magnetron sputtering technique is facilely employed to functionalize CNT membranes by depositing Cu onto premade CNT membranes without using any chemical treatment. A comparative evaluation of the substrate polymeric membrane (mixed cellulose ester (MCE)), MCE sputtered with copper (Cu/MCE), the pristine CNT membrane (CNT), and CNT membrane sputtered with Cu (Cu/CNT) shows that Cu/CNT possesses mechanically stable structures and similar membrane permeability as MCE. More importantly, Cu/CNT outperforms other membranes with high As(III) removal efficiency of above 90%, as compared to less than 10% by MCE and CNT, and 75% by Cu/MCE from water. The performance of Cu/CNT membranes for As(III) removal is also investigated as a function of ionic strength, sputtering time, co-existing ions, solution pH, and the reusability. Further characterizations of As speciation in the filtrate and on Cu/CNT reveal that arsenite removal by Cu/CNT possibly began with Cu-catalyzed oxidation of arsenite to arsenate, followed by adsorptive filtration of arsenate by the membrane. Overall, this study demonstrates that magnetron sputtering is a promising greener technology for the productions of metal-CNT composite membranes for environmental applications.

Magnetron Sputtered Molybdenum Oxide for Application in Polymers Solar Cells

NASA Astrophysics Data System (ADS)

Sendova-Vassileva, M.; Dikov, Hr; Vitanov, P.; Popkirov, G.; Gergova, R.; Grancharov, G.; Gancheva, V.

2016-10-01

Thin films of molybdenum oxide were deposited by radio frequency (RF) magnetron sputtering in Ar from a MoO3 target at different deposition power on glass and silicon substrates. The thickness of the films was determined by profilometer measurements and by ellipsometry. The films were annealed in air at temperatures between 200 and 400°C in air. The optical transmission and reflection spectra were measured. The conductivity of the as deposited and annealed films was determined. The crystal structure was probed by Raman spectroscopy. The oxidation state of the surface was studied by X-ray photoelectron spectroscopy (XPS) spectroscopy. The deposition technique described above was used to experiment with MoOx as a hole transport layer (HTL) in polymer solar cells with bulk hetrojunction active layer, deposited by spin coating. The performance of these layers was compared with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), which is the standard material used in this role. The measured current-voltage characteristics of solar cells with the structure glass/ITO/HTL/Poly(3-hexyl)thiophene (P3HT):[6,6]-phenyl-C61- butyric acid methyl ester (PCBM)/Al demonstrate that the studied MoOx layer is a good HTL and leads to comparable characteristics to those with PEDOT:PSS. On the other hand the deposition by magnetron sputtering guarantees reliable and repeatable HTLs.

Method to control deposition rate instabilities—High power impulse magnetron sputtering deposition of TiO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kossoy, Anna, E-mail: annaeden@hi.is, E-mail: anna.kossoy@gmail.com; Magnusson, Rögnvaldur L.; Tryggvason, Tryggvi K.

2015-03-15

The authors describe how changes in shutter state (open/closed) affect sputter plasma conditions and stability of the deposition rate of Ti and TiO{sub 2} films. The films were grown by high power impulse magnetron sputtering in pure Ar and in Ar/O{sub 2} mixture from a metallic Ti target. The shutter state was found to have an effect on the pulse waveform for both pure Ar and reactive sputtering of Ti also affecting stability of TiO{sub 2} deposition rate. When the shutter opened, the shape of pulse current changed from rectangular to peak-plateau and pulse energy decreased. The authors attribute itmore » to the change in plasma impedance and gas rarefaction originating in geometry change in front of the magnetron. TiO{sub 2} deposition rate was initially found to be high, 1.45 Å/s, and then dropped by ∼40% during the first 5 min, while for Ti the change was less obvious. Instability of deposition rate poses significant challenge for growing multilayer heterostructures. In this work, the authors suggest a way to overcome this by monitoring the integrated average energy involved in the deposition process. It is possible to calibrate and control the film thickness by monitoring the integrated pulse energy and end growth when desired integrated pulse energy level has been reached.« less

Very low pressure high power impulse triggered magnetron sputtering

DOEpatents

Anders, Andre; Andersson, Joakim

2013-10-29

A method and apparatus are described for very low pressure high powered magnetron sputtering of a coating onto a substrate. By the method of this invention, both substrate and coating target material are placed into an evacuable chamber, and the chamber pumped to vacuum. Thereafter a series of high impulse voltage pulses are applied to the target. Nearly simultaneously with each pulse, in one embodiment, a small cathodic arc source of the same material as the target is pulsed, triggering a plasma plume proximate to the surface of the target to thereby initiate the magnetron sputtering process. In another embodiment the plasma plume is generated using a pulsed laser aimed to strike an ablation target material positioned near the magnetron target surface.

Modular compact solid-state modulators for particle accelerators

NASA Astrophysics Data System (ADS)

Zavadtsev, A. A.; Zavadtsev, D. A.; Churanov, D. V.

2017-12-01

The building of the radio frequency (RF) particle accelerator needs high-voltage pulsed modulator as a power supply for klystron or magnetron to feed the RF accelerating system. The development of a number of solid-state modulators for use in linear accelerators has allowed to develop a series of modular IGBT based compact solid-state modulators with different parameters. This series covers a wide range of needs in accelerator technology to feed a wide range of loads from the low power magnetrons to powerful klystrons. Each modulator of the series is built on base of a number of unified solid-state modules connected to the pulse transformer, and covers a wide range of modulators: voltage up to 250 kV, a peak current up to 250 A, average power up to 100 kW and the pulse duration up to 20 μsec. The parameters of the block with an overall dimensions 880×540×250 mm are: voltage 12 kV, peak current 1600 A, pulse duration 20 μsec, average power 10 kW with air-cooling and 40 kW with liquidcooling. These parameters do not represent a physical limit, and modulators to parameters outside these ranges can be created on request.

Threshold voltage tuning in AlGaN/GaN HFETs with p-type Cu2O gate synthesized by magnetron reactive sputtering

NASA Astrophysics Data System (ADS)

Wang, Lei; Li, Liuan; Xie, Tian; Wang, Xinzhi; Liu, Xinke; Ao, Jin-Ping

2018-04-01

In present study, copper oxide films were prepared at different sputtering powers (10-100 W) using magnetron reactive sputtering. The crystalline structure, surface morphologies, composition, and optical band gap of the as-grown films are dependent on sputtering power. As the sputtering power decreasing from 100 to 10 W, the composition of films changed from CuO to quasi Cu2O domination. Moreover, when the sputtering power is 10 W, a relative high hole carrier density and high-surface-quality quasi Cu2O thin film can be achieved. AlGaN/GaN HFETs were fabricated with the optimized p-type quasi Cu2O film as gate electrode, the threshold voltage of the device shows a 0.55 V positive shift, meanwhile, a lower gate leakage current, a higher ON/OFF drain current ratio of ∼108, a higher electron mobility (1465 cm2/Vs), and a lower subthreshold slope of 74 mV/dec are also achieved, compared with the typical Ni/Au-gated HFETs. Therefore, Cu2O have a great potential to develop high performance p-type gate AlGaN/GaN HFETs.

Relationship between plasma parameters and film microstructure in radio frequency magnetron sputter deposition of barium strontium titanate

NASA Astrophysics Data System (ADS)

Panda, B.; Dhar, A.; Nigam, G. D.; Bhattacharya, D.; Ray, S. K.

1998-01-01

Radio frequency magnetron sputtered Ba0.8Sr0.2TiO3 thin films have been deposited on silicon and Si/SiO2/SiN/Pt substrates. The analysis of plasma discharge has been carried out using the Langmuir probe technique. Both the pressure and power have been found to influence the ion density and self-bias of the target. Introduction of oxygen into the discharge effectively decreases the ion density. The structural and electrical properties have been investigated using x-ray diffraction, atomic force microscopy of deposited films and capacitance-voltage, conductance-voltage, and current density-electric field characteristics of fabricated capacitors. The growth and orientation of the films have been found to depend upon the type of substrates and deposition temperatures. The <100> texture in the film is promoted at a pressure 0.25 Torr with a moderately high value of ion density and low ion bombardment energy. Films deposited on Si/SiO2/SiN/Pt substrate have shown higher dielectric constant (191) and lower leakage current density (2.8×10-6 A/cm2 at 100 kV/cm) compared to that on silicon.

Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

NASA Astrophysics Data System (ADS)

Cha, Sungsu; Kim, Yujong; Lee, Byung Cheol; Park, Hyung Dal; Lee, Seung Hyun; Buaphad, Pikad

2017-05-01

KAERI is developing a 6 MeV X-band radio frequency (RF) electron linear accelerator for medical purposes. The proposed X-band accelerator consists of an e-gun, an accelerating structure, two solenoid magnets, two steering magnets, a magnetron, a modulator, and an automatic frequency control (AFC) system. The accelerating structure of the component consists of oxygen-free high-conductivity copper (OFHC). Therefore, the ambient temperature changes the volume, and the resonance frequency of the accelerating structure also changes. If the RF frequency of a 9300 MHz magnetron and the resonance frequency of the accelerating structure do not match, it can degrade the performance. That is, it will decrease the output power, lower the beam current, decrease the X-ray dose rate, increase the reflection power, and result in unstable operation of the accelerator. Accelerator operation should be possible at any time during all four seasons. To prevent humans from being exposed to radiation when it is operated, the accelerator should also be operable through remote monitoring and remote control. Therefore, the AFC system is designed to meet these requirements; it is configured based on the concept of a phase-locked loop (PLL) model, which includes an RF section, an intermediate frequency (IF) [1-3] section, and a local oscillator (LO) section. Some resonance frequency controllers use a DC motor, chain, and potentiometer to store the position and tune the frequency [4,5]. Our AFC system uses a step motor to tune the RF frequency of the magnetron. The maximum tuning turn number of our magnetron frequency tuning shaft is ten. Since the RF frequency of our magnetron is 9300±25 MHz, it gives 5 MHz (∵±25 MHz/10 turns → 50 MHz/10 turns =5 MHz/turn) frequency tuning per turn. The rotation angle of our step motor is 0.72° per step and the total step number per one rotation is 360°/0.72°=500 steps. Therefore, the tuning range per step is 10 kHz/step (=5 MHz per turn/500 steps per turn). The developed system is a more compact new resonance frequency control system. In addition, a frequency measuring part is included and it can measure the real-time resonance frequency from the magnetron. We have succeeded in the stable provisioning of RF power by recording the results of a 0.01% frequency deviation in the AFC during an RF test. Accordingly, in this paper, the detailed design, fabrication, and a high power test of the AFC system for the X-band linac are presented.

Influence of argon pressure and current density on substrate temperature during magnetron sputtering of hot titanium target

NASA Astrophysics Data System (ADS)

Komlev, Anton A.; Minzhulina, Ekaterina A.; Smirnov, Vladislav V.; Shapovalov, Viktor I.

2018-01-01

The paper describes physical characteristics of the hot target sputtering process, which have not been known before. To switch a magnetron over to the hot target regime, a titanium disk of 1 mm thick with a 1-mm-gap was attached on a 4-mm-thick copper plate cooled by running water. A thermocouple sensor was used to investigate the thermal processes occurring in substrates. The study was performed at the discharge current density of 20-40 mA/cm2 and argon pressure of 3-7 mTorr. The accuracy of temperature measurement appeared to be within ± 5%, due the application of a chromel-copel thermocouple. The study reveals that under these conditions the heating curves have the inflection points positioned proportionally to the discharge current density and argon pressure on a time axis. The inflection point appears in the kinetic curves due to the finite value of the target heating time constant. The study shows that the substrate fixed temperature and substrate heating time constant depend on the argon pressure and relate to the current density by the polynomials of the first and second degrees, respectively. The influence of a target on the substrate heating kinetics is considered in an analytical description by the introduction of a multiplier in the form of an exponential function of time. The results of the research make a novel contribution to the field of the sputtering process.

Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

NASA Astrophysics Data System (ADS)

Singh, Ajaib; Schipmann, Susanne; Mathur, Aakash; Pal, Dipayan; Sengupta, Amartya; Klemradt, Uwe; Chattopadhyay, Sudeshna

2017-08-01

The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (<10 nm) were grown on confined polystyrene with ∼2Rg film thickness, where Rg ∼ 20 nm (Rg is the unperturbed radius of gyration of polystyrene, defined by Rg = 0.272 √M0, and M0 is the molecular weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2-7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

In-situ sputtering apparatus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erickson, Mark R.; Poole, Henry J.; Custer, III, Arthur W.

A sputtering apparatus that includes at least a target presented as an inner surface of a confinement structure, the inner surface of the confinement structure is preferably an internal wall of a circular tube. A cathode is disposed adjacent the internal wall of the circular tube. The cathode preferably provides a hollow core, within which a magnetron is disposed. Preferably, an actuator is attached to the magnetron, wherein a position of the magnetron within the hollow core is altered upon activation of the actuator. Additionally, a carriage supporting the cathode and communicating with the target is preferably provided, and amore » cable bundle interacting with the cathode and linked to a cable bundle take up mechanism provided power and coolant to the cathode, magnetron, actuator and an anode of the sputtering apparatus.« less

Theoretical investigation of resonant frequencies of unstrapped magnetron with arbitrary side resonators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yue, Song, E-mail: yuessd@163.com; University of Chinese Academy of Sciences, Beijing 100049; Zhang, Zhao-chuan

In this paper, a sector steps approximation method is proposed to investigate the resonant frequencies of magnetrons with arbitrary side resonators. The arbitrary side resonator is substituted with a series of sector steps, in which the spatial harmonics of electromagnetic field are also considered. By using the method of admittance matching between adjacent steps, as well as field continuity conditions between side resonators and interaction regions, the dispersion equation of magnetron with arbitrary side resonators is derived. Resonant frequencies of magnetrons with five common kinds of side resonators are calculated with sector steps approximation method and computer simulation softwares, inmore » which the results have a good agreement. The relative error is less than 2%, which verifies the validity of sector steps approximation method.« less

Initiation of a Relativistic Magnetron

NASA Astrophysics Data System (ADS)

Kaup, D. J.

2003-10-01

We report on recent results in our studies of relativistic magnetrons. Experimentally, these devices have proven to be very difficult to operate, typically cutting off too quickly after they are initialized, and therefore not delivering the power levels expected [1]. Our analysis is based on our model of a crossed-field device, consisting only of its two dominant modes, a DC background and an RF oscillating mode [2]. This approach has produced generally quantitatively correct values for the operating regime and major features of nonrelativistic devices. We have performed a fully electromagnetic, relativistic analysis of a magnetron of the A6 cylindrical configuration. We will show that when the device should generate maximum power, it enters a regime where the DC background could become potentially unstable. In particular, when a nonrelativistic planar device enters the saturation regime, the DC electron density distribution could become unstable if the vertical DC velocity would ever become equal to the magnitude of the vertical RF velocity [3]. We find that during the initiation phase, for the highest power levels of our model of the A6, near the cathode, the DC vertical velocity does become just less than, and definitely on the order of the magnitude of the vertical RF velocity. Consequently, any localized surge in the currents near the cathode, could easily destroy the smooth upward flow of the electrons, drive the DC background unstable, and thereby shut down the operation of the device. [1] Long-pulse relativistic magnetron experiments, M.R. Lopez, R.M. Gilgenbach, Y.Y. Lau, D.W. Jordan, M.D. Johnston, M.C. Jones, V.B. Neculaes, T.A. Spencer, J.W. Luginsland, M.D. Haworth, R.W.Lemke, D. Price, and L. Ludeking, Proc. of SPIE Aerosense 4720, 10-17, (2002). [2] Theoretical modeling of crossed-field electron vacuum devices, D.J. Kaup, Phys. of Plasmas 8, 2473-80 (2001). [3] Initiation and Stationary Operating States in a Crossed-Field Vacuum Electron Device, D. J. Kaup, Proc. of SPIE Aerosense 4720, 67-74, (2002).

Tunable dielectric properties of Barium Magnesium Niobate (BMN) doped Barium Strontium Titanate (BST) thin films by magnetron sputtering

NASA Astrophysics Data System (ADS)

Alema, Fikadu; Reinholz, Aaron; Pokhodnya, Konstantin

2013-03-01

We report on the tunable dielectric properties of Mg and Nb co-doped Ba0.45Sr0.55TiO3 (BST) thin film prepared by the magnetron sputtering using BST target (pure and doped with BaMg0.33Nb0.67O3 (BMN)) on Pt/TiO2/SiO2/Al2O3 4'' wafers at 700 °C under oxygen atmosphere. The electrical measurements are conducted on 2432 metal-ferroelectric-metal capacitors using Pt as the top and bottom electrode. The crystalline structure, microstructure, and surface morphology of the films are analyzed and correlated to the films dielectric properties. The BMN doped and undoped BST films have shown tunabilities of 48% and 52%; and leakage current densities of 2.2x10-6 A/cm2 and 3.7x10-5 A/cm2, respectively at 0.5 MV/cm bias field. The results indicate that the BMN doped film exhibits a lower leakage current with no significant decrease in tunability. Due to similar electronegativity and ionic radii, it was suggested that both Mg2+ (accepter-type) and Nb5+ (donor-type) dopants substitutTi4+ ion in BST. The improvement in the film dielectric losses and leakage current with insignificant loss of tunability is attributed to the adversary effects of Mg2+ and Nb5+ in BST.

Discharge runaway in high power impulse magnetron sputtering of carbon: the effect of gas pressure, composition and target peak voltage

NASA Astrophysics Data System (ADS)

Vitelaru, Catalin; Aijaz, Asim; Constantina Parau, Anca; Kiss, Adrian Emil; Sobetkii, Arcadie; Kubart, Tomas

2018-04-01

Pressure and target voltage driven discharge runaway from low to high discharge current density regimes in high power impulse magnetron sputtering of carbon is investigated. The main purpose is to provide a meaningful insight of the discharge dynamics, with the ultimate goal to establish a correlation between discharge properties and process parameters to control the film growth. This is achieved by examining a wide range of pressures (2–20 mTorr) and target voltages (700–850 V) and measuring ion saturation current density at the substrate position. We show that the minimum plasma impedance is an important parameter identifying the discharge transition as well as establishing a stable operating condition. Using the formalism of generalized recycling model, we introduce a new parameter, ‘recycling ratio’, to quantify the process gas recycling for specific process conditions. The model takes into account the ion flux to the target, the amount of gas available, and the amount of gas required for sustaining the discharge. We show that this parameter describes the relation between the gas recycling and the discharge current density. As a test case, we discuss the pressure and voltage driven transitions by changing the gas composition when adding Ne into the discharge. We propose that standard Ar HiPIMS discharges operated with significant gas recycling do not require Ne to increase the carbon ionization.

Composition and crystal structure of N doped TiO2 film deposited at different O2 flow rate by direct current sputtering.

PubMed

Ding, Wanyu; Ju, Dongying; Chai, Weiping

2011-06-01

N doped Ti02 films were deposited by direct current pulse magnetron sputtering system at room temperature. The influence of 02 flow rate on the crystal structure of deposited films was studied by Stylus profilometer, X-ray photoelectron spectroscopy, and X-ray diffractometer. The results indicate that the 02 flow rate strongly controls the growth behavior and crystal structure of N doped Ti02 film. It is found that N element mainly exists as substitutional doped state and the chemical stiochiometry is near to TiO1.68±0.06N0.11±0.01 for all film samples. N doped Ti02 film deposited with 2 sccm (standard-state cubic centimeter per minute) 02 flow rate is amorphous structure with high growth rate, which contains both anatase phase and rutile phase crystal nucleuses. In this case, the film displays the mix-phase of anatase and rutile after annealing treatment. While N doped Ti02 film deposited with 12 cm(3)/min 02 flow rate displays anatase phase before and after annealing treatment. And it should be noticed that no TiN phase appears for all samples before and after annealing treatment. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Construction, Test and Delivery of Standardized Coaxial Magnetron.

DTIC Science & Technology

1981-09-23

Cavity Pressurization and Pressure Switch . .. 13 4.0 PERFORNANCE OF BAND IV, VMS-1104 COAXIAL AAGNETRON. 14 4.1 Initial Test of Band IV, VNS-1I04, S/N...of the magnetron. 3.7 Ship Air Pressure Switch The insertion of the magnetron deeper into the cabinet to obtain proper alignment of the tube and...waveguide run required reloca- tion of the ship air pressure switch . The switch was moved approxi- mately two inches deeper into the cabinet and rebolted

Investigation of Structural, Compositional and Anti-Microbial Properties of Copper Thin Film Using Direct Current Magnetron Sputtering for Surgical Instruments

NASA Astrophysics Data System (ADS)

Kalaiselvam, S.; Sandhya, J.; Krishnan, K. V. Hari; Kedharnath, A.; Arulkumar, G.; Roseline, A. Ameelia

Surgical instruments and other bioimplant devices, owing to their importance in the biomedical industry require high biocompatibility to be used in the human body. Nevertheless, issues of compatibility, bacterial infections are quite common in such devices. Hence development of surface coatings on various substrates for implant applications is a promising technique to combat the issues arising in these implant materials. The present investigation aims at coating copper on stainless steel substrate using DC Magnetron sputtering which is used to achieve film of required thickness (0.5-8μm). The deposition pressure, substrate temperature, power supply, distance between the specimen and target are optimized and maintained constant, while the sputtering time (30-110min) is varied. The sputtered copper thin film’s morphology, composition are characterized by SEM and EDAX. X-ray diffraction analysis shows copper oriented on (111) and (002) and copper oxide on (111) planes. The contact angle of copper thin film is 92∘ while AISI 316L shows 73∘. The antimicrobial studies carried in Staphylococcus aureus, Escherichia Coli, Klebsiella pneumonia and Candida albicans show that the maximum reduction was seen upto 35, 26, 54, 39CFU/mL, respectively after 24h. The cell viability is studied by MTT assay test on Vero cell line for 24h, 48h and 72h and average cell viability is 43.85%. The copper release from the thin film to the culture medium is 6691μg/L (maximum) is estimated from AAS studies. The copper coated substrate does not show much reaction with living Vero cells whereas the bacteria and fungi are found to be destroyed.

Effect of Nitrogen Content on Physical and Chemical Properties of TiN Thin Films Prepared by DC Magnetron Sputtering with Supported Discharge

NASA Astrophysics Data System (ADS)

Kavitha, A.; Kannan, R.; Gunasekhar, K. R.; Rajashabala, S.

2017-10-01

Amorphous titanium nitride (TiN) thin films have been prepared on silicon (Si) and glass substrates by direct-current (DC) reactive magnetron sputtering with a supported discharge (triode). Nitrogen gas (N2) at partial pressure of 0.3 Pa, 0.4 Pa, 0.5 Pa, and 0.6 Pa was used to prepare the TiN thin films, maintaining total pressure of argon and N2 of about 0.7 Pa. The chemical, microstructural, optical, and electrical properties of the TiN thin films were systematically studied. Presence of different phases of Ti with nitrogen (N), oxygen (O2), and carbon (C) elements was revealed by x-ray photoelectron spectroscopy characterization. Increase in the nitrogen pressure from 0.3 Pa to 0.6 Pa reduced the optical bandgap of the TiN thin film from 2.9 eV to 2.7 eV. Photoluminescence study showed that TiN thin film deposited at N2 partial pressure of 0.3 Pa exhibited three shoulder peaks at 330 nm, 335 nm, and 340 nm, which disappeared when the sample was deposited with N2 partial pressure of 0.6 Pa. Increase in the nitrogen content decreased the electrical resistivity of the TiN thin film from 3200 μΩ cm to 1800 μΩ cm. Atomic force microscopy studies of the TiN thin films deposited with N2 partial pressure of 0.6 Pa showed a uniform surface pattern associated with accumulation of fine grains. The results and advantages of this method of preparing TiN thin films are also reported.

The main directions in technology investigation of soid oxide fuel cell in Russian Federal Research Center Institute of Physics & Power Engineering (IPPE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ievleva, J.I.; Kolesnikov, V.P.; Mezhertisky, G.S.

1996-04-01

The main direction of science investigations for creation of efficient solid oxide fuel cells (SOFC) in IPPE are considered in this work. The development program of planar SOFC with thin-film electrolyte is shown. General design schemes of experimental SOFC units are presented. The flow design schemes of processes for initial materials and electrodes fabrication are shown. The results of investigations for creation thin-film solid oxide electrolyte at porous cathode by magnetron sputtering from complex metal target in oxidative environment are presented.

Mn-coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetron sputtering for dental applications

NASA Astrophysics Data System (ADS)

Park, Seon-Yeong; Choe, Han-Cheol

2018-02-01

In this study, Mn-coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetrons sputtering for dental applications were studied using different experimental techniques. Mn coating films were formed on Ti-29Nb-xHf alloys by a radio frequency magnetron sputtering technique for 0, 1, 3, and 5 min at 45 W. The microstructure, composition, and phase structure of the coated alloys were examined by optical microscopy, field emission scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The microstructure of Ti-29Nb alloy showed α" phase in the needle-like structure and Ti-29Nb-15Hf alloy showed β phase in the equiaxed structure. As the sputtering time increased, the circular particles of Mn coatings on the Ti-29Nb alloy increased at inside and outside surfaces. As the sputtering time increased, [Mn + Ca/P] ratio of the plasma electrolytic oxidized films in Ti- 29Nb-xHf alloys increased. The corrosion potential (Ecorr) of Mn coatings on the Ti-29Nb alloy showed higher than that of Mn coatings on the Ti-29Nb-15Hf alloy. The passive current density (Ipass) of the Mn coating on the Ti-29Nb alloy and Mn coatings on the Ti-29Nb-15Hf alloy was less noble than the non-Mn coated Ti-29Nb and Ti-29Nb-15Hf alloys surface.

Experimental study on an S-band near-field microwave magnetron power transmission system on hundred-watt level

NASA Astrophysics Data System (ADS)

Zhang, Biao; Jiang, Wan; Yang, Yang; Yu, Chengyang; Huang, Kama; Liu, Changjun

2015-11-01

A multi-magnetron microwave source, a metamaterial transmitting antenna, and a large power rectenna array are presented to build a near-field 2.45 GHz microwave power transmission system. The square 1 m2 rectenna array consists of sixteen rectennas with 2048 Schottky diodes for large power microwave rectifying. It receives microwave power and converts them into DC power. The design, structure, and measured performance of a unit rectenna as well as the entail rectenna array are presented in detail. The multi-magnetron microwave power source switches between half and full output power levels, i.e. the half-wave and full-wave modes. The transmission antenna is formed by a double-layer metallic hole array, which is applied to combine the output power of each magnetron. The rectenna array DC output power reaches 67.3 W on a 1.2 Ω DC load at a distance of 5.5 m from the transmission antenna. DC output power is affected by the distance, DC load, and the mode of microwave power source. It shows that conventional low power Schottky diodes can be applied to a microwave power transmission system with simple magnetrons to realise large power microwave rectifying.

Deposition of undoped and Al doped ZnO thin films using RF magnetron sputtering and study of their structural, optical and electrical properties

NASA Astrophysics Data System (ADS)

Parvathy Venu, M.; Shrisha B., V.; Balakrishna, K. M.; Naik, K. Gopalakrishna

2017-05-01

Undoped ZnO and Al doped ZnO thin films were deposited on glass and p-Si(100) substrates by RF magnetron sputtering technique at room temperature using homemade targets. ZnO target containing 5 at% of Al2O3 as doping source was used for the growth of Al doped ZnO thin films. XRD revealed that the films have hexagonal wurtzite structure with high crystallinity. Morphology and chemical composition of the films have been indicated by FESEM and EDAX studies. A blue shift of the band gap energy and higher optical transmittance has been observed in the case of Al doped ZnO (ZnO:Al) thin films with respect to the ZnO thin films. The as deposited films on p-Si were used to fabricate n-ZnO/p-Si(100) and n-ZnO:Al/p-Si(100) heterojunction diodes and their room temperature current-voltage characteristics were studied.

Corrosion studies of DC reactive magnetron sputtered alumina coating on 304 SS

NASA Astrophysics Data System (ADS)

Thangaraj, Baskar; Mahadevan, Krishnan

2017-12-01

Aluminum oxide films on SS 304 deposited by DC reactive magnetron sputtering technique were studied with respect to the composition of the sputter gas (Ar:O2), gas pressure, substrate temperature, current etc. to achieve good insulating films with high corrosion resistance. The films were characterized by XRD and SEM techniques. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements were made under static conditions in order to evaluate the corrosion performance of the alumina-coated SS 304 for various immersion durations in 0.5 M and 1 M NaCl solution. Alumina-coated SS 304 has low corrosion value of 0.4550 and 1.1090MPY for 24 h immersion time in both solutions. The impedance plots for the alumina coated SS 304 in 1 M NaCl solution at different durations are slightly different to when compared to its immersion in 0.5 M NaCl solutions and are composed of two depressed semi circles. For the alumina coated film, the impedance spectrum decreased, when immersion time increased.

Zinc Oxide-Based Schottky Diode Prepared Using Radio-Frequency Magnetron Cosputtering System

NASA Astrophysics Data System (ADS)

Lai, Bo-Ting; Lee, Ching-Ting; Hong, Jhen-Dong; Yao, Shiau-Lu; Liu, Day-Shan

2010-08-01

The rectifying property of a zinc oxide (ZnO)-based Schottky diode prepared using a radio-frequency (rf) magnetron cosputtering system was improved by enhancing the cosputtered ZnO crystal quality, thereby optimizing the ohmic contact resistance and compensating the Schottky contact surface states. An undoped ZnO layer with a high c-axis orientation and a low internal residual stress was achieved using a postannealing treatment. A homogeneous n-type ZnO-indium tin oxide (ITO) cosputtered film was deposited onto the undoped ZnO layer to optimize the ohmic contact behavior to the Al electrode. The Schottky contact surface of the undoped ZnO layer to the Ni/Au electrode was passivated using an oxygen plasma treatment. Owing to the compensation of the native oxygen vacancies (VO) on the undoped ZnO surface, the leakage current markedly decreased and subsequently led to a quality Schottky diode performance with an ideality factor of 1.23 and a Schottky barrier height of 0.82 eV.

Magnetron Electron Gun,

DTIC Science & Technology

1980-05-23

ULMAGNETRON ELECTRON GUN . (U) .Ay G0 A L GOLOENBERG, T B PANKRATOVA UNCLASSIFIED FTD..In(RS)T41896-?9 4 __ ihD - -111113 MICROCOPY RESOLUTION TEST...CHART NATIONAL BUREAU OF STANDARD 1961 A -_"D-I-D ,RS)T-18q6-79 v FOREIGN TECHNOLOGY DIVISION MAGNETRON ELECTRON GUN by A. L. Gol’denberg, T. B...VISION. WP.AP6. OHIO. FTD -ID(RS)T-1396-79 Date z.-.:a’,-lq -,o • 110ewm /A Is a, -D r.l MAGNETRON ELECTRON GUN A. L. Gol’denberg, T. B. Pankratova and M

SERS spectra of pyridine adsorbed on nickel film prepared by magnetron sputtering

NASA Astrophysics Data System (ADS)

Li, Daoyong; Ouyang, Yu; Chen, Li; Cao, Weiran; Shi, Shaohua

2011-02-01

As a repeating well and cheaper enhancement substrate, the nickel film was fabricated with magnetron sputtering coating instrument. Surface enhanced Raman spectra (SERS) of pyridine adsorbed on this nickel film are compared with the experimental values of gaseous pyridine, the theoretical value of pyridine solution listed in other literatures and our method is better than electro-chemical etching electrode method for large scale preparation. The enhancement factor of the nickel film is calculated and the result indicates that magnetron sputtering coating technology is feasible for obtaining good SERS active surface.

Fabrication of amplitude-phase type diffractive optical elements in aluminium films

NASA Astrophysics Data System (ADS)

Fomchenkov, S. A.; Butt, M. A.

2017-11-01

In the course of studies have been conducted a method of forming the phase diffractive optical elements (DOEs) by direct laser writing in thin films of aluminum. The quality of the aluminum films were investigated depending on the parameters of magnetron sputtering process. Moreover, the parameters of the laser writing process in thin films of aluminum were optimized. The structure of phase diffractive optical elements was obtained by the proposed method.

Coherent Structures and Chaos Control in High-Power Microwave Devices

DTIC Science & Technology

2006-06-29

Theory of Multiresonator Cylindrical Magnetrons 2. High - Power Klystron Research 9 2.1. Determination of the Current Limit on the Confinement of Finite...Size Bunched Pencil Beams in High - Power Relativistic Klystrons 2.2. Exploration of the Possibility of Magnetic Cusp Formation in Highly Bunched...Annular Beams in High - Power Relativistic Klystrons 3. Development of Ellipse-Shaped Ribbon-Beam Theory for HPM Device Applications 12 3.1. Theory of

Origin of Initial Current Peak in High Power Impulse Magnetron Sputtering and Verification by Non-Sputtering Discharge

NASA Astrophysics Data System (ADS)

Zhong-Zhen, Wu; Shu, Xiao; Sui-Han, Cui; Ricky, K. Y. Fu; Xiu-Bo, Tian; Paul, K. Chu; Feng, Pan

2016-07-01

Not Available Supported by the National Natural Science Foundation of China under Grant Nos 51301004 and U1330110, the Guangdong Innovative and Entrepreneurial Research Team Program under Grant No 2013N080, the Shenzhen Science and Technology Research Grant under Grant Nos JCYJ20140903102215536 and JCYJ20150828093127698, and the City University of Hong Kong Applied Research Grant under Grant No 9667104.

Microstructure and dielectric properties of piezoelectric magnetron sputtered w-Sc{sub x}Al{sub 1-x}N thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zukauskaite, Agne; Wingqvist, Gunilla; Palisaitis, Justinas

2012-05-01

Piezoelectric wurtzite Sc{sub x}Al{sub 1-x}N (x = 0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al{sub 2}O{sub 3}(0001) wafers with TiN(111) seed and electrode layers were used as substrates. X-ray diffraction shows that an increase in the Sc content results in the degradation of the crystalline quality. Samples grown at 400 deg. C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 deg. C, the crystal structure is poor and leakage current is high. Transmission electron microscopymore » with energy dispersive x-ray spectroscopy mapping shows a mass separation into ScN-rich and AlN-rich domains for x {>=} 0.2 when substrate temperature is increased from 400 to 800 deg. C. The piezoelectric response of epitaxial Sc{sub x}Al{sub 1-x}N films measured by piezoresponse force microscopy and double beam interferometry shows up to 180% increase by the addition of Sc up to x = 0.2 independent of substrate temperature, in good agreement with previous theoretical predictions based on density-functional theory.« less

Microstructure and dielectric properties of piezoelectric magnetron sputtered w-ScxAl1-xN thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zukauskaite, Agne; Wingqvist, Gunilla; Palisaitis, Justinas

2012-01-01

Piezoelectric wurtzite ScxAl1 xN (x = 0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al2O3(0001) wafers with TiN(111) seed and electrode layers were used as substrates. X-ray diffraction shows that an increase in the Sc content results in the degradation of the crystalline quality. Samples grown at 400 C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 C, the crystal structure is poor and leakage current is high. Transmission electron microscopy with energy dispersive x-ray spectroscopymore » mapping shows a mass separation into ScN-rich and AlN-rich domains for x 0.2 when substrate temperature is increased from 400 to 800 C. The piezoelectric response of epitaxial ScxAl1 xN films measured by piezoresponse force microscopy and double beam interferometry shows up to 180% increase by the addition of Sc up to x = 0.2 independent of substrate temperature, in good agreement with previous theoretical predictions based on density-functional theory.« less

Pulsed-DC selfsputtering of copper

NASA Astrophysics Data System (ADS)

Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

2008-03-01

At standard magnetron sputtering conditions (argon pressure ~0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (~550W/cm2). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%.

Magnetron sputtering system for coatings deposition with activation of working gas mixture by low-energy high-current electron beam

NASA Astrophysics Data System (ADS)

Gavrilov, N. V.; Kamenetskikh, A. S.; Men'shakov, A. I.; Bureyev, O. A.

2015-11-01

For the purposes of efficient decomposition and ionization of the gaseous mixtures in a system for coatings deposition using reactive magnetron sputtering, a low-energy (100-200 eV) high-current electron beam is generated by a grid-stabilized plasma electron source. The electron source utilizes both continuous (up to 20 A) and pulse-periodic mode of discharge with a self-heated hollow cathode (10-100 A; 0.2 ms; 10-1000 Hz). The conditions for initiation and stable burning of the high-current pulse discharge are studied along with the stable generation of a low-energy electron beam within the gas pressure range of 0.01 - 1 Pa. It is shown that the use of the electron beam with controllable parameters results in reduction of the threshold values both for the pressure of gaseous mixture and for the fluxes of molecular gases. Using such a beam also provides a wide range (0.1-10) of the flux density ratios of ions and sputtered atoms over the coating surface, enables an increase in the maximum pulse density of ion current from plasma up to 0.1 A, ensures an excellent adhesion, optimizes the coating structure, and imparts improved properties to the superhard nanocomposite coatings of (Ti,Al)N/a-Si3N4 and TiC/-a-C:H. Mass-spectrometric measurements of the beam-generated plasma composition proved to demonstrate a twofold increase in the average concentration of N+ ions in the Ar-N2 plasma generated by the high-current (100 A) pulsed electron beam, as compared to the dc electron beam.

Full System Model of Magnetron Sputter Chamber - Proof-of-Principle Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walton, C; Gilmer, G; Zepeda-Ruiz, L

2007-05-04

The lack of detailed knowledge of internal process conditions remains a key challenge in magnetron sputtering, both for chamber design and for process development. Fundamental information such as the pressure and temperature distribution of the sputter gas, and the energies and arrival angles of the sputtered atoms and other energetic species is often missing, or is only estimated from general formulas. However, open-source or low-cost tools are available for modeling most steps of the sputter process, which can give more accurate and complete data than textbook estimates, using only desktop computations. To get a better understanding of magnetron sputtering, wemore » have collected existing models for the 5 major process steps: the input and distribution of the neutral background gas using Direct Simulation Monte Carlo (DSMC), dynamics of the plasma using Particle In Cell-Monte Carlo Collision (PIC-MCC), impact of ions on the target using molecular dynamics (MD), transport of sputtered atoms to the substrate using DSMC, and growth of the film using hybrid Kinetic Monte Carlo (KMC) and MD methods. Models have been tested against experimental measurements. For example, gas rarefaction as observed by Rossnagel and others has been reproduced, and it is associated with a local pressure increase of {approx}50% which may strongly influence film properties such as stress. Results on energies and arrival angles of sputtered atoms and reflected gas neutrals are applied to the Kinetic Monte Carlo simulation of film growth. Model results and applications to growth of dense Cu and Be films are presented.« less

High-Hall-Mobility Al-Doped ZnO Films Having Textured Polycrystalline Structure with a Well-Defined (0001) Orientation

NASA Astrophysics Data System (ADS)

Nomoto, Junichi; Makino, Hisao; Yamamoto, Tetsuya

2016-06-01

Five hundred-nanometer-thick ZnO-based textured polycrystalline films consisting of 490-nm-thick Al-doped ZnO (AZO) films deposited on 10-nm-thick Ga-doped ZnO (GZO) films exhibited a high Hall mobility ( μ H) of 50.1 cm2/Vs with a carrier concentration ( N) of 2.55 × 1020 cm-3. Firstly, the GZO films were prepared on glass substrates by ion plating with dc arc discharge, and the AZO films were then deposited on the GZO films by direct current magnetron sputtering (DC-MS). The GZO interface layers with a preferential c-axis orientation play a critical role in producing AZO films with texture development of a well-defined (0001) orientation, whereas 500-nm-thick AZO films deposited by only DC-MS showed a mixture of the c-plane and the other plane orientation, to exhibit a μ H of 38.7 cm2/Vs with an N of 2.22 × 1020 cm-3.

Measured density of copper atoms in the ground and metastable states in argon magnetron discharge correlated with the deposition rate

NASA Astrophysics Data System (ADS)

Naghshara, H.; Sobhanian, S.; Khorram, S.; Sadeghi, N.

2011-01-01

In a dc-magnetron discharge with argon feed gas, densities of copper atoms in the ground state Cu(2S1/2) and metastable state Cu*(2D5/2) were measured by the resonance absorption technique, using a commercial hollow cathode lamp as light source. The operating conditions were 0.3-14 µbar argon pressure and 10-200 W magnetron discharge power. The deposition rate of copper in a substrate positioned at 18 cm from the target was also measured with a quartz microbalance. The gas temperature, in the range 300-380 K, was deduced from the emission spectral profile of N2(C 3Πu - B 3Πg) 0-0 band at 337 nm when trace of nitrogen was added to the argon feed gas. The isotope-shifts and hyperfine structures of electronic states of Cu have been taken into account to deduce the emission and absorption line profiles, and hence for the determination of atoms' densities from the measured absorption rates. To prevent error in the evaluation of Cu density, attributed to the line profile distortion by auto-absorption inside the lamp, the lamp current was limited to 5 mA. Density of Cu(2S1/2) atoms and deposition rate both increased with the enhanced magnetron discharge power. But at fixed power, the copper density augmented with argon pressure whereas the deposition rate followed the opposite trend. Whatever the gas pressure, the density of Cu*(2D5/2) metastable atoms remained below the detection limit of 1 × 1010 cm-3 for magnetron discharge powers below 50 W and hence increased much more rapidly than the density of Cu(2S1/2) atoms, over passing this later at some discharge power, whose value decreases with increasing argon pressure. This behaviour is believed to result from the enhancement of plasma density with increasing discharge power and argon pressure, which would increase the excitation rate of copper into metastable states. At fixed pressure, the deposition rate followed the same trend as the total density of copper atoms in the ground and metastable states. Two important conclusions of this work are (i) copper atoms sputtered from the target under ion bombardment are almost all in the ground state Cu(2S1/2) and hence in the plasma volume they can be excited into the metastable states; (ii) all atoms in the long-lived ground and metastable states contribute to the deposition of copper layer on the substrate.

Magnetron sputtered boron films and TI/B multilayer structures

DOEpatents

Makowiecki, Daniel M.; Jankowski, Alan F.

1993-01-01

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

Magnetron sputtered boron films and Ti/B multilayer structures

DOEpatents

Makowiecki, Daniel M.; Jankowski, Alan F.

1995-01-01

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

Magnetron sputtered boron films and TI/B multilayer structures

DOEpatents

Makowiecki, D.M.; Jankowski, A.F.

1993-04-20

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

Magnetron sputtered boron films and Ti/B multilayer structures

DOEpatents

Makowiecki, D.M.; Jankowski, A.F.

1995-02-14

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence. 6 figs.

Comparative analysis of electrophysical properties of ceramic tantalum pentoxide coatings, deposited by electron beam evaporation and magnetron sputtering methods

NASA Astrophysics Data System (ADS)

Donkov, N.; Mateev, E.; Safonov, V.; Zykova, A.; Yakovin, S.; Kolesnikov, D.; Sudzhanskaya, I.; Goncharov, I.; Georgieva, V.

2014-12-01

Ta2O5 ceramic coatings have been deposited on glass substrates by e-beam evaporation and magnetron sputtering methods. For the magnetron sputtering process Ta target was used. X-ray diffraction measurements show that these coatings are amorphous. XPS survey spectra of the ceramic Ta2O5 coatings were obtained. All spectra consist of well-defined XPS lines of Ta 4f, 4d, 4p and 4s; O 1s; C 1s. Ta 4f doublets are typical for Ta2O5 coatings with two main peaks. Scanning electron microscopy and atomic force microscopy images of the e-beam evaporated and magnetron sputtered Ta2O5 ceramic coatings have revealed a relatively flat surface with no cracks. The dielectric properties of the tantalum pentoxide coatings have been investigated in the frequency range of 100 Hz to 1 MHz. The electrical behaviour of e-beam evaporated and magnetron sputtered Ta2O5 ceramic coatings have also been compared. The deposition process conditions principally effect the structure parameters and electrical properties of Ta2O5 ceramic coatings. The coatings deposited by different methods demonstrate the range of dielectric parameters due to the structural and stoichiometric composition changes

Study of vanadium doped ZnO films prepared by dc reactive magnetron sputtering at different substrate temperatures.

PubMed

Meng, Lijian; Teixeira, Vasco; Dos Santos, M P

2013-02-01

ZnO films doped with vanadium (ZnO:V) have been prepared by dc reactive magnetron sputtering technique at different substrate temperatures (RT-500 degrees C). The effects of the substrate temperature on ZnO:V films properties have been studied. XRD measurements show that only ZnO polycrystalline structure has been obtained, no V2O5 or VO2 crystal phase can be observed. It has been found that the film prepared at low substrate temperature has a preferred orientation along the (002) direction. As the substrate temperature is increased, the (002) peak intensity decreases. When the substrate temperature reaches the 500 degrees C, the film shows a random orientation. SEM measurements show a clear formation of the nano-grains in the sample surface when the substrate temperature is higher than 400 degrees C. The optical properties of the films have been studied by measuring the specular transmittance. The refractive index has been calculated by fitting the transmittance spectra using OJL model combined with harmonic oscillator.

High Temperature Thermal Stability and Oxidation Resistance of Magnetron-sputtered Homogeneous CrAlON Coatings on 430 Steel

NASA Astrophysics Data System (ADS)

Kayani, A.; Wickey, K. J.; Nandasiri, M. I.; Moore, A.; Garratt, E.; AlFaify, S.; Gao, X.; Smith, R. J.; Buchanan, T. L.; Priyantha, W.; Kopczyk, M.; Gannon, P. E.; Gorokhovsky, V. I.

2009-03-01

The requirements of low cost and high-temperature corrosion resistance for bipolar interconnect plates in solid oxide fuel cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. We have investigated the performance of steel plates with homogenous coatings of CrAlON (oxynitrides). The coatings were deposited using RF magnetron sputtering, with Ar as a sputtering gas. Oxygen in these coatings was not intentionally added. Oxygen might have come through contaminated nitrogen gas bottle, leak in the chamber or from the partial pressure of water vapors. Nitrogen was added during the growth process to get oxynitride coating. The Cr/Al composition ratio in the coatings was varied in a combinatorial approach. The coatings were subsequently annealed in air for up to 25 hours at 800° C. The composition of the coated plates and the rate of oxidation were characterized using Rutherford backscattering (RBS) and nuclear reaction analysis (NRA). From our results, we conclude that Al rich coatings are more susceptible to oxidation than Cr rich coatings.

Structure evolution of zinc oxide thin films deposited by unbalance DC magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aryanto, Didik, E-mail: didi027@lipi.go.id; Materials Research Group, Physics Department, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah; Marwoto, Putut

Zinc oxide (ZnO) thin films are deposited on corning glass substrates using unbalanced DC magnetron sputtering. The effect of growth temperature on surface morphology and crystallographic orientation of ZnO thin film is studied using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The surface morphology and crystallographic orientation of ZnO thin film are transformed against the increasing of growth temperature. The mean grain size of film and the surface roughness are inversely and directly proportional towards the growth temperature from room temperature to 300 °C, respectively. The smaller grain size and finer roughness of ZnO thin film are obtainedmore » at growth temperature of 400 °C. The result of AFM analysis is in good agreement with the result of XRD analysis. ZnO thin films deposited in a series of growth temperatures have hexagonal wurtzite polycrystalline structures and they exhibit transformations in the crystallographic orientation. The results in this study reveal that the growth temperature strongly influences the surface morphology and crystallographic orientation of ZnO thin film.« less

Resistance switching in polyvinylidene fluoride (PVDF) thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pramod, K.; Sahu, Binaya Kumar; Gangineni, R. B., E-mail: rameshg.phy@pondiuni.edu.in

2015-06-24

Polyvinylidene fluoride (PDVF), one of the best electrically active polymer material & an interesting candidate to address the electrical control of its functional properties like ferroelectricity, piezoelectricity, pyroelectricity etc. In the current work, with the help of spin coater and DC magnetron sputtering techniques, semi-crystallized PVDF thin films prominent in alpha phase is prepared in capacitor like structure and their electrical characterization is emphasized. In current-voltage (I-V) and resistance-voltage (R-V) measurements, clear nonlinearity and resistance switching has been observed for films prepared using 7 wt% 2-butanone and 7 wt% Dimethyl Sulfoxide (DMSO) solvents.

The Development and Application of the Magnetron,

DTIC Science & Technology

1982-03-31

of *medicine. The power of the magnetron used is from several tens of watts to several hundred watts. Microwave physiotherapy has been used in...clinical practice for the fast cure of arthritis , rheumatism and the subsidence of swelling. Therapeutic results have been excellent. In recent years

Plasma ``anti-assistance'' and ``self-assistance'' to high power impulse magnetron sputtering

NASA Astrophysics Data System (ADS)

Anders, André; Yushkov, Georgy Yu.

2009-04-01

A plasma assistance system was investigated with the goal to operate high power impulse magnetron sputtering (HiPIMS) at lower pressure than usual, thereby to enhance the utilization of the ballistic atoms and ions with high kinetic energy in the film growth process. Gas plasma flow from a constricted plasma source was aimed at the magnetron target. Contrary to initial expectations, such plasma assistance turned out to be contraproductive because it led to the extinction of the magnetron discharge. The effect can be explained by gas rarefaction. A better method of reducing the necessary gas pressure is operation at relatively high pulse repetition rates where the afterglow plasma of one pulse assists in the development of the next pulse. Here we show that this method, known from medium-frequency (MF) pulsed sputtering, is also very important at the much lower pulse repetition rates of HiPIMS. A minimum in the possible operational pressure is found in the frequency region between HiPIMS and MF pulsed sputtering.

Magnetron sputtered boron films

DOEpatents

Makowiecki, Daniel M.; Jankowski, Alan F.

1998-01-01

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence.

Magnetron sputtered boron films

DOEpatents

Makowiecki, D.M.; Jankowski, A.F.

1998-06-16

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence. 8 figs.

Rapid start of oscillations in a magnetron with a "transparent" cathode.

PubMed

Fuks, Mikhail; Schamiloglu, Edl

2005-11-11

We report on the improvement of conditions for the rapid start of oscillations in magnetrons by increasing the amplitude of the operating wave that is responsible for the capture of electrons into spokes. This amplitude increase is achieved by using a hollow cathode with longitudinal strips removed, thereby making the cathode transparent to the wave electric field with azimuthal polarization. In addition, an optimal choice of the number and position of cathode strips provide favorable prebunching of the electron flow over the cathode for fast excitation of the operating mode. Particle-in-cell simulations of the A6 magnetron demonstrate these advantages of this novel cathode.

A time-resolved Langmuir double-probe method for the investigation of pulsed magnetron discharges

NASA Astrophysics Data System (ADS)

Welzel, Th.; Dunger, Th.; Kupfer, H.; Richter, F.

2004-12-01

Langmuir probes are important means for the characterization of plasma discharges. For measurements in plasmas used for the deposition of thin films, the Langmuir double probe is especially suited. With the increasing popularity of pulsed deposition discharges, there is also an increasing need for time-resolved characterization methods. For Langmuir probes, several single-probe approaches to time-resolved measurements are reported but very few for the double probe. We present a time-resolved Langmuir double-probe technique, which is applied to a pulsed magnetron discharge at several 100 kHz used for MgO deposition. The investigations show that a proper treatment of the current measurement is necessary to obtain reliable results. In doing so, a characteristic time dependence of the charge-carrier density during the "pulse on" time containing maximum values of almost 2•1011cm-3 was found. This characteristic time dependence varies with the pulse frequency and the duty cycle. A similar time dependence of the electron temperature is only observed when the probe is placed near the magnesium target.

An Al-doped ZnO electrode grown by highly efficient cylindrical rotating magnetron sputtering for low cost organic photovoltaics

NASA Astrophysics Data System (ADS)

Park, Jun-Hyuk; Ahn, Kyung-Jun; Park, Kang-Il; Na, Seok-In; Kim, Han-Ki

2010-03-01

We report the characteristics of Al-doped zinc oxide (AZO) films prepared by a highly efficient cylindrical rotating magnetron sputtering (CRMS) system for use as a transparent conducting electrode in cost-efficient bulk hetero-junction organic solar cells (OSCs). Using a rotating cylindrical type cathode with an AZO target, whose usage was above 80%, we were able to obtain a low cost and indium free AZO electrode with a low sheet resistance of ~4.59 Ω/sq, a high transparency of 85% in the visible wavelength region and a work function of 4.9 eV at a substrate temperature of 230 °C. Moreover, the neutral poly(3,4-ethylenedioxythiophene) : poly(styrenesulfonate) based OSC fabricated on the CRMS-grown AZO electrode at 230 °C showed an open circuit voltage of 0.5 V, a short circuit current of 8.94 mA cm-2, a fill factor of 45% and power conversion efficiency of 2.01%, indicating that CRMS is a promising cost-efficient AZO deposition technique for low cost OSCs.

Effects of post-deposition annealing ambient on band alignment of RF magnetron-sputtered Y2O3 film on gallium nitride

PubMed Central

2013-01-01

The effects of different post-deposition annealing ambients (oxygen, argon, forming gas (95% N2 + 5% H2), and nitrogen) on radio frequency magnetron-sputtered yttrium oxide (Y2O3) films on n-type gallium nitride (GaN) substrate were studied in this work. X-ray photoelectron spectroscopy was utilized to extract the bandgap of Y2O3 and interfacial layer as well as establishing the energy band alignment of Y2O3/interfacial layer/GaN structure. Three different structures of energy band alignment were obtained, and the change of band alignment influenced leakage current density-electrical breakdown field characteristics of the samples subjected to different post-deposition annealing ambients. Of these investigated samples, ability of the sample annealed in O2 ambient to withstand the highest electric breakdown field (approximately 6.6 MV/cm) at 10−6 A/cm2 was related to the largest conduction band offset of interfacial layer/GaN (3.77 eV) and barrier height (3.72 eV). PMID:23360596

Simulation, fabrication and characterization of ZnO based thin film transistors grown by radio frequency magnetron sputtering.

PubMed

Singh, Shaivalini; Chakrabarti, P

2012-03-01

We report the performance of the thin film transistors (TFTs) using ZnO as an active channel layer grown by radio frequency (RF) magnetron sputtering technique. The bottom gate type TFT, consists of a conventional thermally grown SiO2 as gate insulator onto p-type Si substrates. The X-ray diffraction patterns reveal that the ZnO films are preferentially orientated in the (002) plane, with the c-axis perpendicular to the substrate. A typical ZnO TFT fabricated by this method exhibits saturation field effect mobility of about 0.6134 cm2/V s, an on to off ratio of 102, an off current of 2.0 x 10(-7) A, and a threshold voltage of 3.1 V at room temperature. Simulation of this TFT is also carried out by using the commercial software modeling tool ATLAS from Silvaco-International. The simulated global characteristics of the device were compared and contrasted with those measured experimentally. The experimental results are in fairly good agreement with those obtained from simulation.

The behaviour of arcs in carbon mixed-mode high-power impulse magnetron sputtering

NASA Astrophysics Data System (ADS)

Tucker, M. D.; Putman, K. J.; Ganesan, R.; Lattemann, M.; Stueber, M.; Ulrich, S.; Bilek, M. M. M.; McKenzie, D. R.; Marks, N. A.

2017-04-01

Mixed-mode deposition of carbon is an extension of high-power impulse magnetron sputtering in which a short-lived arc is deliberately allowed to ignite on the target surface to increase the ionised fraction of carbon in the deposition flux. Here we investigate the ignition and evolution of these arcs and examine their behaviour for different conditions of argon pressure, power supply voltage, and current. We find that mixed-mode deposition is sensitive to the condition of the target surface, and changing the operating parameters causes changes in the target surface condition which themselves affect the discharge in a process of negative feedback. Initially the arcs are evenly distributed on the target racetrack, but after a long period of operation the mode of erosion changes and arcs become localised in a small region, resulting in a pronounced nodular structure. We also quantify macroparticle generation and observe a power-law size distribution typical of arc discharges. Fewer particles are generated for operation at lower Ar pressure when the arc spot velocity is higher.

Preparation of magnetron sputtered ZrO2 films on Si for gate dielectric application

NASA Astrophysics Data System (ADS)

Kondaiah, P.; Mohan Rao, G.; Uthanna, S.

2012-11-01

Zirconium oxide (ZrO2) thin films were deposited on to p - Si and quartz substrates by sputtering of zirconium target at an oxygen partial pressure of 4x10-2 Pa and sputter pressure of 0.4 Pa by using DC reactive magnetron sputtering technique. The effect of annealing temperature on structural, optical, electrical and dielectric properties of the ZrO2 films was systematically studied. The as-deposited films were mixed phases of monoclinic and orthorhombic ZrO2. As the annealing temperature increased to 1073 K, the films were transformed in to single phase orthorhombic ZrO2. Fourier transform infrared studies conform the presence of interfacial layer between Si and ZrO2. The optical band gap and refractive index of the as-deposited films were 5.82 eV and 1.81. As the annealing temperature increased to 1073 K the optical band gap and refractive index increased to 5.92 eV and 2.10 respectively. The structural changes were influenced the capacitance-voltage and current-voltage characteristics of Al/ZrO2/p-Si capacitors. The dielectric constant was increased from 11.6 to 24.5 and the leakage current was decreased from 1.65×10-7 to 3.30×10-9 A/ cm2 for the as-deposited and annealed at 1073 K respectively.

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.

Magnetron sputtered boron films for increasing hardness of a metal surface

DOEpatents

Makowiecki, Daniel M [Livermore, CA; Jankowski, Alan F [Livermore, CA

2003-05-27

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence.

Fabrication and characterization of flaky core-shell particles by magnetron sputtering silver onto diatomite

NASA Astrophysics Data System (ADS)

Wang, Yuanyuan; Zhang, Deyuan; Cai, Jun

2016-02-01

Diatomite has delicate porous structures and various shapes, making them ideal templates for microscopic core-shell particles fabrication. In this study, a new process of magnetron sputtering assisted with photoresist positioning was proposed to fabricate lightweight silver coated porous diatomite with superior coating quality and performance. The diatomite has been treated with different sputtering time to investigate the silver film growing process on the surface. The morphologies, constituents, phase structures and surface roughness of the silver coated diatomite were analyzed with SEM, EDS, XRD and AFM respectively. The results showed that the optimized magnetron sputtering time was 8-16 min, under which the diatomite templates were successfully coated with uniform silver film, which exhibits face centered cubic (fcc) structure, and the initial porous structures were kept. Moreover, this silver coating has lower surface roughness (RMS 4.513 ± 0.2 nm) than that obtained by electroless plating (RMS 15.692 ± 0.5 nm). And the infrared emissivity of coatings made with magnetron sputtering and electroless plating silver coated diatomite can reach to the lowest value of 0.528 and 0.716 respectively.

Photoluminescence and cathodoluminescence properties of green emitting SrGa2{S}4 : Eu2+ thin film

NASA Astrophysics Data System (ADS)

Chartier, Céline; Benalloul, Paul; Barthou, Charles; Frigerio, Jean-Marc; Mueller, Gerd O.; Mueller-Mach, Regina; Trottier, Troy

2002-02-01

Photoluminescence and cathodoluminescence properties of SrGa2S4 : Eu2+ thin films prepared by reactive RF magnetron sputtering are investigated. Luminescence performances of the phosphor in the thin film form are compared to those of powder samples: the brightness efficiency of thin films is found to be about 30% of the efficiency of powder at low current density. A ratio higher than 40% is expected at higher current density. Thin film screens for FEDs will become a positive alternative to powder screens provided that film quality and light extraction could be improved by optimization of thickness and deposition parameters.

Corrosion-resistant amorphous metallic films of Mo49Cr33B18 alloy

NASA Technical Reports Server (NTRS)

Ramesham, R.; Distefano, S.; Fitzgerald, D.; Thakoor, A. P.; Khanna, S. K.

1987-01-01

Corrosion-resistant amorphous metallic alloy films of Mo49Cr33B18 with a crystallization temperature of 590 C were deposited onto glass and quartz substrates by magnetron sputter-quench technique. The amorphous nature of the films was confirmed by their diffuse X-ray diffraction patterns. The deposited films are densely packed (zone T) and exhibit low stress and good adhesion to the substrate. Corrosion current of as-deposited coating of MoCrB amorphous metallic alloy is approximately three orders of magnitude less than the corrosion current of 304 stainless steel in 1N H2SO4 solution.

Effect of deposition parameters and heat-treatment on the microstructure, mechanical and electrochemical properties of hydroxyapatite/titanium coating deposited on Ti6Al4V by RF-magnetron sputtering

NASA Astrophysics Data System (ADS)

Qi, Jianwei; Chen, Zhangbo; Han, Wenjun; He, Danfeng; Yang, Yiming; Wang, Qingliang

2017-09-01

Functionally graded HA/Ti coatings were deposited on silicon and Ti6Al4V substrate by radio-frequency (RF) magnetron sputtering. The effect of RF-power, negative bias and heat-treatment on the microstructure, mechanical and electrochemical properties of the coatings were characterized by SEM, XRD, FTIR, AFM Nanoindentation and electrochemical workstation. The obtained results showed that the as-deposited HA/Ti coatings were characteristic of amorphous structure, which transformed into a crystal structure after heat-treatment, and reformed O-H peak. The content of crystallization was increasing with the increase of negative bias. A dense, homogenous, smooth and featured surface, and columnar cross-section structure was observed in SEM observation. AFM results showed that the surface roughness became higher after heat-treatment, and increased with increasing RF-power. The mechanical test indicated that the coating had a higher nanohardness (9.1 GPa) in the case of  -100 V and 250 W than that of Ti6Al4V substrate, and a critical load as high as 17  ±  3.5 N. The electrochemical test confirmed the HA/Ti coating served as a stable protecting barrier in improving the corrosion resistance, which the corrosion current density was 1.3% of Ti6Al4V, but it was significantly influenced by RF-power and negative bias. The contact angle test demonstrated that all the coatings exhibited favorable hydrophilic properties, and it decreased by 20-25% compared to that untreated samples. Thus all results indicated that magnetron sputtering is a promising way for fabricating a better biocompatible ceramic coating by adjusting deposition parameters and post-deposition heat treatments.

A boron and gallium co-doped ZnO intermediate layer for ZnO/Si heterojunction diodes

NASA Astrophysics Data System (ADS)

Lu, Yuanxi; Huang, Jian; Li, Bing; Tang, Ke; Ma, Yuncheng; Cao, Meng; Wang, Lin; Wang, Linjun

2018-01-01

ZnO (Zinc oxide)/Si (Silicon) heterojunctions were prepared by depositing n-type ZnO films on p-type single crystal Si substrates using magnetron sputtering. A boron and gallium co-doped ZnO (BGZO) high conductivity intermediate layer was deposited between aurum (Au) electrodes and ZnO films. The influence of the BGZO layer on the properties of Au/ZnO contacts and the performance of ZnO/Si heterojunctions was investigated. The results show an improvement in contact resistance by introducing the BGZO layer. Compared with the ZnO/Si heterojunction, the BGZO/ZnO/Si heterojunction exhibits a larger forward current, a smaller turn-on voltage and higher ratio of ultraviolet (UV) photo current/dark current.

Heterojunction photodiode on cleaved SiC

NASA Astrophysics Data System (ADS)

Solovan, Mykhailo M.; Farah, John; Kovaliuk, Taras T.; Brus, Viktor V.; Mostovyi, Andrii I.; Maistruk, Eduard V.; Maryanchuk, Pavlo D.

2018-01-01

Graphite/n-SiC Shottky diodes were prepared by means of the recently proposed technique based on the transferring of drawn graphite films onto the n-SiC single crystal substrate. Current-voltage characteristics were measured and analyzed. High quality ohmic contancts were prepared by the DC magnetron sputtering of Ni thin films onto cleaved n-type SiC single crystal substrates. The height of the potential barrier and the series resistance of the graphite/n-SiC junctions were measured and analysed. The dominant current transport mechanisms through the diodes were determined. There was shown that the dominant current transport mechanisms through the graphite/n-SiC Shottky diodes were the multi-step tunnel-recombination at forward bias and the tunnelling mechanisms at reverse bias.

Growth and characterization of zirconium oxynitride films prepared by reactive direct current magnetron sputtering

NASA Astrophysics Data System (ADS)

Venkataraj, S.; Kappertz, O.; Jayavel, R.; Wuttig, M.

2002-09-01

Thin films of zirconium oxynitrides have been deposited onto Si(100) substrates at room temperature by reactive dc magnetron sputtering of a metallic Zr target in an argon-oxygen-nitrogen atmosphere. To prepare oxynitride films the sum of the O2 and N2 flow was kept at 3.5 sccm, while the relative nitrogen content of this mixture was changed stepwise from 0% to 100%. The film structure was determined by x-ray diffraction, while x-ray reflectometry was employed to determine the thickness, density, and surface roughness of the films. The optical properties have been studied by spectroscopic reflectance measurements. X-ray diffraction (XRD) determines that the as-deposited films are crystalline and do not change their monoclinic ZrO2 crystal structure even for nitrogen flows up to 80%. For pure argon-nitrogen sputtering, on the contrary, cubic zirconium nitride (ZrN) has been formed. Nevertheless, even though the crystal structure does not change with increasing nitrogen flow up to 80%, there is clear evidence from nitrogen incorporation from Rutherford backscattering experiments, optical spectroscopy, XRD, and x-ray reflectometry. The latter technique determines that the film density increases from 5.2 to 5.8 g/cm3 with increasing nitrogen flow from 0% to 80%. Simultaneously, the rate of sputtering increases from 0.17 to 0.6 m/s, while the film roughness decreases upon increasing N2 flow. Optical spectroscopy measurements of the film reflectance confirm that fully transparent films can be prepared up to a nitrogen flow of 80%. For these films, the band gap decreases from 4.52 to 3.59 eV with increasing N2 flow, while the refractive index at 650 nm simultaneously increases from 2.11 to 2.26. For 100% N2 flow, i.e., without any oxygen, films with a metallic reflectance are obtained.

Field emission from ZnS nanorods synthesized by radio frequency magnetron sputtering technique

NASA Astrophysics Data System (ADS)

Ghosh, P. K.; Maiti, U. N.; Jana, S.; Chattopadhyay, K. K.

2006-11-01

The field emission property of zinc sulphides nanorods synthesized in the thin film form on Si substrates has been studied. It is seen that ZnS nanorod thin films showed good field emission properties with a low-macroscopic turn-on field (2.9-6.3 V/μm). ZnS nanorods were synthesized by using radio frequency magnetron sputtering of a polycrystalline prefabricated ZnS target at a relatively higher pressure (10 -1 mbar) and at a lower substrate temperature (233-273 K) without using any catalyst. Transmission electron microscopic image showed the formation of ZnS nanorods with high aspect ratio (>60). The field emission data were analysed using Fowler-Nordhiem theory and the nearly straight-line nature of the F-N plots confirmed cold field emission of electrons. It was also found that the turn-on field decreased with the decrease of nanorod's diameters. The optical properties of the ZnS nanorods were also studied. From the measurements of transmittance of the films deposited on glass substrates, the direct allowed bandgap values have been calculated and they were in the range 3.83-4.03 eV. The thickness of the films was ˜600 nm.

High temperature oxidation resistance of magnetron-sputtered homogeneous CrAlON coatings on 430 steel

NASA Astrophysics Data System (ADS)

Garratt, E.; Wickey, K. J.; Nandasiri, M. I.; Moore, A.; AlFaify, S.; Gao, X.; Kayani, A.; Smith, R. J.; Buchanan, T. L.; Priyantha, W.; Kopczyk, M.; Gannon, P. E.

2009-11-01

The requirements of low cost and high-temperature corrosion resistance for bipolar interconnect plates in solid oxide fuel cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. We have investigated the performance of steel plates with homogenous coatings of CrAlON (oxynitrides). The coatings were deposited using RF magnetron sputtering, with Ar as a sputtering gas. Oxygen in these coatings was not intentionally added. Oxygen might have come through contaminated nitrogen gas bottle, leak in the chamber or from the partial pressure of water vapors. Nitrogen was added during the growth process to get oxynitride coating. The Cr/Al composition ratio in the coatings was varied in a combinatorial approach. The coatings were subsequently annealed in air for up to 25 hours at 800 oC. The composition of the coated plates and the rate of oxidation were characterized using Rutherford backscattering (RBS) and nuclear reaction analysis (NRA). Surface characterization was carried out using Atomic Force Microscopy (AFM) and surfaces of the coatings were found smooth on submicron scale. From our results, we conclude that Al rich coatings are more susceptible to oxidation than Cr rich coatings.

Preparation and investigation of sputtered vanadium dioxide films with large phase-transition hysteresis loops

NASA Astrophysics Data System (ADS)

Zhang, Huafu; Wu, Zhiming; He, Qiong; Jiang, Yadong

2013-07-01

Vanadium dioxide (VO2) films with large phase-transition hysteresis loops were fabricated on glass substrates by reactive direct current (DC) magnetron sputtering in Ar/O2 atmosphere and subsequent in situ annealing process in pure oxygen. The crystal structure, chemical composition, morphology and metal-insulator transition (MIT) properties of the deposited films were investigated. The results reveal that the films show a polycrystalline nature with a (0 1 1) preferred orientation and consist of small spheroidal nanoparticles. All the deposited VO2 films show large hysteresis loops due to the small density of nucleating defects and the large interfacial energies, which are determined by the characteristics of the particles in the films, namely the small transversal grain size and the spheroidal shape. The film comprising the smallest spheroidal nanoparticles not only shows a large hysteresis width of 36.3 °C but also shows a low transition temperature of 32.2 °C upon cooling. This experiment facilitates the civilian applications of the VO2 films on glass substrates in optical storage-type devices.

Stoichiometry and tribological behavior of thick Ta(N) coatings produced by direct current magnetron sputtering (DCMS)

NASA Astrophysics Data System (ADS)

Guo, Xiaotong; Niu, Yunsong; Chen, Minghui; Sun, Wenyao; Zhu, Shenglong; Wang, Fuhui

2018-01-01

Thick Ta(N) coating of 51 μm has been successfully obtained by DCMS technology. Ta(N) is a kind of distorted Ta matrix, which is inter-soluble with N-defect lattice structure, forming the disabled bcc structure. From the XRD and XPS investigations, the composition of Ta(N) coating is consisted of bcc-Ta and bcc-TaN0.06, while that of Ta coating mainly contains β-Ta phase. It can be concluded from wear test, nanoindentation test and SEM observations, wear resistance of Ta(N) coating is much better than that of Ta coating, due to its high hardness, H/E, H3/E2 value and low COF value. The wear mechanism of Ta coating is the compound fatigue and abrasive wear, while that of Ta(N) coating is transformed into adhesive wear mechanism. The secondary adhesion of the plastic deformation for the Ta(N) coating can reinforce the coated surface, to improve the load-bearing and anti-wear capacities, and thus improve the wear resistance.

Structure and optical properties of Ge/Si quantum dots formed by driving the evolution of Ge thin films via thermal annealing

NASA Astrophysics Data System (ADS)

Shu, Qijiang; Yang, Jie; Chi, Qingbin; Sun, Tao; Wang, Chong; Yang, Yu

2018-04-01

Ge/Si quantum dots (QDs) are fabricated by driving the transformation of a Ge thin film-deposited using the direct current (DC) magnetron sputtering technique by controlling the subsequent in situ annealing processes. The experimental results indicate that, with the increase in annealing temperature, the volume of Ge QDs increases monotonically, while the QD density initially increases then decreases. The maximal QD density can reach 1.1 × 1011 cm‑2 after a 10 min annealing at 650 °C. The Ge–Ge peak of Ge QDs obtained by Raman spectroscopy initially undergoes a blue shift and then a red shift with increasing annealing temperature. This behavior results from the competition between the dislocation and the strain relaxation in QDs. Concurrently, a series of photoelectric detectors are fabricated to evaluate the photoelectric performance of these annealed Ge QD samples. A high-photoelectricity response is demonstrated in the QD sample annealed at 650 °C. Our results pave a promising way for whole-silicon-material optical-electronic integration based on a simple and practicable fabrication method.

Magnetoelastic Properties of Magnetic Thin Films Using the Magnetooptic Kerr Effect

NASA Astrophysics Data System (ADS)

Mayo, Elizabeth; Lederman, David

1998-03-01

The magnetoelastic properties of Co and Fe thin films were measured using the magnetooptic Kerr effect (MOKE). Films were grown via magnetron sputtering on thin mica substrates. Magnetization loops were measured using MOKE with the magnetic field along different in-plane directions. Subsequently, the samples were mounted on a cylindrical sample holder, which imposed a well-defined strain to the film. This caused the magnetization loops to change dramatically due to the magnetoelastic coefficient of the thin film materials. The effects of the surface roughness and film thickness will also be discussed.

Structure of the metallic films deposited on small spheres trapped in the rf magnetron plasma

NASA Astrophysics Data System (ADS)

Filippov, A. V.; Pal, A. F.; Ryabinkin, A. N.; Serov, A. O.

2016-11-01

Metallic coatings were deposited onto glass spheres having diameters from several to one hundred micrometers by the magnetron sputtering. Two different experimental schemes were exploited. One of them had the traditional configuration where a magnetron sputter was placed at one hundred millimeters from particles. In this scheme, continuous mechanical agitation in a fluidized bed was used to achieve uniformity of coatings. In the second scheme the treated particles (substrates) levitated in a magnetron rf plasma over a sputtered rf electrode (target) at the distance d of few mm from it and at gas pressure p values of 30-100 mTorr. These parameters are essentially different from those in the traditional sputtering. Agitation due to the features of a particle confinement in dusty plasma was used here to obtain uniform coatings. Thickness and morphology of the obtained coatings were studied. As it is known, film growth rate and structure are determined by the substrate temperature, the densities of ion and neutral atom fluxes to the substrate surface, the radiation flux density, and the heat energy produced due to the surface condensation of atoms and recombination of electrons and ions. These parameters particularly depend on the product of p and d. In the case of magnetron rf dusty plasma, it is possible to achieve the pd value several times lower than the lowest value proper to the first traditional case. Completely different dependencies of the film growth rate and structure on the pd value in these sputtering processes were observed and qualitatively explained.

Advanced, phase-locked, 100 kW, 1.3 GHz magnetron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Read, Michael; Ives, R. Lawrence; Bui, Thuc

Calabazas Creek Research, Inc., in collaboration with Fermilab and Communications & Power Industries, LLC, is developing a phase-locked, 100 kW peak, 10 kW average power magnetron-based RF system for driving accelerators. Here, phase locking will be achieved using an approach originating at Fermilab that includes control of both amplitude and phase on a fast time scale.

Advanced, phase-locked, 100 kW, 1.3 GHz magnetron

DOE PAGES

Read, Michael; Ives, R. Lawrence; Bui, Thuc; ...

2017-03-06

Calabazas Creek Research, Inc., in collaboration with Fermilab and Communications & Power Industries, LLC, is developing a phase-locked, 100 kW peak, 10 kW average power magnetron-based RF system for driving accelerators. Here, phase locking will be achieved using an approach originating at Fermilab that includes control of both amplitude and phase on a fast time scale.

Characterization of sp3 bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy.

PubMed

Zdunek, Krzysztof; Chodun, Rafał; Wicher, Bartosz; Nowakowska-Langier, Katarzyna; Okrasa, Sebastian

2018-04-05

This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2kV and a power supply system equipped with 25/50μF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp 3 /sp 2 bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp 3 bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp 3 /sp 2 ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp 3 phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed. Copyright © 2018 Elsevier B.V. All rights reserved.

Stability of Brillouin flow in the presence of slow-wave structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simon, D. H.; Lau, Y. Y.; Greening, G.

2016-09-15

Including a slow-wave structure (SWS) on the anode in the conventional, planar, and inverted magnetron, we systematically study the linear stability of Brillouin flow, which is the prevalent flow in crossed-field devices. The analytic treatment is fully relativistic and fully electromagnetic, and it incorporates the equilibrium density profile, flow profile, and electric field and magnetic field profiles in the linear stability analysis. Using parameters similar to the University of Michigan's recirculating planar magnetron, the numerical data show that the resonant interaction of the vacuum circuit mode and the corresponding smooth-bore diocotron-like mode is the dominant cause for instability. This resonantmore » interaction is far more important than the intrinsic negative (positive) mass property of electrons in the inverted (conventional) magnetron geometry. It is absent in either the smooth-bore magnetron or under the electrostatic assumption, one or both of which was almost always adopted in prior analytical formulation. This resonant interaction severely restricts the wavenumber for instability to the narrow range in which the cold tube frequency of the SWS is within a few percent of the corresponding smooth bore diocotron-like mode in the Brillouin flow.« less

The effect of Substrate temperature on physical and electrical properties of DC magnetron sputtered (Ta2O5)0.85(TiO2)0.15 films

NASA Astrophysics Data System (ADS)

Sekhar, M. Chandra; Uthanna, S.; Martins, R.; Jagadeesh Chandra, S. V.; Elangovan, E.

2012-04-01

Thin films of (Ta2O5)0.85(TiO2)0.15 were deposited on quartz and p-Si substrates by DC reactive magnetron sputtering at different substrate temperatures (Ts) in the range 303 - 873 K. The films deposited at 303 0K were in the amorphous and it transformed to crystalline at substrate temperatures >= 573 0K. The crystallite size was increased from 50 nm to 72 nm with the increase of substrate temperature. The surface morphology was significantly influenced with the substrate temperature. After deposition of the (Ta2O5)0.85(TiO2)0.15 films on Si, aluminium (Al) electrode was deposited to fabricate metal/oxide/semiconductor (MOS) capacitors with a configuration of Al/(Ta2O5)0.85(TiO2)0.15/Si. A low leakage current of 7.7 × 10-5 A/cm2 was obtained from the films deposited at 303 K. The leakage current was decreased to 9.3 × 10-8 A/cm2 with the increase of substrate temperature owing to structural changes. The conduction mechanism of the Al/(Ta2O5)0.85(TiO2)0.15/Si capacitors was analyzed and compared with mechanisms of Poole-Frenkel and Schottky emissions. The optical band gap (Eg) was decreased from 4.45 eV to 4.38 eV with the increase in substrate temperature.

Method and apparatus for ion cyclotron spectrometry

DOEpatents

Dahl, David A [Idaho Falls, ID; Scott, Jill R [Idaho Falls, ID; McJunkin, Timothy R [Idaho Falls, ID

2010-08-17

An ion cyclotron spectrometer may include a vacuum chamber that extends at least along a z-axis and means for producing a magnetic field within the vacuum chamber so that a magnetic field vector is generally parallel to the z-axis. The ion cyclotron spectrometer may also include means for producing a trapping electric field within the vacuum chamber that includes at least a first section that induces a first magnetron effect that increases a cyclotron frequency of an ion and at least a second section that induces a second magnetron effect that decreases the cyclotron frequency of an ion. The cyclotron frequency changes induced by the first and second magnetron effects substantially cancel one another so that an ion traversing the at least first and second sections will experience no net change in cyclotron frequency.

Investigation of electrical and optical properties of low temperature titanium nitride grown by rf-magnetron sputtering

NASA Astrophysics Data System (ADS)

Sosnin, D.; Kudryashov, D.; Mozharov, A.

2017-11-01

Titanium nitride is a promising material due to its low resistivity, high hardness and chemical inertness. Titanium nitride (TiN) can be applied as an ohmic contact for n-GaN and rectifying contact for p-GaN and also as a part of perovskite solar cell. A technology of TiN low temperature reactive rf-magnetron sputtering has been developed. Electrical and optical properties of titanium nitride were studied as a function of the rf-power and gas mixture composition. Reflectance and transmittance spectra were measured. Cross-section and surface SEM image were obtained. 250 nm thin films of TiN with a resistivity of 23.6 μOm cm were obtained by rf-magnetron sputtering at low temperature.

Modélisation d'un transformateur à shunts magnétiques utilisé dans l'alimentation H.T. d'un générateur micro-ondes à magnétron

NASA Astrophysics Data System (ADS)

Chraygane, Mohamed; Teissier, Maurice; Jammal, Ahmad; Masson, Jean-Pierre

1994-11-01

The high voltage power supply for magnetron, used for the modular microwave generators in industrial applications, is of a classical design : a single phase leakage flux transformer supplying a cell, composed of a capacitor and a diode, which multiplies the voltage and stabilizes the current. A π model of this transformer is developed, taking the saturation phenomena and the stabilization process of the magnetron current into account. Three inductances are characterized by the non linear relations between flux and magnetizing current. This model was tested by E.M.T.P. software (Electro-Magnetic Transients Program), near the nominal state. The theoretical results were compared to experimental measurements with a good agreement. L'alimentation haute tension des magnétrons, utilisés comme source d'énergie microondes dans l'industrie, est de conception classique : un transformateur monophasé à fuites magnétiques alimentant une cellule doubleuse de tension et stabilisatrice de courant. Un schéma équivalent en π du transformateur est présenté, prenant en compte la saturation des différentes parties du fer et la stabilisation du courant du magnétron. Trois inductances sont caractérisées par les relations non linéaires entre flux et courant magnétisant. Ce modèle a été testé à l'aide du logiciel de calcul E.M.T.P. (Electro-Magnetic Transients Program), au voisinage du régime nominal. Les résultats théoriques, comparés aux mesures expérimentales, se trouvent en bon accord avec elles.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidt, Susann; Czigany, Zsolt; Greczynski, Grzegorz

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 inertmore » 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.« less

Hydrogenated TiO2 Thin Film for Accelerating Electron Transport in Highly Efficient Planar Perovskite Solar Cells.

PubMed

Yao, Xin; Liang, Junhui; Li, Yuelong; Luo, Jingshan; Shi, Biao; Wei, Changchun; Zhang, Dekun; Li, Baozhang; Ding, Yi; Zhao, Ying; Zhang, Xiaodan

2017-10-01

Intensive studies on low-temperature deposited electron transport materials have been performed to improve the efficiency of n-i-p type planar perovskite solar cells to extend their application on plastic and multijunction device architectures. Here, a TiO 2 film with enhanced conductivity and tailored band edge is prepared by magnetron sputtering at room temperature by hydrogen doping (HTO), which accelerates the electron extraction from perovskite photoabsorber and reduces charge transfer resistance, resulting in an improved short circuit current density and fill factor. The HTO film with upward shifted Fermi level guarantees a smaller loss on V OC and facilitates the growth of high-quality absorber with much larger grains and more uniform size, leading to devices with negligible hysteresis. In comparison with the pristine TiO 2 prepared without hydrogen doping, the HTO-based device exhibits a substantial performance enhancement leading to an efficiency of 19.30% and more stabilized photovoltaic performance maintaining 93% of its initial value after 300 min continuous illumination in the glove box. These properties permit the room-temperature magnetron sputtered HTO film as a promising electron transport material for flexible and tandem perovskite solar cell in the future.

Adhesion analysis for chromium nitride thin films deposited by reactive magnetron sputtering

NASA Astrophysics Data System (ADS)

Rusu, F. M.; Merie, V. V.; Pintea, I. M.; Molea, A.

2016-08-01

The thin film industry is continuously growing due to the wide range of applications that require the fabrication of advanced components such as sensors, biological implants, micro-electromechanical devices, optical coatings and so on. The selection regarding the deposition materials, as well as the deposition technology influences the properties of the material and determines the suitability of devices for certain real-world applications. This paper is focused on the adhesion force for several chromium nitride thin films obtained by reactive magnetron sputtering. All chromium nitride thin films were deposited on a silicon substrate, the discharge current and the argon flow being kept constant. The main purpose of the paper is to determine the influence of deposition parameters on the adhesion force. Therefore some of the deposition parameters were varied in order to study their effect on the adhesion force. Experimentally, the values of the adhesion force were determined in multiple points for each sample using the spectroscopy in point mode of the atomic force microscope. The obtained values were used to estimate the surface energy of the CrN thin films based on two existing mathematical models for the adhesion force when considering the contact between two bodies.

Hybrid solar cells based on dc magnetron sputtered films of n-ITO on APMOVPE grown p-InP

NASA Technical Reports Server (NTRS)

Coutts, T. J.; Li, X.; Wanlass, M. W.; Emery, K. A.; Gessert, T. A.

1988-01-01

Hybrid indium-tin-oxide (ITO)/InP solar cells are discussed. The cells are constructed by dc magnetron sputter deposition of ITO onto high-quality InP films grown by atmospheric pressure metal-organic vapor-phase epitaxy (APMOVPE). A record efficiency of 18.9 percent, measured under standard Solar Energy Research Institute reporting conditions, has been obtained. The p-InP surface is shown to be type converted, principally by the ITO, but with the extent of conversion being modified by the nature of the sputtering gas. The deposition process, in itself, is not responsible for the type conversion. Dark currents have been suppressed by more than three orders of magnitude by the addition of hydrogen to the sputtering gas during deposition of a thin (5 nm) interface layer. Without this layer, and using only the more usual argon/oxygen mixture, the devices had poorer efficiencies and were unstable. A discussion of associated quantum efficiencies and capacitance/voltage measurements is also presented from which it is concluded that further improvements in efficiency will result from better control over the type-conversion process.

Discharge Characteristic of VHF-DC Superimposed Magnetron Sputtering System

NASA Astrophysics Data System (ADS)

Toyoda, Hirotaka; Fukuoka, Yushi; Fukui, Takashi; Takada, Noriharu; Sasai, Kensuke

2014-10-01

Magnetron plasmas are one of the most important tools for sputter deposition of thin films. However, energetic particles from the sputtered target such as backscattered rare gas atoms or oxygen negative ions from oxide targets sometimes induce physical and chemical damages as well as surface roughening to the deposited film surface during the sputtering processes. To suppress kinetic energy of such particles, superposition of RF or VHF power to the DC power has been investigated. In this study, influence of the VHF power superposition on the DC target voltage, which is important factor to determine kinetic energy of high energy particles, is investigated. In the study, 40 MHz VHF power was superimposed to an ITO target and decrease in the target DC voltage was measured as well as deposited film deposition properties such as deposition rate or electrical conductivity. From systematic measurement of the target voltage, it was revealed that the target voltage can be determined by a very simple parameter, i.e., a ratio of VHF power to the total input power (DC and VHF powers) in spite of the DC discharge current. Part of this work was supported by ASTEP, JST.

Carbon film deposition on SnO{sub 2}/Si(111) using DC unbalanced magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aji, A. S.; Darma, Y.

In this paper, carbon deposition on SnO{sub 2} layer using DC unbalanced magnetron-sputtering technique at low temperature has been systematically studied. Sputtering process were carried out at pressure of 4.6×10{sup −2} Torr by keeping the substrate temperature at 300 °C. SnO{sub 2} were growth on silicon (111) substrate using thermal evaporation and continuing with dry oxidation of Sn at 225 °C. Thermal evaporation for high purity Sn was conducted by maintain the current source as high as 40 ampere. The quality of SnO{sub 2} on Si(111) and the characteristic of carbon thin film on SnO{sub 2} were analized by meanmore » XRD, FTIR and Raman spectra. XRD analysis shows that SnO{sub 2} film is growth uniformly on Si(111). FTIR and Raman spectra confirm the formation of thin film carbon on SnO{sub 2}. Additionally, thermal annealing for some sample series have been performed to study their structural stability. The change of atomic structure due to thermal annealing were analized by Raman and XRD spectra.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murzin, I.H.; Tompa, G.S.; Wei, J.

The authors report the results of using sputtering and negative carbon ion sources to prepare thin films of carbon nitride. In this work, they compare the structural, tribological, and optical properties of the carbon nitride films that were prepared by two different ion assisted techniques. In the first approach they used a magnetron gun to sputter deposit carbon in a nitrogen atmosphere. The second method utilized a beam of negatively charged carbon ions of 1 to 5 {micro}A/cm{sup 2} current density impinging the substrate simultaneously with a positive nitrogen ion beam produced by a Kaufman source. They were able tomore » synthesize microscopically smooth coatings with the carbon to nitrogen ratio of 1:0.47. These films possess wear rates lower than 5 {times} 10{sup {minus}7} mm{sup 3}/Nm and friction coefficients in the range of 0.16 to 0.6. Raman spectroscopy revealed that the magnetron sputtered films are more structurally disordered than those formed with the negative carbon ion gun. FTIR showed the presence of the C{triple_bond}N stretching mode in both types of films. Finally, spectroscopic ellipsometry produced films with dielectric constants as low as 2.3 in the photon energy range from 1.2 to 5 eV.« less

Silicon nanowire array architecture for heterojunction electronics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solovan, M. M., E-mail: m.solovan@chnu.edu.ua; Brus, V. V.; Mostovyi, A. I.

2017-04-15

Photosensitive nanostructured heterojunctions n-TiN/p-Si were fabricated by means of titanium nitride thin films deposition (n-type conductivity) by the DC reactive magnetron sputtering onto nano structured single crystal substrates of p-type Si (100). The temperature dependencies of the height of the potential barrier and series resistance of the n-TiN/p-Si heterojunctions were investigated. The dominant current transport mechanisms through the heterojunctions under investigation were determined at forward and reverse bias. The heterojunctions under investigation generate open-circuit voltage V{sub oc} = 0.8 V, short-circuit current I{sub sc} = 3.72 mA/cm{sup 2} and fill factor FF = 0.5 under illumination of 100 mW/cm{sup 2}.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakoglidis, Konstantinos D., E-mail: konba@ifm.liu.se; Schmidt, Susann; Garbrecht, Magnus

The potential of different magnetron sputtering techniques for the synthesis of low friction and wear resistant amorphous carbon nitride (a-CN{sub x}) thin films onto temperature-sensitive AISI52100 bearing steel, but also Si(001) substrates was studied. Hence, a substrate temperature of 150 °C was chosen for the film synthesis. The a-CN{sub x} films were deposited using mid-frequency magnetron sputtering (MFMS) with an MF bias voltage, high power impulse magnetron sputtering (HiPIMS) with a synchronized HiPIMS bias voltage, and direct current magnetron sputtering (DCMS) with a DC bias voltage. The films were deposited using a N{sub 2}/Ar flow ratio of 0.16 at the totalmore » pressure of 400 mPa. The negative bias voltage, V{sub s}, was varied from 20 to 120 V in each of the three deposition modes. The microstructure of the films was characterized by high-resolution transmission electron microscopy and selected area electron diffraction, while the film morphology was investigated by scanning electron microscopy. All films possessed an amorphous microstructure, while the film morphology changed with the bias voltage. Layers grown applying the lowest substrate bias of 20 V exhibited pronounced intercolumnar porosity, independent of the sputter technique. Voids closed and dense films are formed at V{sub s} ≥ 60 V, V{sub s} ≥ 100 V, and V{sub s} = 120 V for MFMS, DCMS, and HiPIMS, respectively. X-ray photoelectron spectroscopy revealed that the nitrogen-to-carbon ratio, N/C, of the films ranged between 0.2 and 0.24. Elastic recoil detection analysis showed that Ar content varied between 0 and 0.8 at. % and increased as a function of V{sub s} for all deposition techniques. All films exhibited compressive residual stress, σ, which depends on the growth method; HiPIMS produces the least stressed films with values ranging between −0.4 and −1.2 GPa for all V{sub s}, while CN{sub x} films deposited by MFMS showed residual stresses up to −4.2 GPa. Nanoindentation showed a significant increase in film hardness and reduced elastic modulus with increasing V{sub s} for all techniques. The harder films were produced by MFMS with hardness as high as 25 GPa. Low friction coefficients, between 0.05 and 0.06, were recorded for all films. Furthermore, CN{sub x} films produced by MFMS and DCMS at V{sub s} = 100 and 120 V presented a high wear resistance with wear coefficients of k ≤ 2.3 × 10{sup −5} mm{sup 3}/Nm. While all CN{sub x} films exhibit low friction, wear depends strongly on the structural and mechanical characteristics of the films. The MFMS mode is best suited for the production of hard CN{sub x} films, although high compressive stresses challenge the application on steel substrates. Films grown in HiPIMS mode provide adequate adhesion due to low residual stress values, at the expense of lower film hardness. Thus, a relatively wide mechanical property envelope is presented for CN{sub x} films, which is relevant for the optimization of CN{sub x} film properties intended to be applied as low friction and wear resistant coatings.« less

Effect of different methods of preliminary surface treatment and magnetron sputtering on the adhesion of Si coatings

NASA Astrophysics Data System (ADS)

Borisov, D. P.; Slabodchikov, V. A.; Kuznetsov, V. M.

2017-05-01

The paper presents research results on the adhesion of Si coatings deposited by magnetron sputtering on NiTi substrates after preliminary surface treatment (cleaning and activation) with low-energy ion beams and gas discharge plasma. The adhesion properties of the coatings obtained by two methods are analyzed and compared using data of scratch and spherical abrasion tests.

Photoluminescence of ZnS-SiO2:Ce Thin Films Deposited by Magnetron Sputtering

NASA Astrophysics Data System (ADS)

Mizuno, Masao

2011-12-01

Photoluminescent emissions of zinc sulfide-silica-cerium thin films deposited by magnetron sputtering were observed. The films consisted of ZnS nanocrystals embedded in amorphous SiO2 matrices. ZnS-SiO2:Ce films exhibited photoluminescence even without postannealing. Their emission spectra showed broad patterns in the visible range; the emitted colors depended on film composition.

Innovative Inverted Magnetron Experiments and Theory

DTIC Science & Technology

2015-06-01

and characterized the Recirculating Planar Magnetron (RPM), a new type of High Power Microwave (HPM) device. Researchers have simulated the operation... power extraction is desired. In simulation, the RPM-CACE was up to 70% efficient, producing peak microwave powers of 420 MW. 15. SUBJECT TERMS High ...type of High Power Microwave (HPM) device. Using HFSS, MAGIC, and ICEPIC, researchers have simulated the operation of the device in both a

Deposition and characterization of molybdenum thin films using dc-plasma magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, Majid, E-mail: majids@hotmail.com; Islam, Mohammad, E-mail: mohammad.islam@gmail.com

2013-12-15

Molebdenum (Mo) thin films were deposited on well-cleaned soda-lime glass substrates using DC-plasma magnetron sputtering. In the design of experiment deposition was optimized for maximum beneficial characteristics by monitoring effect of process variables such as deposition power (100–200 W). Their electrical, structural and morphological properties were analyzed to study the effect of these variables. The electrical resistivity of Mo thin films could be reduced by increasing deposition power. Within the range of analyzed deposition power, Mo thin films showed a mono crystalline nature and the crystallites were found to have an orientation along [110] direction. The surface morphology of thinmore » films showed that a highly dense micro structure has been obtained. The surface roughness of films increased with deposition power. The adhesion of Mo thin films could be improved by increasing the deposition power. Atomic force microscopy was used for the topographical study of the films and to determine the roughness of the films. X-ray diffractrometer and scanning electron microscopy analysis were used to investigate the crystallinity and surface morphology of the films. Hall effect measurement system was used to find resistivity, carrier mobility and carrier density of deposited films. The adhesion test was performed using scotch hatch tape adhesion test. Mo thin films prepared at deposition power of 200 W, substrate temperature of 23°C and Ar pressure of 0.0123 mbar exhibited a mono crystalline structure with an orientation along (110) direction, thickness of ∼550 nm and electrical resistivity value of 0.57 × 10{sup −4} Ω cm.« less

Particle-In-Cell (PIC) simulation of long-anode magnetron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verma, Rajendra Kumar, E-mail: rajendra.verma89@gmail.com; Maurya, Shivendra; Singh, Vindhyavasini Prasad

Long Anode Magnetron (LAM) is a design scheme adopted to attain greater thermal stability and higher power levels for the conventional magnetrons. So a LAM for 5MW Power level at 2.858 GHz was ‘Virtual Prototyped’ using Admittance Matching field theory (AMT) andthen a PIC Study (Beam-wave interaction) was conducted using CST Particle Studio (CST-PS) which is explained in this paper. The convincing results thus obtained were – hot resonant frequency of 2.834 GHz. Output power of 5 MW at beam voltage of 58kV and applied magnetic field of 2200 Gauss with an overall efficiency of 45%. The simulated parameters values on comparisonmore » with the E2V LAM tube (M5028) were in good agreement which validates the feasibility of the design approach.« less

Physical properties of the heterojunction MoOx/n-CdTe as a function of the parameters of CdTe crystals

NASA Astrophysics Data System (ADS)

Mostovyi, Andrii I.; Solovan, Mykhailo M.; Brus, Viktor V.; Pullerits, Toǧnu; Maryanchuk, Pavlo D.

2018-01-01

MoOx/n-CdTe photosensitive heterostructures were prepared by the deposition of molybdenum oxide thin films onto three different n-type CdTe substrates (ρ1=0.4 Ωṡcm, ρ2=10 Ωṡcm, ρ3=40 Ωṡcm) by DC reactive magnetron sputtering. The height of the potential barrier and series resistance of the MoOx/CdTe heterojunctions were investigated. The dominating current transport mechanisms through the heterojunctions were determined at forward and reverse biases.

Optical fiber magnetic field sensors with TbDyFe magnetostrictive thin films as sensing materials.

PubMed

Yang, Minghong; Dai, Jixiang; Zhou, Ciming; Jiang, Desheng

2009-11-09

Different from usually-used bulk magnetostrictive materials, magnetostrictive TbDyFe thin films were firstly proposed as sensing materials for fiber-optic magnetic field sensing characterization. By magnetron sputtering process, TbDyFe thin films were deposited on etched side circle of a fiber Bragg Grating (FBG) as sensing element. There exists more than 45pm change of FBG wavelength when magnet field increase up to 50 mT. The response to magnetic field is reversible, and could be applicable for magnetic and current sensing.

Formation of the YBa2Cu2NbOy Phase in Thin Films (POSTPRINT)

DTIC Science & Technology

2010-03-01

protective layer was deposited on the top of YBCNO film by dc sputtering . A 200 nm 200 nm area film was selected and cut with a Ga ion beam (30 kV...200 TEM at 200 kV. Samples for TEM were prepared using a focused ion beam (FIB (Eindhoven, The Netherlands)) microscope. For TEM examination, a thin Pt...by dc magnetron sputtering deposition of Ag with 93 mm thickness. Transport current measurements were made in liquid nitrogen with the 4-probe method

MgO buffer layers on rolled nickel or copper as superconductor substrates

DOEpatents

Paranthaman, Mariappan; Goyal, Amit; Kroeger, Donald M.; List, III, Frederic A.

2001-01-01

Buffer layer architectures are epitaxially deposited on biaxially-textured rolled-Ni and/or Cu substrates for high current conductors, and more particularly buffer layer architectures such as MgO/Ag/Pt/Ni, MgO/Ag/Pd/Ni, MgO/Ag/Ni, MgO/Ag/Pd/Cu, MgO/Ag/Pt/Cu, and MgO/Ag/Cu. Techniques used to deposit these buffer layers include electron beam evaporation, thermal evaporation, rf magnetron sputtering, pulsed laser deposition, metal-organic chemical vapor deposition (MOCVD), combustion CVD, and spray pyrolysis.

Method for making MgO buffer layers on rolled nickel or copper as superconductor substrates

DOEpatents

Paranthaman, Mariappan; Goyal, Amit; Kroeger, Donald M.; List, III, Frederic A.

2002-01-01

Buffer layer architectures are epitaxially deposited on biaxially-textured rolled-Ni and/or Cu substrates for high current conductors, and more particularly buffer layer architectures such as MgO/Ag/Pt/Ni, MgO/Ag/Pd/Ni, MgO/Ag/Ni, MgO/Ag/Pd/Cu, MgO/Ag/Pt/Cu, and MgO/Ag/Cu. Techniques used to deposit these buffer layers include electron beam evaporation, thermal evaporation, rf magnetron sputtering, pulsed laser deposition, metal-organic chemical vapor deposition (MOCVD), combustion CVD, and spray pyrolysis.

Effect of magnetron sputtering parameters and stress state of W film precursors on WSe2 layer texture by rapid selenization.

PubMed

Li, Hongchao; Gao, Di; Xie, Senlin; Zou, Jianpeng

2016-11-04

Tungsten diselenide (WSe 2 ) film was obtained by rapid selenization of magnetron sputtered tungsten (W) film. To prevent WSe 2 film peeling off from the substrate during selenization, the W film was designed with a double-layer structure. The first layer was deposited at a high sputtering-gas pressure to form a loose structure, which can act as a buffer layer to release stresses caused by WSe 2 growth. The second layer was deposited naturally on the first layer to react with selenium vapour in the next step. The effect of the W film deposition parameters(such as sputtering time, sputtering-gas pressure and substrate bias voltage)on the texture and surface morphology of the WSe 2 film was studied. Shortening the sputtering time, increasing the sputtering-gas pressure or decreasing the substrate bias voltage can help synthesize WSe 2 films with more platelets embedded vertically in the matrix. The stress state of the W film influences the WSe 2 film texture. Based on the stress state of the W film, a model for growth of the WSe 2 films with different textures was proposed. The insertion direction of the van der Waals gap is a key factor for the anisotropic formation of WSe 2 film.

Effect of magnetron sputtering parameters and stress state of W film precursors on WSe2 layer texture by rapid selenization

PubMed Central

Li, Hongchao; Gao, Di; Xie, Senlin; Zou, Jianpeng

2016-01-01

Tungsten diselenide (WSe2) film was obtained by rapid selenization of magnetron sputtered tungsten (W) film. To prevent WSe2 film peeling off from the substrate during selenization, the W film was designed with a double-layer structure. The first layer was deposited at a high sputtering-gas pressure to form a loose structure, which can act as a buffer layer to release stresses caused by WSe2 growth. The second layer was deposited naturally on the first layer to react with selenium vapour in the next step. The effect of the W film deposition parameters(such as sputtering time, sputtering-gas pressure and substrate bias voltage)on the texture and surface morphology of the WSe2 film was studied. Shortening the sputtering time, increasing the sputtering-gas pressure or decreasing the substrate bias voltage can help synthesize WSe2 films with more platelets embedded vertically in the matrix. The stress state of the W film influences the WSe2 film texture. Based on the stress state of the W film, a model for growth of the WSe2 films with different textures was proposed. The insertion direction of the van der Waals gap is a key factor for the anisotropic formation of WSe2 film. PMID:27812031

TiOx deposited by magnetron sputtering: a joint modelling and experimental study

NASA Astrophysics Data System (ADS)

Tonneau, R.; Moskovkin, P.; Pflug, A.; Lucas, S.

2018-05-01

This paper presents a 3D multiscale simulation approach to model magnetron reactive sputter deposition of TiOx⩽2 at various O2 inlets and its validation against experimental results. The simulation first involves the transport of sputtered material in a vacuum chamber by means of a three-dimensional direct simulation Monte Carlo (DSMC) technique. Second, the film growth at different positions on a 3D substrate is simulated using a kinetic Monte Carlo (kMC) method. When simulating the transport of species in the chamber, wall chemistry reactions are taken into account in order to get the proper content of the reactive species in the volume. Angular and energy distributions of particles are extracted from DSMC and used for film growth modelling by kMC. Along with the simulation, experimental deposition of TiOx coatings on silicon samples placed at different positions on a curved sample holder was performed. The experimental results are in agreement with the simulated ones. For a given coater, the plasma phase hysteresis behaviour, film composition and film morphology are predicted. The used methodology can be applied to any coater and any films. This paves the way to the elaboration of a virtual coater allowing a user to predict composition and morphology of films deposited in silico.

Electrical properties of aluminum contacts deposited by DC sputtering method for photovoltaic applications

NASA Astrophysics Data System (ADS)

Krawczak, Ewelina; Gułkowski, Sławomir

2017-10-01

The use of aluminum contacts is common in the process of silicon solar cells production because of low contact resistivity. It has also a great importance in thin film technology for photovoltaics, especially in copper-indium-gallium-diselenide (CIGS) devices. The final stage of CIGS cell production is the top contact deposition of high conductivity layer for lateral current collection. Such material has to be highly optically transparent as well. In order to make a contact, metal is deposited onto TCO layer with minimum shadowing to allow as much light as possible into device. The metal grid contact is being made by deposition of few microns of aluminum. The resistivity of the deposited material as well as resistance between the metal grid and TCO layer plays a great role in high quality solar cell production. This paper presents the results of four point probe conductivity analysis of Al thin films deposited by direct current (DC) magnetron sputtering method. Influence of technological parameters of the Al deposition process on sheet resistance of deposited layers has been showed. In order to obtain the lowest resistivity of the thin contact layer, optimal set of sputtering parameters, i.e. power applied, deposition time and deposition pressure was found. The resistivity of the contact between two adjacent Al metal fingers deposited onto transparent conductive Al-doped zinc oxide film has been also examined.

Structural and magnetic properties of non-stoichiometric Fe1-xO thin films

NASA Astrophysics Data System (ADS)

Muhammed Shameem P., V.; Mekala, Laxman; Kumar, M. Senthil

2018-04-01

The Fe1-xO thin films of various iron deficiencies (x) have been grown at ambient temperature by reactive dc magnetron sputtering technique and their structural and magnetic properties are studied. The structural study shows that the films are polycrystalline. As the iron content (1-x) varies from 0.924 to 0.855 a clear consistent change in the preferential orientation of the grains from [111] to the [200] direction is observed. The magnetization measurements show the possible existence of small superparamagnetic defect clusters at 300 K and large spinel-type defect clusters below the Neel temperature.

Experimental study on TiN coated racetrack-type ceramic pipe

NASA Astrophysics Data System (ADS)

Wang, Jie; Xu, Yan-Hui; Zhang, Bo; Wei, Wei; Fan, Le; Pei, Xiang-Tao; Hong, Yuan-Zhi; Wang, Yong

2015-11-01

TiN film was coated on the internal surface of a racetrack-type ceramic pipe by three different methods: radio-frequency sputtering, DC sputtering and DC magnetron sputtering. The deposition rates of TiN film under different coating methods were compared. The highest deposition rate was 156 nm/h, which was obtained by magnetron sputtering coating. Based on AFM, SEM and XPS test results, the properties of TiN film, such as film roughness and surface morphology, were analyzed. Furthermore, the deposition rates were studied with two different cathode types, Ti wires and Ti plate. According to the SEM test results, the deposition rate of TiN/Ti film was about 800 nm/h with Ti plate cathode by DC magnetron sputtering. Using Ti plate cathode rather than Ti wire cathode can greatly improve the film deposition rate. Supported by National Nature Science Foundation of China (11075157)

A review comparing cathodic arcs and high power impulse magnetron sputtering (HiPIMS)

DOE PAGES

Anders, André

2014-09-02

In this study, high power impulse magnetron sputtering (HiPIMS) has been in the center of attention over the last years as it is an emerging physical vapor deposition (PVD) technology that combines advantages of magnetron sputtering with various forms of energetic deposition of films such as ion plating and cathodic arc plasma deposition. It should not come at a surprise that many extension and variations of HiPIMS make use, intentionally or unintentionally, of previously discovered approaches to film processing such as substrate surface preparation by metal ion sputtering and phased biasing for film texture and stress control. Therefore, in thismore » review, an overview is given on some historical developments and features of cathodic arc and HiPIMS plasmas, showing commonalities and differences. To limit the scope, emphasis is put on plasma properties, as opposed to surveying the vast literature on specific film materials and their properties.« less

Particle-in-Cell Modeling of Magnetron Sputtering Devices

NASA Astrophysics Data System (ADS)

Cary, John R.; Jenkins, T. G.; Crossette, N.; Stoltz, Peter H.; McGugan, J. M.

2017-10-01

In magnetron sputtering devices, ions arising from the interaction of magnetically trapped electrons with neutral background gas are accelerated via a negative voltage bias to strike a target cathode. Neutral atoms ejected from the target by such collisions then condense on neighboring material surfaces to form a thin coating of target material; a variety of industrial applications which require thin surface coatings are enabled by this plasma vapor deposition technique. In this poster we discuss efforts to simulate various magnetron sputtering devices using the Vorpal PIC code in 2D axisymmetric cylindrical geometry. Field solves are fully self-consistent, and discrete models for sputtering, secondary electron emission, and Monte Carlo collisions are included in the simulations. In addition, the simulated device can be coupled to an external feedback circuit. Erosion/deposition profiles and steady-state plasma parameters are obtained, and modifications due to self consistency are seen. Computational performance issues are also discussed. and Tech-X Corporation.

Solid oxide fuel cells with (La,Sr)(Ga,Mg)O3-δ electrolyte film deposited by radio-frequency magnetron sputtering

NASA Astrophysics Data System (ADS)

Wang, Sea-Fue; Lu, His-Chuan; Hsu, Yung-Fu; Hu, Yi-Xuan

2015-05-01

In this study, solid oxide fuel cells (SOFCs) containing a high quality La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) film deposited on anode supported substrate using RF magnetron sputtering are successfully prepared. The anode substrate is composed of two functional NiO/Sm0.2Ce0.8O2-δ (SDC) composite layers with ratios of 60/40 wt% and 50/50 wt% and a current collector layer of pure NiO. The as-deposited LSGM film appears to be amorphous in nature. After post-annealing at 1000 °C, a uniform and dense polycrystalline film with a composition of La0.87Sr0.13Ga0.85Mg0.15O3-δ and a thickness of 3.8 μm is obtained, which was well adhered to the anode substrate. A composite LSGM/La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) layer, with a ratio of 30/70 wt%, is used as the cathode. The SOFC prepared reveals a good mechanical integrity with no sign of cracking, delamination, or discontinuity among the interfaces. The total cell resistance of a single cell with LSGM electrolyte film declines from 0.60 to 0.10 Ω cm2 as the temperature escalates from 600 to 800 °C and the open circuit voltage (OCV) ranges from 0.85 to 0.95 V. The maximum power density (MPD) of the single cell is reported as 0.65, 1.02, 1.30, 1.42, and 1.38 W cm-2 at 600, 650, 700, 750, and 800 °C, respectively. The good cell performance leads to the conclusion that RF magnetron sputtering is a feasible deposition method for preparing good quality LSGM films in SOFCs.

[Effects of magnetron sputtered ZrN on the bonding strength of titanium porcelain].

PubMed

Zhou, Shu; Zhang, Wen-yan; Guang, Han-bing; Xia, Yang; Zhang, Fei-min

2009-04-01

To investigate the effect of magnetron sputtered ZrN on the bonding strength between a low-fusing porcelain (Ti/Vita titankeramik system) and commercially pure cast titanium. Sixteen specimens were randomly assigned to test group and control group (n=8). The control group received no surface treated. Magnetron sputtered ZrN film was deposited on the surface of specimens in the test group. Then the sixteen titanium-porcelain specimens were prepared in a rectangular shape and went through three-point bending test on a universal test machine. The bond strength of Ti/porcelain was recorded. The phase composition of the specimens was analyzed using X-ray diffraction (XRD). The interface at titanium and porcelain and the titanium surface after debonding were observed with a scanning electron microscopy (SEM) and analyzed using energy depressive spectrum (EDS). New phase of ZrN was found with XRD in the test group. Statistical analysis showed higher bond strength following ZrN surface treatment in the test group [(45.991+/-0.648) MPa] than that in the control group [(29.483+/-1.007) MPa] (P=0.000). Bonded ceramic could be observed in test group, the amount of bonded ceramic was more than that in the control group. No obvious bonded ceramic in control group was found. Magnetron sputtered ZrN can improve bond strength of Ti/Vita titankeramik system significantly.

Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Chunwei, E-mail: lcwnefu@126.com, E-mail: xiubotian@163.com; State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001; Tian, Xiubo, E-mail: lcwnefu@126.com, E-mail: xiubotian@163.com

2016-08-15

The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process wasmore » simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process.« less

Photocurrent generation in carbon nitride and carbon nitride/conjugated polymer composites.

PubMed

Byers, Joshua C; Billon, Florence; Debiemme-Chouvy, Catherine; Deslouis, Claude; Pailleret, Alain; Semenikhin, Oleg A

2012-09-26

The semiconductor and photovoltaic properties of carbon nitride (CNx) thin films prepared using a reactive magnetron cathodic sputtering technique were investigated both individually and as composites with an organic conjugated polymer, poly(2,2'-bithiophene) (PBT). The CNx films showed an increasing thickness as the deposition power and/or nitrogen content in the gas mixture increase. At low nitrogen content and low deposition power (25-50 W), the film structure was dominated by the abundance of the graphitic sp(2) regions, whereas at higher nitrogen contents and magnetron power CNx films started to demonstrate semiconductor properties, as evidenced by the occurrence of photoconductivity and the development of a space charge region. However, CNx films alone did not show any reproducible photovoltaic properties. The situation changed, however, when CNx was deposited onto conjugated PBT substrates. In this configuration, CNx was found to function as an acceptor material improving the photocurrent generation both in solution and in solid state photovoltaic devices, with the external quantum efficiencies reaching 1% at high nitrogen contents. The occurrence of the donor-acceptor charge transfer was further evidenced by suppression of the n-doping of the PBT polymer by CNx. Nanoscale atomic force microscopy (AFM) and current-sensing AFM data suggested that CNx may form a bulk heterojunction with PBT.

Investigations on structural and electrical parameters of p-Si/ MgxZn1-xO thin film heterojunction diodes grown by RF magnetron sputtering technique

NASA Astrophysics Data System (ADS)

Singh, Satyendra Kumar; Hazra, Purnima

2018-05-01

This work reports fabrication and characterization of p-Si/ MgxZn1-xO thin film heterojunction diodes grown by RF magnetron sputtering technique. In this work, ZnO powder was mixed with MgO powder at per their weight percentage from 0 to 10% to prepare MgxZn1-xO target. The microstructural, surface morphological and optical properties of as-deposited p-Si/MgxZn1-xO heterostructure thin films have been studied using X-ray Diffraction, atomic force microscopy and variable angle ellipsometer. XRD spectra exhibit that undoped ZnO thin films has preferred crystal orientation in (002) plane. However, with increase in Mg-doping, ZnO (101) crystal plane is enhanced progressively due to phase segregation, even though preferred growth orientation of ZnO crystals is still towards (002) plane. The electrical characteristics of Si/ MgxZn1-xO heterojunction diodes with large area Al/Ti ohmic contacts are evaluated using semiconductor parameter analyzer. With rectification ratio of 27894, reverse saturation current of 20.5 nA and barrier height of 0.724 eV, Si/Mg0.5Zn0.95O thin film heterojunction diode is believed to have potential to be used in wider bandgap nanoelectronic device applications.

Effect of the target power density on high-power impulse magnetron sputtering of copper

NASA Astrophysics Data System (ADS)

Kozák, Tomáš

2012-04-01

We present a model analysis of high-power impulse magnetron sputtering of copper. We use a non-stationary global model based on the particle and energy conservation equations in two zones (the high density plasma ring above the target racetrack and the bulk plasma region), which makes it possible to calculate time evolutions of the averaged process gas and target material neutral and ion densities, as well as the fluxes of these particles to the target and substrate during a pulse period. We study the effect of the increasing target power density under conditions corresponding to a real experimental system. The calculated target current waveforms show a long steady state and are in good agreement with the experimental results. For an increasing target power density, an analysis of the particle densities shows a gradual transition to a metal dominated discharge plasma with an increasing degree of ionization of the depositing flux. The average fraction of target material ions in the total ion flux onto the substrate is more than 90% for average target power densities higher than 500 W cm-2 in a pulse. The average ionized fraction of target material atoms in the flux onto the substrate reaches 80% for a maximum average target power density of 3 kW cm-2 in a pulse.

Single-crystal-like GdNdO{sub x} thin films on silicon substrates by magnetron sputtering and high-temperature annealing for crystal seed layer application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Ziwei; Xiao, Lei; Liang, Renrong, E-mail: wang-j@tsinghua.edu.cn, E-mail: liangrr@tsinghua.edu.cn

2016-06-15

Single-crystal-like rare earth oxide thin films on silicon (Si) substrates were fabricated by magnetron sputtering and high-temperature annealing processes. A 30-nm-thick high-quality GdNdO{sub x} (GNO) film was deposited using a high-temperature sputtering process at 500°C. A Gd{sub 2}O{sub 3} and Nd{sub 2}O{sub 3} mixture was used as the sputtering target, in which the proportions of Gd{sub 2}O{sub 3} and Nd{sub 2}O{sub 3} were controlled to make the GNO’s lattice parameter match that of the Si substrate. To further improve the quality of the GNO film, a post-deposition annealing process was performed at a temperature of 1000°C. The GNO films exhibitedmore » a strong preferred orientation on the Si substrate. In addition, an Al/GNO/Si capacitor was fabricated to evaluate the dielectric constant and leakage current of the GNO films. It was determined that the single-crystal-like GNO films on the Si substrates have potential for use as an insulator layer for semiconductor-on-insulator and semiconductor/insulator multilayer applications.« less

Heterojunction diodes in 3C-SiC/Si system grown by reactive magnetron sputtering: Effects of growth temperature on diode rectification and breakdown

NASA Astrophysics Data System (ADS)

Wahab, Q.; Karlsteen, M.; Nur, O.; Hultman, L.; Willander, M.; Sundgren, J.-E.

1996-09-01

3C-SiC/Si heterojunction diodes were prepared by reactive magnetron sputtering of pure Si in CH4-Ar discharge on Si(111) substrates kept at temperatures (Ts) ranging from 800 to 1000°C. A good diode rectification process started for films grown at Ts≤900°C. Heterojunction diodes grown at Ts = 850°C showed the best performance with a saturation current density of 2.4 × 10-4 A cm-2. Diode reverse breakdown was obtained at a voltage of -110 V. The doping concentration (Nd) of the 3C-SiC films was calculated from 1/C2 vs V plot to be 3 × 1015 cm-3. Band offset values obtained were -0.27 and 1.35 eV for the conduction and valence band, respectively. X-ray diffraction analysis revealed the film grown at Ts = 850°C to be single-phase 3C-SiC. The full width at half maximum of the 3C-SiC(111) peak was only 0.25 degree. Cross-sectional transmission electron microscopy showed the film to be highly (111)-oriented with an epitaxial columnar structure of double positioning domain boundaries.

A soft gamma-ray concentrator using thin-film multilayer structures

NASA Astrophysics Data System (ADS)

Bloser, Peter F.; Aliotta, Paul H.; Echt, Olof; Krzanowski, James E.; Legere, Jason S.; McConnell, Mark L.; Shirazi, Farzane; Tsavalas, John G.; Wong, Emily N.; Kippen, R. Marc

2015-09-01

We have begun to investigate the use of thin-film, multilayer structures to form optics capable of concentrating soft gamma rays with energies greater than 100 keV, beyond the reach of current grazing-incidence hard X-ray mirrors. Alternating layers of low- and high-density materials (e.g., polymers and metals) will channel soft gamma-ray photons via total external reflection. A suitable arrangement of bent structures will then concentrate the incident radiation to a point. Gamma-ray optics made in this way offer the potential for soft gamma-ray telescopes with focal lengths of less than 10 m, removing the need for formation flying spacecraft and opening the field up to balloon-borne instruments. Building on initial investigations at Los Alamos National Laboratory, we are investigating whether it is possible to grow such flexible multi-layer structures with the required thicknesses and smoothness using magnetron sputter and pulsed laser deposition techniques. We present the initial results of tests aimed at fabricating such structures by combining magnetron sputtering with either spin coating or pulsed laser deposition, and demonstrating gamma-ray channeling of 122 keV photons in the laboratory. If successful, this technology offers the potential for transformational increases in sensitivity while dramatically improving the system-level performance of future high-energy astronomy missions through reduced mass and complexity.

Checkerboard deposition of lithium manganese oxide spinel (LiMn2O4) by RF magnetron sputtering on a stainless steel in all-solid-state thin film battery

NASA Astrophysics Data System (ADS)

Hsueh, T. H.; Yu, Y. Q.; Jan, D. J.; Su, C. H.; Chang, S. M.

2018-03-01

All-solid-state thin film lithium batteries (TFLBs) are the most competitive low-power sources to be applied in various kinds of micro-electro-mechanical systems and have been draw a lot of attention in academic research. In this paper, the checkerboard deposition of all-solid-state TFLB was composed of thin film lithium metal anode, lithium phosphorus oxynitride (LiPON) solid electrolyte, and checkerboard deposition of lithium manganese oxide spinel (LiMn2O4) cathode. The LiPON and LiMn2O4 were deposited by a radio frequency magnetron sputtering system, and the lithium metal was deposited by a thermal evaporation coater. The electrochemical characterization of this lithium battery showed the first discharge capacity of 107.8 μAh and the capacity retention was achieved 95.5% after 150 charge-discharge cycles between 4.3V and 3V at a current density of 11 μA/cm2 (0.5C). Obviously, the checkerboard of thin film increased the charge exchange rate; also this lithium battery exhibited high C-rate performance, with better capacity retention of 82% at 220 μA/cm2 (10C).

Direct Simulation Monte Carlo Simulations of Low Pressure Semiconductor Plasma Processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gochberg, L. A.; Ozawa, T.; Deng, H.

2008-12-31

The two widely used plasma deposition tools for semiconductor processing are Ionized Metal Physical Vapor Deposition (IMPVD) of metals using either planar or hollow cathode magnetrons (HCM), and inductively-coupled plasma (ICP) deposition of dielectrics in High Density Plasma Chemical Vapor Deposition (HDP-CVD) reactors. In these systems, the injected neutral gas flows are generally in the transonic to supersonic flow regime. The Hybrid Plasma Equipment Model (HPEM) has been developed and is strategically and beneficially applied to the design of these tools and their processes. For the most part, the model uses continuum-based techniques, and thus, as pressures decrease below 10more » mTorr, the continuum approaches in the model become questionable. Modifications have been previously made to the HPEM to significantly improve its accuracy in this pressure regime. In particular, the Ion Monte Carlo Simulation (IMCS) was added, wherein a Monte Carlo simulation is used to obtain ion and neutral velocity distributions in much the same way as in direct simulation Monte Carlo (DSMC). As a further refinement, this work presents the first steps towards the adaptation of full DSMC calculations to replace part of the flow module within the HPEM. Six species (Ar, Cu, Ar*, Cu*, Ar{sup +}, and Cu{sup +}) are modeled in DSMC. To couple SMILE as a module to the HPEM, source functions for species, momentum and energy from plasma sources will be provided by the HPEM. The DSMC module will then compute a quasi-converged flow field that will provide neutral and ion species densities, momenta and temperatures. In this work, the HPEM results for a hollow cathode magnetron (HCM) IMPVD process using the Boltzmann distribution are compared with DSMC results using portions of those HPEM computations as an initial condition.« less

Development and production of a multilayer-coated x-ray reflecting stack for the Athena mission

NASA Astrophysics Data System (ADS)

Massahi, S.; Ferreira, D. D. M.; Christensen, F. E.; Shortt, B.; Girou, D. A.; Collon, M.; Landgraf, B.; Barriere, N.; Krumrey, M.; Cibik, L.; Schreiber, S.

2016-07-01

The Advanced Telescope for High-Energy Astrophysics, Athena, selected as the European Space Agency's second large-mission, is based on the novel Silicon Pore Optics X-ray mirror technology. DTU Space has been working for several years on the development of multilayer coatings on the Silicon Pore Optics in an effort to optimize the throughput of the Athena optics. A linearly graded Ir/B4C multilayer has been deposited on the mirrors, via the direct current magnetron sputtering technique, at DTU Space. This specific multilayer, has through simulations, been demonstrated to produce the highest reflectivity at 6 keV, which is a goal for the scientific objectives of the mission. A critical aspect of the coating process concerns the use of photolithography techniques upon which we will present the most recent developments in particular related to the cleanliness of the plates. Experiments regarding the lift-off and stacking of the mirrors have been performed and the results obtained will be presented. Furthermore, characterization of the deposited thin-films was performed with X-ray reflectometry at DTU Space and in the laboratory of the Physikalisch-Technische Bundesanstalt at the synchrotron radiation facility BESSY II.

Station-keeping of a high-altitude balloon with electric propulsion and wireless power transmission: A concept study

NASA Astrophysics Data System (ADS)

van Wynsberghe, Erinn; Turak, Ayse

2016-11-01

A stable, ultra long-duration high-altitude balloon (HAB) platform which can maintain stationary position would represent a new paradigm for telecommunications and high-altitude observation and transmission services, with greatly reduced cost and complexity compared to existing technologies including satellites, telecom towers, and unmanned aerial vehicles (UAVs). This contribution proposes a lightweight superpressure balloon platform for deployment to an altitude of 25 km. Electrohydrodynamic (EHD) thrusters are presented to maintain position by overcoming stratospheric winds. Critical to maintaining position is a continual supply of electrical power to operate the on-board propulsion system. One viable solution is to deliver power wirelessly to a high-altitude craft from a ground-based transmitter. Microwave energy, not heavily attenuated by the atmosphere, can be provided remotely from a ground-based generator (magnetron, klystron, etc.) and steered electrically with an antenna array (phased array) at a designated frequency (such as 2.45 or 5.8 GHz). A rectifying antenna ("rectenna") on the bottom of the balloon converts waves into direct current for on-board use. Preliminary mission architecture, energy requirements, and safety concerns for a proposed system are presented along with recommended future work.

Analysis of the Temperature Dependence of the Capacitance-Voltage and Conductance-Voltage Characteristics of Au/TiO2(rutile)/ n-Si Structures

NASA Astrophysics Data System (ADS)

KInacI, BarIş; Özçelik, Süleyman

2013-06-01

The capacitance-voltage-temperature ( C- V- T) and the conductance/angular frequency-voltage-temperature ( G/ω- V- T) characteristics of Au/TiO2(rutile)/ n-Si Schottky barrier diodes (SBDs) were investigated over the temperature range from 200 K to 380 K by considering the series resistance effect. Titanium dioxide (TiO2) was deposited on n-type silicon (Si) substrate using a direct-current (DC) magnetron sputtering system at 200°C. To improve the crystal quality, the deposited film was annealed at 900°C to promote a phase transition from the amorphous to rutile phase. The C -2 versus V plots gave a straight line in the reverse-bias region. The main electrical parameters, such as the doping concentration ( N D), Fermi energy level ( E F), depletion layer width ( W D), barrier height ( ф CV), and series resistance ( R S), of Au/TiO2(rutile)/ n-Si SBDs were calculated from the C- V- T and the G/ω- V- T characteristics. The obtained results show that ф CV, R S, and W D values decrease, while E F and N D values increase, with increasing temperature.

Post-Annealing Effects on Surface Morphological, Electrical and Optical Properties of Nanostructured Cr-Doped CdO Thin Films

NASA Astrophysics Data System (ADS)

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

2018-01-01

Nanostructured Cr-doped CdO thin films were deposited on glass substrates by reactive direct current magnetron sputtering and post-annealed in vacuum from 200°C to 500°C. X-ray diffraction studies confirmed that the films exhibit cubic nature with preferential orientation along the (111) plane. The crystallite size, lattice parameters, unit cell volume and strain in the films were determined from x-ray diffraction analysis. The surface morphology of the films has been characterized by field emission scanning electron microscopy and atomic force microscopy. The electrical properties of the Cr-doped CdO thin films were measured by using a four-probe method and Hall effect system. The lowest electrical resistivity of 2.20 × 10-4 Ω cm and a maximum optical transmittance of 88% have been obtained for the thin films annealed at 500°C. The optical band gap of the films decreased from 2.77 eV to 2.65 eV with the increase of annealing temperature. The optical constants, packing density and porosity of Cr-doped CdO thin films were also evaluated from the transmittance spectra.

TOPICAL REVIEW: Physics and phenomena in pulsed magnetrons: an overview

NASA Astrophysics Data System (ADS)

Bradley, J. W.; Welzel, T.

2009-05-01

This paper reviews the contribution made to the observation and understanding of the basic physical processes occurring in an important type of magnetized low-pressure plasma discharge, the pulsed magnetron. In industry, these plasma sources are operated typically in reactive mode where a cathode is sputtered in the presence of both chemically reactive and noble gases typically with the power modulated in the mid-frequency (5-350 kHz) range. In this review, we concentrate mostly, however, on physics-based studies carried out on magnetron systems operated in argon. This simplifies the physical-chemical processes occurring and makes interpretation of the observations somewhat easier. Since their first recorded use in 1993 there have been more than 300 peer-reviewed paper publications concerned with pulsed magnetrons, dealing wholly or in part with fundamental observations and basic studies. The fundamentals of these plasmas and the relationship between the plasma parameters and thin film quality regularly have whole sessions at international conferences devoted to them; however, since many different types of magnetron geometries have been used worldwide with different operating parameters the important results are often difficult to tease out. For example, we find the detailed observations of the plasma parameter (particle density and temperature) evolution from experiment to experiment are at best difficult to compare and at worst contradictory. We review in turn five major areas of studies which are addressed in the literature and try to draw out the major results. These areas are: fast electron generation, bulk plasma heating, short and long-term plasma parameter rise and decay rates, plasma potential modulation and transient phenomena. The influence of these phenomena on the ion energy and ion energy flux at the substrate is discussed. This review, although not exhaustive, will serve as a useful guide for more in-depth investigations using the referenced literature and also hopefully as an inspiration for future studies.

Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In,Ga)Se2 solar cells.

PubMed

Vermang, Bart; Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika; Kotipalli, Ratan; Henry, Frederic; Flandre, Denis

2014-10-01

Reducing absorber layer thickness below 500 nm in regular Cu(In,Ga)Se 2 (CIGS) solar cells decreases cell efficiency considerably, as both short-circuit current and open-circuit voltage are reduced because of incomplete absorption and high Mo/CIGS rear interface recombination. In this work, an innovative rear cell design is developed to avoid both effects: a highly reflective rear surface passivation layer with nano-sized local point contact openings is employed to enhance rear internal reflection and decrease the rear surface recombination velocity significantly, as compared with a standard Mo/CIGS rear interface. The formation of nano-sphere shaped precipitates in chemical bath deposition of CdS is used to generate nano-sized point contact openings. Evaporation of MgF 2 coated with a thin atomic layer deposited Al 2 O 3 layer, or direct current magnetron sputtering of Al 2 O 3 are used as rear surface passivation layers. Rear internal reflection is enhanced substantially by the increased thickness of the passivation layer, and also the rear surface recombination velocity is reduced at the Al 2 O 3 /CIGS rear interface. (MgF 2 /)Al 2 O 3 rear surface passivated ultra-thin CIGS solar cells are fabricated, showing an increase in short circuit current and open circuit voltage compared to unpassivated reference cells with equivalent CIGS thickness. Accordingly, average solar cell efficiencies of 13.5% are realized for 385 nm thick CIGS absorber layers, compared with 9.1% efficiency for the corresponding unpassivated reference cells.

Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In,Ga)Se2 solar cells

PubMed Central

Vermang, Bart; Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika; Kotipalli, Ratan; Henry, Frederic; Flandre, Denis

2014-01-01

Reducing absorber layer thickness below 500 nm in regular Cu(In,Ga)Se2 (CIGS) solar cells decreases cell efficiency considerably, as both short-circuit current and open-circuit voltage are reduced because of incomplete absorption and high Mo/CIGS rear interface recombination. In this work, an innovative rear cell design is developed to avoid both effects: a highly reflective rear surface passivation layer with nano-sized local point contact openings is employed to enhance rear internal reflection and decrease the rear surface recombination velocity significantly, as compared with a standard Mo/CIGS rear interface. The formation of nano-sphere shaped precipitates in chemical bath deposition of CdS is used to generate nano-sized point contact openings. Evaporation of MgF2 coated with a thin atomic layer deposited Al2O3 layer, or direct current magnetron sputtering of Al2O3 are used as rear surface passivation layers. Rear internal reflection is enhanced substantially by the increased thickness of the passivation layer, and also the rear surface recombination velocity is reduced at the Al2O3/CIGS rear interface. (MgF2/)Al2O3 rear surface passivated ultra-thin CIGS solar cells are fabricated, showing an increase in short circuit current and open circuit voltage compared to unpassivated reference cells with equivalent CIGS thickness. Accordingly, average solar cell efficiencies of 13.5% are realized for 385 nm thick CIGS absorber layers, compared with 9.1% efficiency for the corresponding unpassivated reference cells. PMID:26300619

Improving X-Ray Optics via Differential Deposition

NASA Technical Reports Server (NTRS)

Kilaru, Kiranmayee; Ramsey, Brian D.; Atkins, Carolyn

2017-01-01

Differential deposition, a post-fabrication figure correction technique, has the potential to significantly improve the imaging quality of grazing-incidence X-ray optics. DC magnetron sputtering is used to selectively coat the mirror in order to minimize the figure deviations. Custom vacuum chambers have been developed at NASA MSFC that will enable the implementation of the deposition on X-ray optics. A factor of two improvement has been achieved in the angular resolution of the full-shell X-ray optics with first stage correction of differential deposition. Current efforts are focused on achieving higher improvements through efficient implementation of differential deposition.

Preparation and substrate reactions of superconducting Y-Ba-Cu-O films

NASA Astrophysics Data System (ADS)

Gurvitch, M.; Fiory, A. T.

1987-09-01

Multiple metal-target dc magnetron sputter deposition of a metallic YBa2Cu3 alloy in pure Ar followed by ex situ oxygen annealing was used to prepare superconducting films on various substrates. This work particularly examines film-substrate reactions which are degrading to superconductivity. Better superconductors were obtained using predeposited buffer layers, notably on cubic zirconia and MgO substrates covered with Ag and Nb. Best films have Tc = 80 K, metallic resistivities with a resistance ratio of about 2, and a critical current density of greater than about 10 kA/sq cm at 4.2 K.

Effect of structure and deposition technology on tribological properties of DLC coatings alloyed with VIA group metals

NASA Astrophysics Data System (ADS)

Khrushchov, M.; Levin, I.; Marchenko, E.; Avdyukhina, V.; Petrzhik, M.

2016-07-01

The results of a comprehensive research on atomic structure, phase composition, micromechanical and tribological characteristics of alloyed DLC coatings have been presented. The coatings have been deposited by reactive magnetron sputtering in acetylene-nitrogen gas mixtures of different compositions (a-C:H:Cr), by plasma-assisted chemical vapor deposition in atmospheres of silicone-organic precursor gases (a-C:H:Mo:Si), and by nonreactive magnetron sputtering of a composite target (a-C:H:W).

Deposition of the low resistive ITO-films by means of reactive magnetron sputtering of the In/Sn target on the cold substrate

NASA Astrophysics Data System (ADS)

Zhidik, Y. S.; Troyan, P. E.; Baturina, E. V.; Korzhenko, D. V.; Yurjev, Y. N.

2016-06-01

Detailed information on the deposition technology of the low-resistive ITO-films in oxygen-containing media by magnetron reactive sputtering from the In(90%)/Sn(10%) target on the cold substrate is given. Developed technology allows deposition ITO-films with sheet resistance 2-3 Ω/□, transparency higher than 90%. Developed technology is notable for high reproducibility of results and is compatible with production technology of semiconductor devices of optoelectronics.

A W-band sixth-harmonic magnetron-type slotted peniotron

NASA Astrophysics Data System (ADS)

Hu, Biao; Li, Jiayin; Wu, Xinhui; Li, Tianming; Li, Hao; Wang, Haiyang; Zhao, Xiaoyun

2013-04-01

This paper has numerically investigated operating characteristics of a w-band six-harmonic magnetron-type slotted peniotron with 7 vanes. With the new structure design, a high efficiency of 40% w-band 30 kW medium power microwave source has been achieved and the mode competition can be somewhat suppressed. The main advantage of such a peniotron, based on a permanent magnet, is that it can have much more compact size and lower cost, and its operation gap can be greatly reduced.

Plasma vapor deposited n-indium tin oxide/p-copper indium oxide heterojunctions for optoelectronic device applications

NASA Astrophysics Data System (ADS)

Jaya, T. P.; Pradyumnan, P. P.

2017-12-01

Transparent crystalline n-indium tin oxide/p-copper indium oxide diode structures were fabricated on quartz substrates by plasma vapor deposition using radio frequency (RF) magnetron sputtering. The p-n heterojunction diodes were highly transparent in the visible region and exhibited rectifying current-voltage (I-V) characteristics with a good ideality factor. The sputter power during fabrication of the p-layer was found to have a profound effect on I-V characteristics, and the diode with the p-type layer deposited at a maximum power of 200 W exhibited the highest value of the diode ideality factor (η value) of 2.162, which suggests its potential use in optoelectronic applications. The ratio of forward current to reverse current exceeded 80 within the range of applied voltages of -1.5 to +1.5 V in all cases. The diode structure possessed an optical transmission of 60-70% in the visible region.

Estimation of Electron Temperature on Glass Spherical Tokamak (GLAST)

NASA Astrophysics Data System (ADS)

Hussain, S.; Sadiq, M.; Shah, S. I. W.; GLAST Team

2015-03-01

Glass Spherical Tokamak (GLAST) is a small spherical tokamak indigenously developed in Pakistan with an insulating vacuum vessel. A commercially available 2.45 GHz magnetron is used as pre-ionization source for plasma current startup. Different diagnostic systems like Rogowski coils, magnetic probes, flux loops, Langmuir probe, fast imaging and emission spectroscopy are installed on the device. The plasma temperature inside of GLAST, at the time of maxima of plasma current, is estimated by taking into account the Spitzer resistivity calculations with some experimentally determined plasma parameters. The plasma resistance is calculated by using Ohm's law with plasma current and loop voltage as experimentally determined inputs. The plasma resistivity is then determined by using length and area of the plasma column. Finally, the average plasma electron temperature is predicted to be 12.65eV for taking neon (Ne) as a working gas.

Are the argon metastables important in high power impulse magnetron sputtering discharges?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gudmundsson, J. T., E-mail: tumi@hi.is; Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik; Lundin, D.

2015-11-15

We use an ionization region model to explore the ionization processes in the high power impulse magnetron sputtering (HiPIMS) discharge in argon with a titanium target. In conventional dc magnetron sputtering (dcMS), stepwise ionization can be an important route for ionization of the argon gas. However, in the HiPIMS discharge stepwise ionization is found to be negligible during the breakdown phase of the HiPIMS pulse and becomes significant (but never dominating) only later in the pulse. For the sputtered species, Penning ionization can be a significant ionization mechanism in the dcMS discharges, while in the HiPIMS discharge Penning ionization ismore » always negligible as compared to electron impact ionization. The main reasons for these differences are a higher plasma density in the HiPIMS discharge, and a higher electron temperature. Furthermore, we explore the ionization fraction and the ionized flux fraction of the sputtered vapor and compare with recent experimental work.« less

Metal copper films deposited on cenosphere particles by magnetron sputtering method

NASA Astrophysics Data System (ADS)

Yu, Xiaozheng; Xu, Zheng; Shen, Zhigang

2007-05-01

Metal copper films with thicknesses from several nanometres to several micrometres were deposited on the surface of cenosphere particles by the magnetron sputtering method under different working conditions. An ultrasonic vibrating generator equipped with a conventional magnetron sputtering apparatus was used to prevent the cenosphere substrates from accumulating during film growth. The surface morphology, the chemical composition, the average grain size and the crystallization of cenosphere particles were characterized by field emission scanning electron microscopy (FE-SEM), inductively coupled plasma-atom emission spectrometer, x-ray photoelectron spectroscopy and x-ray diffraction (XRD) analysis, respectively, before and after the plating process. The results indicate that the copper films were successfully deposited on cenosphere particles. It was found from the FE-SEM results that the films were well compacted and highly uniform in thickness. The XRD results show that the copper film coated on cenospheres has a face centred cubic structure and the crystallization of the film sample increases with increasing sputtering power.

Nanoscale Cu{sub 2}O films: Radio-frequency magnetron sputtering and structural and optical studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kudryashov, D. A., E-mail: kudryashovda@apbau.ru; Gudovskikh, A. S.; Babichev, A. V.

2017-01-15

Nanoscale copper (I) oxide layers are formed by magnetron-assisted sputtering onto glassy and silicon substrates in an oxygen-free environment at room temperature, and the structural and optical properties of the layers are studied. It is shown that copper oxide formed on a silicon substrate exhibits a lower degree of disorder than that formed on a glassy substrate, which is supported by the observation of a higher intensity and a smaller half-width of reflections in the diffraction pattern. The highest intensity of reflections in the diffraction pattern is observed for Cu{sub 2}O films grown on silicon at a magnetron power ofmore » 150 W. The absorption and transmittance spectra of these Cu{sub 2}O films are in agreement with the well-known spectra of bulk crystals. In the Raman spectra of the films, phonons inherent in the crystal lattice of cubic Cu{sub 2}O crystals are identified.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hänninen, Tuomas, E-mail: tuoha@ifm.liu.se; Schmidt, Susann; Jensen, Jens

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.more » 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.« less

Infrared metamaterial by RF magnetron sputtered ZnO/Al:ZnO multilayers

NASA Astrophysics Data System (ADS)

Santiago, Kevin C.; Mundle, Rajeh; White, Curtis; Bahoura, Messaoud; Pradhan, Aswini K.

2018-03-01

Hyperbolic metamaterials create artificial anisotropy using metallic wires suspended in dielectric media or alternating layers of a metal and dielectric (Type I or Type II). In this study we fabricated ZnO/Al:ZnO (AZO) multilayers by the RF magnetron sputtering deposition technique. Our fabricated multilayers satisfy the requirements for a type II hyperbolic metamaterial. The optical response of individual AZO and ZnO films, as well as the multilayered film were investigated via UV-vis-IR transmittance and spectroscopic ellipsometry. The optical response of the multilayered system is calculated using the nonlocal-corrected Effective Medium Approximation (EMA). The spectroscopic ellipsometry data of the multilayered system was modeled using a uniaxial material model and EMA model. Both theoretical and experimental studies validate the fabricated multilayers undergo a hyperbolic transition at a wavelength of 2.2 μm. To our knowledge this is the first AZO/ZnO type II hyperbolic metamaterial system fabricated by magnetron sputtering deposition method.

Study of cobalt mononitride thin films prepared using DC and high power impulse magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Rachana, E-mail: dr.rachana.gupta@gmail.com; Pandey, Nidhi; Behera, Layanta

2016-05-23

In this work we studied cobalt mononitride (CoN) thin films deposited using dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS). A Co target was sputtered using pure N{sub 2} gas alone as the sputtering medium. Obtained long-range structural ordering was studies using x-ray diffraction (XRD), short-range structure using Co L{sub 2,3} and N K absorption edges using soft x-ray absorption spectroscopy (XAS) and the surface morphology using atomic force microscopy (AFM). It was found that HiPIMS deposited films have better long-range ordering, better stoichiometric ratio for mononitride composition and smoother texture as compared to dcMS deposited films.more » In addition, the thermal stability of HiPIMS deposited CoN film seems to be better. On the basis of different type of plasma conditions generated in HiPIMS and dcMS process, obtained results are presented and discussed.« less

Low-temperature formation of c-axis-oriented aluminum nitride thin films by plasma-assisted reactive pulsed-DC magnetron sputtering

NASA Astrophysics Data System (ADS)

Takenaka, Kosuke; Satake, Yoshikatsu; Uchida, Giichiro; Setsuhara, Yuichi

2018-01-01

The low-temperature formation of c-axis-oriented aluminum nitride thin films was demonstrated by plasma-assisted reactive pulsed-DC magnetron sputtering. The effects of the duty cycle at the pulsed-DC voltage applied to the Al target on the properties of AlN films formed via inductively coupled plasma (ICP)-enhanced pulsed-DC magnetron sputtering deposition were investigated. With decreasing duty cycle at the target voltage, the peak intensity of AlN(0002) increased linearly. The surface roughness of AlN films decreased since there was an increase in film density owing to the impact of energetic ions on the films together with the enhancement of nitriding associated with the relative increase in N radical flux. The improvement of both the crystallinity and surface morphology of AlN films at low temperatures is considered to be caused by the difference between the relative flux values of ions and sputtered atoms.

Prospects of In/CdTe X- and γ-ray detectors with MoO Ohmic contacts

NASA Astrophysics Data System (ADS)

Maslyanchuk, Olena L.; Solovan, Mykhailo M.; Maistruk, Eduard V.; Brus, Viktor V.; Maryanchuk, Pavlo D.; Gnatyuk, Volodymyr A.; Aoki, Toru

2018-01-01

The present paper analyzes the charge transport mechanisms and spectrometric properties of In/CdTe/MoOx heterojunctions prepared by magnetron sputtering of indium and molybdenum oxide thin films onto semi-insulating p-type single-crystal CdTe semiconductor, produced by Acrorad Co. Ltd. Current-voltage characteristics of the detectors at different temperatures were investigated. The charge transport mechanisms in the heterostructures under investigation were determined: the generation-recombination in the space charge region (SCR) at relatively low voltages and the space charge limited currents at high voltages. The spectra of 137Cs and 241Am isotopes taken at different applied bias voltages are presented. It is shown that the In/CdTe/MoOx structures can be used as X/γ-ray detectors in the spectrometric mode.

Decrease of oxygen vacancy by Zn-doped for improving solar-blind photoelectric performance in β-Ga2O3 thin films

NASA Astrophysics Data System (ADS)

Guo, Daoyou; Qin, Xinyuan; Lv, Ming; Shi, Haoze; Su, Yuanli; Yao, Guosheng; Wang, Shunli; Li, Chaorong; Li, Peigang; Tang, Weihua

2017-11-01

Highly (201) oriented Zn-doped β-Ga2O3 thin films with different dopant concentrations were grown on (0001) sapphire substrates by radio frequency magnetron sputtering. With the increase of Zn dopant concentration, the crystal lattice expands, the energy band gap shrinks, and the oxygen vacancy concentration decreases. Both the metal semiconductor metal (MSM) structure photodetectors based on the pure and Zn-doped β-Ga2O3 thin films exhibit solar blind UV photoelectric property. Compared to the pure β-Ga2O3 photodetector, the Zn-doped one exhibits a lower dark current, a higher photo/dark current ratio, a faster photoresponse speed, which can be attributed to the decreases of oxygen vacancy concentration.[Figure not available: see fulltext.

Fabrication and characterization of anisotype heterojunctions n-TiN/p-CdTe

NASA Astrophysics Data System (ADS)

Solovan, M. M.; Brus, V. V.; Maryanchuk, P. D.; Ilashchuk, M. I.; Rappich, J.; Nickel, N.; Abashin, S. L.

2014-01-01

Photosensitive heterojunctions n-TiN/p-CdTe were fabricated for the first time by means of titanium nitride thin film deposition (n-type conductivity) by the reactive magnetron sputtering onto freshly etched single crystal substrates CdTe (1 1 0) of p-type conductivity. The temperature dependences of the height of the potential barrier and series resistance of the n-TiN/p-CdTe heterojunction were investigated. The dominating current transport mechanisms through the heterojunctions under investigation were determined at forward and reverse bias. The heterojunctions under investigation generate open-circuit voltage Voc = 0.35 V, short-circuit current Isc = 1.88 mA см-2 and fill factor FF = 0.51 under illumination 80 mW сm-2.

Nb and Ta Co-Doped TiO2 Transparent Conductive Thin Films by Magnetron Sputtering: Fabrication, Structure, and Characteristics

NASA Astrophysics Data System (ADS)

Liu, Yang; Peng, Qian; Qiao, Yadong; Yang, Guang

2018-06-01

Nb and Ta co-doped anatase titanium dioxide (NTTO) nanocrystalline thin films were deposited on quartz and Si (100) substrates by RF magnetron sputtering. The influence of RF power on the growth, structure, morphology, and properties of the samples are discussed in detail. X-ray diffraction measurements show that the films are polycrystalline with anatase tetragonal structure, which is further confirmed by Raman spectroscopy analysis. Meanwhile, Raman spectroscopy results indicate that the peak width of E g(1) mode, which is directly correlated to the carrier density, changes obviously with RF power. It is found that the substitution of Nb5+ and Ta5+ at Ti site is significantly improved with the increase of RF power from 150 W to 210 W. For the sample deposited at 210 W, the optical transmittance is above 82% in the visible range and the electrical resistivity is as low as 1.3 × 10-3 Ω cm with carrier density of 1.1 × 1021 cm-3 and Hall mobility of 4.5 cm2 V-1 s-1. The optical and electrical properties of NTTO thin films can be compared to those of Nb or Ta doped anatase TiO2. However, co-doping with Nb and Ta gives a possible platform to complement the limitations of each individual dopant.

Phased Array Technology with Phase and Amplitude Controlled Magnetron for Microwave Power Transmission

NASA Astrophysics Data System (ADS)

Shinohara, N.; Matsumoto, H.

2004-12-01

We need a microwave power transmitter with light weight and high DC-RF conversion efficiency for an economical SSPS (Space Solar Power System). We need a several g/W for a microwave power transmission (MPT) system with a phased array with 0.0001 degree of beam control accuracy (=tan-1 (100m/36,000km)) and over 80 % of DC-RF conversion efficiency when the weight of the 1GW-class SPS is below a several thousand ton - a several tens of thousand ton. We focus a microwave tube, especially magnetron by economical reason and by the amount of mass-production because it is commonly used for microwave oven in the world. At first, we have developed a phase controlled magnetron (PCM) with different technologies from what Dr. Brown developed. Next we have developed a phase and amplitude controlled magnetron (PACM). For the PACM, we add a feedback to magnetic field of the PCM with an external coil to control and stabilize amplitude of the microwave. We succeed to develop the PACM with below 10-6 of frequency stability and within 1 degree of an error in phase and within 1% of amplitude. We can control a phase and amplitude of the PACM and we have developed a phased array the PCMs. With the PCM technology, we have developed a small light weight MPT transmitter COMET (Compact Microwave Energy Transmitter) with consideration of heat radiation for space use and with consideration of mobility to space.

Deposition and characterization of magnetron sputtered bcc tantalum

NASA Astrophysics Data System (ADS)

Patel, Anamika

The goal of this thesis was to provide scientific and technical research results for developing and characterizing tantalum (Ta) coatings on steel substrates deposited by DC magnetron sputtering. Deposition of tantalum on steel is of special interest for the protection it offers to surfaces, e.g. the surfaces of gun barrels against the erosive wear of hot propellant gases and the mechanical damage caused by the motion of launching projectiles. Electro-plated chromium is presently most commonly used for this purpose; however, it is considered to be carcinogenic in its hexavalent form. Tantalum is being investigated as non-toxic alternative to chromium and also because of its superior protective properties in these extreme environments. DC magnetron sputtering was chosen for this investigation of tantalum coatings on steel substrates because it is a versatile industrial proven process for deposition of metals. Sputter deposited Ta films can have two crystallographic structures: (1) body center cubic (bcc) phase, characterized by high toughness and high ductility and (2) a tetragonal beta phase characterized by brittleness and a tendency to fail under stress. It was found in this work that the bcc Ta coatings on steel can be obtained reliably by either of two methods: (1) depositing Ta on a submicron, stoichiometric TaN seed layer reactively sputtered on unheated steel and (2) depositing Ta directly on steel heated above a critical temperature. For argon sputtering gas this critical temperature was found to be 400°C at a pressure of 5 mtorr. With the heavier krypton gas, this critical temperature is reduced to 350°C. X-ray diffraction (XRD) was used to investigate the structure of tantalum and nitride films, and the composition of the nitride films was measured by nuclear reaction analyses (NRA), which were used to study in detail the enhancement of the bcc phase of Ta on steel. The scratch adhesion tests performed with a diamond hemispherical tip of radius 200 mum under increasing loads revealed high critical load values for failure (>15 N) for the bcc coatings versus the low load values (<9 N) for the beta coatings. The coating deposited on TaN interlayers on sputter-etched steel had better adhesion than those on steel surface without sputter etching. The results for this work have demonstrated that by controlling the various process parameters of do magnetron sputtering, high quality bcc Ta coatings of multi-micron thickness with excellent adhesion to steel can be made. An important contribution of this dissertation is in the enhancing an understanding of this process. The impact of this research will be in a number of fields where superior protective castings are needed. These include military applications, electronic components, chemical processing, and others.

Comprehensive surface treatment of high-speed steel tool

NASA Astrophysics Data System (ADS)

Fedorov, Sergey V.; Aleshin, Sergey V.; Swe, Min Htet; Abdirova, Raushan D.; Kapitanov, Alexey V.; Egorov, Sergey B.

2018-03-01

One of the promising directions of hardening of high-speed steel tool is the creation on their surface of the layered structures with the gradient of physic-chemical properties between the wear-resistant coatings to the base material. Among the methods of such surface modification, a special process takes place based on the use of pulsed high-intensity charged particle beams. The high speed of heating and cooling allows structural-phase transformations in the surface layer, which cannot be realized in a stationary mode. The treatment was conducted in a RITM-SP unit, which constitutes a combination of a source of low-energy high-current electron beams "RITM" and two magnetron spraying systems on a single vacuum chamber. The unit enables deposition of films on the surface of the desired product and subsequent liquid-phase mixing of materials of the film and the substrate by an intense pulse electron beam. The article discusses features of the structure of the subsurface layer of high-speed steel M2, modified by surface alloying of a low-energy high-current electron beam, and its effect on the wear resistance of the tool when dry cutting hard to machine Nickel alloy. A significant decrease of intensity of wear of high-speed steel with combined treatment happens due to the displacement of the zone of wear and decrease the radius of rounding of the cutting edge because of changes in conditions of interaction with the material being treated.

Low-temperature plasma simulations with the LSP PIC code

NASA Astrophysics Data System (ADS)

Carlsson, Johan; Khrabrov, Alex; Kaganovich, Igor; Keating, David; Selezneva, Svetlana; Sommerer, Timothy

2014-10-01

The LSP (Large-Scale Plasma) PIC-MCC code has been used to simulate several low-temperature plasma configurations, including a gas switch for high-power AC/DC conversion, a glow discharge and a Hall thruster. Simulation results will be presented with an emphasis on code comparison and validation against experiment. High-voltage, direct-current (HVDC) power transmission is becoming more common as it can reduce construction costs and power losses. Solid-state power-electronics devices are presently used, but it has been proposed that gas switches could become a compact, less costly, alternative. A gas-switch conversion device would be based on a glow discharge, with a magnetically insulated cold cathode. Its operation is similar to that of a sputtering magnetron, but with much higher pressure (0.1 to 0.3 Torr) in order to achieve high current density. We have performed 1D (axial) and 2D (axial/radial) simulations of such a gas switch using LSP. The 1D results were compared with results from the EDIPIC code. To test and compare the collision models used by the LSP and EDIPIC codes in more detail, a validation exercise was performed for the cathode fall of a glow discharge. We will also present some 2D (radial/azimuthal) LSP simulations of a Hall thruster. The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000298.

Studies of PMMA sintering foils with and without coating by magnetron sputtering Pd

NASA Astrophysics Data System (ADS)

Cutroneo, M.; Mackova, A.; Torrisi, L.; Vad, K.; Csik, A.; Ando', L.; Svecova, B.

2017-09-01

Polymethylmethacrylate thin foils were prepared by using physical and chemical processes aimed at changing certain properties. The density and the optical properties were changed obtaining clear and opaque foils. DC magnetron sputtering method was used to cover the foils with thin metallic palladium layers. The high optical absorbent foils were obtained producing microstructured PMMA microbeads with and without thin metallic coatings. Rutherford Backscattering Spectroscopy, optical investigation and microscopy were employed to characterize the prepared foils useful in the field study of laser-matter interaction.

Growth and characterization of a-axis oriented Cr-doped AlN films by DC magnetron sputtering

NASA Astrophysics Data System (ADS)

Panda, Padmalochan; Ramaseshan, R.; Krishna, Nanda Gopala; Dash, S.

2016-05-01

Wurtzite type Cr-doped AlN thin films were grown on Si (100) substrates using DC reactive magnetron sputtering with a function of N2 concentration (15 to 25%). Evolution of crystal structure of these films was studied by GIXRD where a-axis preferred orientation was observed. The electronic binding energy and concentration of Cr in these films were estimated by X-ray photoemission spectroscopy (XPS). We have observed indentation hardness (HIT) of around 28.2 GPa for a nitrogen concentration of 25%.

Growth and characterization of a-axis oriented Cr-doped AlN films by DC magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Panda, Padmalochan; Ramaseshan, R., E-mail: seshan@igcar.gov.in; Dash, S.

2016-05-23

Wurtzite type Cr-doped AlN thin films were grown on Si (100) substrates using DC reactive magnetron sputtering with a function of N{sub 2} concentration (15 to 25%). Evolution of crystal structure of these films was studied by GIXRD where a-axis preferred orientation was observed. The electronic binding energy and concentration of Cr in these films were estimated by X-ray photoemission spectroscopy (XPS). We have observed indentation hardness (H{sub IT}) of around 28.2 GPa for a nitrogen concentration of 25%.

Ultra-hard AlMgB14 coatings fabricated by RF magnetron sputtering from a stoichiometric target

NASA Astrophysics Data System (ADS)

Grishin, A. M.; Khartsev, S. I.; Böhlmark, J.; Ahlgren, M.

2015-01-01

For the first time hard aluminum magnesium boride films were fabricated by RF magnetron sputtering from a single stoichiometric ceramic AlMgB14 target. Optimized processing conditions (substrate temperature, target sputtering power and target-to-substrate distance) enable fabrication of stoichiometric in-depth compositionally homogeneous films with the peak values of nanohardness 88 GPa and Young's modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 and 275 GPa at 200 nm depth in 2 μm thick film.

Controllable transition from positive space charge to negative space charge in an inverted cylindrical magnetron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rane, R., E-mail: ramu@ipr.res.in; Ranjan, M.; Mukherjee, S.

2016-01-15

The combined effect of magnetic field (B), gas pressure (P), and the corresponding discharge voltage on the discharge properties of argon in inverted cylindrical magnetron has been investigated. In the experiment, anode is biased with continuous 10 ms sinusoidal half wave. It is observed that at a comparatively higher magnetic field (i.e., >200 gauss) and lower operating pressure (i.e., <1 × 10{sup −3} mbar), the discharge extinguishes and demands a high voltage to reignite. Discharge current increases with increase in magnetic field and starts reducing at sufficiently higher magnetic field for a particular discharge voltage due to restricted electron diffusion towards the anode.more » It is observed that B/P ratio plays an important role in sustaining the discharge and is constant for a discharge voltage. The discharge is transformed to negative space charge regime from positive space charge regime at certain B/P ratio and this ratio varies linearly with the discharge voltage. The space charge reversal is indicated by the radial profile of the floating potential and plasma potential in between two electrodes for different magnetic fields. At a particular higher magnetic field (beyond 100 gauss), the floating potential increases gradually with the radial distance from cathode, whereas it remains almost constant at lower magnetic field.« less

Fabrication and characterization of La2Zr2O7 films on different buffer architectures for YBa2Cu3O7-δ coated conductors by RF magnetron sputtering.

PubMed

Xu, Da; Liu, Linfei; Xiao, Guina; Li, Yijie

2013-02-27

La2Zr2O7 (LZO) films were grown on different buffer architectures by radio frequency magnetron sputtering for the large-scale application of YBa2Cu3O7-x (YBCO)-coated conductors. The three different buffer architectures were cerium oxide (CeO2), yttria-stabilized zirconia (YSZ)/CeO2, and CeO2/YSZ/CeO2. The microstructure and surface morphology of the LZO film were studied by X-ray diffraction, optical microscopy, field emission scanning electron microscopy, and atomic force microscopy. The LZO films prepared on the CeO2, YSZ/CeO2, and CeO2/YSZ/CeO2 buffer architectures were preferentially c-axis-oriented and highly textured. The in-plane texture of LZO film on CeO2 single-buffer architecture was ∆ φ = 5.5° and the out-of-plane texture was ∆ ω = 3.4°. All the LZO films had very smooth surfaces, but LZO films grown on YSZ/CeO2 and CeO2/YSZ/CeO2 buffer architectures had cracks. The highly textured LZO film grown on CeO2-seed buffered NiW tape was suitable for the epitaxial growth of YBCO film with high currents.

Structural and electrical properties of AlN layers grown on silicon by reactive RF magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazlov, N., E-mail: n.bazlov@spbu.ru; Pilipenko, N., E-mail: nelly.pilipenko@gmail.com; Vyvenko, O.

2016-06-17

AlN films of different thicknesses were deposited on n-Si (100) substrates by reactive radio frequency (rf) magnetron sputtering. Dependences of structure and electrical properties on thickness of deposited films were researched. The structures of the films were analyzed with scanning electron microscopy (SEM) and with transmitting electron microscopy (TEM). Electrical properties of the films were investigated on Au-AlN-(n-Si) structures by means of current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) techniques. Electron microscopy investigations had shown that structure and chemical composition of the films were thickness stratified. Near silicon surface layer was amorphous aluminum oxide one contained trapsmore » of positive charges with concentration of about 4 × 10{sup 18} cm{sup −3}. Upper layers were nanocrystalline ones consisted of both wurzite AlN and cubic AlON nanocrystals. They contained traps both positive and negative charges which were situated within 30 nm distance from silicon surface. Surface densities of these traps were about 10{sup 12} cm{sup −2}. Electron traps with activation energies of (0.2 ÷ 0.4) eV and densities of about 10{sup 10} cm{sup −2} were revealed on interface between aluminum oxide layer and silicon substrate. Their densities varied weakly with the film thickness.« less

A concept for a soft gamma-ray concentrator using thin-film multilayer structures

NASA Astrophysics Data System (ADS)

Bloser, Peter F.; Shirazi, Farzane; Echt, Olof; Krzanowski, James E.; Legere, Jason S.; McConnell, Mark L.; Tsavalas, John G.; Wong, Emily N.; Aliotta, Paul H.

2016-07-01

We are investigating the use of thin-film, multilayer structures to form optics capable of concentrating soft gamma rays with energies greater than 100 keV, beyond the reach of current grazing-incidence hard X-ray mirrors. Alternating layers of low- and high-density materials (e.g., polymers and metals) will channel soft gamma-ray photons via total external reflection. A suitable arrangement of bent structures will then concentrate the incident radiation to a point. Gamma-ray optics made in this way offer the potential for soft gamma-ray telescopes with focal lengths of less than 10 m, removing the need for formation flying spacecraft and opening the field up to balloon-borne instruments. Following initial investigations conducted at Los Alamos National Laboratory, we have constructed and tested a prototype structure using spin coating combined with magnetron sputtering. We are now investigating whether it is possible to grow such flexible multi-layer structures with the required thicknesses and smoothness more quickly by using magnetron sputter and pulsed laser deposition techniques. We present the latest results of our fabrication and gamma-ray channeling tests, and describe our modeling of the sensitivity of potential concentrator-based telescope designs. If successful, this technology offers the potential for transformational increases in sensitivity while dramatically improving the system-level performance of future high-energy astronomy missions through reduced mass and complexity.

Potentiodynamic Polarization Studies and Surface Chemical Composition of Bismuth Titanate (BixTiyOz) Films Produced through Radiofrequency Magnetron Sputtering

PubMed Central

Alfonso, José E.; Olaya, Jhon J.; Pinzón, Manuel J.; Marco, José F.

2013-01-01

The applications of Bismuth Titanate (BixTiyOz) materials have been focused on their electronic and optical properties, but with respect to the use of these compounds in applications like corrosion resistance, have been very few or nonexistent. For this reason, in the present investigation BixTiyOz thin films were deposited using RF magnetron sputtering onto silicon wafers, stainless steel 316L, and titanium alloy (Ti6Al4V) substrates, in order to carry out a study of the corrosion behavior of this compound. The structural properties of the coatings were studied through X-ray diffraction (XRD), the morphology was determined using Scanning Electron Microscopy (SEM), the corrosion resistance behavior of the coated and uncoated substrates was evaluated via the Potentiodynamic Polarization technique, and surface chemical composition was evaluated through X-ray photoelectron spectroscopy (XPS). The XRD results indicated that the films were amorphous. The SEM micrographs showed that the deposited films were homogeneous, but in some cases there were cracks. The potentiodynamic polarization technique showed that the corrosion current in the coated substrates decreased by an order of two magnitudes with respect to the uncoated substrates, but in both cases the corrosion mechanism was pitting due to the pores in the film. The XPS analysis shows that the deposited films contain both Bi3+ and Ti4+. PMID:28788338

Potentiodynamic Polarization Studies and Surface Chemical Composition of Bismuth Titanate (Bi x Ti y O z ) Films Produced through Radiofrequency Magnetron Sputtering.

PubMed

Alfonso, José E; Olaya, Jhon J; Pinzón, Manuel J; Marco, José F

2013-10-08

The applications of Bismuth Titanate (Bi x Ti y O z ) materials have been focused on their electronic and optical properties, but with respect to the use of these compounds in applications like corrosion resistance, have been very few or nonexistent. For this reason, in the present investigation Bi x Ti y O z thin films were deposited using RF magnetron sputtering onto silicon wafers, stainless steel 316L, and titanium alloy (Ti₆Al₄V) substrates, in order to carry out a study of the corrosion behavior of this compound. The structural properties of the coatings were studied through X-ray diffraction (XRD), the morphology was determined using Scanning Electron Microscopy (SEM), the corrosion resistance behavior of the coated and uncoated substrates was evaluated via the Potentiodynamic Polarization technique, and surface chemical composition was evaluated through X-ray photoelectron spectroscopy (XPS). The XRD results indicated that the films were amorphous. The SEM micrographs showed that the deposited films were homogeneous, but in some cases there were cracks. The potentiodynamic polarization technique showed that the corrosion current in the coated substrates decreased by an order of two magnitudes with respect to the uncoated substrates, but in both cases the corrosion mechanism was pitting due to the pores in the film. The XPS analysis shows that the deposited films contain both Bi 3+ and Ti 4+ .

Noise analysis in numerical modeling of crossed fields microwave tubes

NASA Astrophysics Data System (ADS)

BłaŻejewicz, Mariusz; Woźniak, Martyna; Szkop, Emil; RóŻycki, Andrzej; Rychlewski, Michał; Baczewski, Dariusz; Laskowski, Dariusz

2018-04-01

One of the most important parameters that characterize microwave tubes with crossed fields, both amplifiers (CFA), and generating tubes like magnetrons is the noise level. This type of tubes are characterized by relatively high noise levels, which is the main factor limiting their current use in radar transmitters. The main source of noise in microwave tubes of this type is the dispersion of the energy of electrons that are in phase with the spatial wave of the electromagnetic field propagating in the delay line (in case of an amplitron) or in the resonant structure (in case of a magnetron).The results of the research presented in the article concern the technique of determination of Signal to Noise Ratio (SNR) based on the analysis of results obtained during the numerical simulations of the effect of electric charge on a high frequency electromagnetic field. Signal to noise ratio was determined by analysing in-phase and quadrature data recorded in the high frequency simulation. In order to assess the accuracy of the method under investigation, the results from the noise analysis obtained from numerical calculations were compared with the results obtained from real tube measurements performed by a spectrum analyser. On the basis of the research, it appears that performing analysis of noise generated in the interaction area may be useful for preliminary evaluation of the tube at the design stage.

Phase transformation in SiOx/SiO₂ multilayers for optoelectronics and microelectronics applications.

PubMed

Roussel, M; Talbot, E; Pratibha Nalini, R; Gourbilleau, F; Pareige, P

2013-09-01

Due to the quantum confinement, silicon nanoclusters (Si-ncs) embedded in a dielectric matrix are of prime interest for new optoelectronics and microelectronics applications. In this context, SiO(x)/SiO₂ multilayers have been prepared by magnetron sputtering and subsequently annealed to induce phase separation and Si clusters growth. The aim of this paper is to study phase separation processes and formation of nanoclusters in SiO(x)/SiO₂ multilayers by atom probe tomography. Influences of the silicon supersaturation, annealing temperature and SiO(x) and SiO₂ layer thicknesses on the final microstructure have been investigated. It is shown that supersaturation directly determines phase separation regime between nucleation/classical growth and spinodal decomposition. Annealing temperature controls size of the particles and interface with the surrounding matrix. Layer thicknesses directly control Si-nc shapes from spherical to spinodal-like structures. Copyright © 2012 Elsevier B.V. All rights reserved.

Thermoelectric Mixed Thick-/Thin Film Microgenerators Based on Constantan/Silver.

PubMed

Gierczak, Mirosław; Prażmowska-Czajka, Joanna; Dziedzic, Andrzej

2018-01-12

This paper describes the design, manufacturing and characterization of newly developed mixed thick-/thin film thermoelectric microgenerators based on magnetron sputtered constantan (copper-nickel alloy) and screen-printed silver layers. The thermoelectric microgenerator consists of sixteen thermocouples made on a 34.2 × 27.5 × 0.25 mm³ alumina substrate. One of thermocouple arms was made of magnetron-sputtered constantan (Cu-Ni alloy), the second was a Ag-based screen-printed film. The length of each thermocouple arm was equal to 27 mm, and their width 0.3 mm. The distance between the arms was equal to 0.3 mm. In the first step, a pattern mask with thermocouples was designed and fabricated. Then, a constantan layer was magnetron sputtered over the whole substrate, and a photolithography process was used to prepare the first thermocouple arms. The second arms were screen-printed onto the substrate using a low-temperature silver paste (Heraeus C8829A or ElectroScience Laboratories ESL 599-E). To avoid oxidation of constantan, they were fired in a belt furnace in a nitrogen atmosphere at 550/450 °C peak firing temperature. Thermoelectric and electrical measurements were performed using the self-made measuring system. Two pyrometers included into the system were used for temperature measurement of hot and cold junctions. The estimated Seebeck coefficient, α was from the range 35 - 41 µV/K, whereas the total internal resistances R were between 250 and 3200 ohms, depending on magnetron sputtering time and kind of silver ink (the resistance of a single thermocouple was between 15.5 and 200 ohms).

Reconstruction of the static magnetic field of a magnetron

NASA Astrophysics Data System (ADS)

Krüger, Dennis; Köhn, Kevin; Gallian, Sara; Brinkmann, Ralf Peter

2018-06-01

The simulation of magnetron discharges requires a quantitatively correct mathematical model of the magnetic field structure. This study presents a method to construct such a model on the basis of a spatially restricted set of experimental data and a plausible a priori assumption on the magnetic field configuration. The example in focus is that of a planar circular magnetron. The experimental data are Hall probe measurements of the magnetic flux density in an accessible region above the magnetron plane [P. D. Machura et al., Plasma Sources Sci. Technol. 23, 065043 (2014)]. The a priori assumption reflects the actual design of the device, and it takes the magnetic field emerging from a center magnet of strength m C and vertical position d C and a ring magnet of strength m R , vertical position d R , and radius R. An analytical representation of the assumed field configuration can be formulated in terms of generalized hypergeometric functions. Fitting the ansatz to the experimental data with a least square method results in a fully specified analytical field model that agrees well with the data inside the accessible region and, moreover, is physically plausible in the regions outside of it. The outcome proves superior to the result of an alternative approach which starts from a multimode solution of the vacuum field problem formulated in terms of polar Bessel functions and vertical exponentials. As a first application of the obtained field model, typical electron and ion Larmor radii and the gradient and curvature drift velocities of the electron guiding center are calculated.

Thermoelectric Mixed Thick-/Thin Film Microgenerators Based on Constantan/Silver

PubMed Central

Gierczak, Mirosław; Prażmowska-Czajka, Joanna; Dziedzic, Andrzej

2018-01-01

This paper describes the design, manufacturing and characterization of newly developed mixed thick-/thin film thermoelectric microgenerators based on magnetron sputtered constantan (copper-nickel alloy) and screen-printed silver layers. The thermoelectric microgenerator consists of sixteen thermocouples made on a 34.2 × 27.5 × 0.25 mm3 alumina substrate. One of thermocouple arms was made of magnetron-sputtered constantan (Cu-Ni alloy), the second was a Ag-based screen-printed film. The length of each thermocouple arm was equal to 27 mm, and their width 0.3 mm. The distance between the arms was equal to 0.3 mm. In the first step, a pattern mask with thermocouples was designed and fabricated. Then, a constantan layer was magnetron sputtered over the whole substrate, and a photolithography process was used to prepare the first thermocouple arms. The second arms were screen-printed onto the substrate using a low-temperature silver paste (Heraeus C8829A or ElectroScience Laboratories ESL 599-E). To avoid oxidation of constantan, they were fired in a belt furnace in a nitrogen atmosphere at 550/450 °C peak firing temperature. Thermoelectric and electrical measurements were performed using the self-made measuring system. Two pyrometers included into the system were used for temperature measurement of hot and cold junctions. The estimated Seebeck coefficient, α was from the range 35 − 41 µV/K, whereas the total internal resistances R were between 250 and 3200 ohms, depending on magnetron sputtering time and kind of silver ink (the resistance of a single thermocouple was between 15.5 and 200 ohms). PMID:29329203

Effect of Sputtering Current on the Comprehensive Properties of (Ti,Al)N Coating and High-Speed Steel Substrate

NASA Astrophysics Data System (ADS)

Su, Yongyao; Tian, Liangliang; Hu, Rong; Liu, Hongdong; Feng, Tong; Wang, Jinbiao

2018-05-01

To improve the practical property of (Ti,Al)N coating on a high-speed steel (HSS) substrate, a series of sputtering currents were used to obtain several (Ti,Al)N coatings using a magnetron sputtering equipment. The phase structure, morphology, and components of (Ti,Al)N coatings were characterized by x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy, respectively. The performance of (Ti,Al)N coatings, adhesion, hardness, and wear resistance was tested using a scratch tester, micro/nanohardness tester, and tribometer, respectively. Based on the structure-property relationships of (Ti,Al)N coatings, the results show that both the Al content and deposition temperature of (Ti,Al)N coatings increased with sputtering current. A high Al content helped to improve the performance of (Ti,Al)N coatings. However, the HSS substrate was softened during the high sputtering current treatment. Therefore, the optimum sputtering current was determined as 2.5 A that effectively increased the hardness and wear resistance of (Ti,Al)N coating.

Structural, electrical, and photoelectric properties of p-NiO/n-CdTe heterojunctions

NASA Astrophysics Data System (ADS)

Parkhomenko, Hryhorii; Solovan, Mykhaylo; Brus, Viktor; Maystruk, Eduard; Maryanchuk, Pavlo

2018-01-01

p-NiO/n-CdTe-photosensitive heterojunctions were prepared by the deposition of nickel oxide thin films onto n-type single-crystal CdTe substrates by DC reactive magnetron sputtering. The analysis of capacitance-voltage (C-V) characteristics, measured at different frequencies of the small amplitude AC signal and corrected by the effect of the series resistance, provided evidence of the presence of electrically charged interface states, which significantly affect the measured capacitance. The dominant current transport mechanisms in the heterojunctions were determined at forward and reverse biases. Using "light" I-V characteristics, we determined the open-circuit voltage Voc=0.42 V, the short-circuit current Isc=57.5 μA/cm2, and the fill factor FF=0.24 under white light illumination with the intensity of 80 mW.

Thin-film cadmium telluride photovoltaic cells

NASA Astrophysics Data System (ADS)

Compaan, A. D.; Bohn, R. G.

1994-09-01

This report describes work to develop and optimize radio-frequency (RF) sputtering for the deposition of thin films of cadmium telluride (CdTe) and related semiconductors for thin-film solar cells. Pulsed laser physical vapor deposition was also used for exploratory work on these materials, especially where alloying or doping are involved, and for the deposition of cadmium chloride layers. The sputtering work utilized a 2-in diameter planar magnetron sputter gun. The film growth rate by RF sputtering was studied as a function of substrate temperature, gas pressure, and RF power. Complete solar cells were fabricated on tin-oxide-coated soda-lime glass substrates. Currently, work is being done to improve the open-circuit voltage by varying the CdTe-based absorber layer, and to improve the short-circuit current by modifying the CdS window layer.

Fabrication and electrical properties of (111) textured (Ba0.6Sr0.4)TiO3 film on platinized Si substrate

NASA Astrophysics Data System (ADS)

Wang, Yi; Liu, Baoting; Wei, Feng; Yang, Zhimin; Du, Jun

2007-01-01

The authors report the fabrication of (Ba0.6Sr0.4)TiO3 (BST) film on Pt /Si(001) substrate without Ti adhesion layer by magnetron sputtering. X-ray diffraction technique is used to characterize the orientation and phase purity of BST/Pt heterostructure. It is found that both BST and Pt films are (111) textured. The (111) BST films are observed to have high tunability of 49.4%; the dielectric constant and dielectric loss of the BST film are about 682 and 0.015, respectively. The leakage current density of BST film agrees well with the space-charge-limited current theory at room temperature and is only 3.90×10-8A/cm2 at 455kV/cm.

Reactive magnetron sputtering of N-doped carbon thin films on quartz glass for transmission photocathode applications

NASA Astrophysics Data System (ADS)

Balalykin, N. I.; Huran, J.; Nozdrin, M. A.; Feshchenko, A. A.; Kobzev, A. P.; Sasinková, V.; Boháček, P.; Arbet, J.

2018-03-01

N-doped carbon thin films were deposited on a silicon substrate and quartz glass by RF reactive magnetron sputtering using a carbon target and an Ar+N2 gas mixture. During the magnetron sputtering, the substrate holder temperatures was kept at 800 °C. The carbon film thickness on the silicon substrate was about 70 nm, while on the quartz glass it was in the range 15 nm – 60 nm. The elemental concentration in the films was determined by RBS and ERD. Raman spectroscopy was used to evaluate the intensity ratios I D/I G of the D and G peaks of the carbon films. The transmission photocathodes prepared were placed in the hollow-cathode assembly of a Pierce-structure DC gun to produce photoelectrons. The quantum efficiency (QE) was calculated from the laser energy and cathode charge measured. The properties of the transmission photocathodes based on semitransparent N-doped carbon thin films on quartz glass and their potential for application in DC gun technology are discussed.

Solid Lubrication Fundamentals and Applications. Chapter 6

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

2000-01-01

This chapter focuses attention on the friction and wear properties of selected solid lubricating films to aid users in choosing the best lubricant, deposition conditions, and operational variables. For simplicity, discussion of the tribological properties of concern is separated into two parts. The first part of the chapter discusses the different solid lubricating films selected for study including commercially developed solid film lubricants: (1) bonded molybdenum disulfide (MoS2), (2) magnetron-sputtered MoS2, (3) ion-plated silver, (4) ion-plated lead, (5) magnetron-sputtered diamondlike carbon (MS DLC), and (6) plasma-assisted, chemical-vapor-deposited diamondlike carbon (PACVD DEC) films. Marked differences in the friction and wear properties of the different films resulted from the different environmental conditions (ultrahigh vacuum, humid air, and dry nitrogen) and the solid film lubricant materials. The second part of the chapter discusses the physical and chemical characteristics, friction behavior, and endurance life of the magnetron-sputtered MoS2 films. The role of interface species and the effects of applied load, film thickness, oxygen pressure, environment, and temperature on the friction and wear properties are considered.

A new method of nanocrystalline nickel powder formation by magnetron sputtering on the water-soluble substrates

NASA Astrophysics Data System (ADS)

Tučkutė, S.; Urbonavičius, M.; Lelis, M.; Maiorov, M.; Díaz Ordaz, J. R.; Milčius, D.

2018-01-01

Due to the accurate and relatively easy control magnetron sputtering is an attractive technique for the synthesis of metallic particles. This work describes a new method of nickel powder production by depositing nickel on the surface of sodium chloride particles which were used as the template and are soluble in water. Ni powder with flake-like structure was obtained after washing Ni coated salt particles in ultrasonic cleaner. Salt particles and nickel powder were characterized using scanning electron microscope (SEM), energy-dispersive x-ray spectrometer, XRD and X-ray photoelectron spectroscopy (XPS) techniques. SEM images showed that thickness of the received Ni particles varied in the nanoscale and depended on the magnetron deposition time but did not depend on the size of salt particles. On the other hand initial size of the salt particles was successfully employed a measure to control lateral dimensions of Ni powder. XRD and XPS analysis results revealed that Ni particles had metallic core and oxidized shell which was a cause of the slightly deteriorated magnetic properties.

Optical sideband spectroscopy of a single ion in a Penning trap

NASA Astrophysics Data System (ADS)

Mavadia, S.; Stutter, G.; Goodwin, J. F.; Crick, D. R.; Thompson, R. C.; Segal, D. M.

2014-03-01

We perform resolved optical sideband spectroscopy on a single 40Ca+ ion in a Penning trap. We probe the electric quadrupole allowed S1/2↔D5/2 transition at 729 nm and observe equally spaced sidebands for the three motional modes. The axial mode, parallel to the trap axis, is a one-dimensional harmonic oscillator, whereas the radial cyclotron and magnetron modes are circular motions perpendicular to the magnetic field. The total energy associated with the magnetron motion is negative, but here we probe only the (positive) kinetic energy. From the equivalent Doppler widths of the sideband spectra corresponding to the three motions we find effective temperatures of 1.1±0.2 mK, 7±3 mK, and 42±8 μK for the axial, modified cyclotron, and magnetron modes, respectively. These should be compared to the cooling limits, estimated using optimal laser parameters, of 0.38 mK, 0.8 mK, and ˜10 μK. In future work we aim to perform resolved-sideband cooling of the ion on the 729-nm transition.

Influence of microstructure and surface topography on the electrical conductivity of Cu and Ag thin films obtained by magnetron sputtering

NASA Astrophysics Data System (ADS)

Polonyankin, D. A.; Blesman, A. I.; Postnikov, D. V.

2017-05-01

Conductive thin films formation by copper and silver magnetron sputtering is one of high technological areas for industrial production of solar energy converters, energy-saving coatings, flat panel displays and touch control panels because of their high electrical and optical properties. Surface roughness and porosity, average grain size, internal stresses, orientation and crystal lattice type, the crystallinity degree are the main physical properties of metal films affecting their electrical resistivity and conductivity. Depending on the film thickness, the dominant conduction mechanism can affect bulk conductivity due to the flow of electron gas, and grain boundary conductivity. The present investigation assesses the effect of microstructure and surface topography on the electrical conductivity of magnetron sputtered Cu and Ag thin films using X-ray diffraction analysis, scanning electron and laser interference microscopy. The highest specific conductivity (78.3 MS m-1 and 84.2 MS m-1, respectively, for copper and silver films at the thickness of 350 nm) were obtained with the minimum values of roughness and grain size as well as a high degree of lattice structuredness.

UV-photodetector based on NiO/diamond film

NASA Astrophysics Data System (ADS)

Chang, Xiaohui; Wang, Yan-Feng; Zhang, Xiaofan; Liu, Zhangcheng; Fu, Jiao; Fan, Shuwei; Bu, Renan; Zhang, Jingwen; Wang, Wei; Wang, Hong-Xing; Wang, Jingjing

2018-01-01

In this study, a NiO/diamond UV-photodetector has been fabricated and investigated. A single crystal diamond (SCD) layer was grown on a high-pressure-high-temperature Ib-type diamond substrate by using a microwave plasma chemical vapor deposition system. NiO films were deposited directly by the reactive magnetron sputtering technique in a mixture gas of oxygen and argon onto the SCD layer. Gold films were patterned on NiO films as electrodes to form the metal-semiconductor-metal UV-photodetector which shows good repeatability and a 2 orders of magnitude UV/visible rejection ratio. Also, the NiO/diamond photodetector has a higher responsivity and a wider response range in contrast to a diamond photodetector.

Influence of sputtering pressure on optical constants of a-GaAs1-xNx thin films

NASA Astrophysics Data System (ADS)

Baoshan, Jia; Yunhua, Wang; Lu, Zhou; Duanyuan, Bai; Zhongliang, Qiao; Xin, Gao; Baoxue, Bo

2012-08-01

Amorphous GaAs1-xNx (a-GaAs1-xNx) thin films have been deposited at room temperature by a reactive magnetron sputtering technique on glass substrates with different sputtering pressures. The thickness, nitrogen content, carrier concentration and transmittance of the as-deposited films were determined experimentally. The influence of sputtering pressure on the optical band gap, refractive index and dispersion parameters (Eo, Ed) has been investigated. An analysis of the absorption coefficient revealed a direct optical transition characterizing the as-deposited films. The refractive index dispersions of the as-deposited a-GaAs1-xNx films fitted well to the Cauchy dispersion relation and the Wemple model.

Sputtered Gum metal thin films showing bacterial inactivation and biocompatibility.

PubMed

Achache, S; Alhussein, A; Lamri, S; François, M; Sanchette, F; Pulgarin, C; Kiwi, J; Rtimi, S

2016-10-01

Super-elastic Titanium based thin films Ti-23Nb-0.7Ta-2Zr-(O) (TNTZ-O) and Ti-24Nb-(N) (TN-N) (at.%) were deposited by direct current magnetron sputtering (DCMS) in different reactive atmospheres. The effects of oxygen doping (TNTZ-O) and/or nitrogen doping (TN-N) on the microstructure, mechanical properties and biocompatibility of the as-deposited coatings were investigated. Nano-indentation measurements show that, in both cases, 1sccm of reactive gas in the mixture is necessary to reach acceptable values of hardness and Young's modulus. Mechanical properties are considered in relation to the films compactness, the compressive stress and the changes in the grain size. Data on Bacterial inactivation and biocompatibility are reported in this study. The biocompatibility tests showed that O-containing samples led to higher cells proliferation. Bacterial inactivation was concomitant with the observed pH and surface potential changes under light and in the dark. The increased cell fluidity leading to bacterial lysis was followed during the bacterial inactivation time. The increasing cell wall fluidity was attributed to the damage of the bacterial outer cell which losing its capacity to regulate the ions exchange in and out of the bacteria. Copyright © 2016 Elsevier B.V. All rights reserved.

Metal-insulator transition properties of sputtered silicon-doped and un-doped vanadium dioxide films at terahertz range

NASA Astrophysics Data System (ADS)

Zhang, Huafu; Wu, Zhiming; Niu, Ruihua; Wu, Xuefei; he, Qiong; Jiang, Yadong

2015-03-01

Silicon-doped and un-doped vanadium dioxide (VO2) films were synthesized on high-purity single-crystal silicon substrates by means of reactive direct current magnetron sputtering followed by thermal annealing. The structure, morphology and metal-insulator transition properties of silicon-doped VO2 films at terahertz range were measured and compared to those of un-doped VO2 films. X-ray diffraction and scanning electron microscopy indicated that doping the films with silicon significantly affects the preferred crystallographic orientation and surface morphologies (grain size, pores and characteristics of grain boundaries). The temperature dependence of terahertz transmission shows that the transition temperature, hysteresis width and transition sharpness greatly depend on the silicon contents while the transition amplitude was relatively insensitive to the silicon contents. Interestingly, the VO2 film doped with a silicon content of 4.6 at.% shows excellent terahertz switching characteristics, namely a small hysteresis width of 4.5 °C, a giant transmission modulation ratio of about 82% and a relatively low transition temperature of 56.1 °C upon heating. This work experimentally indicates that silicon doping can effectively control not only the surface morphology but also the metal-insulator transition characteristics of VO2 films at terahertz range.

Role of annealing temperature on microstructural and electro-optical properties of ITO films produced by sputtering

NASA Astrophysics Data System (ADS)

Senol, Abdulkadir; Gulen, Mahir; Yildirim, Gurcan; Ozturk, Ozgur; Varilci, Ahmet; Terzioglu, Cabir; Belenli, Ibrahim

2013-03-01

In this study, we investigate the effect of annealing temperature on electrical, optical and microstructural properties of indium tin oxide (ITO) films deposited onto Soda lime glass substrates by conventional direct current (DC) magnetron reactive sputtering technique at 100 watt using an ITO ceramic target (In2O3:SnO2, 90:10 wt. %) in argon atmosphere at room temperature. The films obtained are exposed to the calcination process at different temperature up to 700 ° C. Resistivity, Hall Effect, X-ray diffractometer (XRD), ultra violet-visible spectrometer (UV-vis) and atomic force microscopy (AFM) measurements are performed to characterize the samples. Moreover, phase purity, surface morphology, optical and photocatalytic properties of the films are compared with each other. Furthermore, mobility, carrier density and conductivity characteristics of the samples prepared are carried out as function of temperature in the range of 80-300 K at the magnetic field of 0.550 T. The results obtained show that all the properties depend strongly on the annealing temperature and in fact the film annealed at 400 ° C obtains the better optical properties due to the high refractive index while the film produced at 100 °C exhibits much better photoactivity than the other films as a result of the large optical energy band gap.

Enhancement of soft X-ray reflectivity and interface stability in nitridated Pd/Y multilayer mirrors.

PubMed

Xu, Dechao; Huang, Qiushi; Wang, Yiwen; Li, Pin; Wen, Mingwu; Jonnard, Philippe; Giglia, Angelo; Kozhevnikov, Igor V; Wang, Kun; Zhang, Zhong; Wang, Zhanshan

2015-12-28

Pd/Y multilayer mirrors operating in the soft X-ray region are characterized by a high theoretical reflectance, reaching 65% at normal incidence in the 8-12 nm wavelength range. However, a severe intermixing of neighboring Pd and Y layers results in an almost total disappearance of the interfaces inside the multilayer structures fabricated by direct current magnetron sputtering and thus a dramatic reflectivity decrease. Based on grazing incidence X-ray reflectometry and X-ray photoelectron spectroscopy, we demonstrate that the stability of the interfaces in Pd/Y multilayer structures can be essentially improved by adding a small amount of nitrogen (4-8%) to the working gas (Ar). High resolution transmission electron microscopy shows that the interlayer width is only 0.9 nm and 0.6 nm for Y(N)-on-Pd(N) and Pd(N)-on-Y(N) interfaces, respectively. A well-defined crystalline texture of YN (200) is observed on the electron diffraction pattern. As a result, the measured reflectance of the Pd(N)/Y(N) multilayer achieves 30% at λ = 9.3 nm. The peak reflectivity value is limited by the remaining interlayers and the formation of the YN compound inside the yttrium layers, resulting in an increased absorption.

Fabrication of eco-friendly PNP transistor using RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Kumar, B. Santhosh; Harinee, N.; Purvaja, K.; Shanker, N. Praveen; Manikandan, M.; Aparnadevi, N.; Mukilraj, T.; Venkateswaran, C.

2018-05-01

An effort has been made to fabricate a thin film transistor using eco-friendly oxide semiconductor materials. Oxide semiconductor materials are cost - effective, thermally and chemically stable with high electron/hole mobility. Copper (II) oxide is a p-type semiconductor and zinc oxide is an n-type semiconductor. A pnp thin film transistor was fabricated using RF magnetron sputtering. The films deposited have been subjected to structural characterization using AFM. I-V characterization of the fabricated device, Ag/CuO/ZnO/CuO/Ag, confirms transistor behaviour. The mechanism of electron/hole transport of the device is discussed below.

Oleophobic optical coating deposited by magnetron PVD

NASA Astrophysics Data System (ADS)

Bernt, D.; Ponomarenko, V.; Pisarev, A.

2016-09-01

Thin oxinitride films of Zn-Sn-O-N and Si-Al-O-N were deposited on glass by reactive magnetron sputtering at various nitrogen-to-oxygen ratios. Nitrogen added to oxygen led to decrease of the surface roughness and increase of oleophobic properties studied by the oil-drop test. The best oleophobity was obtained for Zn-Sn-O-N oxinitride at Zn:Sn=1:1 and N:O=1:2. Improved oleophobic properties were also demonstrated if the oxinitride film was deposited on top of the multilayer coating as the final step in the industrial cycle of production of energy efficient glass.

Space-charge effects in Penning ion traps

NASA Astrophysics Data System (ADS)

Porobić, T.; Beck, M.; Breitenfeldt, M.; Couratin, C.; Finlay, P.; Knecht, A.; Fabian, X.; Friedag, P.; Fléchard, X.; Liénard, E.; Ban, G.; Zákoucký, D.; Soti, G.; Van Gorp, S.; Weinheimer, Ch.; Wursten, E.; Severijns, N.

2015-06-01

The influence of space-charge on ion cyclotron resonances and magnetron eigenfrequency in a gas-filled Penning ion trap has been investigated. Off-line measurements with K39+ using the cooling trap of the WITCH retardation spectrometer-based setup at ISOLDE/CERN were performed. Experimental ion cyclotron resonances were compared with ab initio Coulomb simulations and found to be in agreement. As an important systematic effect of the WITCH experiment, the magnetron eigenfrequency of the ion cloud was studied under increasing space-charge conditions. Finally, the helium buffer gas pressure in the Penning trap was determined by comparing experimental cooling rates with simulations.

Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersson, Joakim; Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore; Ni, Pavel

Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side-on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

Self-organization and self-limitation in high power impulse magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anders, Andre

The plasma over the racetrack in high power impulse magnetron sputtering develops in traveling ionization zones. Power densities can locally reach 10{sup 9} W/m{sup 2}, which is much higher than usually reported. Ionization zones move because ions are 'evacuated' by the electric field, exposing neutrals to magnetically confined, drifting electrons. Drifting secondary electrons amplify ionization of the same ionization zone where the primary ions came from, while sputtered and outgassing atoms are supplied to the following zone(s). Strong density gradients parallel to the target disrupt electron confinement: a negative feedback mechanism that stabilizes ionization runaway.

Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore; Andersson, Joakim; Ni, Pavel

Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

In situ stress evolution during magnetron sputtering of transition metal nitride thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abadias, G.; Guerin, Ph.

2008-09-15

Stress evolution during reactive magnetron sputtering of TiN, ZrN, and TiZrN layers was studied using real-time wafer curvature measurements. The presence of stress gradients is revealed, as the result of two kinetically competing stress generation mechanisms: atomic peening effect, inducing compressive stress, and void formation, leading to a tensile stress regime predominant at higher film thickness. No stress relaxation is detected during growth interrupt in both regimes. A change from compressive to tensile stress is evidenced with increasing film thickness, Ti content, sputtering pressure, and decreasing bias voltage.

ZnO:Al Thin Film Gas Sensor for Detection of Ethanol Vapor

PubMed Central

Chou, Shih Min; Teoh, Lay Gaik; Lai, Wei Hao; Su, Yen Hsun; Hon, Min Hsiung

2006-01-01

The ZnO:Al thin films were prepared by RF magnetron sputtering on Si substrate using Pt as interdigitated electrodes. The structure was characterized by XRD and SEM analyses, and the ethanol vapor gas sensing as well as electrical properties have been investigated and discussed. The gas sensing results show that the sensitivity for detecting 400 ppm ethanol vapor was ∼20 at an operating temperature of 250°C. The high sensitivity, fast recovery, and reliability suggest that ZnO:Al thin film prepared by RF magnetron sputtering can be used for ethanol vapor gas sensing.

Magnetron-Sputtered Amorphous Metallic Coatings

NASA Technical Reports Server (NTRS)

Thakoor, A. P.; Mehra, M.; Khanna, S. K.

1985-01-01

Amorphous coatings of refractory metal/metalloid-based alloys deposited by magnetron sputtering provide extraordinary hardness and wear resistance. Sputtering target fabricated by thoroughly mixing powders of tungsten, rhenium, and boron in stated proportions and pressing at 1,200 degrees C and 3,000 lb/in. to second power (21 MPa). Substrate lightly etched by sputtering before deposition, then maintained at bias of - 500 V during initial stages of film growth while target material sputtered onto it. Argon gas at pressure used as carrier gas for sputter deposition. Coatings dense, pinhole-free, extremely smooth, and significantly resistant to chemical corrosion in acidic and neutral aqueous environments.

Optical and electrical properties of p-type transparent conducting CuAlO2 thin film synthesized by reactive radio frequency magnetron sputtering technique

NASA Astrophysics Data System (ADS)

Saha, B.; Thapa, R.; Jana, S.; Chattopadhyay, K. K.

2010-10-01

Thin films of p-type transparent conducting CuAlO2 have been synthesized through reactive radio frequency magnetron sputtering on silicon and glass substrates at substrate temperature 300°C. Reactive sputtering of a target fabricated from Cu and Al powder (1:1.5) was performed in Ar+O2 atmosphere. The deposition parameters were optimized to obtain phase pure, good quality CuAlO2 thin films. The films were characterized by studying their structural, morphological, optical and electrical properties.

Evaporation-assisted high-power impulse magnetron sputtering: The deposition of tungsten oxide as a case study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hemberg, Axel; Dauchot, Jean-Pierre; Snyders, Rony

2012-07-15

The deposition rate during the synthesis of tungsten trioxide thin films by reactive high-power impulse magnetron sputtering (HiPIMS) of a tungsten target increases, above the dc threshold, as a result of the appropriate combination of the target voltage, the pulse duration, and the amount of oxygen in the reactive atmosphere. This behavior is likely to be caused by the evaporation of the low melting point tungsten trioxide layer covering the metallic target in such working conditions. The HiPIMS process is therefore assisted by thermal evaporation of the target material.

Formation of the N-MWCNT/TiOx nanocomposite structure using magnetron method for gas sensing application

NASA Astrophysics Data System (ADS)

Bolotov, V. V.; Kan, V. E.; Knyazev, E. V.; Davletkildeev, N. A.; Nesov, S. N.; Ponomareva, I. V.; Sokolov, D. V.; Korusenko, P. M.

2017-08-01

The nanocomposite structures N-MWCNT/TiOx based on nitrogen-doped multi-walled carbon nanotubes (N-MWCNT) have been synthesized using magnetron sputtering. The morphology, structure, composition and also the electro-physical properties of the nanocomposite structures have been investigated. The changes of the Fermi level position and the electrical conductivity of N-MWCNT and N-MWCNT/TiOx structures at the adsorption of the oxidizing and reducing gas molecules have been studied. The obtained nanocomposite structures demonstrate the wide perspectives as the sensing media for gas micro- and nanosensors.

Physical vapor deposition and metalorganic chemical vapor deposition of yttria-stabilized zirconia thin films

NASA Astrophysics Data System (ADS)

Kaufman, David Y.

Two vapor deposition techniques, dual magnetron oblique sputtering (DMOS) and metalorganic chemical vapor deposition (MOCVD), have been developed to produce yttria-stabilized zirconia (YSZ) films with unique microstructures. In particular, biaxially textured thin films on amorphous substrates and dense thin films on porous substrates have been fabricated by DMOS and MOCVD, respectively. DMOS YSZ thin films were deposited by reactive sputtering onto Si (native oxide surface) substrates positioned equidistant between two magnetron sources such that the fluxes arrived at oblique angles with respect to the substrate normal. Incident fluxes from two complimentary oblique directions were necessary for the development of biaxial texture. The films displayed a strong [001] out-of-plane orientation with the <110> direction in the film aligned with the incident flux. Biaxial texture improved with increasing oblique angle and film thickness, and was stronger for films deposited with Ne than with Ar. The films displayed a columnar microstructure with grain bundling perpendicular to the projected flux direction, the degree of which increased with oblique angle and thickness. The texture decreased by sputtering at pressures at which the flux of sputtered atoms was thermalized. These results suggested that grain alignment is due to directed impingement of both sputtered atoms and reflected energetic neutrals. The best texture, a {111} phi FWHM of 23°, was obtained in a 4.8 mum thick film deposited at an oblique angle of 56°. MOCVD YSZ thin films were deposited in a vertical cold-wall reactor using Zr(tmhd)4 and Y(tmhd)3 precursors. Fully stabilized YSZ films with 9 mol% could be deposited by controlling the bubbler temperatures. YSZ films on Si substrates displayed a transition at 525°C from surface kinetic limited growth, with an activation energy of 5.5 kJ/mole, to mass transport limited growth. Modifying the reactor by lowering the inlet height and introducing an Ar baffle ring increased the growth rates to 2.5 mum/hr. Dense, gas impermeable 4-6 mum YSZ thin films were deposited on porous (La,Sr)Mno3 cathode substrates. Solid oxide fuel cells, fabricated by sputtering on a Ni-YSZ anode, achieved open circuit voltages ≥94% theoretical, and maximum power densities at 750°C comparable with commercial conventional SOFC's operated at higher temperatures.

Annealing dependent evolution of columnar nanostructures in RF magnetron sputtered PTFE films for hydrophobic applications

NASA Astrophysics Data System (ADS)

Tripathi, S.; De, Rajnarayan; Maidul Haque, S.; Divakar Rao, K.; Misal, J. S.; Prathap, C.; Das, S. C.; Patidar, Manju M.; Ganesan, V.; Sahoo, N. K.

2018-01-01

Present communication focuses on a relatively less explored direction of producing rough polytetrafluoroethylene (PTFE) surfaces for possible hydrophobic applications. The experiments were carried out to make rough PTFE films without losing much of the transmission, which is an important factor while designing futuristic solar cell protection covers. After annealing temperature optimization, as grown RF magnetron sputtered PTFE films (prepared at 160 W RF power) were subjected to vacuum annealing at 200 °C for different time durations ranging from 1 to 4 h. The films show morphological evolution exhibiting formation and growth of columnar nanostructures that are responsible for roughening of the films due to annealing induced molecular migration and rearrangement. In agreement with this, qualitative analysis of corresponding x-ray reflectivity data shows modification in film thickness, which may again be attributed to the growth of columns at the expense of the atoms of remaining film molecules. However, the observations reveal that the film annealed at 200 °C for 2 h gives a combination of patterned columnar structures and reasonable transmission of >85% (in 500-1000 nm wavelength range), both of which are deteriorated when the films are annealed either at high temperature beyond 200 °C or for long durations >3 h. In addition, attenuated total reflection-Fourier transform infrared spectroscopy results reveal that the molecular bonds remain intact upon annealing at any temperature within the studied range indicating the stable nature of the films.

Microstructural and mechanical characteristics of Ni–Cr thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petley, Vijay; Sathishkumar, S.; Thulasi Raman, K.H.

2015-06-15

Highlights: • Ni–Cr thin films of varied composition deposited by DC magnetron co-sputtering. • Thin film with Ni–Cr: 80–20 at% composition exhibits most distinct behavior. • The films were tensile tested and exhibited no cracking till the substrate yielding. - Abstract: Ni–Cr alloy thin films have been deposited using magnetron co-sputtering technique at room temperature. Crystal structure was evaluated using GIXRD. Ni–Cr solid solution upto 40 at% of Cr exhibited fcc solid solution of Cr in Ni and beyond that it exhibited bcc solid solution of Ni in Cr. X-ray diffraction analysis shows formation of (1 1 1) fiber texturemore » in fcc and (2 2 0) fiber texture in bcc Ni–Cr thin films. Electron microscopy in both in-plane and transverse direction of the film surface revealed the presence of columnar microstructure for films having Cr upto 40 at%. Mechanical properties of the films are evaluated using nanoindentation. The modulus values increased with increase of Cr at% till the film is fcc. With further increase in Cr at% the modulus values decreased. Ni–Cr film with 20 at% Ni exhibits reduction in modulus and is correlated to the poor crystallization of the film as reflected in XRD analysis. The Ni–Cr thin film with 80 at% Ni and 20 at% Cr exhibited the most distinct columnar structure with highest electrical resistivity, indentation hardness and elastic modulus.« less

Multi-Frequency Recirculating Planar Magnetrons

NASA Astrophysics Data System (ADS)

Greening, Geoffrey Bruce

The cavity magnetron is generally accepted as the standard for compactness and high microwave power with applications in industry, science, and defense, with the latter including counter-electronics. In this application, magnetrons are limited because they are narrowband devices. To expand the range of frequencies that can be produced using a single magnetron, a novel multi-frequency variant of the Recirculating Planar Magnetron (RPM) was designed, fabricated, and experimentally demonstrated. This multi-frequency RPM (MFRPM) was the first high-power magnetron capable of generating multiple microwave frequencies simultaneously and demonstrated the first known instance of harmonic frequency-locking in a magnetron. The MFRPM design consisted of two planar cavity arrays coupled by cylindrical electron recirculation bends. The two arrays formed a 1 GHz L-Band Oscillator (LBO) and a 2 GHz S-Band Oscillator (SBO). Experiments were conducted using a 0.1-0.3 T axial magnetic field produced using a pulsed pair of Helmholtz coils and a -300 kV, 200-400 ns, 1-5 kA pulse applied to a Mode-Control Cathode (MCC) using the MELBA-C Marx generator. Six experimental configurations were tested using three anodes (the isolated LBO, the isolated SBO, and the MFRPM), two microwave loads (a standard, matched load, and a waveguide taper load used to characterize the LBO frequency harmonics), and two axial magnetic fields (uniform and nonuniform). Using these configurations, an in-depth characterization of MFRPM operation determined 1) the identity of the observed electromagnetic modes, and the degree of mode competition, 2) the frequencies, powers, and other electrical characteristics associated with those modes and the LBO frequency harmonics, 3) the magnetic fields corresponding to optimal operation, 4) the operational impact of a nonuniform axial magnetic field, and 5) the origin and performance characteristics of a novel harmonic frequency-locked state observed in the MFRPM. The uniform magnetic field consistently yielded better performance relative to the nonuniform magnetic field. In the harmonic frequency-locked state at 0.17 T with the uniform magnetic field, the MFRPM LBO produced 32 +/- 3 MW at 0.984 +/- 0.001 GHz, and the SBO produced 13 +/- 2 MW at 1.970 +/- 0.002 GHz. Relative to the other operating states, the locked state was remarkably consistent. In B = 0.16-0.17 T, the phase drift during a typical locked shot was 8 +/- 4°, and the lock duration was 14 +/- 3 ns. The average phase difference between the oscillators was 93+/-17°. The locking appeared to be Adler-like, where the LBO was the driving oscillator and the SBO was the driven oscillator. Changes in the relative phase difference between the oscillators correlated with changes in the magnetic field, suggesting the coupling occurred through the second harmonic content of the LBO-modulated electron beam as it propagated from the LBO to the SBO. A comparison of the experimental results for this locked state with a new theory for harmonic locking was inconclusive. Using the uniform magnetic field at 0.17 T, the LBO second harmonic power was 178 +/- 60 kW at 1.962 +/- 0.013 GHz. The LBO fourth harmonic power was 5 +/- 1 kW at 3.916 +/- 0.018 GHz. In general, LBO harmonic powers increased when the fundamental circuit modes were operating at reduced power with considerable mode competition. Harmonic powers were also as much as 150% higher using the nonuniform magnetic field relative to the uniform magnetic field.

Silicon Nitride for Direct Water-Splitting and Corrosion Mitigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Head, J.; Turner, J.A.

2006-01-01

Todays fossil fuels are becoming harder to obtain, creating pollution problems, and posing hazards to people’s health. One alternative to fossil fuels is hydrogen, capable of serving as a clean and efficient energy carrier. Certain semiconductors are able to harness the energy of photons and direct it into water electrolysis in a process known as photoelectrochemical water splitting. Triple junction devices integrate three semiconductors of different band gaps resulting in a monolithic material that absorbs over a broader spectrum. Amorphous silicon (a-Si) is one such material that, when stacked in tandem, possesses water-splitting capabilities. Even though a-Si is capable ofmore » splitting water, it is an unstable material in solution and therefore requires a coating to protect the surface from corrosion. A stable, transparent material that has the potential for corrosion protection is silicon nitride. In this study, silicon nitride thin films were grown using DC magnetron sputtering with varying amounts of argon and nitrogen added to the system. X-ray diffraction indicated amorphous silicon nitride films. Current as a function of potential was determined from cyclic voltammetry measurements. Mott-Schottky analysis showed n-type behavior with absorption and transmission measurements indicated variation in flatband potentials. Variation in band gap values ranging from 1.90 to 4.0 eV. Corrosion measurements reveal that the silicon nitride samples exhibit both p-type and n-type behavior. Photocurrent over a range of potentials was greater in samples that were submerged in acidic electrolyte. Silicon nitride shows good stability in acidic, neutral, and basic solutions, indicative of a good material for corrosion mitigation.« less

Current-voltage characteristics of n-AlMgZnO/p-GaN junction diodes

NASA Astrophysics Data System (ADS)

Hsueh, Kuang-Po; Cheng, Po-Wei; Cheng, Yi-Chang; Sheu, Jinn-Kong; Yeh, Yu-Hsiang; Chiu, Hsien-Chin; Wang, Hsiang-Chun

2013-03-01

This study investigates the temperature dependence of the current-voltage (I-V) characteristics of Al-doped MgxZn1-xO/p-GaN junction diodes. Specifically, this study reports the deposition of n-type Al-doped MgxZn1-xO (AMZO) films on p-GaN using a radio-frequency (RF) magnetron sputtering system followed by annealing at 700, 800, 900, and 1000 °C in a nitrogen ambient for 60 seconds, respectively. The AMZO/GaN films were thereafter analyzed using Hall measurement and the x-ray diffraction (XRD) patterns. The XRD results show that the diffraction angles of the annealed AMZO films remain the same as that of GaN without shifting. The n-AMZO/p-GaN diode with 900 °C annealing had the lowest leakage current in forward and reverse bias. However, the leakage current of the diodes did not change significantly with an increase in annealing temperatures. These findings show that the n-AMZO/p-GaN junction diode is feasible for GaN-based heterojunction bipolar transistors (HBTs) and UV light-emitting diodes (LEDs).

Perpendicular magnetic anisotropy in Mn2CoAl thin film

NASA Astrophysics Data System (ADS)

Sun, N. Y.; Zhang, Y. Q.; Fu, H. R.; Che, W. R.; You, C. Y.; Shan, R.

2016-01-01

Heusler compound Mn2CoAl (MCA) is attracting more attentions due to many novel properties, such as high resistance, semiconducting behavior and suggestion as a spin-gapless material with a low magnetic moment. In this work, Mn2CoAl epitaxial thin film was prepared on MgO(100) substrate by magnetron sputtering. The transport property of the film exhibits a semiconducting-like behavior. Moreover, our research reveals that perpendicular magnetic anisotropy (PMA) can be induced in very thin Mn2CoAl films resulting from Mn-O and Co-O bonding at Mn2CoAl/MgO interface, which coincides with a recent theoretical prediction. PMA and low saturation magnetic moment could lead to large spin-transfer torque with low current density in principle, and thus our work may bring some unanticipated Heusler compounds into spintronics topics such as the domain wall motion and the current-induced magnetization reversal.

Electrical and ferroelectric properties of RF sputtered PZT/SBN on silicon for non-volatile memory applications

NASA Astrophysics Data System (ADS)

Singh, Prashant; Jha, Rajesh Kumar; Singh, Rajat Kumar; Singh, B. R.

2018-02-01

We report the integration of multilayer ferroelectric film deposited by RF magnetron sputtering and explore the electrical characteristics for its application as the gate of ferroelectric field effect transistor for non-volatile memories. PZT (Pb[Zr0.35Ti0.65]O3) and SBN (SrBi2Nb2O9) ferroelectric materials were selected for the stack fabrication due to their large polarization and fatigue free properties respectively. Electrical characterization has been carried out to obtain memory window, leakage current density, PUND and endurance characteristics. Fabricated multilayer ferroelectric film capacitor structure shows large memory window of 17.73 V and leakage current density of the order 10-6 A cm-2 for the voltage sweep of -30 to +30 V. This multilayer gate stack of PZT/SBN shows promising endurance property with no degradation in the remnant polarization for the read/write iteration cycles upto 108.

Conducted noise analysis and protection of 45 kJ/s, ±50 kV capacitor charging power supply when interfaced with repetitive Marx based pulse power system.

PubMed

Naresh, P; Patel, Ankur; Sharma, Archana

2015-09-01

Pulse power systems with highly dynamic loads like klystron, backward wave oscillator (BWO), and magnetron generate highly dynamic noise. This noise leads to frequent failure of controlled switches in the inverter stage of charging power supply. Designing a reliable and compatible power supply for pulse power applications is always a tricky job when charging rate is in multiples of 10 kJ/s. A ±50 kV and 45 kJ/s capacitor charging power supply based on 4th order LCLC resonant topology has been developed for a 10 Hz repetitive Marx based system. Conditions for load independent constant current and zero current switching (ZCS) are derived mathematically. Noise generated at load end due to dynamic load is tackled effectively and reduction in magnitude noise voltage is achieved by providing shielding between primary and secondary of high voltage high frequency transformer and with LCLC low pass filter. Shielding scales down the ratio between coupling capacitance (Cc) and the collector-emitter capacitance of insulated gate bi-polar transistor switch, which in turn reduces the common mode noise voltage magnitude. The proposed 4th order LCLC resonant network acts as a low pass filter for differential mode noise in the reverse direction (from load to source). Power supply has been tested repeatedly with 5 Hz repetition rate with repetitive Marx based system connected with BWO load working fine without failure of single switch in the inverter stage.

A study of structural, electrical, and optical properties of p-type Zn-doped SnO2 films versus deposition and annealing temperature

NASA Astrophysics Data System (ADS)

Le, Tran; Phuc Dang, Huu; Luc, Quang Ho; Hieu Le, Van

2017-04-01

This study presents a detailed investigation of the structural, electrical, and optical properties of p-type Zn-doped SnO2 versus the deposition and annealing temperature. Using a direct-current (DC) magnetron sputtering method, p-type transparent conductive Zn-doped SnO2 (ZTO) films were deposited on quartz glass substrates. Zn dopants incorporated into the SnO2 host lattice formed the preferred dominant SnO2 (1 0 1) and (2 1 1) planes. X-ray photoelectron spectroscopy (XPS) was used for identifying the valence state of Zn in the ZTO film. The electrical property of ZTO films changed from n-type to p-type at the threshold temperature of 400 °C, and the films achieved extremely high conductivity at the optimum annealing temperature of 600 °C after annealing for 2 h. The best conductive property of the film was obtained on a 10 wt% ZnO-doped SnO2 target with a resistivity, hole concentration, and hole mobility of 0.22 Ω · cm, 7.19  ×  1018 cm-3, and 3.95 cm2 V-1 s-1, respectively. Besides, the average transmission of films was  >84%. The surface morphology of films was examined using scanning electron microscopy (SEM). Moreover, the acceptor level of Zn2+ was identified using photoluminescence spectra at room temperature. Current-voltage (I-V) characteristics revealed the behavior of a p-ZTO/n-Si heterojunction diode.

Conducted noise analysis and protection of 45 kJ/s, ±50 kV capacitor charging power supply when interfaced with repetitive Marx based pulse power system

NASA Astrophysics Data System (ADS)

Naresh, P.; Patel, Ankur; Sharma, Archana

2015-09-01

Pulse power systems with highly dynamic loads like klystron, backward wave oscillator (BWO), and magnetron generate highly dynamic noise. This noise leads to frequent failure of controlled switches in the inverter stage of charging power supply. Designing a reliable and compatible power supply for pulse power applications is always a tricky job when charging rate is in multiples of 10 kJ/s. A ±50 kV and 45 kJ/s capacitor charging power supply based on 4th order LCLC resonant topology has been developed for a 10 Hz repetitive Marx based system. Conditions for load independent constant current and zero current switching (ZCS) are derived mathematically. Noise generated at load end due to dynamic load is tackled effectively and reduction in magnitude noise voltage is achieved by providing shielding between primary and secondary of high voltage high frequency transformer and with LCLC low pass filter. Shielding scales down the ratio between coupling capacitance (Cc) and the collector-emitter capacitance of insulated gate bi-polar transistor switch, which in turn reduces the common mode noise voltage magnitude. The proposed 4th order LCLC resonant network acts as a low pass filter for differential mode noise in the reverse direction (from load to source). Power supply has been tested repeatedly with 5 Hz repetition rate with repetitive Marx based system connected with BWO load working fine without failure of single switch in the inverter stage.

Biotribological behavior of Ag-ZrCxN1-x coatings against UHMWPE for joint prostheses devices.

PubMed

Calderon V, S; Sánchez-López, J C; Cavaleiro, A; Carvalho, S

2015-01-01

This study aims to evaluate the structural, mechanical and tribological properties of zirconium carbonitrides (ZrCxN1-x) coatings with embedded silver nanoparticles, produced with the intention of achieving a material with enhanced multi-functional properties, including mechanical strength, corrosion resistance, tribological performance and antibacterial behavior suitable for their use in joint prostheses. The coatings were deposited by direct current (DC) reactive magnetron sputtering onto 316 L stainless steel, changing the silver content from 0 to 20 at% by modifying the current density applied to the targets. Different nitrogen and acetylene gas fluxes were used as reactive gases. The coatings revealed different mixtures of crystalline ZrCxN1-x, silver nanoparticles and amorphous carbon phases. The hardness of the films was found to be mainly controlled by the ratio between the hard (ZrCxN1-x) and soft (Ag and amorphous carbon) phases in the films, fluctuating between 7.4 and 20.4 GPa. The coefficient of friction, measured against ultra-high molecular weight polyethylene (UHMWPE) in Hank's balanced salt solution with 10 gL(-1) albumin, is governed by the surface roughness and hardness. The UHMWPE wear rates were in the same order of magnitude (between 1.4 and 2.0 × 10(-6)mm(3)N(-1)m(-1)), justified by the effect of the protective layer of albumin formed during the tests. The small differences were due to the hydrophobic/hydrophilic character of the surface, as well as to the silver content. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of Hydrogen Exposure on Mechanical and Tribological Behavior of CrxN Coatings Deposited at Different Pressures on IN718

PubMed Central

Obrosov, Aleksei; Sutygina, Alina N.; Volinsky, Alex A.; Manakhov, Anton; Weiß, Sabine; Kashkarov, Egor B.

2017-01-01

In the current study, the properties of the CrxN coatings deposited on the Inconel 718 superalloy using direct current reactive magnetron sputtering are investigated. The influence of working pressure on the microstructure, mechanical, and tribological properties of the CrxN coatings before and after high-temperature hydrogen exposure is studied. The cross-sectional scanning electron micrographs indicate the columnar structure of the coatings, which changes from dense and compact columns to large columns with increasing working pressure. The Cr/N ratio increases from 1.4 to 1.9 with increasing working pressure from 300 to 900 mPa, respectively. X-ray diffraction analysis reveals a change from mixed hcp-Cr2N and fcc-CrN structure to approximately stoichiometric Cr2N phase. After gas-phase hydrogenation, the coating deposited at 300 mPa exhibits the lowest hydrogen absorption at 600 °C of all investigated coatings. The results indicate that the dense mixed cubic and hexagonal structure is preferential for hydrogen permeation resistance due to the presence of cubic phase with higher packing density in comparison to the hexagonal structure. After hydrogenation, no changes in phase composition were observed; however, a small amount of hydrogen is accumulated in the coatings. An increase of coating hardness and elastic modulus was observed after hydrogen exposure. Tribological tests reveal that hydrogenation leads to a decrease of the friction coefficient up to 20%–30%. The best value of 0.25 was reached for hydrogen exposed CrxN coating deposited at 300 mPa. PMID:28772923

Characterization of ZnO:SnO{sub 2} (50:50) thin film deposited by RF magnetron sputtering technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cynthia, S. R.; Sanjeeviraja, C.; Ponmudi, S.

2016-05-06

Zinc oxide (ZnO) and tin oxide (SnO{sub 2}) thin films have attracted significant interest recently for use in optoelectronic application such as solar cells, flat panel displays, photonic devices, laser diodes and gas sensors because of their desirable electrical and optical properties and wide band gap. In the present study, thin films of ZnO:SnO{sub 2} (50:50) were deposited on pre-cleaned microscopic glass substrate by RF magnetron sputtering technique. The substrate temperature and RF power induced changes in structural, surface morphological, compositional and optical properties of the films have been studied.

Numerical Simulation of Single-anode and Double-anode Magnetron Injection Guns for 127.5 GHz 1 MW Gyrotron

NASA Astrophysics Data System (ADS)

Singh, Udaybir; Kumar, Nitin; Kumar, Anil; Purohit, Laxmi Prasad; Sinha, Ashok Kumar

2011-07-01

This paper presents the design of two types of magnetron injection guns (MIG's) for 1 MW, 127.5 GHz gyrotron. TE24,8 mode has been chosen as the operating mode. In-house developed code MIGSYN has been used to estimate the initial gun parameters. The electron trajectory tracing program EGUN and in-house developed code MIGANS have been used to optimize the single-anode and the double-anode design for 80 kV, 40 A MIG. The parametric analysis of MIG has also been presented. The advantages and the disadvantages of each kind of configuration have been critically examined.

High quality boron carbon nitride/ZnO-nanorods p-n heterojunctions based on magnetron sputtered boron carbon nitride films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, J. C.; Department of Engineering Physics, Polytechnique Montréal, Montreal, Quebec H3A 3A7; Jha, S. K., E-mail: skylec@gmail.com, E-mail: apwjzh@cityu.edu.hk

2014-11-10

Boron carbon nitride (BCN) films were synthesized on Si (100) and fused silica substrates by radio-frequency magnetron sputtering from a B{sub 4}C target in an Ar/N{sub 2} gas mixture. The BCN films were amorphous, and they exhibited an optical band gap of ∼1.0 eV and p-type conductivity. The BCN films were over-coated with ZnO nanorod arrays using hydrothermal synthesis to form BCN/ZnO-nanorods p-n heterojunctions, exhibiting a rectification ratio of 1500 at bias voltages of ±5 V.

Tribological characterization of TiN coatings prepared by magnetron sputtering

NASA Astrophysics Data System (ADS)

Makwana, Nishant S.; Chauhan, Kamlesh V.; Sonera, Akshay L.; Chauhan, Dharmesh B.; Dave, Divyeshkumar P.; Rawal, Sushant K.

2018-05-01

Titanium nitride (TiN) coating deposited on aluminium and brass pin substrates using RF reactive magnetron sputtering. The structural properties and surface morphology were characterized by X-ray diffraction (XRD), atomic force microscope (AFM) and field emission scanning electron microscope (FE-SEM). There was formation of (101) Ti2N, (110) TiN2 and (102) TiN0.30 peaks at 3.5Pa, 2Pa and 1.25Pa sputtering pressure respectively. The tribological properties of coating were inspected using pin on disc tribometer equipment. It was observed that TiN coated aluminium and brass pins demonstrated improved wear resistance than uncoated aluminium and brass pins.

Drifting potential humps in ionization zones: The “propeller blades” of high power impulse magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anders, André; Ni, Pavel; Panjan, Matjaž

2013-09-30

Ion energy distribution functions measured for high power impulse magnetron sputtering show features, such as a broad peak at several 10 eV with an extended tail, as well as asymmetry with respect to E×B, where E and B are the local electric and magnetic field vectors, respectively. Here it is proposed that those features are due to the formation of a potential hump of several 10 V in each of the traveling ionization zones. Potential hump formation is associated with a negative-positive-negative space charge that naturally forms in ionization zones driven by energetic drifting electrons.

Flexible OLED fabrication with ITO thin film on polymer substrate

NASA Astrophysics Data System (ADS)

Kim, Sung Il; Lee, Kyo Woong; Bhusan Sahu, Bibhuti; Geon Han, Jeon

2015-09-01

This paper reports the synthesis of flexible indium tin oxide (ITO) films in a dual pulse magnetron sputtering (DPMS) system at low temperature (<100 °C) deposition condition. This study also presents experimental demonstration of the ITO films for their possible use in the fabrication of organic light emitting diode (OLED) device, and the device performance on the super polycarbonate substrates. The presented data reveals the feasibility of ITO films, with a very low sheet resistance of ∼30 Ω/□ and high transmittance of ∼88% at 550 nm, simply by the magnetron pulse mode operations with increasing pulse frequency from 0 to 50 kHz.

Effect of Silver Dopants on the ZnO Thin Films Prepared by a Radio Frequency Magnetron Co-Sputtering System

PubMed Central

Liu, Fang-Cheng; Li, Jyun-Yong; Chen, Tai-Hong; Chang, Chun-How; Lee, Ching-Ting; Hsiao, Wei-Hua; Liu, Day-Shan

2017-01-01

Ag-ZnO co-sputtered films at various atomic ratios of Ag (Ag/(Ag + Zn) at.%) were prepared by a radio frequency magnetron cosputtering system, using the co-sputtered targets of Ag and ZnO. The activation of the Ag acceptors (AgZn) and the formation of the Ag aggregations (Ag0) in the ZnO matrix were investigated from XRD, Raman scattering, and XPS measurements. The Ag-ZnO co-sputtered film behaving like a p-type conduction was achievable after annealing at 350 °C under air ambient for 1 h. PMID:28773159

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.

Characterization and device applications of ZnO films deposited by high power impulse magnetron sputtering (HiPIMS)

NASA Astrophysics Data System (ADS)

Partridge, J. G.; Mayes, E. L. H.; McDougall, N. L.; Bilek, M. M. M.; McCulloch, D. G.

2013-04-01

ZnO films have been reactively deposited on sapphire substrates at 300 °C using a high impulse power magnetron sputtering deposition system and characterized structurally, optically and electronically. The unintentionally doped n-type ZnO films exhibit high transparency, moderate carrier concentration (˜5 × 1018 cm-3) and a Hall mobility of 8.0 cm2 V-1 s-1, making them suitable for electronic device applications. Pt/ZnO Schottky diodes formed on the HiPIMS deposited ZnO exhibited rectification ratios up to 104 at ±2 V and sensitivity to UV light.

Satellite Power Study (SPS) concept definition study (Exhibit D). Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

Hanley, G. M.

1981-01-01

Efforts concentrated on updating of the Rockwell reference concept, definition of new system options, studies of special emphasis topics, further definition of the transportation system, and further program definition. The Rockwell reference satellite concept has a gallium arsenide (GaAs) solar cell array having flat concentrators with an effective concentration ratio of 1.83at end of life. Alternatives to this concept includes solid state power amplifiers or magnetrons for dc/RF conversion and multibandgap solar cells for solar to dc energy conversion. Two solid state concepts were studied. It was determined that the magnetron approach was the lowest mass and cost system.

Room-temperature fabrication of a Ga-Sn-O thin-film transistor

NASA Astrophysics Data System (ADS)

Matsuda, Tokiyoshi; Takagi, Ryo; Umeda, Kenta; Kimura, Mutsumi

2017-08-01

We have succeeded in forming a Ga-Sn-O (GTO) film for a thin-film transistor (TFT) using radio-frequency (RF) magnetron sputtering at room temperature without annealing process. It is achieved that the field-effect mobility is 0.83 cm2 V-1 s-1 and the on/off ratio is roughly 106. A critical process parameter is the deposition pressure during the RF magnetron sputtering, which determines a balance between competing mechanisms of sputtering damages and chemical reactions, because the film quality has to be enhanced solely during the sputtering deposition. This result suggests a possibility of rare-metal free amorphous metal-oxide semiconductors.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kunj, Saurabh, E-mail: saurabhkunj22@gmail.com; Sreenivas, K.

2016-05-23

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 (O{sub 2}/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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vitelaru, Catalin; National Institute for Optoelectronics, Magurele-Bucharest, RO 077125; Lundin, Daniel

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.

Localized heating of electrons in ionization zones: Going beyond the Penning-Thornton paradigm in magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anders, Andre

2014-12-07

The fundamental question of how energy is supplied to a magnetron discharge is commonly answered by the Penning-Thornton paradigm invoking secondary electrons. Huo et al. (Plasma Sources Sci. Technol. 22, 045005, (2013)) used a global discharge model to show that electron heating in the electric field of the magnetic presheath is dominant. In this contribution, this concept is applied locally taking into account the electric potential structure of ionization zones. Images of ionization zones can and should be interpreted as diagrams of the localization of electric potential and related electron energy, where certain collisions promote or dampen their formation.

Rietveld-refinement and optical study of the Fe doped ZnO thin film by RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Kumar, Arun; Dhiman, Pooja; Singh, M.

2017-05-01

Fe Doped ZnO Dilute Magnetic Semiconductor thin film prepared by RF magnetron sputtering on glass substrate and Influence of 3% Fe-doping on structural and Optical properties has been studied. The Rietveld-refinement analysis shows that Fe doping has a significant effect on crystalline structure, grain size and strain in the thin film. Two dimensional and three-dimensional atom probe tomography of the thin film shows that Fe ions are randomly distributed which is supported by Xray Diffraction (XRD). Fe-doping is found to effectively modify the band gap energy up to 3.5 eV.

Study on the effect of hydrogen addition on the variation of plasma parameters of argon-oxygen magnetron glow discharge for synthesis of TiO{sub 2} films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saikia, Partha, E-mail: partha.008@gmail.com; Institute of Physics, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago; Saikia, Bipul Kumar

2016-04-15

We report the effect of hydrogen addition on plasma parameters of argon-oxygen magnetron glow discharge plasma in the synthesis of H-doped TiO{sub 2} films. The parameters of the hydrogen-added Ar/O{sub 2} plasma influence the properties and the structural phases of the deposited TiO{sub 2} film. Therefore, the variation of plasma parameters such as electron temperature (T{sub e}), electron density (n{sub e}), ion density (n{sub i}), degree of ionization of Ar and degree of dissociation of H{sub 2} as a function of hydrogen content in the discharge is studied. Langmuir probe and Optical emission spectroscopy are used to characterize the plasma.more » On the basis of the different reactions in the gas phase of the magnetron discharge, the variation of plasma parameters and sputtering rate are explained. It is observed that the electron and heavy ion density decline with gradual addition of hydrogen in the discharge. Hydrogen addition significantly changes the degree of ionization of Ar which influences the structural phases of the TiO{sub 2} film.« less

Influence of Substrate Temperature on Structural, Electrical and Optical Properties of Ito Thin Films Prepared by RF Magnetron Sputtering

NASA Astrophysics Data System (ADS)

He, Bo; Zhao, Lei; Xu, Jing; Xing, Huaizhong; Xue, Shaolin; Jiang, Meng

2013-10-01

In this paper, we investigated indium-tin-oxide (ITO) thin films on glass substrates deposited by RF magnetron sputtering using ceramic target to find the optimal condition for fabricating optoelectronic devices. The structural, electrical and optical properties of the ITO films prepared at various substrate temperatures were investigated. The results indicate the grain size increases with substrate temperature increases. As the substrate temperature grew up, the resistivity of ITO films greatly decreased. The ITO film possesses high quality in terms of electrode functions, when substrate temperature is 480°C. The resistivity is as low as 9.42 × 10-5 Ω•cm, while the carrier concentration and mobility are as high as 3.461 × 1021 atom/cm3 and 19.1 cm2/Vṡs, respectively. The average transmittance of the film is about 95% in the visible region. The novel ITO/np-Silicon frame, which prepared by RF magnetron sputtering at 480°C substrate temperature, can be used not only for low-cost solar cell, but also for high quantum efficiency of UV and visible lights enhanced photodetector for various applications.

Distribution of Fe atom density in a dc magnetron sputtering plasma source measured by laser-induced fluorescence imaging spectroscopy

NASA Astrophysics Data System (ADS)

Shibagaki, K.; Nafarizal, N.; Sasaki, K.; Toyoda, H.; Iwata, S.; Kato, T.; Tsunashima, S.; Sugai, H.

2003-10-01

Magnetron sputtering discharge is widely used as an efficient method for thin film fabrication. In order to achieve the optimized fabrication, understanding of the kinetics in plasmas is essential. In the present work, we measured the density distribution of sputtered Fe atoms using laser-induced fluorescence imaging spectroscopy. A dc magnetron plasma source with a Fe target was used. An area of 20 × 2 mm in front of the target was irradiated by a tunable laser beam having a planar shape. The picture of laser-induced fluorescence on the laser beam was taken using an ICCD camera. In this way, we obtained the two-dimensional image of the Fe atom density. As a result, it has been found that the Fe atom density observed at a distance of several centimeters from the target is higher than that adjacent to the target, when the Ar gas pressure was relatively high. It is suggested from this result that some gas-phase production processes of Fe atoms are available in the plasma. This work has been performed under the 21st Century COE Program by the Ministry of Education, Culture, Sports, Science and Technology in Japan.

Development of selective surfaces. Semiannual technical progress report, September 11, 1978-April 30, 1979. [Multilayer coatings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thornton, J.A.

1979-06-15

Magnetron sputtering technology, which permits coatings to be deposited over large areas with significantly increased deposition rates, is reviewed with particular emphasis on cylindrical magnetrons and their application to reactive sputtering. Work is reported in which cylindrical-post magnetron sputtering sources have been used to deposit both graded and multi-layered cermet-type coatings by sputtering chromium and type 304 stainless steel in Ar and O/sub 2/ and Ar and CO gas mixtures under various conditions of reactive gas injection. The substrates are aluminum-coated glass and aluminum foil. The coatings are of an interference type, typically about 100 nm thick, with a metal-rich,more » highly absorbing layer adjacent to the substrate and a dielectric material at the surface. In some cases a reactively sputtered aluminum oxide anti-reflective surface layer has also been used. No advantages have been found for using chromium as opposed to the more readily available stainless steel. The reactive sputtering with CO is attractive because under many conditions the sputtering rates are relatively large compared to oxygen. Hemispherical absorptance and emittance data are reported. Typical absorptances are about 0.90 with emittances of 0.10.« less

BiVO{sub 4} photoanodes for water splitting with high injection efficiency, deposited by reactive magnetron co-sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Haibo; Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin; Freudenberg, Norman

2016-04-15

Photoactive bismuth vanadate (BiVO{sub 4}) 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 BiVO{sub 4} films were investigated. Phase-pure monoclinic BiVO{sub 4} films, which are more photoactive than the tetragonal BiVO{sub 4} phase, were obtained under slightly vanadium-rich conditions. After annealing of the Mo-doped BiVO{sub 4} films, the photocurrent increased 2.6 times compared to undoped films. After optimization of the BiVO{sub 4} film thickness, the photocurrent densities (without a catalyst or a blocking layer ormore » a hole scavenger) exceeded 1.2 mA/cm{sup 2} at a potential of 1.23 V{sub RHE} 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 BiVO{sub 4} films opens new possibilities for the fabrication of large-scale devices for water splitting.« less

Elementary surface processes during reactive magnetron sputtering of chromium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monje, Sascha; Corbella, Carles, E-mail: carles.corbella@rub.de; 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 oxidationmore » 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.« less

[Effect of niobium nitride on the bonding strength of titanium porcelain by magnetron sputtering].

PubMed

Wang, Shu-shu; Zhang, La-bao; Guang, Han-bing; Zhou, Shu; Zhang, Fei-min

2010-05-01

To investigate the effect of magnetron sputtered niobium nitride (NbN) on the bonding strength of commercially pure cast titanium (Ti) and low-fusing porcelain (Ti/Vita titankeramik system). Sixty Ti specimens were randomly divided into four groups, group T1, T2, T3 and T4. All specimens of group T1 and T2 were first treated with 120 microm blasted Al2O3 particles, and then only specimens of group T2 were treated with magnetron sputtered NbN film. All specimens of group T3 and T4 were first treated with magnetron sputtered NbN film and then only specimens of group T4 were treated with 120 microm blasted Al2O3 particles. The composition of the deposits were analyzed by X-ray diffraction (XRD). A universal testing machine was used to perform the three-point bending test to evaluate the bonding strength of Ti and porcelain. The microstructure of NbN, the interface of Ti-porcelain and the fractured Ti surface were observed with scanning electron microscopy (SEM) and energy depressive spectrum (EDS), and the results were compared. The XRD results showed that the NbN deposits were cubic crystalline phases. The bonding strength of Ti and porcelain in T1 to T4 group were (27.2+/-0.8), (43.1+/-0.6), (31.4+/-1.0) and (44.9+/-0.6) MPa. These results were analyzed by one-way analysis of variance and differences between groups were compared using least significant difference test. Significant inter-group differences were found among all groups (P<0.05). The results of SEM showed that with treatment of Al2O3 or NbN, alone, pre-cracks were found in the interface of Ti-porcelain, while samples treated with both Al2O3 and NbN had better bond. EDS of Ti-porcelain interface showed oxidation occurred in T1, T2 and T3, but was well controlled in T4. Magnetron sputtered NbN can prevent Ti from being oxidized, and can improve the bonding strength of Ti/Vita titankeramik system. Al2O3 blast can also improve the bonding strength of Ti/Vita titankeramik system.

Investigation of ISIS and Brookhaven National Laboratory ion source electrodes after extended operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lettry J.; Alessi J.; Faircloth, D.

2012-02-23

Linac4 accelerator of Centre Europeen de Recherches Nucleaires is under construction and a RF-driven H{sup -} ion source is being developed. The beam current requirement for Linac4 is very challenging: 80 mA must be provided. Cesiated plasma discharge ion sources such as Penning or magnetron sources are also potential candidates. Accelerator ion sources must achieve typical reliability figures of 95% and above. Investigating and understanding the underlying mechanisms involved with source failure or ageing is critical when selecting the ion source technology. Plasma discharge driven surface ion sources rely on molybdenum cathodes. Deformation of the cathode surfaces is visible aftermore » extended operation periods. A metallurgical investigation of an ISIS ion source is presented. The origin of the deformation is twofold: Molybdenum sputtering by cesium ions digs few tenths of mm cavities while a growth of molybdenum is observed in the immediate vicinity. The molybdenum growth under hydrogen atmosphere is hard and loosely bound to the bulk. It is, therefore, likely to peel off and be transported within the plasma volume. The observation of the cathode, anode, and extraction electrodes of the magnetron source operated at BNL for two years are presented. A beam simulation of H{sup -}, electrons, and Cs{sup -} ions was performed with the IBSimu code package to qualitatively explain the observations. This paper describes the operation conditions of the ion sources and discusses the metallurgical analysis and beam simulation results.« less

Investigation of ISIS and Brookhaven National Laboratory ion source electrodes after extended operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lettry, J.; Gerardin, A.; Pereira, H.

2012-02-15

Linac4 accelerator of Centre Europeen de Recherches Nucleaires is under construction and a RF-driven H{sup -} ion source is being developed. The beam current requirement for Linac4 is very challenging: 80 mA must be provided. Cesiated plasma discharge ion sources such as Penning or magnetron sources are also potential candidates. Accelerator ion sources must achieve typical reliability figures of 95% and above. Investigating and understanding the underlying mechanisms involved with source failure or ageing is critical when selecting the ion source technology. Plasma discharge driven surface ion sources rely on molybdenum cathodes. Deformation of the cathode surfaces is visible aftermore » extended operation periods. A metallurgical investigation of an ISIS ion source is presented. The origin of the deformation is twofold: Molybdenum sputtering by cesium ions digs few tenths of mm cavities while a growth of molybdenum is observed in the immediate vicinity. The molybdenum growth under hydrogen atmosphere is hard and loosely bound to the bulk. It is, therefore, likely to peel off and be transported within the plasma volume. The observation of the cathode, anode, and extraction electrodes of the magnetron source operated at BNL for two years are presented. A beam simulation of H{sup -}, electrons, and Cs{sup -} ions was performed with the IBSimu code package to qualitatively explain the observations. This paper describes the operation conditions of the ion sources and discusses the metallurgical analysis and beam simulation results.« less

Structural and electrical characterization of annealed Si1-xCx/SiC thin film prepared by magnetron sputtering

NASA Astrophysics Data System (ADS)

Huang, Shi-Hua; Liu, Jian

2014-05-01

Si-rich Si1—xCx /SiC multilayer thin films are prepared using magnetron sputtering, subsequently followed by thermal annealing in the range of 800-1200 °C. The influences of annealing temperature (Ta) on the formation of Si and/or SiC nanocrystals (NCs) and on the electrical characteristics of the multilayer film are investigated by using a variety of analytical techniques, including X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectrometry (FT-IR), current—voltage (I—V) technique, and capacitance-voltage (C—V) technique. XRD and Raman analyses indicate that Si NCs begin to form in samples for Ta >= 800 °C. At annealing temperatures of 1000 °C or higher, the formation of Si NCs is accompanied by the formation of SiC NCs. With the increase in the annealing temperature, the shift of FT-IR Si—C bond absorption spectra toward a higher wave number along with the change of band shape can be explained by a Si—C transitional phase between the loss of substitutional carbon and the formation of SiC precipitates and a precursor for the growth of SiC crystalline. The C—V and I—V results indicate that the interface quality of Si1—xCx/SiC multilayer film is improved significantly and the leakage current is reduced rapidly for Ta >= 1000 °C, which can be ascribed to the formation of Si and SiC NCs.

Influence of nitrogen admixture to argon on the ion energy distribution in reactive high power pulsed magnetron sputtering of chromium

NASA Astrophysics Data System (ADS)

Breilmann, W.; Maszl, C.; Hecimovic, A.; von Keudell, A.

2017-04-01

Reactive high power impulse magnetron sputtering (HiPIMS) of metals is of paramount importance for the deposition of various oxides, nitrides and carbides. The addition of a reactive gas such as nitrogen to an argon HiPIMS plasma with a metal target allows the formation of the corresponding metal nitride on the substrate. The addition of a reactive gas introduces new dynamics into the plasma process, such as hysteresis, target poisoning and the rarefaction of two different plasma gases. We investigate the dynamics for the deposition of chromium nitride by a reactive HiPIMS plasma using energy- and time-resolved ion mass spectrometry, fast camera measurements and temporal and spatially resolved optical emission spectroscopy. It is shown that the addition of nitrogen to the argon plasma gas significantly changes the appearance of the localized ionization zones, the so-called spokes, in HiPIMS plasmas. In addition, a very strong modulation of the metal ion flux within each HiPIMS pulse is observed, with the metal ion flux being strongly suppressed and the nitrogen molecular ion flux being strongly enhanced in the high current phase of the pulse. This behavior is explained by a stronger return effect of the sputtered metal ions in the dense plasma above the racetrack. This is best observed in a pure nitrogen plasma, because the ionization zones are mostly confined, implying a very high local plasma density and consequently also an efficient scattering process.

Magnetron sputtered diamond-like carbon microelectrodes for on-chip measurement of quantal catecholamine release from cells

PubMed Central

Gao, Yuanfang; Chen, Xiaohui; Gupta, Sanju; Gillis, Kevin D.; Gangopadhyay, Shubhra

2008-01-01

Carbon electrodes are widely used in electrochemistry due to their low cost, wide potential window, and low and stable background noise. Carbon-fiber electrodes (CFE) are commonly used to electrochemically measure “quantal” catecholamine release via exocytosis from individual cells, but it is difficult to integrate CFEs into lab-on-a-chip devices. Here we report the development of nitrogen doped diamond-like carbon (DLC:N) microelectrodes on a chip to monitor quantal release of catecholamines from cells. Advantages of DLC:N microelectrodes are that they are batch producible at low cost, and are harder and more durable than graphite films. The DLC:N microelectrodes were prepared by a magnetron sputtering process with nitrogen doping. The 30 μm by 40 μm DLC:N microelectrodes were patterned onto microscope glass slides by photolithography and lift-off technology. The properties of the DLC:N microelectrodes were characterized by AFM, Raman spectroscopy and cyclic voltammetry. Quantal catecholamine release was recorded amperometrically from bovine adrenal chromaffin cells on the DLC:N microelectrodes. Amperometric spikes due to quantal release of catecholamines were similar in amplitude and area as those recorded using CFEs and the background current and noise levels of microchip DLC:N electrodes were also comparable to CFEs. Therefore, DLC:N microelectrodes are suitable for microchip-based high-throughput measurement of quantal exocytosis with applications in basic research, drug discovery and cell-based biosensors. PMID:18493856

Method for sequentially processing a multi-level interconnect circuit in a vacuum chamber

NASA Technical Reports Server (NTRS)

Routh, D. E.; Sharma, G. C. (Inventor)

1982-01-01

The processing of wafer devices to form multilevel interconnects for microelectronic circuits is described. The method is directed to performing the sequential steps of etching the via, removing the photo resist pattern, back sputtering the entire wafer surface and depositing the next layer of interconnect material under common vacuum conditions without exposure to atmospheric conditions. Apparatus for performing the method includes a vacuum system having a vacuum chamber in which wafers are processed on rotating turntables. The vacuum chamber is provided with an RF sputtering system and a DC magnetron sputtering system. A gas inlet is provided in the chamber for the introduction of various gases to the vacuum chamber and the creation of various gas plasma during the sputtering steps.

Magnetoresistive sensitivity and uniaxial anisotropy of spin-valve microstrips with a synthetic antiferromagnet

NASA Astrophysics Data System (ADS)

Chernyshova, T. A.; Milyaev, M. A.; Naumova, L. I.; Proglyado, V. V.; Bannikova, N. S.; Maksimova, I. K.; Petrov, I. A.; Ustinov, V. V.

2017-05-01

Microobjects (strips) were formed by contact photolithography using Ta/Ni80Fe20/Co90Fe10/Cu/Co90Fe10/Ru/Co90Fe10/Fe50Mn50/Ta spin-valves prepared by magnetron sputtering. A mutually perpendicular arrangement of uniaxial and unidirectional anisotropy axes in microobjects has been formed using two different thermomagnetic treatment regimes. The magnetoresistive sensitivity of spin valve and spin-valve-based microobject has been found to depend on the mutual arrangement of the easy magnetization axis and direction of magnetic field applied upon thermomagnetic treatment. The obtained data have been interpreted taking into account changes in the induced anisotropy and anisotropy due to the shape of the microobject.

Spin Hall magnetoresistance in CoFe 2O 4/Pt films

DOE PAGES

Wu, Hao; Qintong, Zhang; Caihua, Wan; ...

2015-05-13

Pulse laser deposition and magnetron sputtering techniques have been employed to prepare MgO(001)//CoFe 2O 4/Pt samples. Cross section transmission electron microscope results prove that the CoFe 2O 4 film epitaxially grew along (001) direction. X-ray magnetic circular dichroism results show that magnetic proximity effect in this sample is negligible. Magnetoresistance (MR) properties confirm that spin Hall MR (SMR) dominates in this system. Spin Hall effect-induced anomalous Hall voltage was also observed in this sample. Lastly, these results not only demonstrate the universality of SMR effect but also demonstrate the utility in spintronics of CoFe 2O 4 as a new typemore » of magnetic insulator.« less

Residual stress analysis for oxide thin film deposition on flexible substrate using finite element method

NASA Astrophysics Data System (ADS)

Chen, Hsi-Chao; Huang, Chen-Yu; Lin, Ssu-Fan; Chen, Sheng-Hui

2011-09-01

Residual or internal stresses directly affect a variety of phenomena including adhesion, generation of crystalline defects, perfection of epitaxial layers and formation of film surface growths such as hillocks and whiskers. Sputtering oxide films with high density promote high compressive stress, and it offers researchers a reference if the value of residual stress could be analyzed directly. Since, the study of residual stress of SiO2 and Nb2O5 thin film deposited by DC magnetron sputtered on hard substrate (BK7) and flexible substrate (PET and PC). A finite element method (FEM) with an equivalent-reference-temperature (ERT) technique had been proposed and used to model and evaluate the intrinsic strains of layered structures. The research has improved the equivalent reference temperature (ERT) technique of the simulation of intrinsic strain for oxygen film. The results have also generalized two models connecting to the lattice volume to predict the residual stress of hard substrate and flexible substrate with error of 3% and 6%, respectively.

Metal-Coated Cenospheres Obtained via Magnetron Sputter Coating: A New Precursor for Syntactic Foams

NASA Astrophysics Data System (ADS)

Shishkin, A.; Hussainova, I.; Kozlov, V.; Lisnanskis, M.; Leroy, P.; Lehmhus, D.

2018-05-01

Syntactic foams (SFs) and metal matrix syntactic foams (MMSFs) represent an advanced type of metal matrix composites (MMCs) based on hollow microspheres as particulate reinforcement. In general, SF and MMSFs allow tailoring of properties through choice of matrix, reinforcement, and volume fraction of the latter. A further handle for property adjustment is surface modification of the reinforcing particles. The present study introduces cenospheres for use as filler material in SF and MMSFs and as lightweight filler with electromagnetic interference shielding properties in civil engineering, which have been surface coated by means of physical vapor deposition, namely vibration-assisted sputter coating using a magnetron sputtering system. Altogether four types of such cenosphere-based composite powders (CPs) with an original particle size range of 50-125 µm (average particle size d50 75 µm) were studied. Surface films deposited on these were composed of Cu, stainless steel, Ti, and Ti-TiN double layers. For Cu coatings, the deposited metal film thickness was shown to be dependent on the sputtering energy. Scanning electron microscope backscattering images revealed nonporous films uniform in thickness directly after sputtering. Film thickness varied between 0.15 µm and 2.5 µm, depending on coating material and sputtering parameters. From these materials, samples were produced without addition of metal powders, exhibiting metal contents as low as 8-10 wt.% based on the coating alone. Obtained samples had an apparent density of 1.1-1.9 g/cm3 and compressive strengths ranging from 22 MPa to 135 MPa.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crăciunescu, Corneliu M., E-mail: corneliu.craciunescu@upt.ro; Mitelea, Ion, E-mail: corneliu.craciunescu@upt.ro; Budău, Victor, E-mail: corneliu.craciunescu@upt.ro

Shape memory alloy films belonging to the NiTi-based systems were deposited on heated and unheated substrates, by magnetron sputtering in a custom made system, and their structure and composition was analyzed using electron microscopy. Several substrates were used for the depositions: glass, Cu-Zn-Al, Cu-Al-Ni and Ti-NiCu shape memory alloy ribbons and kapton. The composition of the Ti-Ni-Cu films showed limited differences, compared to the one of the target and the microstructure for the DC magnetron sputtering revealed crystallized structure with features determined on peel off samples from a Si wafer. Both inter and transcrystalline fractures were observed and related tomore » the interfacial stress developed on cooling from deposition temperature.« less

One-step aluminium-assisted crystallization of Ge epitaxy on Si by magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Ziheng, E-mail: ziheng.liu@unsw.edu.au; Hao, Xiaojing; Ho-Baillie, Anita

In this work, one-step aluminium-assisted crystallization of Ge on Si is achieved via magnetron sputtering by applying an in-situ low temperature (50 °C to 150 °C) heat treatment in between Al and Ge depositions. The effect of heat treatment on film properties and the growth mechanism of Ge epitaxy on Si are studied via X-ray diffraction, Raman and transmission electron microscopy analyses. Compared with the conventional two-step process, the one-step aluminium-assisted crystallization requires much lower thermal budget and results in pure Ge epitaxial layer, which may be suitable for use as a virtual substrate for the fabrication of III-V solar cells.

Effect of Zinc Oxide Film Deposition Position on the Characteristics of Zinc Oxide Thin Film Transistors Fabricated by Low-Temperature Magnetron Sputtering

NASA Astrophysics Data System (ADS)

Takechi, Kazushige; Nakata, Mitsuru; Eguchi, Toshimasa; Otsuki, Shigeyoshi; Yamaguchi, Hirotaka; Kaneko, Setsuo

2008-09-01

We report on the effect of zinc oxide (ZnO) film deposition position on the characteristics of ZnO thin-film transistors (TFTs) fabricated by magnetron sputtering with no intentional heating of the substrate. We evaluate the properties of ZnO (channel semiconductor) films deposited at various positions with respect to the target position. We show that the film deposition at a position off-centered from the target results in good TFT characteristics. This might be due to the fact that the off-centered deposition position is effective for suppressing the effect of energetic negative ions in the plasma.

Alfven's critical ionization velocity observed in high power impulse magnetron sputtering discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brenning, N.; Lundin, D.

2012-09-15

Azimuthally rotating dense plasma structures, spokes, have recently been detected in several high power impulse magnetron sputtering (HiPIMS) devices used for thin film deposition and surface treatment, and are thought to be important for plasma buildup, energizing of electrons, as well as cross-B transport of charged particles. In this work, the drift velocities of these spokes are shown to be strongly correlated with the critical ionization velocity, CIV, proposed by Alfven. It is proposed as the most promising approach in combining the CIV and HiPIMS research fields is to focus on the role of spokes in the process of electronmore » energization.« less

FAST TRACK COMMUNICATION: Deposition of amino-rich thin films by RF magnetron sputtering of nylon

NASA Astrophysics Data System (ADS)

Kylián, O.; Hanuš, J.; Choukourov, A.; Kousal, J.; Slavínská, D.; Biederman, H.

2009-07-01

RF magnetron sputtering of a nylon target in different gas mixtures was studied in order to evaluate the capability of this process to deposit amino-rich coatings needed in a wide range of biomedical applications. It has been demonstrated that both the deposition rate of the coatings and the surface density of primary amino groups are strongly linked with working gas mixture composition. From this point of view, a sufficiently high deposition rate as well as the highest amine efficiency reaching a NH2/C value of 18% was observed in the N2/H2 discharge, which leads to the surface exhibiting a high rate of protein adsorption.

Effect of Rapid Thermal Annealing on the Electrical Characteristics of ZnO Thin-Film Transistors

NASA Astrophysics Data System (ADS)

Remashan, Kariyadan; Hwang, Dae-Kue; Park, Seong-Ju; Jang, Jae-Hyung

2008-04-01

Thin-film transistors (TFTs) with a bottom-gate configuration were fabricated with an RF magnetron sputtered undoped zinc oxide (ZnO) channel layer and plasma-enhanced chemical vapor deposition (PECVD) grown silicon nitride as a gate dielectric. Postfabrication rapid thermal annealing (RTA) and subsequent nitrous oxide (N2O) plasma treatment were employed to improve the performance of ZnO TFTs in terms of on-current and on/off current ratio. The RTA treatment increases the on-current of the TFT significantly, but it also increases its off-current. The off-current of 2×10-8 A and on/off current ratio of 3×103 obtained after the RTA treatment were improved to 10-10 A and 105, respectively, by the subsequent N2O plasma treatment. The better device performance can be attributed to the reduction of oxygen vacancies at the top region of the channel due to oxygen incorporation from the N2O plasma. X-ray photoelectron spectroscopy (XPS) analysis of the TFT samples showed that the RTA-treated ZnO surface has more oxygen vacancies than as-deposited samples, which results in the increased drain current. The XPS study also showed that the subsequent N2O plasma treatment reduces oxygen vacancies only at the surface of ZnO so that the better off-current and on/off current ratio can be obtained.

Enhanced properties of tungsten thin films deposited with a novel HiPIMS approach

NASA Astrophysics Data System (ADS)

Velicu, Ioana-Laura; Tiron, Vasile; Porosnicu, Corneliu; Burducea, Ion; Lupu, Nicoleta; Stoian, George; Popa, Gheorghe; Munteanu, Daniel

2017-12-01

Despite the tremendous potential for industrial use of tungsten (W), very few studies have been reported so far on controlling and tailoring the properties of W thin films obtained by physical vapor deposition techniques and, even less, for those deposited by High Power Impulse Magnetron Sputtering (HiPIMS). This study presents results on the deposition process and properties characterization of nanocrystalline W thin films deposited on silicon and molybdenum substrates (100 W average sputtering power) by conventional dc magnetron sputtering (dcMS) and HiPIMS techniques. Topological, structural, mechanical and tribological properties of the deposited thin films were investigated. It was found that in HiPIMS, both deposition process and coatings properties may be optimized by using an appropriate magnetic field configuration and pulsing design. Compared to the other deposited samples, the W films grown in multi-pulse (5 × 3 μs) HiPIMS assisted by an additional magnetic field, created with a toroidal-shaped permanent magnet placed in front of the magnetron cathode, show significantly enhanced properties, such as: smoother surfaces, higher homogeneity and denser microstructure, higher hardness and Young's modulus values, better adhesion to the silicon substrate and lower coefficient of friction. Mechanical behaviour and structural changes are discussed based on plasma diagnostics results.

[Effect of vacuum deposition technology on the metal-porcelain bond strength of a new type of CO-CR ceramic and framework dental alloy].

PubMed

Wu, Jun-ling; Chao, Yong-lie; Ji, Ping; Gao, Xu

2007-10-01

To investigate the effect of a new engineering technique of vacuum deposition-plasma magnetron reactive sputter deposition technique on the metal-porcelain bond strength of a new type of Co-Cr ceramic and framework dental alloy. Before porcelain painted on the specimens, the standardized metal strips made from DA9-4 dental alloy were coated with a thin Al2O3 ceramic film by plasma magnetron reactive sputter deposition technique. The conformation, structure and thickness of the ceramic film were analyzed. The specimens for three-point bending test made from DA9-4 alloy and VMK95 porcelain were used for metal-porcelain bond strength measurement, in the same time the interface of metal-porcelain and element distribution were also observed. The flexural bonding strength of metal-porcelain of sputtering group and control group were (180.55+/-16.45) MPa and (143.80+/-24.49) MPa. The flexural bonding strength of metal-porcelain of sputtering group was higher than control group significantly through statistical analysis (P<0.01). The plasma magnetron reactive sputter deposition technique has a positive effect in improving the bonding strength of DA9-4 dental alloy and ceramic.

Engineering aspect of the microwave ionosphere nonlinear interaction experiment (MINIX) with a sounding rocket

NASA Astrophysics Data System (ADS)

Nagatomo, Makoto; Kaya, Nobuyuki; Matsumoto, Hiroshi

The Microwave Ionosphere Nonlinear Interaction Experiment (MINIX) is a sounding rocket experiment to study possible effects of strong microwave fields in case it is used for energy transmission from the Solar Power Satellite (SPS) upon the Earth's atmosphere. Its secondary objective is to develop high power microwave technology for space use. Two rocket-borne magnetrons were used to emit 2.45 GHz microwave in order to make a simulated condition of power transmission from an SPS to a ground station. Sounding of the environment radiated by microwave was conducted by the diagnostic package onboard the daughter unit which was separated slowly from the mother unit. The main design drivers of this experiment were to build such high power equipments in a standard type of sounding rocket, to keep the cost within the budget and to perform a series of experiments without complete loss of the mission. The key technology for this experiment is a rocket-borne magnetron and high voltage converter. Location of position of the daughter unit relative to the mother unit was a difficult requirement for a spin-stabilized rocket. These problems were solved by application of such a low cost commercial products as a magnetron for microwave oven and a video tape recorder and camera.

Microhardness variation and related microstructure in Al-Cu alloys prepared by HF induction melting and RF sputtering

NASA Astrophysics Data System (ADS)

Boukhris, N.; Lallouche, S.; Debili, M. Y.; Draissia, M.

2009-03-01

The materials under consideration are binary aluminium-copper alloys (10 at% to 90.3 at%Cu) produced by HF melting and RF magnetron sputtering. The resulting micro structures have been observed by standard metallographic techniques, X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. Vickers microhardness of bulk Al-Cu alloys reaches a maximum of 1800 MPa at 70.16 at%Cu. An unexpected metastable θ ' phase has been observed within aluminium grain in Al-37 at%Cu. The mechanical properties of a family of homogeneous Al{1-x}Cu{x} (0 < x < 0.92) thin films made by radiofrequency (13.56 MHz) cathodic magnetron sputtering from composite Al-Cu targets have been investigated. The as-deposited microstructures for all film compositions consisted of a mixture of the two expected face-centred-cubic (fcc) Al solid solution and tetragonal θ (Al{2}Cu) phases. The microhardness regularly increases and the grain size decreases both with copper concentration. This phenomenon of significant mechanical strengthening of aluminium by means of copper is essentially due to a combination between solid solution effects and grain size refinement. This paper reports some structural features of different Al-Cu alloys prepared by HF melting and RF magnetron on glass substrate sputtering.

Combinatorial study of low-refractive Mg-F-Si-O nano-composites deposited by magnetron co-sputtering from compound targets

NASA Astrophysics Data System (ADS)

Mertin, Stefan; Länzlinger, Tony; Sandu, Cosmin S.; Scartezzini, Jean-Louis; Muralt, Paul

2018-03-01

Deposition of nano-composite Mg-F-Si-O films on optical grade silica glass was studied employing RF magnetron co-sputtering from magnesium fluoride (MgF2) and fused silica (SiO2) targets. The aim was to obtain a stable and reliable sputtering process for optical coatings exhibiting a refractive index lower than the one of quartz glass (1.46 at 550 nm) without adding gaseous fluorine to the deposition process. The two magnetrons were installed in a confocal way at 45° off-axis with respect to a static substrate, thus creating a lateral gradient in the thin-film composition. The deposited Mg-F-Si-O coatings were structurally analysed by electron dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The obtained films consist of MgF2 nanocrystals embedded in a SiO2-rich amorphous matrix. Spectroscopic ellipsometry and spectrophotometry measurements showed that they are highly transparent exhibiting a very-low extinction coefficient k and a refractive index n in the desired range between the one of MgF2 (1.38) and SiO2 (1.46). Films with n = 1.424 and 1.435 at 550 nm were accomplished with absorption below the detection threshold.

Composite targets in HiPIMS plasmas: Correlation of in-vacuum XPS characterization and optical plasma diagnostics

NASA Astrophysics Data System (ADS)

Layes, Vincent; Monje, Sascha; Corbella, Carles; Schulz-von der Gathen, Volker; von Keudell, Achim; de los Arcos, Teresa

2017-05-01

In-vacuum characterization of magnetron targets after High Power Impulse Magnetron Sputtering (HiPIMS) has been performed by X-ray photoelectron spectroscopy (XPS). Al-Cr composite targets (circular, 50 mm diameter) mounted in two different geometries were investigated: an Al target with a small Cr disk embedded at the racetrack position and a Cr target with a small Al disk embedded at the racetrack position. The HiPIMS discharge and the target surface composition were characterized in parallel for low, intermediate, and high power conditions, thus covering both the Ar-dominated and the metal-dominated HiPIMS regimes. The HiPIMS plasma was investigated using optical emission spectroscopy and fast imaging using a CCD camera; the spatially resolved XPS surface characterization was performed after in-vacuum transfer of the magnetron target to the XPS chamber. This parallel evaluation showed that (i) target redeposition of sputtered species was markedly more effective for Cr atoms than for Al atoms; (ii) oxidation at the target racetrack was observed even though the discharge ran in pure Ar gas without O2 admixture, the oxidation depended on the discharge power and target composition; and (iii) a bright emission spot fixed on top of the inserted Cr disk appeared for high power conditions.

Tribological properties, corrosion resistance and biocompatibility of magnetron sputtered titanium-amorphous carbon coatings

NASA Astrophysics Data System (ADS)

Dhandapani, Vishnu Shankar; Subbiah, Ramesh; Thangavel, Elangovan; Arumugam, Madhankumar; Park, Kwideok; Gasem, Zuhair M.; Veeraragavan, Veeravazhuthi; Kim, Dae-Eun

2016-05-01

Amorphous carbon incorporated with titanium (a-C:Ti) was coated on 316L stainless steel (SS) by magnetron sputtering technique to attain superior tribological properties, corrosion resistance and biocompatibility. The morphology, topography and functional groups of the nanostructured a-C:Ti coatings in various concentrations were analyzed using atomic force microscopy (AFM), Raman, X-Ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Raman and XPS analyses confirmed the increase in sp2 bonds with increasing titanium content in the a-C matrix. TEM analysis confirmed the composite nature of the coating and the presence of nanostructured TiC for Ti content of 2.33 at.%. This coating showed superior tribological properties compared to the other a-C:Ti coatings. Furthermore, electrochemical corrosion studies were performed against stimulated body fluid medium in which all the a-C:Ti coatings showed improved corrosion resistance than the pure a-C coating. Preosteoblasts proliferation and viability on the specimens were tested and the results showed that a-C:Ti coatings with relatively high Ti (3.77 at.%) content had better biocompatibility. Based on the results of this work, highly durable coatings with good biocompatibility could be achieved by incorporation of optimum amount of Ti in a-C coatings deposited on SS by magnetron sputtering technique.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, S. K.; Mohan, S.; Bysakh, S.

The formation of surface oxide layer as well as compositional changes along the thickness for NiTi shape memory alloy thin films deposited by direct current magnetron sputtering at substrate temperature of 300 °C in the as-deposited condition as well as in the postannealed (at 600 °C) condition have been thoroughly studied by using secondary ion mass spectroscopy, x-ray photoelectron spectroscopy, and scanning transmission electron microscopy-energy dispersive x-ray spectroscopy techniques. Formation of titanium oxide (predominantly titanium dioxide) layer was observed in both as-deposited and postannealed NiTi films, although the oxide layer was much thinner (8 nm) in as-deposited condition. The depletionmore » of Ti and enrichment of Ni below the oxide layer in postannealed films also resulted in the formation of a graded microstructure consisting of titanium oxide, Ni{sub 3}Ti, and B2 NiTi. A uniform composition of B2 NiTi was obtained in the postannealed film only below a depth of 200–250 nm from the surface. Postannealed film also exhibited formation of a ternary silicide (Ni{sub x}Ti{sub y}Si) at the film–substrate interface, whereas no silicide was seen in the as-deposited film. The formation of silicide also caused a depletion of Ni in the film in a region ∼250–300 nm just above the film substrate interface.« less

Pulsed-Plasma Physical Vapor Deposition Approach Toward the Facile Synthesis of Multilayer and Monolayer Graphene for Anticoagulation Applications.

PubMed

Vijayaraghavan, Rajani K; Gaman, Cezar; Jose, Bincy; McCoy, Anthony P; Cafolla, Tony; McNally, Patrick J; Daniels, Stephen

2016-02-01

We demonstrate the growth of multilayer and single-layer graphene on copper foil using bipolar pulsed direct current (DC) magnetron sputtering of a graphite target in pure argon atmosphere. Single-layer graphene (SG) and few-layer graphene (FLG) films are deposited at temperatures ranging from 700 °C to 920 °C within <30 min. We find that the deposition and post-deposition annealing temperatures influence the layer thickness and quality of the graphene films formed. The films were characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and optical transmission spectroscopy techniques. Based on the above studies, a diffusion-controlled mechanism was proposed for the graphene growth. A single-step whole blood assay was used to investigate the anticoagulant activity of graphene surfaces. Platelet adhesion, activation, and morphological changes on the graphene/glass surfaces, compared to bare glass, were analyzed using fluorescence microscopy and SEM techniques. We have found significant suppression of the platelet adhesion, activation, and aggregation on the graphene-covered surfaces, compared to the bare glass, indicating the anticoagulant activity of the deposited graphene films. Our production technique represents an industrially relevant method for the growth of SG and FLG for various applications including the biomedical field.

Correlation between optical properties and chemical composition of sputter-deposited germanium oxide (GeOx) films

NASA Astrophysics Data System (ADS)

Murphy, N. R.; Grant, J. T.; Sun, L.; Jones, J. G.; Jakubiak, R.; Shutthanandan, V.; Ramana, C. V.

2014-05-01

Germanium oxide (GeOx) films were grown on (1 0 0) Si substrates by reactive Direct-Current (DC) magnetron sputter-deposition using an elemental Ge target. The effects of oxygen gas fraction, Г = O2/(Ar + O2), on the deposition rate, structure, chemical composition and optical properties of GeOx films have been investigated. The chemistry of the films exhibits an evolution from pure Ge to mixed Ge + GeO + GeO2 and then finally to GeO2 upon increasing Г from 0.00 to 1.00. Grazing incidence X-ray analysis indicates that the GeOx films grown were amorphous. The optical properties probed by spectroscopic ellipsometry indicate that the effect of Г is significant on the optical constants of the GeOx films. The measured index of refraction (n) at a wavelength (λ) of 550 nm is 4.67 for films grown without any oxygen, indicating behavior characteristic of semiconducting Ge. The transition from germanium to mixed Ge + GeO + GeO2 composition is associated with a characteristic decrease in n (λ = 550 nm) to 2.62 and occurs at Г = 0.25. Finally n drops to 1.60 for Г = 0.50-1.00, where the films become GeO2. A detailed correlation between Г, n, k and stoichiometry in DC sputtered GeOx films is presented and discussed.

Oxidizing annealing effects on VO2 films with different microstructures

NASA Astrophysics Data System (ADS)

Dou, Yan-Kun; Li, Jing-Bo; Cao, Mao-Sheng; Su, De-Zhi; Rehman, Fida; Zhang, Jia-Song; Jin, Hai-Bo

2015-08-01

Vanadium dioxide (VO2) films have been prepared by direct-current magnetron sputter deposition on m-, a-, and r-plane sapphire substrates. The obtained VO2 films display different microstructures depending on the orientation of sapphire substrates, i.e. mixed microstructure of striped grains and equiaxed grains on m-sapphire, big equiaxed grains on a-sapphire and fine-grained microstructure on r-sapphire. The VO2 films were treated by the processes of oxidation in air. The electric resistance and infrared transmittance of the oxidized films were characterized to examine performance characteristics of VO2 films with different microstructures in oxidation environment. The oxidized VO2 films on m-sapphire exhibit better electrical performance than the other two films. After air oxidization for 600 s at 450 °C, the VO2 films on m-sapphire show a resistance change of 4 orders of magnitude over the semiconductor-to-metal transition. The oxidized VO2 films on a-sapphire have the highest optical modulation efficiency in infrared region compared to other samples. The different performance characteristics of VO2 films are understood in terms of microstructures, i.e. grain size, grain shape, and oxygen vacancies. The findings reveal the correlation of microstructures and performances of VO2 films, and provide useful knowledge for the design of VO2 materials to different applications.

Stable p-i-n FAPbBr 3 devices with improved efficiency using sputtered ZnO as electron transport layer [Stable p-i-n FAPbBr 3 devices with improved efficiency using sputtered inorganic electron transport layer

DOE PAGES

Subbiah, Anand S.; Agarwal, Sumanshu; Mahuli, Neha; ...

2017-02-10

Here, radio-frequency magnetron sputtering is demonstrated as an effective tool to deposit highly crystalline thin zinc oxide (ZnO) layer directly on perovskite absorber as an electron transport layer (ETL). As an absorber, formamidinium lead tribromide (FAPbBr 3) is fabricated through a modified single-step solution process using hydrogen bromide (HBr) as an additive resulting in complete surface coverage and highly crystalline material. A planar p-i-n device architecture with spin-coated poly-(3,4-ethylenedioxythiophene):poly-styrenesulfonic acid (PEDOT:PSS) as hole transport material (HTM) and sputtered ZnO as ETL results in a short circuit current density of 9.5 mA cm -2 and an open circuit potential of 1.19more » V. Numerical simulations are performed to validate the underlying loss mechanisms. The use of phenyl C 60 butyric acid methyl ester (PCBM) interface layer between FAPbBr 3 and sputter-coated ZnO offers shielding from potential plasma-related interface damage. The modified interface results in a better device efficiency of 8.3% with an open circuit potential of 1.35 V. Such devices offer better stability under continuous illumination under ambient conditions in comparison with the conventional organic ETL (PCBM)-based devices.« less

Magnetron sputtering fabrication and photoelectric properties of WSe2 film solar cell device

NASA Astrophysics Data System (ADS)

Mao, Xu; Zou, Jianpeng; Li, Hongchao; Song, Zhengqi; He, Siru

2018-06-01

Tungsten diselenide (WSe2) films with different growing orientations exhibit diverse photoelectric properties. The WSe2 film with C-axis⊥substrate texture has been prepared and applied to thin-film solar cells. W nanofilms with a thickness of 270 nm were deposited onto the Mo bottom electrode and then heat-treated in selenium vapor to synthesize WSe2 films with a thickness of 1 μm. ZnO films were deposited onto WSe2 films to form a P-N junction and ITO films were deposited subsequently as the conductive layer. X-ray diffractometry, scanning electron microscopy and UV-vis-NIR spectro-analysis instrument were employed to analyze the phase composition, optical absorptivity and micromorphology of WSe2 films and the WSe2 solar cell device. WSe2 films exhibit excellent photoelectric performance with an optical absorption coefficient greater than 105 cm-1 across the visible spectrum. The calculated direct and indirect band gap of the WSe2 films is 1.48 eV and 1.25 eV, respectively. With the application of standard glass/Mo/WSe2/ZnO/ITO/Ag device structure, the open-circuit voltage of the battery device is 82 mV. The short-circuit current density is 2.98 mA/cm2 and the filling factor is 0.32. The photoelectric conversion efficiency of the WSe2 film solar cell device is 0.79%.

Fast Fabrication of a Stable Perovskite Solar Cell with an Ultrathin Effective Novel Inorganic Hole Transport Layer.

PubMed

Huang, Aibin; Lei, Lei; Zhu, Jingting; Yu, Yu; Liu, Yan; Yang, Songwang; Bao, Shanhu; Cao, Xun; Jin, Ping

2017-04-18

With the aim of fabricating simple, reproducible, and scalable perovskite solar cells (PSCs) with least time consumption, a novel CoO x hole transport layer (HTL) was first proposed and introduced in this work. The CoO x HTL thickness was minimized to about 10 nm with complete coverage on the FTO substrate (F-doped SnO 2 ) by direct current magnetron sputtering. The ultrathin HTL could minimize the incident light loss caused by cobalt ion absorption and reduce the carrier transport loss by shortening the transport path. Copper was incorporated into the CoO x lattice to address the low conductivity of the CoO x film and the energy-level mismatch between CoO x and the perovskite material. On the basis of cobalt-copper binary oxide (Co 1-y Cu y O x ), the highest power conversion efficiency (PCE) of about 10% was achieved, which was acceptable for mass production. Moreover, the deposition of such Co 1-y Cu y O x films takes only 2 min without size limitation of substrates. A well-functioned device based on the Co 1-y Cu y O x HTL could hence be fabricated within 100 min. Excellent stability was demonstrated as well, with over 90% of the initial PCE remaining after being stored in a dark and humid environment (relative humidity 60%) for 12 days.

Stable p-i-n FAPbBr 3 devices with improved efficiency using sputtered ZnO as electron transport layer [Stable p-i-n FAPbBr 3 devices with improved efficiency using sputtered inorganic electron transport layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subbiah, Anand S.; Agarwal, Sumanshu; Mahuli, Neha

Here, radio-frequency magnetron sputtering is demonstrated as an effective tool to deposit highly crystalline thin zinc oxide (ZnO) layer directly on perovskite absorber as an electron transport layer (ETL). As an absorber, formamidinium lead tribromide (FAPbBr 3) is fabricated through a modified single-step solution process using hydrogen bromide (HBr) as an additive resulting in complete surface coverage and highly crystalline material. A planar p-i-n device architecture with spin-coated poly-(3,4-ethylenedioxythiophene):poly-styrenesulfonic acid (PEDOT:PSS) as hole transport material (HTM) and sputtered ZnO as ETL results in a short circuit current density of 9.5 mA cm -2 and an open circuit potential of 1.19more » V. Numerical simulations are performed to validate the underlying loss mechanisms. The use of phenyl C 60 butyric acid methyl ester (PCBM) interface layer between FAPbBr 3 and sputter-coated ZnO offers shielding from potential plasma-related interface damage. The modified interface results in a better device efficiency of 8.3% with an open circuit potential of 1.35 V. Such devices offer better stability under continuous illumination under ambient conditions in comparison with the conventional organic ETL (PCBM)-based devices.« less

Negative differential resistance and resistive switching in SnO2/ZnO interface

NASA Astrophysics Data System (ADS)

Pant, Rohit; Patel, Nagabhushan; Nanda, K. K.; Krupanidhi, S. B.

2017-09-01

We report a very stable negative differential resistance (NDR) and resistive switching (RS) behavior of highly transparent thin films of the SnO2/ZnO bilayer, deposited by magnetron sputtering. When this bilayer of SnO2/ZnO was annealed at temperatures above 400 °C, ZnO diffuses into SnO2 at the threading dislocations and gaps between the grain boundaries, leading to the formation of a ZnO nanostructure surrounded by SnO2. Such a configuration forms a resonant tunneling type structure with SnO2/ZnO/SnO2…….ZnO/SnO2 interface formation. Interestingly, the heterostructure exhibits a Gunn diode-like behavior and shows NDR and RS irrespective of the voltage sweep direction, which is the characteristic of unipolar devices. A threshold voltage of ˜1.68 V and a peak-to-valley ratio of current ˜2.5 are observed for an electrode separation of 2 mm, when the bias is swept from -5 V to +5 V. It was also observed that the threshold voltage can be tuned with changing distance between the electrodes. The device shows a very stable RS with a uniform ratio of about 3.4 between the high resistive state and the low resistive state. Overall, the results demonstrate the application of SnO2/ZnO bilayer thin films in transparent electronics.

Mechanical Properties of TiTaHfNbZr High-Entropy Alloy Coatings Deposited on NiTi Shape Memory Alloy Substrates

NASA Astrophysics Data System (ADS)

Motallebzadeh, A.; Yagci, M. B.; Bedir, E.; Aksoy, C. B.; Canadinc, D.

2018-04-01

TiTaHfNbZr high-entropy alloy (HEA) thin films with thicknesses of about 750 and 1500 nm were deposited on NiTi substrates by RF magnetron sputtering using TiTaHfNbZr equimolar targets. The thorough experimental analysis on microstructure and mechanical properties of deposited films revealed that the TiTaHfNbZr films exhibited amorphous and cauliflower-like structure, where grain size and surface roughness increased concomitant with film thickness. More importantly, the current findings demonstrate that the TiTaHfNbZr HEA films with mechanical properties of the same order as those of the NiTi substrate constitute promising biomedical coatings effective in preventing Ni release.

Mechanical Properties of TiTaHfNbZr High-Entropy Alloy Coatings Deposited on NiTi Shape Memory Alloy Substrates

NASA Astrophysics Data System (ADS)

Motallebzadeh, A.; Yagci, M. B.; Bedir, E.; Aksoy, C. B.; Canadinc, D.

2018-06-01

TiTaHfNbZr high-entropy alloy (HEA) thin films with thicknesses of about 750 and 1500 nm were deposited on NiTi substrates by RF magnetron sputtering using TiTaHfNbZr equimolar targets. The thorough experimental analysis on microstructure and mechanical properties of deposited films revealed that the TiTaHfNbZr films exhibited amorphous and cauliflower-like structure, where grain size and surface roughness increased concomitant with film thickness. More importantly, the current findings demonstrate that the TiTaHfNbZr HEA films with mechanical properties of the same order as those of the NiTi substrate constitute promising biomedical coatings effective in preventing Ni release.

Bandgap-Engineered Zinc-Tin-Oxide Thin Films for Ultraviolet Sensors.

PubMed

Cheng, Tien-Hung; Chang, Sheng-Po; Chang, Shoou-Jinn

2018-07-01

Zinc-tin-oxide thin-film transistors were prepared by radio frequency magnetron co-sputtering, while an identical zinc-tin-oxide thin film was deposited simultaneously on a clear glass substrate to facilitate measurements of the optical properties. When we adjusted the deposition power of ZnO and SnO2, the bandgap of the amorphous thin film was dominated by the deposition power of SnO2. Since the thin-film transistor has obvious absorption in the ultraviolet region owing to the wide bandgap, the drain current increases with the generation of electron-hole pairs. As part of these investigations, a zinc-tin-oxide thin-film transistor has been fabricated that appears to be very promising for ultraviolet applications.

In Vitro and In Vivo Effectiveness of an Innovative Silver-Copper Nanoparticle Coating of Catheters To Prevent Methicillin-Resistant Staphylococcus aureus Infection

PubMed Central

Ballo, Myriam K. S.; Pulgarin, César; Hopf, Nancy; Berthet, Aurélie; Kiwi, John; Moreillon, Philippe; Bizzini, Alain

2016-01-01

In this study, silver/copper (Ag/Cu)-coated catheters were investigated for their efficacy in preventing methicillin-resistant Staphylococcus aureus (MRSA) infection in vitro and in vivo. Ag and Cu were sputtered (67/33% atomic ratio) on polyurethane catheters by direct-current magnetron sputtering. In vitro, Ag/Cu-coated and uncoated catheters were immersed in phosphate-buffered saline (PBS) or rat plasma and exposed to MRSA ATCC 43300 at 104 to 108 CFU/ml. In vivo, Ag/Cu-coated and uncoated catheters were placed in the jugular vein of rats. Directly after, MRSA (107 CFU/ml) was inoculated in the tail vein. Catheters were removed 48 h later and cultured. In vitro, Ag/Cu-coated catheters preincubated in PBS and exposed to 104 to 107 CFU/ml prevented the adherence of MRSA (0 to 12% colonization) compared to uncoated catheters (50 to 100% colonization; P < 0.005) and Ag/Cu-coated catheters retained their activity (0 to 20% colonization) when preincubated in rat plasma, whereas colonization of uncoated catheters increased (83 to 100%; P < 0.005). Ag/Cu-coating protection diminished with 108 CFU/ml in both PBS and plasma (50 to 100% colonization). In vivo, Ag/Cu-coated catheters reduced the incidence of catheter infection compared to uncoated catheters (57% versus 79%, respectively; P = 0.16) and bacteremia (31% versus 68%, respectively; P < 0.05). Scanning electron microscopy of explanted catheters suggests that the suboptimal activity of Ag/Cu catheters in vivo was due to the formation of a dense fibrin sheath over their surface. Ag/Cu-coated catheters thus may be able to prevent MRSA infections. Their activity might be improved by limiting plasma protein adsorption on their surfaces. PMID:27353266

Influence of Discharge Current on Phase Transition Properties of High Quality Polycrystalline VO2 Thin Film Fabricated by HiPIMS

PubMed Central

Lin, Tiegui; Wang, Jian; Liu, Gang; Wang, Langping; Wang, Xiaofeng; Zhang, Yufen

2017-01-01

To fabricate high-quality polycrystalline VO2 thin film with a metal–insulator transition (MIT) temperature less than 50 °C, high-power impulse magnetron sputtering with different discharge currents was employed in this study. The as-deposited VO2 films were characterized by a four-point probe resistivity measurement system, visible-near infrared (IR) transmittance spectra, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy. The resistivity results revealed that all the as-deposited films had a high resistance change in the phase transition process, and the MIT temperature decreased with the increased discharge current, where little deterioration in the phase transition properties, such as the resistance and transmittance changes, could be found. Additionally, XRD patterns at various temperatures exhibited that some reverse deformations that existed in the MIT process of the VO2 film, with a large amount of preferred crystalline orientations. The decrease of the MIT temperature with little deterioration on phase transition properties could be attributed to the reduction of the preferred grain orientations. PMID:28772990

Challenges/issues of NIS used in particle accelerator facilities

NASA Astrophysics Data System (ADS)

Faircloth, Dan

2013-09-01

High current, high duty cycle negative ion sources are an essential component of many high power particle accelerators. This talk gives an overview of the state-of-the-art sources used around the world. Volume, surface and charge exchange negative ion production processes are detailed. Cesiated magnetron and Penning surface plasma sources are discussed along with surface converter sources. Multicusp volume sources with filament and LaB6 cathodes are described before moving onto RF inductively coupled volume sources with internal and external antennas. The major challenges facing accelerator facilities are detailed. Beam current, source lifetime and reliability are the most pressing. The pros and cons of each source technology is discussed along with their development programs. The uncertainties and unknowns common to these sources are discussed. The dynamics of cesium surface coverage and the causes of source variability are still unknown. Minimizing beam emittance is essential to maximizing the transport of high current beams; space charge effects are very important. The basic physics of negative ion production is still not well understood, theoretical and experimental programs continue to improve this, but there are still many mysteries to be solved.

Angular distribution of hybridization in sputtered carbon thin film

NASA Astrophysics Data System (ADS)

Liu, Y.; Wang, H.; Wei, Z. C.

2017-08-01

The sp3/sp2 ratio of sputtered carbon thin film depends on the ion bombardment process and tailors the physical properties of carbon thin film. In present work, we report the angular distribution of hybridization in magnetron sputtered carbon thin film for the first time. By x-ray photoelectron spectra analyses, it is found that the sp3/sp2 ratio increases linearly with increasing the deposition angle from 0 to 90 degree, which could be attributed to the enhancement of direct knocking-out of near-surface target atoms. In addition, we also derive the sp3/sp2 ratio by simulation on complex permittivity in terahertz frequency using a modified percolation approximation tunneling model. Those derived data consist with the results from x-ray photoelectron spectroscopy.

Triple probe interrogation of spokes in a HiPIMS discharge

NASA Astrophysics Data System (ADS)

Lockwood Estrin, F.; Karkari, S. K.; Bradley, J. W.

2017-07-01

Using a triple probe situated above the racetrack and inside the magnetic trap of a magnetron, rotating spoke-like structures have been clearly identified in a single HiPIMS pulse as periodic modulations of the electron temperature T e, electron density n e, ion saturation current I isat, floating potential V f and plasma potential V p. The spokes rotate in the E  ×  B direction with a velocity of ~8.8 km s-1. Defining the spoke shape from the footprint of the ion current, they deliver to flush-mounted probes embedded in the target, each spoke can be characterised by a dense but cool leading edge (n e ~ 2.0  ×  1019 m-3, T e ~ 2.1 eV) and a relatively hotter but more rarefied trailing edge (n e ~ 1  ×  1019 m-3, T e ~ 3.9 eV). Measurements of V p show a potential hump towards the rear of the spoke, separated from regions of the highest density, with plasma potentials up to 8 V more positive than the inter-spoke regions. Azimuthal electric fields of ~1 kV m-1 associated with these structures are calculated. Transforming the triple probe time-traces to functions of the azimuthal angle θ and assuming a Gaussian radial profile for the plasma parameters, 2D spatial maps of n e, T e and V p have been constructed as well as the target ion current density J p from the embedded probes. The phase relationship between T e, V p and n e can be clearly seen using this representation with n e leading T e and V p with a phase shift between them of ~50°. Regions of maximum ion current to the target, delivered by individual spokes, coincide with the overlap of regions of high n e and T e measured above the target at a height of 15 mm. Ions created at elevated positions above the target in the observed dense region will take several micro-seconds to reach that surface, so contributing to the target ion current in the following spokes.

Control and enhancement of the oxygen storage capacity of ceria films by variation of the deposition gas atmosphere during pulsed DC magnetron sputtering

NASA Astrophysics Data System (ADS)

Eltayeb, Asmaa; Vijayaraghavan, Rajani K.; McCoy, Anthony; Venkatanarayanan, Anita; Yaremchenko, Aleksey A.; Surendran, Rajesh; McGlynn, Enda; Daniels, Stephen

2015-04-01

In this study, nanostructured ceria (CeO2) films are deposited on Si(100) and ITO coated glass substrates by pulsed DC magnetron sputtering using a CeO2 target. The influence on the films of using various gas ambients, such as a high purity Ar and a gas mixture of high purity Ar and O2, in the sputtering chamber during deposition are studied. The film compositions are studied using XPS and SIMS. These spectra show a phase transition from cubic CeO2 to hexagonal Ce2O3 due to the sputtering process. This is related to the transformation of Ce4+ to Ce3+ and indicates a chemically reduced state of CeO2 due to the formation of oxygen vacancies. TGA and electrochemical cyclic voltammetry (CV) studies show that films deposited in an Ar atmosphere have a higher oxygen storage capacity (OSC) compared to films deposited in the presence of O2. CV results specifically show a linear variation with scan rate of the anodic peak currents for both films and the double layer capacitance values for films deposited in Ar/O2 mixed and Ar atmosphere are (1.6 ± 0.2) × 10-4 F and (4.3 ± 0.5) × 10-4 F, respectively. Also, TGA data shows that Ar sputtered samples have a tendency to greater oxygen losses upon reduction compared to the films sputtered in an Ar/O2 mixed atmosphere.

Low dark current and high speed ZnO metal–semiconductor–metal photodetector on SiO{sub 2}/Si substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Çalışkan, Deniz, E-mail: dcaliskan@fen.bilkent.edu.tr; Department of Nanotechnology and Nanomedicine, Hacettepe University, 06800 Beytepe, Ankara; Bütün, Bayram

2014-10-20

ZnO thin films are deposited by radio-frequency magnetron sputtering on thermally grown SiO{sub 2} on Si substrates. Pt/Au contacts are fabricated by standard photolithography and lift-off in order to form a metal-semiconductor-metal (MSM) photodetector. The dark current of the photodetector is measured as 1 pA at 100 V bias, corresponding to 100 pA/cm{sup 2} current density. Spectral photoresponse measurement showed the usual spectral behavior and 0.35 A/W responsivity at a 100 V bias. The rise and fall times for the photocurrent are measured as 22 ps and 8 ns, respectively, which are the lowest values to date. Scanning electron microscope image shows high aspect ratio andmore » dense grains indicating high surface area. Low dark current density and high speed response are attributed to high number of recombination centers due to film morphology, deducing from photoluminescence measurements. These results show that as deposited ZnO thin film MSM photodetectors can be used for the applications needed for low light level detection and fast operation.« less

Development of nanostructured PVD coatings for total knee replacement joints using HIPIMS

NASA Astrophysics Data System (ADS)

Sugumaran, Arunprabhu A.

The aim of this study was to develop thin film coatings for total knee replacement joints using high power impulse magnetron sputtering (HIPIMS). An industrial size four cathode magnetron sputtering system equipped with direct current (DC) and HIPIMS power supplies was used for this purpose. Initially, Plasma diagnostics were carried out using optical emission spectroscopy (OES) while sputtering Ti target in Ar + N2 atmosphere by utilizing various HIP IMS/conventional DCMS (henceforth UBM) source combinations by varying the process parameters such as coil current and N2 flow. Then, single layer titanium nitride (TiN) coating was deposited by varying the degree of HIPIMS utilisation and the process parameters such as bias voltage and coil current to thoroughly understand the effect of degree of HIPIMS utilisation on the microstructure, residual stress, texture, mechanical, tribological and corrosion properties of such coatings. The degree of HIPIMS utilisation was altered by increasing the number of HIPIMS targets used for the deposition. Four different source combinations were used for this purpose, as follows: 4 cathodes in conventional DCMS mode to deposit pure UBM coating, 1 HIPIMS + 3UBM and 2HIPIMS + 2UBM cathodes to deposit combined HIPIMS/UBM coatings and 2HIPIMS cathodes to deposit pure HIPIMS coatings. TiN/NbN, TiCN/NbCN and CrN/NbN multilayer coatings were deposited on CoCr alloy test buttons along with other (HSS, SS and Si) substrates since our intended application is on total knee replacement joints made of CoCr alloy. The knowledge gained by investigating the TiN (Ar + N[2]) plasma and the properties of TiN was used to determine the process parameters for depositing the multilayer coatings. X- ray diffraction (XRD) technique was used for calculating the texture, residual stress and bilayer thickness of the coatings. Nanoindentation method was used to determine the nano hardness of the coatings. The adhesion strength of the coatings was estimated by scratch and Rockwell indentation tests. Pin on disc method was used for the tribological studies such as coefficient of friction and coefficient of wear. Surface roughness measurements were carried out using a surface profiler. Microstructural characterisation of the coatings was carried out using scanning electron microscope (SEM) and transmission electron microscope (TEM). Potentiodynamic polarisation method was utilised to study the corrosion performance of the coatings. Raman spectroscopy was used to study the constituents of the corrosion products and evaluate the corrosion damage. OES measurements revealed that the degree of metal ions (Ti[1+]) increased with increasing degree of HIPIMS utilisation. The hardness, tribological and corrosion properties of TiN coatings improved with increasing degree of HIPIMS utilisation. TiN and multilayer coatings deposited by HIPIMS exhibited a smooth columnar microstructure without any voided region along the column boundaries. TiN/NbN, TiCN/NbCN and CrN/NbN multilayer coatings deposited on CoCr alloy, HSS and SS test buttons exhibited superior mechanical, tribological and corrosion properties as compared to the underlying substrate.

Characterization on RF magnetron sputtered niobium pentoxide thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Usha, N.; Sivakumar, R., E-mail: krsivakumar1979@yahoo.com; Sanjeeviraja, C.

2014-10-15

Niobium pentoxide (Nb{sub 2}O{sub 5}) thin films with amorphous nature were deposited on microscopic glass substrates at 100°C by rf magnetron sputtering technique. The effect of rf power on the structural, morphological, optical, and vibrational properties of Nb{sub 2}O{sub 5} films have been investigated. Optical study shows the maximum average transmittance of about 87% and the optical energy band gap (indirect allowed) changes between 3.70 eV and 3.47 eV. AFM result indicates the smooth surface nature of the samples. Photoluminescence measurement showed the better optical quality of the deposited films. Raman spectra show the LO-TO splitting of Nb-O stretching ofmore » Nb{sub 2}O{sub 5} films.« less

Effect of ZnO buffer layer on phase transition properties of vanadium dioxide thin films

NASA Astrophysics Data System (ADS)

Zhu, Huiqun; Li, Lekang; Li, Chunbo

2016-03-01

VO2 thin films were prepared on ZnO buffer layers by DC magnetron sputtering at room temperature using vanadium target and post annealing at 400 °C. The ZnO buffer layers with different thickness deposited on glass substrates by magnetron sputtering have a high visible and near infrared optical transmittance. The electrical resistivity and the phase transition properties of the VO2/ZnO composite thin films in terms of temperature were investigated. The results showed that the resistivity variation of VO2 thin film with ZnO buffer layer deposited for 35 min was 16 KΩ-cm. The VO2/ZnO composite thin films exhibit a reversible semiconductor-metal phase transition at 48 °C.

Reversible superhydrophilicity and hydrophobicity switching of V2O5 thin films deposited by magnetron sputtering

NASA Astrophysics Data System (ADS)

Zhang, Chunzi; Peng, Zhiguang; Cui, Xiaoyu; Neil, Eric; Li, Yuanshi; Kasap, Safa; Yang, Qiaoqin

2018-03-01

V2O5 thin films are well-known "smart" materials due to their reversible wettability under UV irradiation and dark storage. Their surfaces are usually hydrophobic and turn into hydrophilic under UV irradiation. However, the V2O5 thin films deposited by magnetron sputtering in present work are superhydrophilic and turned into hydrophobic after days' of storage in air. This change can be recovered by heating. The effects of many factors including surface roughness, irradiation from visible light, UV, & X-ray, and storage in air & vacuum on the reversible switching of wettability were investigated. The results show that air absorption is the main factor causing the film surface change from superhydrophilicity to hydrophobicity.

Investigation of optical properties of ternary Zn-Ti-O thin films prepared by magnetron reactive co-sputtering

NASA Astrophysics Data System (ADS)

Netrvalová, Marie; Novák, Petr; Šutta, Pavol; Medlín, Rostislav

2017-11-01

Zn-Ti-O thin films with different concentrations of titanium were deposited by reactive magnetron co-sputtering in a reactive Ar/O2 atmosphere from zinc and titanium targets. It was found that with increasing Ti content the structure of the films gradually changes from a fully crystalline pure ZnO wurtzite structure with a strongly preferred columnar orientation to an amorphous Zn-Ti-O material with 12.5 at.% Ti. The optical parameters (spectral refractive index and extinction coefficient, optical band gap) and thickness of the films were analysed by the combined evaluation of ellipsometric measurements and measurements of transmittance on a UV-vis spectrophotometer. For evaluation of optical parameters was used Cody-Lorentz dispersion model.

Enhanced tunability of magnetron sputtered Ba0.5Sr0.5TiO3 thin films on c-plane sapphire substrates

NASA Astrophysics Data System (ADS)

Fardin, E. A.; Holland, A. S.; Ghorbani, K.; Reichart, P.

2006-07-01

Thin films of Ba0.5Sr0.5TiO3 (BST) were deposited on c-plane (0001) sapphire by rf magnetron sputtering and investigated by complementary materials analysis methods. Microwave properties of the films, including tunability and Q factor were measured from 1to20GHz by patterning interdigital capacitors (IDCs) on the film surface. The tunability is correlated with texture, strain, and grain size in the deposited films. An enhanced capacitance tunability of 56% at a bias field of 200kV/cm and total device Q of more than 15 (up to 20GHz) were achieved following postdeposition annealing at 900°C.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Satyendra Kumar; Tripathi, Shweta; Hazra, Purnima

2016-05-06

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 inmore » optoelectronic and photonic devices.« less

Particle visualization in high-power impulse magnetron sputtering. II. Absolute density dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Britun, Nikolay, E-mail: nikolay.britun@umons.ac.be; Palmucci, Maria; Konstantinidis, Stephanos

2015-04-28

Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. The present, second, paper of the study is related to the discharge characterization in terms of the absolute density of species using resonant absorption spectroscopy. The results on the time-resolved density evolution of the neutral and singly-ionized Ti ground state atoms as well as the metastable Ti and Ar atoms during the discharge on- and off-time are presented. Among the others, the questions related to the inversion of population of the Ti energy sublevels, as well as to re-normalization of the two-dimensional density maps in terms ofmore » the absolute density of species, are stressed.« less

Particle visualization in high-power impulse magnetron sputtering. I. 2D density mapping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Britun, Nikolay, E-mail: nikolay.britun@umons.ac.be; Palmucci, Maria; Konstantinidis, Stephanos

2015-04-28

Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. This paper deals with two-dimensional density mapping in the discharge volume obtained by laser-induced fluorescence imaging. The time-resolved density evolution of Ti neutrals, singly ionized Ti atoms (Ti{sup +}), and Ar metastable atoms (Ar{sup met}) in the area above the sputtered cathode is mapped for the first time in this type of discharges. The energetic characteristics of the discharge species are additionally studied by Doppler-shift laser-induced fluorescence imaging. The questions related to the propagation of both the neutral and ionized discharge particles, as well as to theirmore » spatial density distributions, are discussed.« less

FAST TRACK COMMUNICATION: Ferroelectric properties and dielectric responses of multiferroic BiFeO3 films grown by RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Qi, Xiaoding; Tsai, Po-Chou; Chen, Yi-Chun; Ko, Cheng-Hung; Huang, Jung-Chun-Andrew; Chen, In-Gann

2008-12-01

Multiferroic BiFeO3 films have been grown on LaNiO3-x/SrTiO3 and Pt/Si substrates by RF magnetron sputtering. The films showed fully saturated ferroelectric hysteresis loops with large remanent polarization of 64 µC cm-2, suitable for most device applications. Piezoresponse force microscopy confirmed that the films were electrically writable. In addition to the high-frequency intrinsic dielectric loss of epitaxial films, the Argand diagram also revealed low-frequency contributions from both dc conductivity and interfacial polarization at electrodes. For polycrystalline films on Pt/Si, the dominant contribution to dielectric loss was space charge polarization at grain boundaries.

Effect of sputtering power on MgF2 thin films deposited by sputtering technique under fluorine trapping

NASA Astrophysics Data System (ADS)

De, Rajnarayan; Haque, S. Maidul; Tripathi, S.; Prathap, C.; Rao, K. Divakar; Sahoo, N. K.

2016-05-01

A non-conventional magnetron sputtering technique was explored to deposit magnesium fluoride thin films using the concept of fluorine gas trapping without the introduction of additional fluorine gas flow inside the chamber. The effect of magnetron power from 50 W to 250 W has been explored on structural, optical and physical properties of the samples. Polycrystalline nature with tetragonal crystallinity of the films has been confirmed by GIXRD measurements along with thickness dependency. Monotonic increase of attenuation coefficient (k) with RF power has been explained in terms of target compound dissociation probability. In conclusion, with fluorine trapping method, the samples deposited at lower RF powers (<100 W) are found to be more suitable for optical applications.

ION MAGNETRON

DOEpatents

Gow, J.D.; Layman, R.W.

1962-10-31

A magnetohydrodynamic device or plasma generator of the ion magnetron class is described wherein a long central electrode is disposed along the axis of an evacuated cylinder. A radial electric field and an axial magnetic field are provided between the cylsnder and the electrode, forming a plasma trapping and heating region. For maximum effectiveness, neutral particles from the cylinder wall must be prevented from entering such region This is effected by forming a cylindrical sheath of electrons near the cylinder wall for ionizing undesired neutral particles, which are then trapped and removed by the magnetic field. An annular filament at one end of the device provides the electrons, which follow the axial magnetic field to a reflecting electrode at the opposite end of the device. (AEC)

Magnetic dipole discharges. II. Cathode and anode spot discharges and probe diagnostics

NASA Astrophysics Data System (ADS)

Stenzel, R. L.; Urrutia, J. M.; Ionita, C.; Schrittwieser, R.

2013-08-01

The high current regime of a magnetron-type discharge has been investigated. The discharge uses a permanent magnet as a cold cathode which emits secondary electrons while the chamber wall or a grounded electrode serves as the anode. As the discharge voltage is increased, the magnet develops cathode spots, which are short duration arcs that provide copious electrons to increase the discharge current dramatically. Short (1 μs), high current (200 A) and high voltage (750 V) discharge pulses are produced in a relaxation instability between the plasma and a charging capacitor. Spots are also observed on a negatively biased plane Langmuir probe. The probe current pulses are as large as those on the magnet, implying that the high discharge current does not depend on the cathode surface area but on the properties of the spots. The fast current pulses produce large inductive voltages, which can reverse the electrical polarity of the magnet and temporarily operate it as an anode. The discharge current may also oscillate at the frequency determined by the charging capacitor and the discharge circuit inductance. Each half cycle of high-current current pulses exhibits a fast (≃10 ns) current rise when a spot is formed. It induces high frequency (10-100 MHz) transients and ringing oscillations in probes and current circuits. Most probes behave like unmatched antennas for the electromagnetic pulses of spot discharges. Examples are shown to distinguish the source of oscillations and some rf characteristics of Langmuir probes.

"CHON" particles: The interstellar component of cometary dust

NASA Technical Reports Server (NTRS)

Lien, David J.

1998-01-01

Interstellar dust is characterized by strong absorption in the ultraviolet and the mid-IR. Current models of interstellar dust are based on three chemically distinct components: a form of carbon (usually graphite), a silicate, and a blend of polycyclic aromatic hydrocarbons or other carbonaceous material. Previous work using effective medium theories to understand the optical properties of cometary dust suggested that an amalgam of materials could reproduce the observed interstellar and cometary dust features. Recently, Lawler and Brownlee (1992) re-analyzed the PIA and PUMA-1 data sets from the Giotto flyby of P/Halley and discovered that the so-called "CHON" particles were actually composed of a blend of carbon-bearing and silicon-bearing materials. Based on effective medium theories, the absorption spectrum of such a material would display the spectral features of each of the components - strong UV absorption from the carbonaceous component and strong absorption in the IR from the silicate component. To test this idea, vapor-deposited samples were created using two different deposition techniques: sputtering with an argon RF magnetron and deposition from an argon plasma torch. Two different compositions were tested: a blend of graphite and silica in a 7:1 ratio and an amalgam of materials whose approximate composition matches the "CHON"-silicate abundances for the uncompressed PIA data set of Lawler and Brownlee: graphite, iron oxide, magnesium oxide, ammonium sulfate, calcium carbonate, and silica in mass ratios of 6:4.3:4:2.2:1:9. The samples were finely ground and pressed into 2" diameter disks using a 40 ton press. In all, four different experiments were performed: one with each of the compositions (C:SiO and "CHON") in both the RF magnetron and the plasma torch chambers. The RF magnetron created a uniform dark thin film on the substrate surface, and the plasma torch created a coating of small (<100 micron) diameter grey particles. The spectra of all four samples show a strong, broad absorption feature at around 220 nm as well as a strong but narrower absorption peak near 10 microns. The RF magnetron sputtered samples showed some sub-structure in the UV, and the peak of the absorption was shifted toward longer wavelengths. The UV absorption in the plasma torch deposited samples have no sub-structure, and the peak absorption is very near 220 nm. Strong absorption near 9 microns is seen in the spectra from both sample preparation techniques, and is consistent with the IR spectra of some terrestrial silicates. Other features, particularly at 6.2 and 8.6 microns, are seen in the interstellar medium. A strong feature near 2 microns is due to absorbed water in the sample. Based on the results of these experiments, there is evidence that a material with a composition similar to that detected in "CHON" particles in the coma of P/Halley have a spectral signature which reproduces the main absorption features of interstellar dust. This suggests that the "CHON" particles could be the interstellar component of cometary dust.

Perpendicular magnetic anisotropy in Mn{sub 2}CoAl thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, N. Y.; Zhang, Y. Q.; Che, W. R.

Heusler compound Mn{sub 2}CoAl (MCA) is attracting more attentions due to many novel properties, such as high resistance, semiconducting behavior and suggestion as a spin-gapless material with a low magnetic moment. In this work, Mn{sub 2}CoAl epitaxial thin film was prepared on MgO(100) substrate by magnetron sputtering. The transport property of the film exhibits a semiconducting-like behavior. Moreover, our research reveals that perpendicular magnetic anisotropy (PMA) can be induced in very thin Mn{sub 2}CoAl films resulting from Mn-O and Co-O bonding at Mn{sub 2}CoAl/MgO interface, which coincides with a recent theoretical prediction. PMA and low saturation magnetic moment could leadmore » to large spin-transfer torque with low current density in principle, and thus our work may bring some unanticipated Heusler compounds into spintronics topics such as the domain wall motion and the current-induced magnetization reversal.« less

Evaluation of double-layer density modulated Si thin films as Li-ion battery anodes

NASA Astrophysics Data System (ADS)

Taha Demirkan, Muhammed; Yurukcu, Mesut; Dursun, Burcu; Demir-Cakan, Rezan; Karabacak, Tansel

2017-10-01

Double-layer density modulated silicon thin films which contain alternating low and high density Si film layers were fabricated by magnetron sputtering. Two different samples consisting of alternating layers of high-density/low-density and low-density/high-density Si thin film layers were investigated as anode electrodes in Li-ion batteries. Si thin film in which the terminating layer at the top is low density Si layer-quoted as low-density/high-density film (LD/HD)- exhibits better performance than Si thin film that has high density layer at the top, -quoted as high-density/low-density (HD/LD). A highly stabilized cycling performance with the specific charge capacities of 2000 mAh g-1 at the 150th cycle at C/2 current density, and 1200 mAh g-1 at the 240th cycle at 10 C current density were observed for the LD/HD Si anode in the presence of fluoroethylene carbonate (FEC) electrolyte additive.

Experimental Investigation of Electron Cloud Containment in a Nonuniform Magnetic Field

NASA Technical Reports Server (NTRS)

Eninger, J. E.

1974-01-01

Dense clouds of electrons were generated and studied in an axisymmetric, nonuniform magnetic field created by a short solenoid. The operation of the experiment was similar to that of a low-pressure (approximately 0.000001 Torr) magnetron discharge. Discharge current characteristics are presented as a function of pressure, magnetic field strength, voltage, and cathode end-plate location. The rotation of the electron cloud is determined from the frequency of diocotron waves. In the space charge saturated regime of operation, the cloud is found to rotate as a solid body with frequency close to V sub a/phi sub a where V sub a is the anode voltage and phi suba is the total magnetic flux. This result indicates that, in regions where electrons are present, the magnetic field lines are electrostatic equipotentials (E bar, B bar = 0). Equilibrium electron density distributions suggested by this conditions are integrated with respect to total ionizing power and are found consistent with measured discharge currents.

Self-consistent simulation of an electron beam for a new autoresonant x-ray generator based on TE 102 rectangular mode

NASA Astrophysics Data System (ADS)

Dugar-Zhabon, V. D.; Orozco, E. A.; Herrera, A. M.

2016-02-01

The space cyclotron autoresonance interaction of an electron beam with microwaves of TE 102 rectangular mode is simulated. It is shown that in these conditions the beam electrons can achieve energies which are sufficient to generate hard x-rays. The physical model consists of a rectangular cavity fed by a magnetron oscillator through a waveguide with a ferrite isolator, an iris window and a system of dc current coils which generates an axially symmetric magnetic field. The 3D magnetic field profile is that which maintains the electron beam in the space autoresonance regime. To simulate the beam dynamics, a full self-consistent electromagnetic particle-in-cell code is developed. It is shown that the injected 12keV electron beam of 0.5A current is accelerated to energy of 225keV at a distance of an order of 17cm by 2.45GHz standing microwave field with amplitude of 14kV/cm.

Magnetic Effects in a Moderate-Temperature, High-Beta, Toroidal Plasma Device

NASA Astrophysics Data System (ADS)

Edwards, W. F.; Singh, A. K.; Held, E. D.

2011-10-01

A small toroidal machine (STOR-1M; minor radius 4.5 cm), on loan from the University of Saskatchewan, has been modified to operate at hydrogen ionization levels ~0.1%, beta values between 0.1 and 1, electron number density ~5x1016/m3, temperature ~5 eV, and applied toroidal magnetic field ~20 gauss. Plasma is generated using magnetron-produced microwaves. Langmuir and Hall probes determine radial profiles of electron number density, temperature, and magnetic field. For most values of the externally-applied magnetic field, the internal field is the same with or without plasma, however, in a narrow window of B, diamagnetism and other effects are present. The effect is observed with no externally induced current; plasma currents are self generated through some sort of relaxation process. Beta and radius conditions correlate well with similar magnetic structures in the laboratory (eg., plasma focus, Z pinch) and in space (eg., Venus flux ropes, solar coronal loops).

The influence of superimposed DC current on electrical and spectroscopic characteristics of HiPIMS discharge

NASA Astrophysics Data System (ADS)

Zuo, Xiao; Chen, Rende; Liu, Jingzhou; Ke, Peiling; Wang, Aiying

2018-01-01

The electrical characteristics and spectroscopic properties have been comprehensively investigated in a DC superimposed high power impulse magnetron sputtering (DC-HiPIMS) deposition system in this paper. The influence of superimposed DC current on the variation of target and substrate current waveforms, active species and electron temperatures with pulse voltages are focused. The peak target currents in DC-HiPIMS are lower than in HiPIMS. The time scales of the two main discharge processes like ionization and gas rarefaction in DC-HiPIMS are analyzed. When the pulse voltage is higher than 600 V, the gas rarefaction effect becomes apparent. Overall, the ionization process is found to be dominant in the initial ˜100 μs during each pulse. The active species of Ar and Cr in DC-HiPIMS are higher than in HiPIMS unless that the pulse voltage reaches 900 V. However, the ionization degree in HiPIMS exceeds that in DC-HiPIMS at around 600 V. The electron temperature calculated by modified Boltzmann plot method based on corona model has a precipitous increase from 0.87 to 25.0 eV in HiPIMS, but varies mildly after the introduction of the superimposed DC current. Additionally, the current from plasma flowing to the substrate is improved when a DC current is superimposed with HiPIMS.

Wear Behavior of Low-Cost, Lightweight TiC/Ti-6Al-4V Composite Under Fretting: Effectiveness of Solid-Film Lubricant Counterparts

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Street, Kenneth W., Jr.; Sanders, Jeffrey H.; Hager, Carl H., Jr.; Zabinski, Jeffrey S.; VanderWal, Randall L.; Andrews, Rodney; Lerch, Bradley A.

2007-01-01

The wear behavior of low-cost, lightweight 10-wt% TiC-particulate-reinforced Ti-6Al-4V matrix composite (TiC/Ti- 6Al-4V) was examined under fretting at 296, 423, and 523 K in air. Bare 10-wt% TiC/Ti-6Al-4V hemispherical pins were used in contact with dispersed multiwalled carbon nanotubes (MWNTs), magnetron-sputtered diamondlike carbon/chromium (DLC/Cr), magnetron-sputtered graphite-like carbon/chromium (GLC/Cr), and magnetron-sputtered molybdenum disulphide/titanium (MoS2/Ti) deposited on Ti-6Al-4V, Ti-48Al-2Cr-2Nb, and nickel-based superalloy 718. When TiC/Ti-6Al-4V was brought into contact with bare Ti-6Al-4V, bare Ti-48Al-2Cr-2Nb, and bare nickel-based superalloy 718, strong adhesion, severe galling, and severe wear occurred. However, when TiC/Ti-6Al-4V was brought into contact with MWNT, DLC/Cr, GLC/Cr, and MoS2/Ti coatings, no galling occurred in the contact, and relatively minor wear was observed regardless of the coating. All the solid-film lubricants were effective from 296 to 523 K, but the effectiveness of the MWNT, DLC/Cr, GLC/Cr, and MoS2/Ti coatings decreased as temperature increased.

Structural characterization of precious-mean quasiperiodic Mo/V single-crystal superlattices grown by dual-target magnetron sputtering

NASA Astrophysics Data System (ADS)

Birch, J.; Severin, M.; Wahlström, U.; Yamamoto, Y.; Radnoczi, G.; Riklund, R.; Sundgren, J.-E.; Wallenberg, L. R.

1990-05-01

A class of quasiperiodic superlattice structures, which can be generated by the concurrent inflation rule A-->AmB and B-->A (where m=positive integer), has been studied both theoretically and experimentally. Given that the ratios between the thicknesses of the two superlattice building blocks, A and B, are chosen to be γ(m)=[m+(m2+4)1/2]/2 (known as the ``precious means''), then the x-ray- and electron-diffraction peak positions are analytically found to be located at the wave vectors q=2πΛ-1r[γ(m)]k, where r and k are integers and Λ is an average superlattice wavelength. The analytically obtained results have been compared to experimental results from single-crystalline Mo/V superlattice structures, generated with m=1, 2, and 3. The superlattices were grown by dual-target dc-magnetron sputtering on MgO(001) substrates kept at 700 °C. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) showed that the analytical model mentioned above predicts the peak positions of the experimental XRD and SAED spectra with a very high accuracy. Furthermore, numerical calculations of the diffraction intensities based on a kinematical model of diffraction showed good agreement with the experimental data for all three cases. In addition to a direct verification of the quasiperiodic modulation, both conventional and high-resolution cross-sectional transmission electron microscopy (XTEM) showed that the superlattices are of high crystalline quality with sharp interfaces. Based on lattice resolution images, the width of the interfaces was determined to be less than two (002) lattice-plane spacings (~=0.31 nm).

RBS, XRR and optical reflectivity measurements of Ti-TiO{sub 2} thin films deposited by magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drogowska, K.; Institute of Materials Science, Technische Universitaet Darmstadt, Petersenstrasse 23, 64287 Darmstadt; Tarnawski, Z., E-mail: tarnawsk@agh.edu.pl

2012-02-15

Highlights: Black-Right-Pointing-Pointer The single-, bi- and tri-layered films of Ti-TiO{sub 2} deposited onto Si(1 1 1) substrates. Black-Right-Pointing-Pointer Three methods RBS, XRR, optical reflectometer were used. Black-Right-Pointing-Pointer The real thickness of each layer was smaller than 50 nm. Black-Right-Pointing-Pointer Ti and TiO{sub 2} film-densities were slightly lower than the corresponding bulk values. -- Abstract: Single-, bi- and tri-layered films of Ti-TiO{sub 2} system were deposited by d.c. pulsed magnetron sputtering from metallic Ti target in an inert Ar or reactive Ar + O{sub 2} atmosphere. The nominal thickness of each layer was 50 nm. The chemical composition and its depthmore » profile were determined by Rutherford backscattering spectroscopy (RBS). Crystallographic structure was analysed by means of X-ray diffraction (XRD) at glancing incidence. X-ray reflectometry (XRR) was used as a complementary method for the film thickness and density evaluation. Modelling of the optical reflectivity spectra of Ti-TiO{sub 2} thin films deposited onto Si(1 1 1) substrates provided an independent estimate of the layer thickness. The combined analysis of RBS, XRR and reflectivity spectra indicated the real thickness of each layer less than 50 nm with TiO{sub 2} film density slightly lower than the corresponding bulk value. Scanning Electron Microscopy (SEM) cross-sectional images revealed the columnar growth of TiO{sub 2} layers. Thickness estimated directly from SEM studies was found to be in a good agreement with the results of RBS, XRR and reflectivity spectra.« less

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

Synthesis and characterization of delafossite thin films by reactive RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Asmat Uceda, Martin Antonio

This work presents a comparative study on optical and electrical properties of CuAlO2 thin films on sapphire (0001) substrates deposited with two different growth conditions using reactive RF-magnetron sputtering technique from metallic Cu and Al targets. CuAlO2 is a very promising material for transparent electronic applications, it is intended that comparison of results obtained from both approaches, could lead to optimization and control of the physical properties of this material, namely its electrical conductivity and optical transmittance. All samples were heat treated at 1100°C using rapid thermal annealing with varying time and rate of cooling. The effect of sputtering conditions and different annealing time on phase formation and evolution is studied with X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is found that for most of the samples CuAlO2 phase is formed after 60 min of annealing time, but secondary phases were also present that depend on the deposition conditions. However, pure CuAlO2 phase was obtained for annealed CuO on sapphire films with annealing time of 60 min. The optical properties obtained from UV-Visible spectroscopic measurement reveals indirect and direct optical band gaps for CuAlO2 films and were found to be 2.58 and 3.72 eV respectively. The films show a transmittance of about 60% in the visible range. Hall effect measurements indicate p-type conductivity. Van der Pauw technique was used to measure resistivity of the samples. The highest electrical conductivity and charge carrier concentration obtained were of 1.01x10-1S.cm -1 and 3.63 x1018 cm-3 respectively.

Design and Fabrication of the Second-Generation KID-Based Light Detectors of CALDER

NASA Astrophysics Data System (ADS)

Colantoni, I.; Cardani, L.; Casali, N.; Cruciani, A.; Bellini, F.; Castellano, M. G.; Cosmelli, C.; D'Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

2018-04-01

The goal of the cryogenic wide-area light detectors with excellent resolution project is the development of light detectors with large active area and noise energy resolution smaller than 20 eV RMS using phonon-mediated kinetic inductance detectors (KIDs). The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double readout of the light and the heat released by particles interacting in the bolometers. In this work we present the fabrication process, starting from the silicon wafer arriving to the single chip. In the first part of the project, we designed and fabricated KID detectors using aluminum. Detectors are designed by means of state-of-the-art software for electromagnetic analysis (SONNET). The Al thin films (40 nm) are evaporated on high-quality, high-resistivity (> 10 kΩ cm) Si(100) substrates using an electron beam evaporator in a HV chamber. Detectors are patterned in direct-write mode, using electron beam lithography (EBL), positive tone resist poly-methyl methacrylate and lift-off process. Finally, the chip is diced into 20 × 20 mm2 chips and assembled in a holder OFHC (oxygen-free high conductivity) copper using PTFE support. To increase the energy resolution of our detectors, we are changing the superconductor to sub-stoichiometric TiN (TiN x ) deposited by means of DC magnetron sputtering. We are optimizing its deposition by means of DC magnetron reactive sputtering. For this kind of material, the fabrication process is subtractive and consists of EBL patterning through negative tone resist AR-N 7700 and deep reactive ion etching. Critical temperature of TiN x samples was measured in a dedicated cryostat.

Enhancement of the electrical characteristics of thin-film transistors with indium-zinc-tin oxide/Ag/indium-zinc-tin oxide multilayer electrodes

NASA Astrophysics Data System (ADS)

Oh, Dohyun; Yun, Dong Yeol; Cho, Woon-Jo; Kim, Tae Whan

2014-08-01

Transparent indium-zinc-tin oxide (IZTO)-based thin-film transistors (TFTs) with IZTO/Ag/IZTO multilayer electrodes were fabricated on glass substrates using a tilted dual-target radio-frequency magnetron sputtering system. The IZTO TFTs with IZTO/Ag/IZTO multilayer electrodes exhibited a high optical transmittance in a visible region. The threshold voltage, the mobility, and the on/off-current ratio of the TFTs with IZTO/Ag/IZTO multilayer electrodes were enhanced in comparison with those of the TFTs with ITO electrodes. The source/drain contact resistance of the IZTO TFTs with IZTO/Ag/IZTO multilayer electrodes was smaller than that of the IZTO TFTs with ITO electrodes, resulting in enhancement of their electrical characteristics.

Fabrication and investigation of photosensitive MoOx/n-CdTe heterojunctions

NASA Astrophysics Data System (ADS)

Solovan, M. M.; Gavaleshko, N. M.; Brus, V. V.; Mostovyi, A. I.; Maryanchuk, P. D.; Tresso, E.

2016-10-01

MoOx/n-CdTe photosensitive heterostructures were prepared by the deposition of molybdenum oxide thin films onto n-type single-crystal CdTe substrates by DC reactive magnetron sputtering. The obtained heterojunctions possessed sharply defined rectifying properties with the rectification ration RR ˜ 106. The temperature dependences of the height of the potential barrier and series resistance of the MoOx/CdTe heterojunctions were investigated. The dominating current transport mechanisms through the heterojunctions were determined at forward and reverse biases. The analysis of capacitance-voltage (C-V) characteristics, measured at different frequencies of the small amplitude AC signal and corrected by the effect of the series resistance, provided evidence of the presence of electrically charged interface states, which significantly affect the measured capacitance.

Cr/B 4C multilayer mirrors: Study of interfaces and X-ray reflectance

DOE PAGES

Burcklen, C.; Soufli, R.; Gullikson, E.; ...

2016-03-24

Here, we present an experimental study of the effect of layer interfaces on the x-ray reflectance in Cr/B 4C multilayer interference coatings with layer thicknesses ranging from 0.7 nm to 5.4 nm. The multilayers were deposited by magnetron sputtering and by ion beam sputtering. Grazing incidence x-ray reflectometry, soft x-ray reflectometry, and transmission electron microscopy reveal asymmetric multilayer structures with a larger B 4C-on-Cr interface, which we modeled with a 1–1.5 nm thick interfacial layer. Reflectance measurements in the vicinity of the Cr L 2,3 absorption edge demonstrate fine structure that is not predicted by simulations using the currently tabulatedmore » refractive index (optical constants) values for Cr.« less