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Sample records for dioxide thin film

  1. Cathodic electrodeposition of nanocrystalline titanium dioxide thin films

    SciTech Connect

    Natarajan, C.; Nogami, G.

    1996-05-01

    A new technique for depositing nanocrystalline titanium dioxide thin films on electronically conducting glass was developed. This technique is a two-stage process: (i) cathodic electrodeposition of titanium oxyhydroxide gel film from aqueous solution containing a Ti precursor and (ii) subsequent heat-treatment of this gel film results in the formation of titanium dioxide film. The deposition potential may have a considerable effect on the formation of nanocrystalline film. The nanocrystalline titanium dioxide film shows reversible electrochromism in lithium-ion-containing organic electrolyte. The coloration and bleaching throughout the visible and near-IR range can be switched on and off within a few seconds.

  2. Metalizable Polymer Thin Films in Supercritical Carbon Dioxide

    SciTech Connect

    Koga,T.; Jerome, J.; Rafailovich, M.; Sokolov, J.; Gordon, C.

    2005-01-01

    We report an environmentally 'green' method to improve adhesion at a polymer/metal interface by using supercritical carbon dioxide (scCO 2 ). Spun-cast polystyrene (PS) and poly(methyl methacrylate) (PMMA) thin films on cleaned Si wafers were used for this study. Film thicknesses of both polymer films were prepared in the range of 100 Angstroms to 1600 Angstroms. We exposed the films to scCO 2 in the pressure-temperature (P-T) range corresponding to the density-fluctuation ridge, where the excess swelling of both polymer films occurred, and then froze the swollen structures by quick evaporation of CO2. A chromium (Cr) layer with film thickness of 300-400 Angstroms was deposited onto the exposed film by using an E-beam evaporator. X-ray reflectivity (XR) measurements showed that the interfacial width between the Cr and exposed polymer layers increased by a factor of about two compared with that without exposure to scCO 2. In addition, the large interfacial broadening was found to occur irrespective of the thickness of both polymer films. After the XR measurements, the dewetting structures of the PS/Cr films induced by additional annealing were characterized by using atomic force microscopy, showing improved surface morphology in the exposed films. Contact angle measurements showed that a decrease in interfacial tension with exposure to scCO 2 accompanied the increase in interfacial width.

  3. Redox processes in silicon dioxide thin films using copper microelectrodes

    NASA Astrophysics Data System (ADS)

    Tappertzhofen, S.; Menzel, S.; Valov, I.; Waser, R.

    2011-11-01

    Although SiO2 is a typical insulator, we demonstrate an electrochemical characteristic of the Cu/Cu+ oxidation at the interface with 30 nm thick silicon dioxide thin films studied by cyclic voltammetry. This study reveals the process of anodic oxidation and subsequent reduction of oxidized Cu ions injected in the SiO2 layer with special attention to the kinetics of the redox process. We estimated the diffusion coefficient and the mobility of Cu ions in SiO2. The results gain deeper insight in the processes involved during resistive switching of Cu/SiO2 based nonvolatile memory devices.

  4. Photocatalytic production of hydrogen from fixed titanium dioxide thin film

    NASA Astrophysics Data System (ADS)

    Okoye, Njideka Helen

    This thesis is focused on further developing of an efficient method for the photocatalytic hydrogen production. The research aimed to use thin films deposited with TiO2 and doped with Pt in order to substitute slurry solutions that are currently being used. A new depositing experimental approach to manufacture the thin films was proposed and tested for both physical properties and chemical reactivity. Therefore, the experiment was designed into two parts: The first part was on the manufacturing and the physical characterization of titanium dioxide deposited on glass surfaces and the second part was focused on the ability of the thin film to produce hydrogen. For the second part, a photochemical reactor vessel was used to properly place the glass slides to UV-irradiation. This was yielded by a mercury lamp located at the centre of the reactor. The thesis is organized into five different chapters including introduction, literature review, characterization of TiO2 coated surface, experimental design and hydrogen production, finally conclusive observations and future work. Hydrogen production by photodecomposition of water into H2 and O2 has a very low efficiency due to rapid reverse reaction and, as mentioned above, it usually requires a slurry type of solution. This needs additional processing steps such as filtration and recycling of particles. Therefore, it is important to develop an efficient process for hydrogen production. TiO2 coated surfaces could be an excellent technological alternative. In this study, a sol-gel method was used to produce a transparent TiO 2 thin film which was deposited on a glass substrate by using a new coating technique introduced in this work for H2 production. The TiO2 deposited film on a glass substrate by using the spraying method of coating was characterized for physical analysis (surface characteristics, size of nanoparticles and distribution, etc.) by using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission

  5. High frequency impedance spectra on the chromium dioxide thin film

    SciTech Connect

    Fu, C. M.; Lai, C. J.; Wu, J. S.; Huang, J. C. A.; Wu, C.-C.; Shyu, S.-G.

    2001-06-01

    We report on the study of high frequency magnetotransport properties of the chromium dioxide (CrO{sub 2}) thin films, grown on Si substrate using chemical vapor deposition. The film exhibits a ferromagnetic transition with a Curie temperature near 390 K. The temperature dependent spontaneous magnetization follows Bloch{close_quote}s law. The impedance spectra, being analyzed based on the fundamental electrodynamics, are demonstrated to be in a low-loss dielectric limit along with the occurrence of dielectric relaxation and magnetization response. The specific features of impedance spectra, distinct from the usual metallic ferromagnet, are attributed to the half metallic nature of CrO{sub 2}. The results explore the possibility for high frequency device applications.

  6. Titanium dioxide thin film deposited on flexible substrate by multi-jet electrospraying

    NASA Astrophysics Data System (ADS)

    Ni, Daihong; Yi, Wuming; Cao, Zhoubin; Gu, Wenhua

    2015-10-01

    Titanium dioxide thin film plays an important role in thin film solar cells, and has promising future in everyday applications including air cleaning and self-cleaning glass. With the concepts of flexible solar cells and wearable devices being more and more popular, there is increasing interest to coat titanium dioxide thin films on flexible substrates, such as aluminum foils. Many methods have been used to fabricate titanium dioxide thin films, such as dip-coating, spin coating, aerosol spray, plasma-assisted coating, electrospraying, and so on. Among them, electrospraying is especially suitable for thin film deposition on flexible substrates. This work reports fabrication of dense and uniform titanium dioxide thin films on glass as well as flexible aluminum foil using multi-jet electrospraying technique.

  7. Quantum capacitance in thin film vanadium dioxide metal insulator transition

    NASA Astrophysics Data System (ADS)

    Wu, Zhe; Knighton, Talbot; Tarquini, Vinicio; Torres, David; Wang, Tongyu; Sepulveda, Nelson; Huang, Jian

    We present capacitance measurements of the electronic density of states performed in high quality vanadium dioxide (VO2) thin films on sapphire (Al2O3) substrate. These films show the expected metal insulator transition near 60 °C with resistivity changing by 3 orders of magnitude with a hysteresis of 10 °C. To make a capacitive probe, a gate is suspended above the film surface using a flip-chip method with microfabricated supports. The geometric capacitance per-area reached is 40 pF/mm2. Such a large capacitance can be significantly modified by electron interaction and band charging/discharging which appear as an extra term known as the quantum capacitance (Cq). An AC signal applied to the gate allows measurement of the changing density of states (DOS) across the MIT. The DOS abruptly increases as the sample is heated through the transition point. Conversely the low temperature drop of d μ / d n is consistent with an energy gap opening in the insulating phase. These parameters shed light on the transition mechanism. NSF DMR-1105183, NSF ECCS 1306311.

  8. Deposition and characterization of titanium dioxide and hafnium dioxide thin films for high dielectric applications

    NASA Astrophysics Data System (ADS)

    Yoon, Meeyoung

    The industry's demand for higher integrated circuit density and performance has forced the gate dielectric layer thickness to decrease rapidly. The use of conventional SiO2 films as gate oxide is reaching its limit due to the rapid increase in tunneling current. Therefore, a need for a high dielectric material to produce large oxide capacitance and low leakage current has emerged. Metal-oxides such as titanium dioxide (TiO2) and hafnium dioxide (HfO2) are attractive candidates for gate dielectrics due to their electrical and physical properties suitable for high dielectric applications. MOCVD of TiO2 using titanium isopropoxide (TTIP) precursor on p-type Si(100) has been studied. Insertion of a TiO x buffer layer, formed by depositing metallic Ti followed by oxidation, at the TiO2/Si interface has reduced the carbon contamination in the TiO2 film. Elemental Ti films, analyzed by in-situ AES, were found to grow according to Stranski-Krastanov mode on Si(100). Carbon-free, stoichiometric TiO2 films were successfully produced on Si(100) without any parasitic SiO2 layers at the TiO 2/Si interface. Electron-beam deposition of HfO2 films on Si(100) has also been investigated in this work. HfO2 films are formed by depositing elemental Hf on Si(100) and then oxidizing it either in O2 or O 3. XPS results reveal that with oxidation Hf(4f) peak shifts +3.45eV with 02 and +3.65eV with O3 oxidation. LEED and AFM studies show that the initially ordered crystalline Hf becomes disordered after oxidation. The thermodynamic stability of HfO2 films on Si has been studied using a unique test-bed structure of Hf/O3/Si. Post-Oxidation of Layer Deposition (POLD) has been employed to produce HfO2 films with a desired thickness. XPS results indicate that stoichiometric HfO 2 films were successfully produced using the POLD process. The investigation of the growth and thin film properties of TiO 2 and HfO2 using oxygen and ozone has laid a foundation for the application of these metal

  9. Chemical vapor deposition and characterization of titanium dioxide thin films

    NASA Astrophysics Data System (ADS)

    Gilmer, David Christopher

    1998-12-01

    The continued drive to decrease the size and increase the speed of micro-electronic Metal-Oxide-Semiconductor (MOS) devices is hampered by some of the properties of the SiOsb2 gate dielectric. This research has focused on the CVD of TiOsb2 thin films to replace SiOsb2 as the gate dielectric in MOS capacitors and transistors. The relationship of CVD parameters and post-deposition anneal treatments to the physical and electrical properties of thin films of TiOsb2 has been studied. Structural and electrical characterization of TiOsb2 films grown from the CVD precursors tetraisopropoxotitanium (IV) (TTIP) and TTIP plus Hsb2O is described in Chapter 3. Both types of deposition produced stoichiometric TiOsb2 films comprised of polycrystalline anatase, but the interface properties were dramatically degraded when water vapor was added. Films grown with TTIP in the presence of Hsb2O contained greater than 50% more hydrogen than films grown using only TTIP and the hydrogen content of films deposited in both wet and dry TTIP environments decreased sharply with a post deposition Osb2 anneal. A significant thickness variation of the dielectric constant was observed which could be explained by an interfacial oxide and the finite accumulation thickness. Fabricated TiOsb2 capacitors exhibited electrically equivalent SiOsb2 gate dielectric thicknesses and leakage current densities as low as 38, and 1×10sp{-8} Amp/cmsp2 respectively. Chapter 4 discusses the low temperature CVD of crystalline TiOsb2 thin films deposited using the precursor tetranitratotitanium (IV), TNT, which produces crystalline TiOsb2 films of the anatase phase in UHV-CVD at temperatures as low as 184sp°C. Fabricated TiOsb2 capacitors exhibited electrically equivalent SiOsb2 gate dielectric thicknesses and leakage current densities as low as 17, and 1×10sp{-8} Amp/cmsp2 respectively. Chapter 5 describes the results of a comparison of physical and electrical properties between TiOsb2 films grown via LPCVD using

  10. Resistance-Strain Relation On Vanadium Dioxide Thin Films

    NASA Astrophysics Data System (ADS)

    Amiri, Ali; Leclair, Patrick; Gupta, Arun

    Vanadium dioxide is a strongly correlated material with a sharp metal to insulator transition at ~341 K. It is well known that the strain along c-axis can change the transition temperature, but the other effects of the strain have not been drawing much attention. In this work we have studied the effects of the strain on resistance changes in the polycrystalline and epitaxial films. Polycrystalline films of VO2 are deposited on the Pb(Mg1/3Nb2/3)0.72Ti0.28O3(001) (PMN-PT) using a SiO2 buffer layer. The strain on film is tuned by applying a bias electric field through the piezoelectric substrate, and the resistance is measured using four-probe method. The epitaxial films of VO2 are grown on TiO2 (001) and have been glued to PMN-PT substrate to transfer strain. The change in the resistance of the epitaxial films is measured to be only about 30% more than polycrystalline films for the same amount of strain. We have studied the strain-induced resistance changes as a function of temperature. we have shown that the resistance is more sensitive to strain in the metallic phase.

  11. Specific features of hydrogenation of chromium-doped polycrystalline thin vanadium dioxide films

    NASA Astrophysics Data System (ADS)

    Andreev, V. N.; Klimov, V. A.; Kompan, M. E.; Melekh, B. A.

    2014-09-01

    It has been found that hydrogen penetration into chromium-doped polycrystalline thin vanadium dioxide films occurs with a lower rate than in the case of pure vanadium dioxide films. It has been shown that hydrogenation of films with low chromium concentrations is accompanied by a decrease in the phase transition temperature below T c = 340 K. However, at room temperature in these hydrogenated films, no traces of M1 monoclinic phase have been observed. As the chromium concentration increases, hydrogenation ceases to be accompanied by the decrease in the phase transition temperature.

  12. Chemical vapour deposition of thermochromic vanadium dioxide thin films for energy efficient glazing

    SciTech Connect

    Warwick, Michael E.A.; Binions, Russell

    2014-06-01

    Vanadium dioxide is a thermochromic material that undergoes a semiconductor to metal transitions at a critical temperature of 68 °C. This phase change from a low temperature monoclinic structure to a higher temperature rutile structure is accompanied by a marked change in infrared reflectivity and change in resistivity. This ability to have a temperature-modulated film that can limit solar heat gain makes vanadium dioxide an ideal candidate for thermochromic energy efficient glazing. In this review we detail the current challenges to such glazing becoming a commercial reality and describe the key chemical vapour deposition technologies being employed in the latest research. - Graphical abstract: Schematic demonstration of the effect of thermochromic glazing on solar radiation (red arrow represents IR radiation, black arrow represents all other solar radiation). - Highlights: • Vanadium dioxide thin films for energy efficient glazing. • Reviews chemical vapour deposition techniques. • Latest results for thin film deposition for vanadium dioxide.

  13. Half-metallic Chromium dioxide thin films for spintronic applications

    NASA Astrophysics Data System (ADS)

    Pathak, Manjit

    2011-12-01

    CrO2 is a well-established half-metallic oxide with near perfect spin polarization -- known to have the highest spin polarization among all known materials theoretically as well as experimentally. This means that the conduction electrons in CrO2 have only one kind of spin i.e. conduction is due only to the majority spin electrons. Because of its high spin polarization, CrO2 stands as an ideal and one of the most attractive candidates for spin-electronic applications as well as of fundamental interests. The enormous potential of CrO2 is still untapped since thin film growth modes, interface/surface properties and various factors affecting them are not very well understood or, relatively unknown. Reported works confirm strained growth of (100) CrO2 films and strain free growth of (110) CrO2 films on iso-structural TiO 2 substrates investigated using X-ray diffraction. Superconducting quantum interference device (SQUID) and element specific X-ray magnetic circular dichroism (XMCD) techniques were employed to investigate the effect of this substrate-induced strain on the magnetic properties of the films. Magnetic tunnel junctions (MTJ) were fabricated with CrO2, Cr2O3 [natural oxide of Cr] as the thin insulating barrier and Co as the other ferromagnetic electrode using photolithography. I..V characteristics of this spin-electronic device are reported. Also, results on the low pressure chemical vapor deposition (CVD) growth of CrO2 and its comparison with standard growth technique under atmospheric pressure are reported.

  14. Anisotropic vanadium dioxide sculptured thin films with superior thermochromic properties.

    PubMed

    Sun, Yaoming; Xiao, Xiudi; Xu, Gang; Dong, Guoping; Chai, Guanqi; Zhang, Hua; Liu, Pengyi; Zhu, Hanmin; Zhan, Yongjun

    2013-01-01

    VO2 (M) STF through reduction of V2O5 STF was prepared. The results illustrate that V2O5 STF can be successfully obtained by oblique angle thermal evaporation technique. After annealing at 550 °C/3 min, the V2O5 STF deposited at 85° can be easily transformed into VO2 STF with slanted columnar structure and superior thermochromic properties. After deposition SiO2 antireflective layer, Tlum of VO2 STF is enhanced 26% and ΔTsol increases 60% compared with that of normal VO2 thin films. Due to the anisotropic microstructure of VO2 STF, angular selectivity transmission of VO2 STF is observed and the solar modulation ability is further improved from 7.2% to 8.7% when light is along columnar direction. Moreover, the phase transition temperature of VO2 STF can be depressed into 54.5 °C without doping. Considering the oblique incidence of sunlight on windows, VO2 STF is more beneficial for practical application as smart windows compared with normal homogenous VO2 thin films. PMID:24067743

  15. Anisotropic vanadium dioxide sculptured thin films with superior thermochromic properties

    PubMed Central

    Sun, Yaoming; Xiao, Xiudi; Xu, Gang; Dong, Guoping; Chai, Guanqi; Zhang, Hua; Liu, Pengyi; Zhu, Hanmin; Zhan, Yongjun

    2013-01-01

    VO2 (M) STF through reduction of V2O5 STF was prepared. The results illustrate that V2O5 STF can be successfully obtained by oblique angle thermal evaporation technique. After annealing at 550°C/3 min, the V2O5 STF deposited at 85° can be easily transformed into VO2 STF with slanted columnar structure and superior thermochromic properties. After deposition SiO2 antireflective layer, Tlum of VO2 STF is enhanced 26% and ΔTsol increases 60% compared with that of normal VO2 thin films. Due to the anisotropic microstructure of VO2 STF, angular selectivity transmission of VO2 STF is observed and the solar modulation ability is further improved from 7.2% to 8.7% when light is along columnar direction. Moreover, the phase transition temperature of VO2 STF can be depressed into 54.5°C without doping. Considering the oblique incidence of sunlight on windows, VO2 STF is more beneficial for practical application as smart windows compared with normal homogenous VO2 thin films. PMID:24067743

  16. Growth and Etch Rate Study of Low Temperature Anodic Silicon Dioxide Thin Films

    PubMed Central

    Ashok, Akarapu; Pal, Prem

    2014-01-01

    Silicon dioxide (SiO2) thin films are most commonly used insulating films in the fabrication of silicon-based integrated circuits (ICs) and microelectromechanical systems (MEMS). Several techniques with different processing environments have been investigated to deposit silicon dioxide films at temperatures down to room temperature. Anodic oxidation of silicon is one of the low temperature processes to grow oxide films even below room temperature. In the present work, uniform silicon dioxide thin films are grown at room temperature by using anodic oxidation technique. Oxide films are synthesized in potentiostatic and potentiodynamic regimes at large applied voltages in order to investigate the effect of voltage, mechanical stirring of electrolyte, current density and the water percentage on growth rate, and the different properties of as-grown oxide films. Ellipsometry, FTIR, and SEM are employed to investigate various properties of the oxide films. A 5.25 Å/V growth rate is achieved in potentiostatic mode. In the case of potentiodynamic mode, 160 nm thickness is attained at 300 V. The oxide films developed in both modes are slightly silicon rich, uniform, and less porous. The present study is intended to inspect various properties which are considered for applications in MEMS and Microelectronics. PMID:24672287

  17. Improvement on Characteristics of Ferroelectric Thin Films Using Supercritical Carbon Dioxide Fluid Treatment

    NASA Astrophysics Data System (ADS)

    Cheng, Chien-Min; Kuan, Ming-Chang; Chen, Kai-Hunag; Tsai, Jen-Hwan

    Electrical and physical properties of as-deposited Bi3.9La0.1Ti2.9V0.1O12 (BLTV) ferroelectric thin films on SiO2/Si(100) substrates were improved by low temperature supercritical carbon dioxide fluid (SCF) process treatment. The as-deposited BLTV ferroelectric thin films were treated by SCF process which mixed with propyl alcohol and pure water. The memory windows increased in C-V curves, and the oxygen vacancy and defect in leakage current density curves were obtained after SCF process treatment. Finally, the improvement properties of as-deposited BLTV thin films after SCF process treatment were investigated by XPS, C-V, and J-E measurement. The mechanism concerning the dependence of electrical properties of the ferroelectric thin films on the SCF process was investigated and discussed.

  18. LPG ammonia and nitrogen dioxide gas sensing properties of nanostructured polypyrrole thin film

    NASA Astrophysics Data System (ADS)

    Bagul, Sagar B.; Upadhye, Deepak S.; Sharma, Ramphal

    2016-05-01

    Nanostructured Polypyrrole thin film was synthesized by easy and economic chemical oxidative polymerization technique on glass at room temperature. The prepared thin film of Polypyrrole was characterized by optical absorbance study by UV-visible spectroscopy and electrical study by I-V measurement system. The optical absorbance spectrum of Polypyrrole shows two fundamental peaks in region of 420 and 890 nm, which confirms the formation of Polypyrrole on glass substrate. The I-V graph of nanostructured Polypyrrole represents the Ohmic nature. Furthermore, the thin film of Polypyrrole was investigated by Scanning electron microscopy for surface morphology study. The SEM micrograph represents spherical nanostructured morphology of Polypyrrole on glass substrate. In order to investigate gas sensing properties, 100 ppm of LPG, Ammonia and Nitrogen Dioxide were injected in the gas chamber and magnitude of resistance has been recorded as a function of time in second. It was observed that nanostructured Polypyrrole thin film shows good sensing behavior at room temperature.

  19. Slow trap response of zirconium dioxide thin films on silicon

    NASA Astrophysics Data System (ADS)

    Harasek, S.; Lugstein, A.; Wanzenboeck, H. D.; Bertagnolli, E.

    2003-08-01

    In this work, we explore the electrical properties of a metal-oxide-semiconductor system that incorporates a high-k zirconia dielectric with an equivalent oxide thickness of 3 nm deposited by metalorganic chemical vapor deposition. In general, the thin films examined exhibit excellent electrical properties. However, dynamic I-V measurements unveil the presence of trapping sites with response times up to 3 s. By applying a recently proposed model, this slow trap response can be consistently explained by traps located at the inner interface of a two-layer dielectric consisting of the high-k material itself and a transition layer in contact with the semiconductor. Trap energies are found to be distributed around two distinct levels.

  20. Thermal oxidation-grown vanadium dioxide thin films on FTO (Fluorine-doped tin oxide) substrates

    NASA Astrophysics Data System (ADS)

    Tong, Guoxiang; Li, Yi; Wang, Feng; Huang, Yize; Fang, Baoying; Wang, Xiaohua; Zhu, Huiqun; Li, Liu; Shen, Yujian; Zheng, Qiuxin; Liang, Qian; Yan, Meng; Qin, Yuan; Ding, Jie

    2013-11-01

    By deposition of metallic vanadium on FTO substrate in Argon atmosphere at room temperature, the sample was then annealed in furnace for 2 h at the temperature of 410 °C in air ambient. (1 1 0) -orientated vanadium dioxide films were prepared on the FTO surface. A maximum transmittance of ˜40% happened at 900-1250 nm region at room temperature. The change of optical transmittance at this region was ˜25% between semiconducting and metallic states. In particular, vanadium dioxide thin films on FTO exhibit semiconductor-metal phase transition at ˜51 °C, the width of the hysteresis loop is ˜8 °C.

  1. Electron-beam-evaporated thin films of hafnium dioxide for fabricating electronic devices

    SciTech Connect

    Xiao, Zhigang; Kisslinger, Kim

    2015-06-17

    Thin films of hafnium dioxide (HfO2) are widely used as the gate oxide in fabricating integrated circuits because of their high dielectric constants. In this paper, the authors report the growth of thin films of HfO2 using e-beam evaporation, and the fabrication of complementary metal-oxide semiconductor (CMOS) integrated circuits using this HfO2 thin film as the gate oxide. The authors analyzed the thin films using high-resolution transmission electron microscopy and electron diffraction, thereby demonstrating that the e-beam-evaporation-grown HfO2 film has a polycrystalline structure and forms an excellent interface with silicon. Accordingly, we fabricated 31-stage CMOS ring oscillator to test the quality of the HfO2 thin film as the gate oxide, and obtained excellent rail-to-rail oscillation waveforms from it, denoting that the HfO2 thin film functioned very well as the gate oxide.

  2. Electron-beam-evaporated thin films of hafnium dioxide for fabricating electronic devices

    DOE PAGESBeta

    Xiao, Zhigang; Kisslinger, Kim

    2015-06-17

    Thin films of hafnium dioxide (HfO2) are widely used as the gate oxide in fabricating integrated circuits because of their high dielectric constants. In this paper, the authors report the growth of thin films of HfO2 using e-beam evaporation, and the fabrication of complementary metal-oxide semiconductor (CMOS) integrated circuits using this HfO2 thin film as the gate oxide. The authors analyzed the thin films using high-resolution transmission electron microscopy and electron diffraction, thereby demonstrating that the e-beam-evaporation-grown HfO2 film has a polycrystalline structure and forms an excellent interface with silicon. Accordingly, we fabricated 31-stage CMOS ring oscillator to test themore » quality of the HfO2 thin film as the gate oxide, and obtained excellent rail-to-rail oscillation waveforms from it, denoting that the HfO2 thin film functioned very well as the gate oxide.« less

  3. Enhanced performance of room-temperature-grown epitaxial thin films of vanadium dioxide

    SciTech Connect

    Nag, Joyeeta; Payzant, E Andrew; More, Karren Leslie; HaglundJr., Richard F

    2011-01-01

    Stoichiometric vanadium dioxide in bulk, thin film and nanostructured forms exhibits an insulator-to-metal transition (IMT) accompanied by a structural phase transformation, induced by temperature, light, electric fields, doping or strain. We have grown epitaxial films of vanadium dioxide on c-plane (0001) of sapphire using two different procedures involving (1) room temperature growth followed by annealing and (2) direct high temperature growth. Strain at the film-substrate interface due to growth at different temperatures leads to interesting differences in morphologies and phase transition characteristics. Comparison of the morphologies and switching characteristics of the two films shows that contrary to conventional wisdom, the room-temperature grown films have smoother, more continuous morphologies and better switching performance, consistent with the behavior of epitaxially grown semiconductors.

  4. Spin coated unsubstituted copper phthalocyanine thin films for nitrogen dioxide sensors

    NASA Astrophysics Data System (ADS)

    Chakane, Sanjay; Datir, Ashok; Koinkar, Pankaj

    2015-03-01

    Copper phthalocyanine (CuPc) is synthesized chemically and used for making CuPc thin films using spin coating technique. Films were prepared from trifluroacetic acid (TFA) and chlorobenzene mixed solution on the glass substrate. Spin coated films of unsubstituted CuPc films were heat annealed at 150°C for 2 h duration and were used to study NO2 gas sensing characteristics. α-phase of CuPc is noted by UV-visible absorption spectra. IR spectra of undoped CuPc films and doped CuPc films with NO2 revealed that, doping of nitrogen dioxide modifies and deletes some of the bands. The effect of NO2 at various concentrations from 50 ppm to 500 ppm in atmospheric air at room temperature on the electrical conductivity of CuPc films was studied. Sensitivity, response time and repeatability of the CuPc sensor were discussed in this paper.

  5. Electrodeposited nanostructured lead dioxide as a thin film electrode for a lightweight lead-acid battery

    NASA Astrophysics Data System (ADS)

    Egan, D. R. P.; Low, C. T. J.; Walsh, F. C.

    Thin films of nanostructured lead dioxide are investigated as a positive electrode material for a lightweight lead-acid battery. The films are obtained by constant current deposition from electrolytes of lead methanesulfonate in methanesulfonic acid. The films are tested in two conditions namely (a) cyclic voltammetry and (b) constant current battery cycling in sulfuric acid. The charge and discharge current density, charge density and charge efficiency are measured as a function of cycle number. The effect of deposition conditions, such as solution temperature (295 and 333 K), type of substrate and electrolyte additive (hexadecyltrimethylammonium hydroxide), on the electrochemical performance of the PbO 2 in sulfuric acid is investigated. It is found that the as-deposited lead dioxide film is compact and nanostructured β-phase structure. Following successive cycling in sulfuric acid, the compact thin film gradually transforms into a porous microstructure consisting of positive active material (PbO 2 and PbSO 4), several tens of nanometres size. The charge density, discharge density and peak discharge current density of the PbO 2 improve with cycling of the thin film electrode.

  6. An Examination Of Vanadium Dioxide Thin Film As An Erasable/Reuseable Medium For Optical Recording

    NASA Astrophysics Data System (ADS)

    Case, W. E.; Smith, J. L.; Eden, D. D.

    1983-11-01

    Vanadium dioxide undergoes a thermally induced first order phase change from semiconductor to metal near 67°C. In thin-film form, significant optical contrast can be produced at visible wavelengths on switching from low to high temperature phases. If the film is locally heated (e.g. by means of a laser) so that the temperature is driven above the transition point, the color or reflectance is changed only in that local region. Upon removal of the heat source the temperature returns to equilibrium. The local contrast, however, is either removed (dynamic operation), or stored indefinitely (memory operation) depending on the equilibrium or "bias" temperature. This storage option is possible because the material deposited as a thin film exhibits hysteresis, i.e., the curve describing the state of the film vs. temperature is double valued in the transition region. In order to erase information from a film region, that region must be lowered in temperature to a level below the onset of hysteresis. The general properties of vanadium dioxide thin film suggest a material suitable for recording optical information in a high density, digital format allowing erasure and reuse. Practical feasibility has been examined at Vought during the past year by a series of performance measurements. For example, laser writing of one micron diameter spots in less than 50 nanoseconds has been accomplished, and the amount of energy required for writing is compatible with laser diodes. These measurement results and data on contrast, storage time, and film surface morphology will be presented. The size of individual crystallites comprising the vanadium dioxide film is expected to fix ultimate spatial resolution.

  7. Silicon dioxide thin film mediated single cell nucleic acid isolation.

    PubMed

    Bogdanov, Evgeny; Dominova, Irina; Shusharina, Natalia; Botman, Stepan; Kasymov, Vitaliy; Patrushev, Maksim

    2013-01-01

    A limited amount of DNA extracted from single cells, and the development of single cell diagnostics make it necessary to create a new highly effective method for the single cells nucleic acids isolation. In this paper, we propose the DNA isolation method from biomaterials with limited DNA quantity in sample, and from samples with degradable DNA based on the use of solid-phase adsorbent silicon dioxide nanofilm deposited on the inner surface of PCR tube. PMID:23874571

  8. Silicon Dioxide Thin Film Mediated Single Cell Nucleic Acid Isolation

    PubMed Central

    Bogdanov, Evgeny; Dominova, Irina; Shusharina, Natalia; Botman, Stepan; Kasymov, Vitaliy; Patrushev, Maksim

    2013-01-01

    A limited amount of DNA extracted from single cells, and the development of single cell diagnostics make it necessary to create a new highly effective method for the single cells nucleic acids isolation. In this paper, we propose the DNA isolation method from biomaterials with limited DNA quantity in sample, and from samples with degradable DNA based on the use of solid-phase adsorbent silicon dioxide nanofilm deposited on the inner surface of PCR tube. PMID:23874571

  9. Thin-film zinc/manganese dioxide electrodes based on microporous polymer foils

    NASA Astrophysics Data System (ADS)

    Barbic, P. A.; Binder, L.; Voss, S.; Hofer, F.; Grogger, W.

    Thin-film electrodes allow manufacturing of flat batteries of variable design which can be used for the development of smaller electric appliances. Substituting the metal carrier by conductive plastics leads to a considerable reduction of battery weight. Usually the electroactive materials are deposited onto the surface of the carrier. A significant improvement of the originally poor adherence between polymer foil and electroactive layers can be achieved by mechanical (surface roughening) or chemical (etching) pretreatment. Another way to form extremely thin electrodes having a thickness in the range of some ten micrometers is reported here. First, a metallic layer is deposited onto one surface of a 25 μm thin porous polypropylene foil. Subsequently, the electroactive materials are electrolytically deposited into the pores of the metallized foil providing the required conductive connection through the plastic matrix by themselves. In this case the flexibility of the polymer has a positive influence on the problem of volume change of manganese dioxide during charging and discharging, respectively, because the plastic provides flexible `mechanical struts' which act as a `binder' and therefore prevent increasing internal resistance due to contact problems. Assembling a zinc filled polymer and a manganese dioxide filled one in such a way that both metallic back-layers are in contact, a thin bipolar zinc/manganese dioxide electrode can be obtained.

  10. Optical properties of vanadium dioxide thin film in nanoparticle structure

    NASA Astrophysics Data System (ADS)

    Fang, Baoying; Li, Yi; Tong, Guoxiang; Wang, Xiaohua; Yan, Meng; Liang, Qian; Wang, Feng; Qin, Yuan; Ding, Jie; Chen, Shaojuan; Chen, Jiankun; Zheng, Hongzhu; Yuan, Wenrui

    2015-09-01

    The thermo-optic effect and infrared optical properties of VO2 nanoparticles were studied to obtain an optical material with special property that can be used in smart windows. The reflectance and transmittance spectra of the VO2 nanoparticles with different duty cycles at different temperatures were simulated with a specific dispersion relation. Vanadium metal nanoparticles were deposited on glass substrate by magnetic reactive sputtering with porous alumina template (AAO) mask, and the VO2 nanoparticles were prepared by thermal oxidation. The nanostructure and optical properties of the VO2 nanoparticles were characterized by atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and spectrophotometry. The method of preparation of the sample is economical and the phase transition temperature is observed to drop to 43 °C. The transmission at 1700 nm exhibits a variation of 29% between the metallic and semiconducting states. The VO2 nanoparticles exhibit a significant thermochromic property. The transmittance of the VO2 nanoparticles is improved compared with the VO2 film. The decrease in phase transition temperature and the enhancement of optical properties demonstrate that VO2 film in nanoparticle structure is a viable candidate material for smart windows.

  11. Effect of Sprayed Solution Volume on Physical Properties of Titanium Dioxide Thin Films

    NASA Astrophysics Data System (ADS)

    Naffouti, Wafa; Ben Nasr, Tarek; Briot, Olivier; Kamoun-Turki, Najoua

    2015-10-01

    Titanium dioxide (TiO2) thin films were deposited on glass substrates by spray pyrolysis technique from different solution volumes. We studied the effect of sprayed solution volume on the structural, morphological and optical properties of TiO2 films. X-ray diffraction studies revealed the presence of an anatase phase with a tetragonal structure with (101) preferred orientation. The best crystallinity was obtained in the case of a sprayed solution volume of 60 ml. Also, this film had a lower average surface roughness (RMS) as measured by atomic force microscopy. Transmission and reflection optical analysis showed interference phenomena indicating a smooth reflecting surface of the film. An indirect band gap of about 3.46 eV was found, indicating a potential use of these films in solar cell devices. Based on the optical measurements, the film thickness was determined by the envelope method, which was in agreement with the scanning electron microscopy result. Wemple-Di Domenico single oscillator and Spitzer-Fan models were used to study the optical constants of the films grown from different sprayed solution volumes. Photoluminescence emission intensity was found to increase with increasing film crystallinity, and the spectra showed ultraviolet and visible emissions corresponding to intrinsic emission and trap levels within the band gap, respectively.

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

    NASA Astrophysics Data System (ADS)

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

    1994-12-01

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

  13. Pulsed Laser Deposited Ferromagnetic Chromium Dioxide thin Films for Applications in Spintronics

    NASA Astrophysics Data System (ADS)

    Dwivedi, S.; Jadhav, J.; Sharma, H.; Biswas, S.

    Stable rutile type tetragonal chromium dioxide (CrO2) thin films have been deposited on lattice-matched layers of TiO2 by KrF excimer laser based pulsed laser deposition (PLD) technique using Cr2O3 target. The TiO2 seed layer was deposited on oxidized Si substrates by the same PLD process followed by annealing at 1100 °C for 4 h. The lattice-matched interfacial layer is required for the stabilization of Cr (IV) phase in CrO2, since CrO2 behaves as a metastable compound under ambient conditions and readily converts into its stable phase of Cr (III) oxide, Cr2O3. Analyses with X-ray diffraction (XRD), Glancing-angle XRD (GIXRD), Raman spectroscopy and grazing-angle Fourier transform infra-red (FTIR) spectroscopy confirm the presence of tetragonal CrO2 phase in the as-deposited films. Microstructure and surface morphology in the films were studied with field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). Electrical and magnetic characterizations of the films were performed at room temperature. Such type of stable half-metallic CrO2 thin films with low field magnetoresistive switching behaviour are in demand for applications as diverse as spin-FETs, magnetic sensors, and magneto-optical devices.

  14. Chemical sensing employingpH sensitive emeraldine base thin film for carbon dioxide detection

    NASA Astrophysics Data System (ADS)

    Irimia-Vladu, Mihai

    Respiration, or CO2 evolution, is a universal indicator for all the biological activities. Among many potential applications, the measurement of CO2 evolution has been found to be a rapid and nondestructive means for examining microbial contamination of food. The sensor developed in this work consists of a thin emeraldine base-polyaniline (EB-PAni) film. In the first half of the project the effect of carbon dioxide over the conductivity of a composite film of emeraldine base polyaniline and poly(vinyl alcohol) in N-methyl pyrrolidone (NMP) respectively was tested. Argon gas or mixture of argon and 5% CO2 were circulated through the glass cell containing the polymer film deposited on interdigitated electrode and exposed to specific humidity levels fixed by aqueous supersaturated salt solutions. In the second half of the project, a thin emeraldine base film in NMP was directly deposited on interdigitated electrode and the respective sensor inserted in water. Carbonic acid solutions of various pHs were generated by bubbling specific mixtures of carbon dioxide and argon. Conductivity measurements were performed by impedance spectroscopy throughout the project. The sensing mechanism is based on intermediate stages of the transformation of the emeraldine base polyaniline to a conductive salt type (ES-PAni). This EB-ES transformation is the consequence of the exposure of EB-PAni to a protonic acid and is accompanied by a change in the conductivity of the polymer film. Carbonic acid, unfortunately, is a very weak acid and is unable to induce a conductivity change, but the intermediate steps that predetermine this transformation are detected by impedance spectroscopy even when the overall conductivity of the film is unchanged. The composite thin film developed in the first part of the project showed poor sensing characteristics: limited dynamic range, drift, instability and slow time response. However, the sensor design employed in the second half of this work, coupled with

  15. Nitrogen dioxide sensing properties of sprayed tungsten oxide thin film sensor: Effect of film thickness.

    PubMed

    Ganbavle, V V; Mohite, S V; Agawane, G L; Kim, J H; Rajpure, K Y

    2015-08-01

    We report a study on effect of film thickness on NO2 sensing properties of sprayed WO3 thin films. WO3 thin films varying in thicknesses are deposited onto the glass substrates by simple spray pyrolysis technique by varying the volume of spray solution.Thin film gas sensors are characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and photoluminescence (PL) techniques to study their physical properties. Film having thickness 745nm has shown highest gas response of 97% with 12 and 412s response and recovery times, respectively towards 100ppm NO2 concentration. Gas response of 20% is observed towards 10ppm NO2 at 200°C operating temperature. Sensitivity of the optimal sensor is 0.83%/ppm when operating at 200°C with 10ppm lower detection limit. The response of the sensor is reproducible and WO3 films are highly selective towards NO2 in presence of mist of various interfering gases viz. H2S, NH3, LPG, CO and SO2. PMID:25898119

  16. Phase-selective vanadium dioxide (VO{sub 2}) nanostructured thin films by pulsed laser deposition

    SciTech Connect

    Masina, B. N. E-mail: slafane@cdta.dz; Lafane, S. E-mail: slafane@cdta.dz; Abdelli-Messaci, S.; Kerdja, T.; Wu, L.; Akande, A. A.; Mwakikunga, B.

    2015-10-28

    Thin films of monoclinic nanostructured vanadium dioxide are notoriously difficult to produce in a selective manner. To date, post-annealing, after pulsed laser deposition (PLD), has been used to revert the crystal phase or to remove impurities, and non-glass substrates have been employed, thus reducing the efficacy of the transparency switching. Here, we overcome these limitations in PLD by optimizing a laser-ablation and deposition process through optical imaging of the laser-induced plasma. We report high quality monoclinic rutile-type vanadium dioxide (VO{sub 2}) (M1) nanoparticles without post-annealing, and on a glass substrate. Our samples demonstrate a reversible metal-to-insulator transition at ∼43 °C, without any doping, paving the way to switchable transparency in optical materials at room temperature.

  17. Phase-selective vanadium dioxide (VO2) nanostructured thin films by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Masina, B. N.; Lafane, S.; Wu, L.; Akande, A. A.; Mwakikunga, B.; Abdelli-Messaci, S.; Kerdja, T.; Forbes, A.

    2015-10-01

    Thin films of monoclinic nanostructured vanadium dioxide are notoriously difficult to produce in a selective manner. To date, post-annealing, after pulsed laser deposition (PLD), has been used to revert the crystal phase or to remove impurities, and non-glass substrates have been employed, thus reducing the efficacy of the transparency switching. Here, we overcome these limitations in PLD by optimizing a laser-ablation and deposition process through optical imaging of the laser-induced plasma. We report high quality monoclinic rutile-type vanadium dioxide (VO2) (M1) nanoparticles without post-annealing, and on a glass substrate. Our samples demonstrate a reversible metal-to-insulator transition at ˜43 °C, without any doping, paving the way to switchable transparency in optical materials at room temperature.

  18. Passive Chemiresistor Sensor Based on Iron (II) Phthalocyanine Thin Films for Monitoring of Nitrogen Dioxide

    NASA Astrophysics Data System (ADS)

    Shu, John Hungjen

    In this dissertation, an alternate, new approach was investigated to produce a nonreversible, passive, iron (II) phthalocyanine (FePc) thin film sensor that does not require continuous power for operation. The sensor was manufactured using standard microelectronics fabrication procedures, with emphasis on low cost and sensor consistency. The sensor substrate consists of a gold interdigitated electrode pattern deposited on an oxidized silicon or quartz wafer. The FePc thin film is then vacuum sublimed over the interdigitated electrodes to form the finalized sensor. Different thicknesses and morphologies of FePc thin films were fabricated. Once sensor fabrication was accomplished, the general response, temperature dependence, concentration dependence, specificity, and longevity of FePc thin film sensors were investigated. To evaluate general sensor reponse, sensors were exposed to 100 ppm nitrogen dioxide in nitrogen, with a flow rate of 0.25 liters per minute (L/min), at the temperatures of -46, 20, and 71 °C. For each case, the resistance of the sensor decreased exponentially as a function of exposure duration and reached saturation within 25 minutes. The resistance decrease was measured to be four, three, and two orders of magnitude for the exposure temperatures of -46, 20, and 71 .C respectively. In these experiments, sub-zero temperature detection of nitrogen dioxide with FePc thin films was reported for the first time. It was found that the response at -46 °C was greater than at 20 or 71 °C. To evaluate temperature dependence, sensors were thermal cycled in the range of -50 to 80 °C, first under ultra-high purity nitrogen gas at 0.25 L/min, and then under 100 ppm nitrogen dioxide gas at 0.25 L/min. Intrinsic FePc film conductivity was measured by thermal cycling sensors under nitrogen gas. Extrinsic FePc film conductivity was measured by thermal cycling sensors under nitrogen dioxide gas. Results from these tests indicated that the temperature dependence of

  19. Chemical vapour deposition of nitrogen-doped titanium dioxide thin films.

    PubMed

    Alexandrov, S E; Baryshnikova, M V; Filatov, L A; Shahmin, A L; Andreeva, V D

    2011-09-01

    Nitrogen-doped titanium dioxide is often considered as a promising nanomaterial for photocatalytic applications. Here we report the first results of a study of APCVD of N-doped TiO2 thin films prepared with the use of ammonia as a source of nitrogen and titanium tetraisopropoxide (TTIP) as a source of Ti and O atoms. The obtained films were analyzed with X-ray diffraction, infrared spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, UV-Vis spectroscopy, and ellipsometry. It was found that the film growth rate in the TTIP-NH3-Ar reaction system varied insignificantly with substrate temperature in the range of 450,..., 750 degrees C and did not exceed 4.4 nm/min. Yellow and orange layers with nitrogen content of about 7.6% were formed at the deposition temperature higher than 600 degrees C. The results of the structure analysis of the deposited films showed that addition of ammonia led to stabilization of the amorphous phase in the films. The effect of ammonia on optical and photocatalytic properties was also considered. PMID:22097568

  20. Thin Films

    NASA Astrophysics Data System (ADS)

    Naffouti, Wafa; Nasr, Tarek Ben; Mehdi, Ahmed; Kamoun-Turki, Najoua

    2014-11-01

    Titanium dioxide (TiO2) thin films were synthesized on glass substrates by spray pyrolysis. The effect of solution flow rate on the physical properties of the films was investigated by use of x-ray diffraction (XRD), scanning electron microscopy, atomic force microscopy (AFM), and spectrophotometry techniques. XRD analysis revealed the tetragonal anatase phase of TiO2 with highly preferred (101) orientation. AFM images showed that grain size on top of TiO2 thin films depended on solution flow rate. An indirect band gap energy of 3.46 eV was determined by means of transmission and reflection measurements. The envelope method, based on the optical transmission spectrum, was used to determine film thickness and optical constants, for example real and imaginary parts of the dielectric constant, refractive index, and extinction coefficient. Ultraviolet and visible photoluminescence emission peaks were observed at room temperature. These peaks were attributed to the intrinsic emission and to the surface defect states, respectively.

  1. Optical switching of vanadium dioxide thin films deposited by reactive pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Soltani, M.; Chaker, M.; Haddad, E.; Kruzelecky, R. V.; Nikanpour, D.

    2004-05-01

    The parameters of reactive pulsed laser deposition were successfully optimized for fabrication of vanadium dioxide thin films. It is observed that the O2 concentration in Ar gas and the total deposition pressure are critical in stabilizing the single VO2 phase. Thermochromic VO2 and V1-xWxO2 (x=0.014) thin films were synthesized on various substrates (silicon, quartz, and sapphire) at 5% of O2/Ar ratio gas and total pressure of 90 mTorr. The structural properties of the deposited films were analyzed by x-ray diffraction, while their semiconductor-to-metal phase transitions were studied by electrical resistivity using the four-point technique and infrared transmittance from room temperature up to 100 °C. The observed transition temperature was about 36 °C for W-doped VO2 compared to 68 °C for VO2 films. This transition temperature was then lowered by about 22.85 °C per 1 at. % of W added. The temperature coefficient of resistance was about 1.78%/°C for VO2 and about 1.90%/°C for W-doped VO2. Using the pump-probe experiment, the application of these thermochromic films as optical switches was demonstrated at the wavelength of 1.55 μm. The transmission switching was about 25 dB for VO2 and 28 dB for W-doped VO2. In addition, application of VO2 on optical fiber components was demonstrated by direct VO2 coating on the end faces of cleaved single mode optical fibers and optical fiber connectors. .

  2. Optical switching and photoluminescence in erbium-implanted vanadium dioxide thin films

    SciTech Connect

    Lim, Herianto Stavrias, Nikolas; Johnson, Brett C.; McCallum, Jeffrey C.; Marvel, Robert E.; Haglund, Richard F.

    2014-03-07

    Vanadium dioxide (VO{sub 2}) is under intensive consideration for optical switching due to its reversible phase transition, which features a drastic and rapid shift in infrared reflectivity. Classified as an insulator–to–metal transition, the phase transition in VO{sub 2} can be induced thermally, electrically, and optically. When induced optically, the transition can occur on sub-picosecond time scales. It is interesting to dope VO{sub 2} with erbium ions (Er{sup 3+}) and observe their combined properties. The first excited-state luminescence of Er{sup 3+} lies within the wavelength window of minimal transmission-loss in silicon and has been widely utilized for signal amplification and generation in silicon photonics. The incorporation of Er{sup 3+} into VO{sub 2} could therefore result in a novel photonic material capable of simultaneous optical switching and amplification. In this work, we investigate the optical switching and photoluminescence in Er-implanted VO{sub 2} thin films. Thermally driven optical switching is demonstrated in the Er-implanted VO{sub 2} by infrared reflectometry. Photoluminescence is observed in the thin films annealed at ∼800 °C or above. In addition, Raman spectroscopy and a statistical analysis of switching hysteresis are carried out to assess the effects of the ion implantation on the VO{sub 2} thin films. We conclude that Er-implanted VO{sub 2} can function as an optical switch and amplifier, but with reduced switching quality compared to pure VO{sub 2}.

  3. Carbon dioxide and water adsorption on highly epitaxial Delafossite CuFeO2 thin film

    NASA Astrophysics Data System (ADS)

    Rojas, S.; Joshi, T.; Borisov, P.; Sarabia, M.; Lederman, D.; Cabrera, A. L.

    2015-03-01

    Thermal programmed desorption (TPD) of CO2 and H2O from a 200 nm thick CuFeO2 Delafossite surface was performed in a standard UHV chamber, The CuFeO2 thin film grown using Pulsed Laser Deposition (PLD) over an Al2O3 (0001) substrate with controlled O2 atmosphere resulted with highly epitaxial crystal structure. The adsorption/desorption of CO2 and H2O process was also monitored with X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). Our results revealed that carbon dioxide interacts with CuFeO2 forming Fe carbonates compounds on its surface. Hydroxides were also formed on the surface due to water presence. Using TPD data, Arrhenius plots for CO2 and water desorption were done and activation energy for desorption was obtained. Funds FONDECyT 1130372; Thanks to P. Ferrari.

  4. Current-modulated optical properties of vanadium dioxide thin films in the phase transition region

    SciTech Connect

    Zhang, Shuyan; Kats, Mikhail A.; Cui, Yanjie; Zhou, You; Yao, Yu; Ramanathan, Shriram; Capasso, Federico

    2014-11-24

    Vanadium dioxide (VO{sub 2}) is a correlated electron material which undergoes an insulator-metal transition proximal to room temperature. The large change of optical properties across this phase transition is promising for tunable optical and optoelectronic devices especially at infrared frequencies. We demonstrate the ability to locally tune the optical properties on the micron scale through a simple design consisting of two electrodes patterned on a VO{sub 2} thin film. By current injection between the electrodes, a localized conducting path (metallic phase) can be formed within the insulating background. The width of the conducting path can be controlled by varying the applied current. Fourier transform infrared imaging shows that this current-modulated reflectance changes significantly over a distance on the order of the wavelength in the mid-infrared spectral range.

  5. Titanium Isopropoxide Precursor Volume Consumption as a Function of Temperature for Titanium Dioxide Thin Films Grown by Atomic Layer Deposition

    NASA Astrophysics Data System (ADS)

    Constantin, Costel

    2012-02-01

    Atomic layer deposition (ALD) offers tremendous opportunities for controlling material synthesis on an atomic level and for creating nanolayers with unique new functionalities. ALD is a chemical gas phase thin film deposition method based on alternating surface reactions that employs two or more precursors. ALD is often used for growth of high k dielectric constant oxide films. Titanium dioxide material have a k value of 80, and a band gap of ˜ 3 eV, and due to strong oxidizing properties thin films coated on construction materials and glass have fog proof, and self cleaning properties. Our ALD reactor employs liquid Titanium Isopropoxide [TiOCH(CH3)24] as a metal precursor and distilled H2O as an oxygen source to grow thin films of titanium dioxide [TiO2] on silicon [Si], gallium nitride [GaN], and Aluminium foil [Al-foil] substrates. Titanium Isopropoxide exhibit a vapor pressure surge above 40^o C and we report the volume precursor consumption as a function of precursor temperature and thin film thickness for ALD grown TiO2 on Si, GaN, and Al-foil substrates. We will also present dielectric constants of the TiO2 thin films measured with a variable angle spectroscopic ellipsometer.

  6. Lithium-inserted vanadium dioxide (LixVO2) thin films

    NASA Astrophysics Data System (ADS)

    Khan, Mohammad S. R.

    1996-04-01

    Thermochromic switching between a low-temperature and high-temperature less transparent state is possible in thin films based on vanadium dioxide (VO2). The critical temperature Tc at which the transition takes place in VO2 is on the order of 68 degrees Celsius which can be depressed towards a comfortable temperature by several techniques, including dopants. Dopants can be inserted by electrochemical means. This work is an exploratory study of the electrochromism of LixVO2 with a view to 'smart window' applications. Thin films of LixVO2 (0 less than or equal to x less than or equal to 0.43) were made by reactive sputtering and annealing electrolyte of LiClO4 and propylene carbonate. A maximum lithium content of x equals 0.43 was accomplished. Optical spectral response at wavelength pertinent to solar radiation was reported. Lithium insertion increased the transmittance gradually and reversibly i.e. LixVO2 showed electrochromism and bleached under Li insertion. LixVO2 also showed thermochroism, although to a smaller degree than VO2 and was most transparent at low temperature. Temperature- dependent electrical conductivity and thermoelectric power measurements were also performed. A conductivity transition by approximately 3 orders of magnitude was seen at approximately 60 degrees Celsius in VO2. This transition decreased in proportion with the amount of Li intercalation and was less than one order of magnitude in Li0.43VO2. Lithiation also decreased Tc by a few degrees Celsius. The thermoelectric power showed a well defined increase when Tc was exceeded.

  7. Ultrafast Pump-Probe Studies of the Light-Induced MIT and Recovery of Niobium Dioxide Thin Films

    NASA Astrophysics Data System (ADS)

    Beebe, Melissa; Klopf, J. Michael; Kittiwatanakul, Salinporn; Lu, Jiwei; Wolf, Stuart A.; Lukaszew, R. Alejandra

    Niobium dioxide (NbO2) is a highly correlated binary oxide that, like vanadium dioxide (VO2) , exhibits a first-order insulator-to-metal transition (IMT) at a material-dependent critical temperature, accompanied by a structural transformation from monoclinic to rutile. The nature of the IMT in VO2 has been discussed at length, while fewer studies have been carried out on NbO2. Previous studies show that the IMT can also be optically induced in VO2 on a sub-picosecond timescale; here, we present the first ultrafast pump-probe studies showing this optically-induced transition in NbO2 thin films and compare these results to similar ones carried out on VO2 thin films.

  8. Defect-mediated room temperature ferromagnetism in vanadium dioxide thin films

    NASA Astrophysics Data System (ADS)

    Yang, Tsung-Han; Nori, Sudhakar; Zhou, Honghui; Narayan, Jagdish

    2009-09-01

    High quality epitaxial undoped vanadium oxide (VO2) thin films on c-plane sapphire (0001) substrate have been grown using pulsed laser deposition technique. The as-grown films exhibited excellent structural and transport properties without requiring further annealing treatments for these oxygen-deficient oxide films. The epitaxial growth has been achieved via domain matching epitaxy, where matching of integral multiples of planes occurs across the film-substrate interface. The magnetic properties of vanadium oxide (VO2) films investigated at different temperatures in the range of 10-360 K showed significant magnetic hysteresis as well as saturation of the magnetic moment. The origin of ferromagnetic properties with an estimated Curie temperature above 500 K is discussed in the absence of magnetic impurities in VO2 thin films as determined by x-ray photoelectron spectroscopy, x-ray diffraction, and transmission electron microscopy.

  9. Epitaxial niobium dioxide thin films by reactive-biased target ion beam deposition

    SciTech Connect

    Wang, Yuhan; Comes, Ryan B.; Kittiwatanakul, Salinporn; Wolf, Stuart A.; Lu, Jiwei

    2015-03-01

    Epitaxial NbO2 thin films were synthesized on Al2O3 (0001) substrates via reactive bias target ion beam deposition. X-ray diffraction and Raman spectra were used to confirm the tetragonal phase of pure NbO2. Through XPS, it was found that there was a ~ 1.3 nm thick Nb2O5 layer on the surface and the bulk of the thin film was NbO2. The epitaxial relationship between NbO2 film and substrate was determined. Electrical transport measurement as a function of temperature showed that the conduction mechanism could be described by variable range hopping mechanism.

  10. Effect of porous morphology on phase transition in vanadium dioxide thin films

    SciTech Connect

    Xu, Hui Yan; Ma, Fei; Huang, Yu Hong; Li, Jin Ping; Xu, Ke Wei

    2015-11-15

    Vanadium oxide (VO{sub 2}) thin films were prepared on Si (100) substrates by direct current magnetron sputtering at room temperature, and then, postannealing was conducted at 450 °C for 2 h in vacuum. Structural characterizations demonstrated that the thin films exhibited porous morphology upon thermal annealing and the porosity and pore size depended on the oxygen flow rate in the process of film fabrication. Raman spectra were measured in the temperature range of 303–343 K, and resistance measurement was conducted in the temperature range of 293–363 K, to study the influence of porous morphology on the phase transition in VO{sub 2} thin films. It was illustrated that the porous morphology could provide a free space to release the stress induced in the monoclinic-to-tetragonal phase transition of VO{sub 2}, and lower the transition temperature to a certain degree.

  11. Photooxidation of organic impurities in water using thin films of titanium dioxide

    SciTech Connect

    Matthews, R.W.

    1987-06-04

    Results of the destruction of organic solutes in a simple, thin film TiO2 reactor are described. The reactor was illuminated with a 20-W blacklight UV fluorescent tube and the aqueous stream containing the organic solute flowed past the stationary photocatalyst. In the continuous recirculation mode, the destructive rate of each solute obeyed approximately first-order kinetics. The reaction rate constant decreased with increasing solute concentration. The times for 50% destruction of 500 cmT of 10 M solutions of each of the solutes salicylic acid, phenol, 2-chlorophenol, 4-chlorophenol, benzoic acid, 2-naphthol, naphthalene, and fluorescein were 7.1, 7.2, 8.2, 8.7, 6.9, 8.5, 4.3, and 6.4 min, respectively. It was found that the observed apparent first-order dependence and the change in rate constant with concentration could by explained in terms of the integrated form of the Langmuir adsorption isotherm. A marked dependence of the destruction rate on flow rate was observed and an expression developed which allows the calculation of the destruction curve with good precision at any solute concentration and flow rate. A corresponding curve was observed for the formation of carbon dioxide from salicylic acid solution. It was shown that hydroxylation of the aromatic ring to give salicylic acid is a minor reaction path in the destruction of benzoic acid. The maximum quantum yield for the destruction of salicyclic acid at 25C was found to be 0.022. The activation energy for the photooxidation of salicyclic acid was determined to be 11.0 +/- 0.8 kJ mol .

  12. Dynamic optical limiting experiments on vanadium dioxide and vanadium pentoxide thin films irradiated by a laser beam

    SciTech Connect

    Wang Weiping; Luo Yongquan; Zhang Dayong; Luo Fei

    2006-05-10

    Vanadium dioxide (VO2) and vanadium pentoxide (V2O5) thin films are irradiated by a near-infrared continuous-wave laser beam and the dynamic optical limiting performance is measured. The temperature varying with time of the films induced by a laser beam is also recorded by an IR thermal sensor. Under the irradiation of a laser beam with an intensity of 255 W/cm2 and a spot diameter of 2 mm, the laser beam transmittance of the VO2 film decreases from 47% before phase transition to 28% after phase transition, and the response time is {approx}200 ms; the laser beam transmittance of the V2O5 film decreases from 51% before phase transition to 24% after phase transition, and the response time is {approx}40 ms. The optical limiting is realized by this laser heating-induced phase transition.

  13. Bench Scale Thin Film Composite Hollow Fiber Membranes for Post-Combustion Carbon Dioxide Capture

    SciTech Connect

    Glaser, Paul; Bhandari, Dhaval; Narang, Kristi; McCloskey, Pat; Singh, Surinder; Ananthasayanam, Balajee; Howson, Paul; Lee, Julia; Wroczynski, Ron; Stewart, Frederick; Orme, Christopher; Klaehn, John; McNally, Joshua; Rownaghi, Ali; Lu, Liu; Koros, William; Goizueta, Roberto; Sethi, Vijay

    2015-04-01

    GE Global Research, Idaho National Laboratory (INL), Georgia Institute of Technology (Georgia Tech), and Western Research Institute (WRI) proposed to develop high performance thin film polymer composite hollow fiber membranes and advanced processes for economical post-combustion carbon dioxide (CO2) capture from pulverized coal flue gas at temperatures typical of existing flue gas cleanup processes. The project sought to develop and then optimize new gas separations membrane systems at the bench scale, including tuning the properties of a novel polyphosphazene polymer in a coating solution and fabricating highly engineered porous hollow fiber supports. The project also sought to define the processes needed to coat the fiber support to manufacture composite hollow fiber membranes with high performance, ultra-thin separation layers. Physical, chemical, and mechanical stability of the materials (individual and composite) towards coal flue gas components was considered via exposure and performance tests. Preliminary design, technoeconomic, and economic feasibility analyses were conducted to evaluate the overall performance and impact of the process on the cost of electricity (COE) for a coal-fired plant including capture technologies. At the onset of the project, Membranes based on coupling a novel selective material polyphosphazene with an engineered hollow fiber support was found to have the potential to capture greater than 90% of the CO2 in flue gas with less than 35% increase in COE, which would achieve the DOE-targeted performance criteria. While lab-scale results for the polyphosphazene materials were very promising, and the material was incorporated into hollow-fiber modules, difficulties were encountered relating to the performance of these membrane systems over time. Performance, as measured by both flux of and selectivity for CO2 over other flue gas constituents was found to deteriorate over time, suggesting a system that was

  14. Structural and optical characterisation of tin dioxide thin films by sol-gel dip coating technique

    NASA Astrophysics Data System (ADS)

    Lekshmy, S. Sujatha; Berlin, I. John; Maneeshya, L. V.; Anitha; Joy, K.

    2015-02-01

    Tin oxide (SnO2) thin films were deposited on quartz substrates using sol-gel dip coating technique. X-ray diffraction (XRD) pattern indicated that the film annealed in air at 350°C was amorphous in nature, whereas, the films annealed in oxygen atmosphere at 350°C showed crystalline phase. The films were further annealed in oxygen atmosphere at 450°C and 550°C. All the diffraction peaks can be indexed to the tetragonal phase of SnO2 The surface morphology (SEM) showed that surface of all films were continuous and without micro cracks. The Energy dispersive X-ray spectroscopy (EDXS) spectra indicated an increase in the concentration of oxygen content with increase in annealing temperature. The energy band gap value for the film annealed in air was 3.88 eV. The optical band gap increased to 4.05 eV when annealed in O2 atmosphere. The photoluminescence (PL) spectra showed the presence of emission peaks in UV region and visible region of the electromagnetic spectra. Transparent oxide semiconductor SnO2 film finds potential application as an active channel layer for transparent thin film transistor.

  15. High-quality germanium dioxide thin films with low interface state density using a direct neutral beam oxidation process

    NASA Astrophysics Data System (ADS)

    Wada, Akira; Zhang, Rui; Takagi, Shinichi; Samukawa, Seiji

    2012-05-01

    High-quality germanium dioxide (GeO2) as a gate oxide is in high demand for use in future high mobility Ge-channel field-effect transistors. GeO2 thin films were directly formed by using a damage-free and low-temperature process of neutral beam oxidation (NBO) after treatment with hydrogen (H) radicals. GeO2 thin films (equivalent oxide thickness (EOT) = 1.7 nm) with a high-quality interface and an extremely low interface state density (<1 × 1011 cm-2 eV-1) could be formed even at low temperature (300 °C) by combining the H radical treatment, which resulted in the removal of native oxides, with the NBO process we developed.

  16. Titanium dioxide-coated fluorine-doped tin oxide thin films for improving overall photoelectric property

    NASA Astrophysics Data System (ADS)

    Li, Bao-jia; Huang, Li-jing; Ren, Nai-fei; Zhou, Ming

    2014-01-01

    Titanium (Ti) layers were deposited by direct current (DC) magnetron sputtering on commercial fluorine-doped tin oxide (FTO) glasses, followed by simultaneous oxidation and annealing treatment in a tubular furnace to prepare titanium dioxide (TiO2)/FTO bilayer films. Large and densely arranged grains were observed on all TiO2/FTO bilayer films. The presence of TiO2 tetragonal rutile phase in the TiO2/FTO bilayer films was confirmed by X-ray diffraction (XRD) analysis. The results of parameter optimization indicated that the TiO2/FTO bilayer film, which was formed by adopting a temperature of 400 °C and an oxygen flow rate of 15 sccm, had the optimal overall photoelectric property with a figure of merit of 2.30 × 10-2 Ω-1, higher than 1.78 × 10-2 Ω-1 for the FTO single-layer film. After coating a 500 nm-thick AZO layer by DC magnetron sputtering on this TiO2/FTO bilayer film, the figure of merit of the trilayer film achieved to a higher figure of merit of 3.12 × 10-2 Ω-1, indicating further improvement of the overall photoelectric property. This work may provide a scientific basis and reference for improving overall photoelectric property of transparent conducting oxide (TCO) films.

  17. Vanadium dioxide thin films prepared on silicon by low temperature MBE growth and ex-situ annealing

    NASA Astrophysics Data System (ADS)

    Homm, Pia; van Bilzen, Bart; Menghini, Mariela; Locquet, Jean-Pierre; Ivanova, Todora; Sanchez, Luis; Sanchis, Pablo

    Vanadium dioxide (VO2) is a material that shows an insulator to metal transition (IMT) near room temperature. This property can be exploited for applications in field effect devices, electro-optical switches and nonlinear circuit components. We have prepared VO2 thin films on silicon wafers by combining a low temperature MBE growth with an ex-situ annealing at high temperature. We investigated the structural, electrical and optical characteristics of films with thicknesses ranging from 10 to 100 nm. We have also studied the influence of the substrate cleaning. The films grown with our method are polycrystalline with a preferred orientation in the (011) direction of the monoclinic phase. For the films produced on silicon with a native oxide, an IMT at around 75 °C is observed. The magnitude of the resistance change across the IMT decreases with thickness while the refractive index at room temperature corresponds with values reported in the literature for thin films. The successful growth of VO2 films on silicon with good electrical and optical properties is an important step towards the integration of VO2 in novel devices. The authors acknowledge financial support from the FWO project G052010N10 and EU-FP7 SITOGA project. PH acknowledges support from Becas Chile - CONICYT.

  18. Thin Film?

    NASA Astrophysics Data System (ADS)

    Kariper, İ. Afşin

    2014-09-01

    This study focuses on the critical surface tension of lead sulfite (PbSO3) crystalline thin film produced with chemical bath deposition on substrates (commercial glass).The PbSO3 thin films were deposited at room temperature at different deposition times. The structural properties of the films were defined and examined according to X-ray diffraction (XRD) and the XRD results such as dislocation density, average grain size, and no. of crystallites per unit area. Atomic force microscopy was used to measure the film thickness and the surface properties. The critical surface tension of the PbSO3 thin films was measured with an optical tensiometer instrument and calculated using the Zisman method. The results indicated that the critical surface tension of films changed in accordance with the average grain size and film thickness. The film thickness increased with deposition time and was inversely correlated with surface tension. The average grain size increased according to deposition time and was inversely correlated with surface tension.

  19. Epitaxial niobium dioxide thin films by reactive-biased target ion beam deposition

    SciTech Connect

    Wang, Yuhan Kittiwatanakul, Salinporn; Lu, Jiwei; Comes, Ryan B.; Wolf, Stuart A.

    2015-03-15

    Epitaxial NbO{sub 2} thin films were synthesized on Al{sub 2}O{sub 3} (0001) substrates via reactive bias target ion beam deposition. X-ray diffraction and Raman spectra were used to confirm the tetragonal phase of pure NbO{sub 2}. Through XPS, it was found that there was a ∼1.3 nm thick Nb{sub 2}O{sub 5} layer on the surface and the bulk of the thin film was NbO{sub 2}. The epitaxial relationship between the NbO{sub 2} film and the substrate was determined. Electrical transport measurement was measured up to 400 K, and the conduction mechanism was discussed.

  20. Deodorisation effect of diamond-like carbon/titanium dioxide multilayer thin films deposited onto polypropylene

    NASA Astrophysics Data System (ADS)

    Ozeki, K.; Hirakuri, K. K.; Masuzawa, T.

    2011-04-01

    Many types of plastic containers have been used for the storage of food. In the present study, diamond-like carbon (DLC)/titanium oxide (TiO2) multilayer thin films were deposited on polypropylene (PP) to prevent flavour retention and to remove flavour in plastic containers. For the flavour removal test, two types of multilayer films were prepared, DLC/TiO2 films and DLC/TiO2/DLC films. The residual gas concentration of acetaldehyde, ethylene, and turmeric compounds in bottle including the DLC/TiO2-coated and the DLC/TiO2/DLC-coated PP plates were measured after UV radiation, and the amount of adsorbed compounds to the plates was determined. The percentages of residual gas for acetaldehyde, ethylene, and turmeric with the DLC/TiO2 coated plates were 0.8%, 65.2% and 75.0% after 40 h of UV radiation, respectively. For the DLC/TiO2/DLC film, the percentages of residual gas for acetaldehyde, ethylene and turmeric decreased to 34.9%, 76.0% and 85.3% after 40 h of UV radiation, respectively. The DLC/TiO2/DLC film had a photocatalytic effect even though the TiO2 film was covered with the DLC film.

  1. Idiosyncrasies of Physical Vapor Deposition Processes from Various Knudsen Cells for Quinacridone Thin Film Growth on Silicon Dioxide

    PubMed Central

    2015-01-01

    Thin films of quinacridone deposited by physical vapor deposition on silicon dioxide were investigated by thermal desorption spectroscopy (TDS), mass spectrometry (MS), atomic force microscopy (AFM), specular and grazing incidence X-ray diffraction (XRD, GIXD), and Raman spectroscopy. Using a stainless steel Knudsen cell did not allow the preparation of a pure quinacridone film. TDS and MS unambiguously showed that in addition to quinacridone, desorbing at about 500 K (γ-peak), significant amounts of indigo desorbed at about 420 K (β-peak). The existence of these two species on the surface was verified by XRD, GIXD, and Raman spectroscopy. The latter spectroscopies revealed that additional species are contained in the films, not detected by TDS. In the film mainly composed of indigo a species was identified which we tentatively attribute to carbazole. The film consisting of mainly quinacridone contained in addition p-sexiphenyl. The reason for the various decomposition species effusing from the metal Knudsen cell is the comparably high sublimation temperature of the hydrogen bonded quinacridone. With special experimental methods and by using glass Knudsen-type cells we were able to prepare films which exclusively consist of molecules either corresponding to the β-peak or the γ-peak. These findings are of relevance for choosing the proper deposition techniques in the preparation of quinacridone films in the context of organic electronic devices. PMID:26401189

  2. Formation of titanium monoxide (001) single-crystalline thin film induced by ion bombardment of titanium dioxide (110)

    NASA Astrophysics Data System (ADS)

    Pabón, B. M.; Beltrán, J. I.; Sánchez-Santolino, G.; Palacio, I.; López-Sánchez, J.; Rubio-Zuazo, J.; Rojo, J. M.; Ferrer, P.; Mascaraque, A.; Muñoz, M. C.; Varela, M.; Castro, G. R.; de La Fuente, O. Rodríguez

    2015-02-01

    A plethora of technological applications justify why titanium dioxide is probably the most studied oxide, and an optimal exploitation of its properties quite frequently requires a controlled modification of the surface. Low-energy ion bombardment is one of the most extended techniques for this purpose and has been recently used in titanium oxides, among other applications, to favour resistive switching mechanisms or to form transparent conductive layers. Surfaces modified in this way are frequently described as reduced and defective, with a high density of oxygen vacancies. Here we show, at variance with this view, that high ion doses on rutile titanium dioxide (110) induce its transformation into a nanometric and single-crystalline titanium monoxide (001) thin film with rocksalt structure. The discovery of this ability may pave the way to new technical applications of ion bombardment not previously reported, which can be used to fabricate heterostructures and interfaces.

  3. Structure and interaction of polymer thin films with supercritical carbon dioxide

    NASA Astrophysics Data System (ADS)

    Sirard, Stephen Michael

    2003-06-01

    An understanding of colloid stability in CO2 as well as the interaction of CO2 with polymer thin films is necessary for the intelligent design of CO2-based processes for future materials applications. In-situ spectroscopic ellipsometry (SE) was used to measure the thickness and optical properties of nanoscale poly(dimethylsiloxane) (PDMS) and poly(methyl methacrylate) films exposed to compressed CO2 . Both the sorption and CO2-induced dilation of the thin films were measured simultaneously with SE and deviations between the thin films and the corresponding bulk films may be attributed to excess CO 2 at the free interface as well as the influence of film confinement and the compressible nature of CO2 on the orientation and mobility of the polymers. SE was also used to measure sorption equilibrium and kinetics and CO2-induced dilation of polyimide (6FDA-DAM:DABA 2:1) thin films to determine how a gas separation membrane's structure affects its susceptibility to CO2-induced plasticization. Both thermal annealing and chemical crosslinking reduced the polymer dilation to prevent large increases in the CO2 diffusion coefficient at high CO2 pressures. The CO2 permeability and polymer free volume strongly depend on the annealing temperature, and different effects are observed for the crosslinked and uncrosslinked membranes and for the thick and thin membranes. Neutron reflectivity (NR) and SE were used to characterize the structure of end-grafted d-PDMS brushes on SiOx wafers exposed to compressed CO2. NR revealed two distinct regions in the segment density profile as a function of distance from the surface. The thickness and volume fraction profiles for the brush change much more with solvent quality than has been seen in previous studies with incompressible solvents, due to the high asymmetry in the intermolecular interactions, as well as the large compressibility and free volume differences between the polymer segments and the solvent. Turbidity versus time measurements

  4. Thin Films

    NASA Astrophysics Data System (ADS)

    Khorshidi, Zahra; Bahari, Ali; Gholipur, Reza

    2014-11-01

    Effect of annealing temperature on the characteristics of sol-gel-driven Ta ax La(1- a) x O y thin film spin-coated on Si substrate as a high- k gate dielectric was studied. Ta ax La(1- a) x O y thin films with different amounts of a were prepared (as-prepared samples). X-ray diffraction measurements of the as-prepared samples indicated that Ta0.3 x La0.7 x Oy film had an amorphous structure. Therefore, Ta0.3 x La0.7 x O y film was chosen to continue the present studies. The morphology of Ta0.3 x La0.7 x O y films was studied using scanning electron microscopy and atomic force microscopy techniques. The obtained results showed that the size of grain boundaries on Ta0.3 x La0.7 x O y film surfaces was increased with increasing annealing temperature. Electrical and optical characterizations of the as-prepared and annealed films were investigated as a function of annealing temperature using capacitance-voltage ( C- V) and current density-voltage ( J- V) measurements and the Tauc method. The obtained results demonstrated that Ta0.3 x La0.7 x O y films had high dielectric constant (≈27), wide band gap (≈4.5 eV), and low leakage current density (≈10-6 A/cm2 at 1 V).

  5. Photocatalytic anatase titanium dioxide thin films deposition by an atmospheric pressure blown arc discharge

    NASA Astrophysics Data System (ADS)

    Boscher, Nicolas D.; Olivier, Sébastien; Maurau, Rémy; Bulou, Simon; Sindzingre, Thierry; Belmonte, Thierry; Choquet, Patrick

    2014-08-01

    TiO2 thin films are deposited by means of an atmospheric pressure blown arc discharge fed with nitrogen and titanium bis(acetylacetonate) diisopropoxide (TIPO) as precursor. Different power densities and distances between the plasma nozzle, the precursor injector and the substrate are investigated and different morphologies, compositions and crystallinities of the coatings are generated. The photocatalytic properties of the coatings, determined from the degradation of stearic acid shined by a 254 nm UV light, are shown to be strongly related to the film characteristic and therefore to the deposition parameters.

  6. Influence of ferroelectric substrates on the photochemical reactivity of titanium dioxide thin films

    NASA Astrophysics Data System (ADS)

    Burbure, Nina

    The efficiency of particulate photocatalysts used to split water is limited by the recombination of photogenerated electrons and holes and the back reaction of intermediate species to reform water. This efficiency could be improved by better spatial separation of charge carriers and reaction sites. The primary goal of this work is to test the hypothesis that dipolar fields in ferroelectric substrates can drive photogenerated electrons and holes in opposite directions, thus creating spatially distinct locations for photochemical oxidation and reduction reactions on the surfaces of supported TiO2 thin films. To investigate this, thin films of TiO2 (10 to 100 nm) were grown on polycrystalline, ferroelectric BaTiO3 and BiFeO3 substrates by pulsed laser deposition. The films grown on BaTiO 3 were characterized by electron backscatter diffraction, which showed that some substrate orientations stabilize the anatase phase while others stabilize rutile. Specifically, orientations within about 25° of (100) BaTiO3 promote the growth of biaxially orientated anatase such that [001] BaTiO3 is parallel to [001] anatase and [110] BaTiO3 is parallel to [110] anatase. Orientations further from (100) stabilize the growth or rutile. While the rutile growth is epitaxial, there is no single orientation relationship. The photochemical properties of the surface were probed using the photochemical reduction of Ag+ to Ag0 and the photochemical oxidation of Pb2+ to Pb4+ These specific oxidation and reduction reactions were chosen because they leave behind insoluble reaction products (Ag and PbO2) on the surface that allow the location of the reaction to be determined. The same locations of the surface were imaged by atomic force microscopy before and after the reaction and the heights of the reaction product on the surface were used as a measure of the extent of the reactivity. In this study, we found that the ferroelectric substrate does influence reactivity on the surface of the thin film

  7. The Reactions of Acetone with the Surfaces of Uranium Dioxide Single Crystal and Thin Film

    SciTech Connect

    King,R.; Senanayake, S.; Chong, S.; Idriss, H.

    2007-01-01

    The reaction of acetone, as an example of a carbonyl compound, is studied over UO2 (1 1 1) single crystal and thin film surfaces. Over the stoichiometric single crystal surface, acetone is molecularly and weakly adsorbed with a computed activation energy for desorption in the range of 95-65 kJ/mol with pre-exponential factors between 1011 and 1013 s-1. On the contrary, acetone reacts very strongly on the O-defected single crystal and thin film surfaces. In addition to total decomposition evidence of aldolization and cyclization reactions were seen. The thin film of UO2 was studied by synchrotron light, providing high resolution photoelectron spectroscopy in the core level, and high sensitivity in the both the core and valence band regions. The U5f line was considerably enhanced at grazing angle when compared to that obtained at normal angle for the O-defected surface, showing that the surface is more reduced than the next layers. The U 4f lines indicated the presence of U cations in lower oxidation states than +4 for the O-defected surface. These lines were considerably attenuated upon adsorption of acetone, due to surface oxidation by C{double_bond}O bond dissociation. The reaction pathway for acetone on the O-defected surface is presented, and compared to that of the previously studied acetaldehyde molecule.

  8. Bidirectional laser triggering in highly-resistive vanadium-dioxide thin films by using a 966-nm pump laser diode

    NASA Astrophysics Data System (ADS)

    Kim, Jihoon; Kim, Bong-Jun; Yu, Bong-Ahn; Kang, Hyun Wook; Nam, Seung Yun; Oh, Junghwan; Lee, Yong Wook

    2016-01-01

    By incorporating a 966-nm pump laser diode, we realized bidirectional laser triggering in a twoterminal planar device based on a highly-resistive vanadium-dioxide (VO2) thin film grown by using the pulsed laser deposition method. Bidirectional laser triggering of up to 10 mA was achieved by directly illuminating the VO2 film with a focused infrared laser beam, and the transient responses of the laser-triggered currents were analyzed. A switching contrast between the off-state and the on-state currents was measured as ˜3571, and the rising and the falling times were measured as ˜40 and ˜20 ms, respectively, when laser pulses with a pulse width of 100 ms excited the VO2-based device.

  9. Ferromagnetic resonance of patterned chromium dioxide thin films grown by selective area chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Durrant, C. J.; Jokubaitis, M.; Yu, W.; Mohamad, H.; Shelford, L. R.; Keatley, P. S.; Xiao, Gang; Hicken, R. J.

    2015-05-01

    A selective area chemical vapour deposition technique has been used to fabricate continuous and patterned epitaxial CrO2 thin films on (100)-oriented TiO2 substrates. Precessional magnetization dynamics were stimulated both electrically and optically, and probed by means of time-resolved Kerr microscopy and vector network analyser ferromagnetic resonance techniques. The dependence of the precession frequency and the effective damping parameter upon the static applied magnetic field were investigated. All films exhibited a large in-plane uniaxial anisotropy. The effective damping parameter was found to exhibit strong field dependence in the vicinity of the hard axis saturation field. However, continuous and patterned films were found to possess generally similar dynamic properties, confirming the suitability of the deposition technique for fabrication of future spintronic devices.

  10. Role of annealing temperatures on structure polymorphism, linear and nonlinear optical properties of nanostructure lead dioxide thin films

    NASA Astrophysics Data System (ADS)

    Zeyada, H. M.; Makhlouf, M. M.

    2016-04-01

    The powder of as synthesized lead dioxide (PbO2) has polycrystalline structure β-PbO2 phase of tetragonal crystal system. It becomes nanocrystallites α-PbO2 phase with orthorhombic crystal system upon thermal deposition to form thin films. Annealing temperatures increase nanocrystallites size from 28 to 46 nm. The optical properties of α-PbO2 phase were calculated from absolute values of transmittance and reflectance at nearly normal incidence of light by spectrophotometer measurements. The refractive and extinction indices were determined and showed a response to annealing temperatures. The absorption coefficient of α-PbO2 films is >106 cm-1 in UV region of spectra. Analysis of the absorption coefficient spectra near optical edge showed indirect allowed transition. Annealing temperature decreases the value of indirect energy gap for α-PbO2 films. The dispersion parameters such as single oscillator energy, dispersion energy, dielectric constant at high frequency and lattice dielectric constant were calculated and its variations with annealing temperatures are reported. The nonlinear refractive index (n2), third-order nonlinear susceptibility (χ(3)) and nonlinear absorption coefficient (βc) were determined. It was found that χ(3), n2 and β increase with increasing photon energy and decrease with increasing annealing temperature. The pristine film of α-PbO2 has higher values of nonlinear optical constants than for annealed films; therefore it is suitable for applications in manufacturing nonlinear optical devices.

  11. Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications.

    PubMed

    Skuza, J R; Scott, D W; Mundle, R M; Pradhan, A K

    2016-01-01

    We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5-10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT. PMID:26884225

  12. Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications

    NASA Astrophysics Data System (ADS)

    Skuza, J. R.; Scott, D. W.; Mundle, R. M.; Pradhan, A. K.

    2016-02-01

    We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5-10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT.

  13. Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications

    PubMed Central

    Skuza, J. R.; Scott, D. W.; Mundle, R. M.; Pradhan, A. K.

    2016-01-01

    We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5–10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT. PMID:26884225

  14. Dye sensitized solar cells based on nanowire sculptured thin film titanium dioxide photoanodes

    NASA Astrophysics Data System (ADS)

    Pursel, Sean M.

    Energy harvested from the sun using photovoltaics (PVs) is a renewable resource in high demand. Photovoltaics convert photons into electron-hole pairs which are then separated and used for electrical power. 75 TW of energy arrives from the sun every year onto US soil. Harvesting it all would provide enough energy to power the entire world for more than five years. It is this abundance of energy that makes PVs an attractive alternative to fossil fuels. PVs currently produce 0.15% of the energy consumed in the US. Production needs to grow as the worldwide demand for energy is projected to almost double by 2050. Fundamental and device based PV research have made steady efficiency gains in silicon based devices and thin film devices have started to become commercially viable. However, less expensive devices with suitable efficiency have not been fully developed. Dye sensitized solar cells (DSSCs) are one such device which has been optimized using standard components. However, device efficiency has not increased significantly since DSSCs were first conceived in 1991. Interestingly, none of the standard components are optimized, but act in a synergistic way in the most efficient devices. This research, along with other parallel research, attempts to optimize a single component of DSSCs with the goal of combining efforts to produce a device with increased efficiency. This research attempts to optimize the TiO2 photoanode used in DSSCs in terms of electron collection, dye coverage, light harvesting, and novel electrolyte infiltration by replacing the standard colloidal structure with nanowires deposited using physical vapor deposition at an oblique angle to form sculptured thin films. The results are quantified through standard photovoltaic testing, electrochemical impedance spectroscopy, UV-Vis-NIR spectroscopy, and general materials characterization techniques. The nanowire photoanodes are engineered during deposition using reactive evaporation, substrate heating

  15. Infrared reflectance and photoemission spectroscopy studies across the phase transition boundary in thin film vanadium dioxide

    SciTech Connect

    Ruzmetov, Dmitry; Zawilski, Kevin; Senanayake, Sanjaya D; Narayanamurti, Venkatesh; Ramanathan, Shriram

    2008-01-01

    Optical properties and valence band density of states near the Fermi level of high-quality VO2 thin films have been investigated by mid-infrared reflectometry and hard-UV (h = 150 eV) photoemission spectroscopy. An exceptionally large change in reflectance from 2 to 94% is found upon the thermally driven metal insulator transition (MIT). The infrared dispersion spectra of the reflectance across the MIT are presented and evidence for the percolative nature of the MIT is pointed out. The discrepancy between the MIT temperatures defined from the electrical and optical properties is found and its origin is discussed. The manifestation of the MIT is observed in the photoemission spectra of the V 3d levels. The analysis of the changes of the V 3d density of states is done and the top valence band shift upon the MIT is measured to be 0.6 eV.

  16. Thermopower analysis of metal-insulator transition temperature modulations in vanadium dioxide thin films with lattice distortion

    NASA Astrophysics Data System (ADS)

    Katase, Takayoshi; Endo, Kenji; Ohta, Hiromichi

    2015-07-01

    Insulator-to-metal (MI) phase transition in vanadium dioxide (V O2) thin films with controlled lattice distortion was investigated by thermopower measurements. V O2 epitaxial films with different crystallographic orientations, grown on (0001 ) α -A l2O3 , (11 2 ¯0 ) α -A l2O3 , and (001 ) Ti O2 substrates, showed significant decrease of absolute value of Seebeck coefficient (S ) from ˜200 to 23 μ V K-1 , along with a sharp drop in electrical resistivity (ρ ) , due to the transition from an insulator to a metal. The MI transition temperatures observed both in ρ (Tρ) and S (TS) for the V O2 films systematically decrease with lattice shrinkage in the pseudorutile structure along the c axis, accompanying a broadening of the MI transition temperature width. Moreover, the onset TS, where the insulating phase starts to become metallic, is much lower than the onset Tρ. This difference is attributed to the sensitivity of S for the detection of hidden metallic domains in the majority insulating phase, which cannot be detected in ρ measurements. Consequently, S measurements provide a straightforward and excellent approach for a deeper understanding of the MI transition process in V O2 .

  17. Semiconductor-to-metal Transition Control in Novel Vanadium Dioxide/Silicon and Vanadium Dioxide/Sapphire Epitaxial Thin Film Heterostructures for Device Applications

    NASA Astrophysics Data System (ADS)

    Gupta, Alok

    Novel functionalities of Vanadium dioxide (VO2), such as, several orders of magnitude transition in resistivity and IR transmittance, provide an exciting opportunity for the development of next generation memory, sensor, and field-effect based devices. A critical issue in the development of practical devices based on metal oxides is the integration of high quality epitaxial oxide thin films with the existing silicon technology which is based on silicon (100) substrates. However, silicon is not suitable for epitaxial growth of oxides owing to its tendency to readily form an amorphous oxide layer or silicide at the film-substrate interface. The oxide films deposited directly on silicon exhibit poor crystallinity and are not suitable for device applications. To overcome this challenge, appropriate substrate templates must be developed for the growth of oxide thin films on silicon substrates. The primary objective of this dissertation was to develop an integration methodology of VO2 with Si (100) substrates so they could be used in "smart" sensor type of devices along with other multifunctional devices on the same silicon chip. This was achieved by using yttria-stabilized zirconia (YSZ) template layer deposited in situ. It will be shown that if the deposition conditions are controlled properly, YSZ can be grown epitaxially on silicon substrates even if the native oxide is not etched completely prior to deposition. I have used this approach to integrate VO2 thin films with Si (100) substrates using pulsed laser deposition (PLD) technique. The deposition methodology of integrating VO2 thin films on silicon using various other template layers will also be discussed. The detailed x-ray diffraction, transmission electron microscopy (TEM), electrical characterization results for the deposited films will be presented. In the framework on domain matching epitaxy, epitaxial growth of VO2 (tetragonal crystal structure at growth temperature) on both tetragonal and cubic YSZ has

  18. Characterizing the sensitivity, selectivity, and reversibility of the metal-doped phthalocyanine thin-films used with the Interdigitated Gate Electrode Field-Effect Transistor (IGEFET) to detect organophosphorous compounds and nitrogen dioxide

    NASA Astrophysics Data System (ADS)

    Howe, Clayton P.

    1991-12-01

    This study investigated the sensitivity, reversibility, and selectivity of the thin film coatings used on the interdigitated gate electrode field effect transistor (IGEFET) gas microsensor. These responses were quantified based on the dc resistance changes and frequency domain responses of the microsensor. The thin film materials included: copper phthalocyanine (CuPc), nickel phthalocyanine (NiPc), and cobalt phthalocyanine (CoPc). The challenge gases included: diisopropyl methylphosphonate (DIMP), dimethyl methylphosphonate (DMMP), nitrogen dioxide, ammonia, and boron trifluoride. Tests of the CuPc thin films and nitrogen dioxide challenges established the primary set of test parameters expected to maximize the selectivity, sensitivity, and reversibility of the thin film coatings. A series of experiments performed at 150 C tested the other thin film materials, on the IGEFET sensors, when challenged by listed gases. At 150 C, the nitrogen dioxide and ammonia interacted with all three film types, the boron trifluoride interacted weakly, the DIMP and DMMP show no response.

  19. Mixed-Phase Solidification of Thin Silicon Films on Silicon Dioxide

    NASA Astrophysics Data System (ADS)

    Chahal, Monica

    In this thesis, we present a new beam-induced melt-mediated crystallization process called mixed-phase solidification (MPS) that can produce defect-free, large-grain polycrystalline-Si films with strong (100)-surface texture (>99%) on SiO2. Such a combination of microstructural attributes makes the resulting MPS material well-suited for high-performance electronic and photovoltaic applications. A systematic parametric study of the single- and multi-scan MPS process is performed using thin Si films on SiO2 irradiated via a continuous-wave (CW) laser system. We employ an in situ microscopic viewing system to directly observe and understand melting and solidification during the MPS process. Additionally, in order to investigate the grain boundary melting phenomenon, we have conducted “rapid-quench” demarcation experiments and established a one-to-one correspondence between the in situ data and the single-/multi-scan MPS processed microstructure. The experimental results show an incremental increase in grain size and (100)-surface texture with an increase in scan number. The grain size is found to reach an apparent soft saturation value as the number of scans increases. For a given number of scans, a decrease in power or an increase in velocity is found to decrease the grain size and (100)-surface texture. Increases in film thickness lead to an increase in grain size, but a reduction in (100)-surface texturing. Based on what we have experimentally observed, as well as what has been previously established regarding the radiative-melting of Si, we propose a thermodynamic model to account for the microstructural evolution observed in the MPS process (i.e., partial-melting and solidification of polycrystalline-Si films). The model is built on two fundamental considerations: (1) the near-equilibrium environment within which thermodynamic factors dominate the transitions, and (2) the dynamically balanced, yet continuously changing, thermal surroundings. According to our

  20. Dye-sensitization of titanium dioxide thin films by Ru(II)-bpp-bpy complexes

    NASA Astrophysics Data System (ADS)

    Falaras, Polycarpos; Chryssou, Katerina; Stergiopoulos, Thomas; Arabatzis, Ioannis; Katsaros, Georgios; Catalano, Vincent J.; Kurtaran, Raif; Hugot-Le Goff, Anne; Bernard, Marie-Claude

    2003-02-01

    New dyes of the type Ru(II)(bdmpp)(bpy) [where bdmpp is 2,6-bis(3,5-dimethyl-N-pyrazoyl)pyridine and bpy is 2,2'-bipyridine-4,4'-dicarboxylic acid] are prepared and characterized by infra-red (IR), mass (MS) and electrospray mass spectroscopy (ES-MS) as well as 1H NMR (1D and 2D) spectroscopies. The compounds present broad and very high intensity MLCT absorption bands in the visible and can be chemically anchored on TiO2 films via ester-like linkage involving carboxylato groups. These complexes have been tested with success as potential molecular antennas in dye-sensitized solar cells. Both opaque and transparent nanocrystalline TiO2 thin film electrodes obtained by a doctor blade technique sensitized by these complexes were incorporated in a sandwich type regenerative photoelectrochemical solar cell containing 0.1M LiI +0.01M I2 in propylene carbonate as well as a platinized conductive glass counter electrode. The cell was characterized by Raman spectroscopy under anodic and cathodic bias. Two new vibration bands were observed in the lower frequency region. The first one at 112 cm-1 is due to tri-iodide formed on the photoactive electrode, and the second one at 167 cm-1 is a sign of the dye/iodide interaction and corresponds to a vibration in a chemically stable "DI" intermediate species. Under direct sunlight illumination (solar irradiance of 60 mW/cm2) by using a composite polymer solid state electrolye, the cell ITO/TiO2/(Ru(II)(bdmpp)(bpy)(NCS))(PF6)/electrolyte/Pt-ITO produced a continuous photocurrent as high as 4.29mA/cm2, and gave IPCE values about half of the corresponding values obtained by the standard N3 dye under the same conditions. The photovoltage is about 600 mV and the overall energy conversion cell"s efficiency is as high as 1.72%.

  1. Physical Characterization and Effect of Effective Surface Area on the Sensing Properties of Tin Dioxide Thin Solid Films in a Propane Atmosphere

    PubMed Central

    Gómez-Pozos, Heberto; González-Vidal, José Luis; Torres, Gonzalo Alberto; de la Luz Olvera, María; Castañeda, Luis

    2014-01-01

    The physical properties and the effect of effective surface area (ESA) on the sensing properties of tin dioxide [SnO2] thin films in air and propane [C3H8] atmosphere as a function of operating temperature and gas concentration have been studied in this paper. SnO2 thin films with different estimated thicknesses (50, 100 and 200 nm) were deposited on glass substrates by the chemical spray technique. Besides, they were prepared at two different deposition temperatures (400 and 475 °C). Tin chloride [SnCl4 · 5H2O] with 0.2 M concentration value and ethanol [C2H6O] were used as tin precursor and solvent, respectively. The morphological, and structural properties of the as-prepared films were analyzed by AFM and XRD, respectively. Gas sensing characteristics of SnO2 thin solid films were measured at operating temperatures of 22, 100, 200, and 300 °C, and at propane concentration levels (0, 5, 50, 100, 200, 300, 400, and 500 ppm). ESA values were calculated for each sample. It was found that the ESA increased with the increasing thickness of the films. The results demonstrated the importance of the achieving of a large effective surface area for improving gas sensing performance. SnO2 thin films deposited by spray chemical were chosen to study the ESA effect on gas sensing properties because their very rough surfaces were appropriate for this application. PMID:24379046

  2. Host thin films incorporating nanoparticles

    NASA Astrophysics Data System (ADS)

    Qureshi, Uzma

    The focus of this research project was the investigation of the functional properties of thin films that incorporate a secondary nanoparticulate phase. In particular to assess if the secondary nanoparticulate material enhanced a functional property of the coating on glass. In order to achieve this, new thin film deposition methods were developed, namely use of nanopowder precursors, an aerosol assisted transport technique and an aerosol into atmospheric pressure chemical vapour deposition system. Aerosol assisted chemical vapour deposition (AACVD) was used to deposit 8 series of thin films on glass. Five different nanoparticles silver, gold, ceria, tungsten oxide and zinc oxide were tested and shown to successfully deposit thin films incorporating nanoparticles within a host matrix. Silver nanoparticles were synthesised and doped within a titania film by AACVD. This improved solar control properties. A unique aerosol assisted chemical vapour deposition (AACVD) into atmospheric pressure chemical vapour deposition (APCVD) system was used to deposit films of Au nanoparticles and thin films of gold nanoparticles incorporated within a host titania matrix. Incorporation of high refractive index contrast metal oxide particles within a host film altered the film colour. The key goal was to test the potential of nanopowder forms and transfer the suspended nanopowder via an aerosol to a substrate in order to deposit a thin film. Discrete tungsten oxide nanoparticles or ceria nanoparticles within a titanium dioxide thin film enhanced the self-cleaning and photo-induced super-hydrophilicity. The nanopowder precursor study was extended by deposition of zinc oxide thin films incorporating Au nanoparticles and also ZnO films deposited from a ZnO nanopowder precursor. Incorporation of Au nanoparticles within a VO: host matrix improved the thermochromic response, optical and colour properties. Composite VC/TiC and Au nanoparticle/V02/Ti02 thin films displayed three useful

  3. Two-Functional Direct Current Sputtered Silver-Containing Titanium Dioxide Thin Films.

    PubMed

    Musil, J; Louda, M; Cerstvy, R; Baroch, P; Ditta, I B; Steele, A; Foster, H A

    2009-04-01

    The article reports on structure, mechanical, optical, photocatalytic and biocidal properties of Ti-Ag-O films. The Ti-Ag-O films were reactively sputter-deposited from a composed Ti/Ag target at different partial pressures of oxygen pO(2) on unheated glass substrate held on floating potential U(fl). It was found that addition of ~2 at.% of Ag into TiO(2) film has no negative influence on UV-induced hydrophilicity of TiO(2) film. Thick (~1,500 nm) TiO(2)/Ag films containing (200) anatase phase exhibit the best hydrophilicity with water droplet contact angle (WDCA) lower than 10° after UV irradiation for 20 min. Thick (~1,500 nm) TiO(2)/Ag films exhibited a better UV-induced hydrophilicity compared to that of thinner (~700 nm) TiO2/Ag films. Further it was found that hydrophilic TiO(2)/Ag films exhibit a strong biocidal effect under both the visible light and the UV irradiation with 100% killing efficiency of Escherichia coli ATCC 10536 after UV irradiation for 20 min. Reported results show that single layer of TiO(2) with Ag distributed in its whole volume exhibits, after UV irradiation, simultaneously two functions: (1) excellent hydrophilicity with WDCA < 10° and (2) strong power to kill E. coli even under visible light due to direct toxicity of Ag. PMID:20596342

  4. Growth behavior of titanium dioxide thin films at different precursor temperatures

    PubMed Central

    2012-01-01

    The hydrophilic TiO2 films were successfully deposited on slide glass substrates using titanium tetraisopropoxide as a single precursor without carriers or bubbling gases by a metal-organic chemical vapor deposition method. The TiO2 films were employed by scanning electron microscopy, Fourier transform infrared spectrometry, UV-Visible [UV-Vis] spectroscopy, X-ray diffraction, contact angle measurement, and atomic force microscopy. The temperature of the substrate was 500°C, and the temperatures of the precursor were kept at 75°C (sample A) and 60°C (sample B) during the TiO2 film growth. The TiO2 films were characterized by contact angle measurement and UV-Vis spectroscopy. Sample B has a very low contact angle of almost zero due to a superhydrophilic TiO2 surface, and transmittance is 76.85% at the range of 400 to 700 nm, so this condition is very optimal for hydrophilic TiO2 film deposition. However, when the temperature of the precursor is lower than 50°C or higher than 75°C, TiO2 could not be deposited on the substrate and a cloudy TiO2 film was formed due to the increase of surface roughness, respectively. PMID:22280933

  5. Synthesis, fractionation, and thin film processing of nanoparticles using the tunable solvent properties of carbon dioxide gas expanded liquids

    NASA Astrophysics Data System (ADS)

    Anand, Madhu

    nanoparticle populations. This study details the influence of various factors on the size separation process, such as the types of nanoparticles, ligand type and solvent type as well as the use of recursive fractionation and the time allowed for settling during each fractionation step. This size selective precipitation technique was also applied to fractionate and separate polydisperse dispersions of CdSe/ZnS semiconductor nanocrystals into very distinct size and color fractions based solely on the pressure tunable solvent properties of CO2 expanded liquids. This size selective precipitation of nanoparticles is achieved by finely tuning the solvent strength of the CO2/organic solvent medium by simply adjusting the applied CO2 pressure. These subtle changes affect the balance between osmotic repulsive and van der Waals attractive forces thereby allowing fractionation of the nanocrystals into multiple narrow size populations. Thermodynamic analysis of nanoparticle size selective fractionation was performed to develop a theoretical model based on the thermodynamic properties of gas expanded liquids. We have used the general phenomenon of nanoparticle precipitation with CO2 expanded liquids to create dodecanethiol stabilized gold nanoparticle thin films. This method utilizes CO2 as an anti-solvent for low defect, wide area gold nanoparticle film formation employing monodisperse gold nanoparticles. Dodecanethiol stabilized gold particles are precipitated from hexane by controllably expanding the solution with carbon dioxide. Subsequent addition of carbon dioxide as a dense supercritical fluid then provides for removal of the organic solvent while avoiding the dewetting effects common to evaporating solvents. Unfortunately, the use of carbon dioxide as a neat solvent in nanoparticles synthesis and processing is limited by the very poor solvent strength of dense phase CO2. As a result, most current techniques employed to synthesize and disperse nanoparticles in neat carbon dioxide

  6. Interdigitated electrode (IDE) based on titanium dioxide (TiO2) thin films for biosensor application

    NASA Astrophysics Data System (ADS)

    Nordin, N.; Hashim, U.; Azizah, N.

    2016-07-01

    Sensor is the device that can detect and produce output or response that comes from any input from the physical environment. In this study, sensor is developed by simple photolithography process to create a small IDE device. The device is coated with Titanium Dioxide (TiO2) to give the positive result in detection. The result shows the device with coating stabilized at 2.46×10-10 compare to device without TiO2 which only at 2.24×10-10. IDE device is reusable and can use many times for different kind of detection.

  7. Morphological Control of Poly(ethylene oxide)/Polystyrene Blend Thin Films by Using Supercritical Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Chen, Xiameng

    Polymer blend thin films have been paid great attention to technological applications including adhesion, coatings, liquid crystal alignment, electronics, optics, biotechnology, and sensors. In this thesis, I investigated the effect of supercritical CO2 (scCO2) as a green solvent for poly(ethylene oxide)/polystyrene (PEO/PS) blend thin films. We prepared a series of PEO/PS blend thin films with different PEO compositions thickness ranging from 20 nm to 50 nm. As a control experiment, we also processed the same PEO/PS films at high temperature (150 °C) under vacuum. Comparison of these experimental results by using atomic force microscopy and optical microscopy clarified the significant plasticization effect of scCO2 on the phase separation, crystallization of PEO, and the swelling behavior of PS.

  8. Nucleation of pentacene thin films on silicon dioxide modified with hexamethyldisilazane

    SciTech Connect

    Killampalli, Aravind S.; Engstrom, J.R.

    2006-04-03

    Nucleation and growth of pentacene on silicon dioxide surfaces modified with hexamethyldisilazane, HN[Si(CH{sub 3}){sub 3}]{sub 2}, has been examined using supersonic molecular beam techniques and atomic force microscopy. Similar to growth on clean SiO{sub 2} surfaces, the rate of deposition at a fixed incident flux decreases with increasing kinetic energy of incident pentacene, indicative of trapping mediated adsorption. Unlike clean, unmodified SiO{sub 2} surfaces, however, growth on the modified surface exhibits characteristics of heterogeneous nucleation, where the maximum island density is independent of deposition rate. Further, islands in the submonolayer regime are two molecules high, unlike the one molecule high islands observed on clean SiO{sub 2}.

  9. Interdigitated electrode (IDE) for porcine detection based on titanium dioxide (TiO2) thin films

    NASA Astrophysics Data System (ADS)

    Nordin, N.; Hashim, U.; Azizah, N.

    2016-07-01

    Interdigited Electrode (IDE) porcine detection can be accomplished to authenticate the halal issue that has been a concern to Muslim not only in Malaysia but all around the world. The method used is photolithography that used the p-type photoresist on the spin coater with 2500 rpm. Bare IDEs device is deposited with Titanium Dioxide (TiO2) to improve the performance of the device. The result indicates that current-voltage (I-V) measurement of porcine probe line slightly above porcine target due to negative charges repelled each other. The IDE device can detect the porcine presence in food as lowest as 1.0 µM. Better performance of the device can be achieved with the replacement of gold deposited to trigger more sensitivity of the device.

  10. Method for characterizing the contact resistance of metal-vanadium dioxide thin film interfaces

    SciTech Connect

    Percy, R.; Stan, M.; Weikle, R. M.; Kittiwatanakul, S.; Lu, J.; Wolf, S.

    2014-07-14

    The standard method for determining the contact resistance of planar metal-semiconductor interfaces can underestimate the true contact resistance under normal operating conditions, as it relies on the resistivity of the semiconductor material remaining constant during measurement. However, the strong temperature dependence of the resistivity of VO{sub 2} requires a modified approach that maintains a constant power density dissipated within the film to account for Joule heating. We develop a method for measuring contact resistance in semiconductors with a high thermal coefficient of resistivity, demonstrate this method with an example, and compare the results with the standard technique.

  11. Photocatalytic property of titanium dioxide thin films deposited by radio frequency magnetron sputtering in argon and water vapour plasma

    NASA Astrophysics Data System (ADS)

    Sirghi, L.; Hatanaka, Y.; Sakaguchi, K.

    2015-10-01

    The present work is investigating the photocatalytic activity of TiO2 thin films deposited by radiofrequency magnetron sputtering of a pure TiO2 target in Ar and Ar/H2O (pressure ratio 40/3) plasmas. Optical absorption, structure, surface morphology and chemical structure of the deposited films were comparatively studied. The films were amorphous and included a large amount of hydroxyl groups (about 5% of oxygen atoms were bounded to hydrogen) irrespective of the intentional content of water in the deposition chamber. Incorporation of hydroxyl groups in the film deposited in pure Ar plasma is explained as contamination of the working gas with water molecules desorbed by plasma from the deposition chamber walls. However, intentional input of water vapour into the discharge chamber decreased the deposition speed and roughness of the deposited films. The good photocatalytic activity of the deposited films could be attributed hydroxyl groups in their structures.

  12. The relationship between photocatalytic activity and photochromic state of nanoparticulate silver surface loaded titanium dioxide thin-films.

    PubMed

    Kafizas, Andreas; Dunnill, Charles W; Parkin, Ivan P

    2011-08-14

    Anatase titania thin-films were prepared by a modified spray-pyrolysis method. Glass substrates were coated at room temperature with an aerosol-spray of a titania sol-gel solution and then annealed at 500 °C to form rough, transparent, crystalline thin-films of anatase TiO(2). Silver nanoparticles were deposited on the surface of these films by a photo-assisted deposition method; films were dip-coated in methanolic solutions of silver nitrate salt and then photo-irradiated for 5 h with UVC light. The AgNO(3) concentration was adjusted to create an array of films with varying silver loadings. The films displayed photochromism; changing colour to orange-brown in UV-light to colourless under white light. The rates of photochromic change, when subjected to four different lighting conditions (UVC, UVA, white light and dark), were analysed by UV-visible spectroscopy. By assessing the photocatalytic activity to these light sources it was found that the initial photochromic state of the material had a profound effect on the films photocatalytic ability. This effect was more pronounced in the more concentrated silver loaded films; where significant enhancements in photoactivity occurred when reactions were initiated from the photo-reduced state. The mode of improved photocatalysis was attributed to the photo-generated electron trapping by silver nanoparticles, which stabilised photo-generated holes and drove photo-oxidation processes. We believe this is the first study in which the relationship between the photochromic state of a thin-film and its subsequent photocatalytic activity is reported. PMID:21720647

  13. Photocatalytic generation of dissolved oxygen and oxyhemoglobin in whole blood based on the indirect interaction of ultraviolet light with a semiconducting titanium dioxide thin film

    NASA Astrophysics Data System (ADS)

    Gilbert, Richard J.; Carleton, Linda M.; Dasse, Kurt A.; Martin, Peter M.; Williford, Ralph E.; Monzyk, Bruce F.

    2007-10-01

    Most current artificial lung technologies require the delivery of oxygen to the blood via permeable hollow fibers, depending on membrane diffusivity and differential partial pressure to drive gas exchange. We have identified an alternative approach in which dissolved oxygen (DO) is generated directly from the water content of blood through the indirect interaction of ultraviolet (UV) light with a semiconducting titanium dioxide thin film. This reaction is promoted by photon absorption and displacement of electrons from the photoactive film and yields a cascading displacement of electron "holes" to the aqueous interface resulting in the oxidation of water molecules to form DO. Anatase TiO2 (photocatalyst) and indium tin oxide (ITO) (electrically conductive and light transparent) coatings were deposited onto quartz flow-cell plates by direct current reactive magnetron sputtering. The crystal structure of the films was evaluated by grazing incidence x-ray diffraction, which confirmed that the primary crystal phase of the TiO2 thin film was anatase with a probable rutile secondary phase. Surface topology and roughness were determined by atomic force microscopy, demonstrating a stochastically uniform array of nanocrystallites. UV illumination of the titanium dioxide thin film through the quartz/ITO surface resulted in the rapid increase of DO and oxyhemoglobin in adjacent flowing blood on the opposite TiO2 surface at a rate of 1.0×10-5 mmol O2/s. The rate of oxyhemoglobin generation was linearly proportional to residence time adjacent to the photoactive surface in a flow-through test cell under steady-state conditions. Preliminary biocompatibility for the proposed photocatalytic effect on whole blood demonstrated no increase in the rate of hemolysis or generation of toxic byproducts of photo-oxidation. These results demonstrate the feasibility and safety of employing optoelectronic mechanisms to promote oxygenation of hemoglobin in whole blood and provide

  14. PHOTOCATALYTIC GENERATION OF DISSOLVED OXYGEN AND OXYHEMOGLOBIN IN WHOLE BLOOD BASED ON THE INDIRECT INTERACTION OF UV LIGHT WITH A SEMICONDUCTING TITANIUM DIOXIDE THIN FILM

    SciTech Connect

    Gilbert, Richard J.; Carleton, Linda M.; Dasse, Kurt A.; Martin, Peter M.; Williford, Rick E.; Monzyk, Bruce F.

    2007-10-01

    Most current artificial lung technologies require the delivery of oxygen to the blood via permeable hollow fibers, depending on membrane diffusivity and differential partial pressure to drive gas exchange. We have identified an alternative approach in which dissolved oxygen (DO) is generated directly from the water content of blood through the indirect interaction of UV light with a semi-conducting titanium dioxide thin film. This reaction is promoted by photon absorption and displacement of electrons from the photoactive film, and yields a cascading displacement of electron “holes” to the aqueous interface resulting in the oxidation of water molecules to form DO. Anatase TiO2 (photocatalyst) and ITO (electrically conductive and light transparent) coatings were deposited onto quartz flow-cell plates by DC reactive magnetron sputtering. The crystal structure of the films was evaluated by grazing incidence X-Ray Diffraction (GIXRD), which confirmed that the primary crystal phase of the TiO2 thin film was anatase with a probable rutile secondary phase. Surface topology and roughness were determined by atomic force microscopy, demonstrating a stochastically uniform array of nanocrystallites. UV illumination of the titanium dioxide thin film through the quartz/ITO surface resulted in the rapid increase of DO and oxyhemoglobin in adjacent flowing blood on the opposite TiO2 surface at a rate of 1.28 x 10-5 mmol O2/sec. The rate of oxyhemoglobin generation was linearly proportional to residence time adjacent to the photoactive surface in a flow-through test cell under steady-state conditions. Preliminary biocompatibility for the proposed photocatalytic effect on whole blood demonstrated no increase in the rate of hemolysis or generation of toxic byproducts of photo-oxidation. These results demonstrate the feasibility and safety of employing optoelectronic mechanisms to promote oxygenation of hemoglobin in whole blood, and provide substantiation for the use of this

  15. Photoluminescence of dense nanocrystalline titanium dioxide thin films: effect of doping and thickness and relation to gas sensing.

    PubMed

    Mercado, Candy; Seeley, Zachary; Bandyopadhyay, Amit; Bose, Susmita; McHale, Jeanne L

    2011-07-01

    The photoluminescence (PL) of dense nanocrystalline (anatase) TiO(2) thin films is reported as a function of calcination temperature, thickness, and tungsten and nickel doping. The dependence of the optical absorption, Raman spectra, and PL spectra on heat treatment and dopants reveals the role of oxygen vacancies, crystallinity, and phase transformation in the performance of TiO(2) films used as gas sensors. The broad visible PL from defect states of compact and undoped TiO(2) films is found to be much brighter and less sensitive to the presence of oxygen than that of mesoporous films. The dense nanocrystalline grains and the nanoparticles comprising the mesoporous film are comparable in size, demonstrating the importance of film morphology and carrier transport in determining the intensity of defect photoluminescence. At higher calcination temperatures, the transformation to rutile results in the appearance of a dominant near-infrared peak. This characteristic change in the shape of the PL spectra demonstrates efficient capture of conduction band electrons by the emerging rutile phase. The W-doped samples show diminished PL with quenching on the red side of the emission spectrum occurring at lower concentration and eventual disappearance of the PL at higher W concentration. The results are discussed within the context of the performance of the TiO(2) thin films as CO gas sensors and the chemical nature of luminescent defects. PMID:21702459

  16. Pyrolyzed thin film carbon

    NASA Technical Reports Server (NTRS)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  17. Influence of ion beam parameters on the electrical and optical properties of ion-assisted reactively evaporated vanadium dioxide thin films

    SciTech Connect

    Case, F.C.

    1987-07-01

    Large reductions in the phase transition temperature of vanadium dioxide thin films have been achieved in the past by doping with elements such as tungsten or niobium; however, considerable degradation of electrical and optical properties are routinely observed. In this investigation, a technique is described which significantly reduces the transition temperature to doped values, without sacrificing film quality. Vanadium oxide films were deposited at room temperature by ion-assisted reactive evaporation and subsequently annealed in flowing oxygen. Deposition parameters include a range of argon-to-oxygen ion ratios, ion energies and fluxes, and background oxygen pressures. The impact of these parameters on microstructural, electrical, and optical properties, as well as on transition temperature, will be discussed.

  18. Metal-insulator transition characteristics of vanadium dioxide thin films synthesized by ultrasonic nebulized spray pyrolysis of an aqueous combustion mixture

    NASA Astrophysics Data System (ADS)

    Bharathi, R.; Naorem, Rameshwari; Umarji, A. M.

    2015-08-01

    We report the synthesis of high quality vanadium dioxide (VO2) thin films by a novel spray pyrolysis technique, namely ultrasonic nebulized spray pyrolysis of aqueous combustion mixture (UNSPACM). This simple and cost effective two step process involves synthesis of a V2O5 film on an LaAlO3 substrate followed by a controlled reduction to form single phase VO2. The formation of M1 phase (P21/c) is confirmed by Raman spectroscopic studies. A thermally activated metal-insulator transition (MIT) was observed at 61 ^\\circ C, where the resistivity changes by four orders of magnitude. Activation energies for the low conduction phase and the high conduction phase were obtained from temperature variable resistance measurements. The infrared spectra also show a dramatic change in reflectance from 13% to over 90% in the wavelength range of 7-15 μ m. This indicates the suitability of the films for optical switching applications at infrared frequencies.

  19. Formation of low pressure chemically vapour deposited W thin film on silicon dioxide for gate electrode application

    NASA Astrophysics Data System (ADS)

    Sone, Jae Hyun; Kim, Sun-Oo; Kim, Ki-Joon; Kim, Hyoung Sub; Kim, Hyeong Joon

    1994-12-01

    We have investigated the feasibility that low pressure chemically vapor deposited W can be used as a gate electrode material of metal-oxide-semiconductor (MOS) field effect transistors. We improved adhesion of the W film to SiO2 by using a pulsing injection of source gas. The pulsing injection of the reactant gas enhances the desorption of byproduct gases from the surface of the growing film and thus more W nuclei formed on SiO2. Tungsten thin films were deposited on the SiO2/Si with a deposition rate of 1000-2000 A/min. The deposition was carried out at various temperatures of 300-750 C and various SiH4:WF6 ratios of 0.6-1.5. The higher adhesion strength and resistivity of W thin films were achieved at the higher SiH4:WF6 ratio and higher deposition temperature. X-ray diffraction analysis showed that the crystal structure of all W films, deposited at various temperatures, was alpha-W in spite of either high reactant gas ratio or high temperature. Since W thin films had good adhesion to SiO2, MOS structure capacitors were fabricated with a W electrode via wet chemical processes and their electrical properties were also characterized. The extreme value distribution function of dielectric breakdown strength indicates that the thin SiO2 layer was significantly degraded by the diffused F ions. However, the stacked gate dielectric of SiO2 and Si3N4 layers instead of the single SiO2 layer was not degraded by the W gate electrode, since the Si3N4 layer protected SiO2 from chemical attack or restricted the F diffusion during deposition of the W gate electrode.

  20. Swift heavy ion irradiation induced phase transformation in undoped and niobium doped titanium dioxide composite thin films

    NASA Astrophysics Data System (ADS)

    Gautam, Subodh K.; Chettah, Abdelhak; Singh, R. G.; Ojha, Sunil; Singh, Fouran

    2016-07-01

    Study reports the effect of swift heavy ion (SHI) irradiation induced phase transformation in undoped and Niobium doped anatase TiO2 composite thin films. Investigations were carried out at different densities of electronic excitations (EEs) using 120 MeV Ag and 130 MeV Ni ions irradiations. Films were initially annealed at 900 °C and results revealed that undoped films were highly stable in anatase phase, while the Nb doped films showed the composite nature with the weak presence of Niobium penta-oxide (Nb2O5) phase. The effect at low density of EEs in undoped film show partial anatase to rutile phase transformation; however doped film shows only further growth of Nb2O5 phase beside the anatase to rutile phase transformation. At higher density of EEs induced by Ag ions, registered continuous ion track of ∼3 nm in lattice which leads to nano-crystallization followed by decomposition/amorphization of rutile TiO2 and Nb2O5 phases in undoped and doped films, respectively. However, Ni ions are only induced discontinuous sequence of ion tracks with creation of damage and disorder and do not show amorphization in the lattice. The in-elastic thermal spike calculations were carried out for anatase TiO2 phase to understand the effect of EEs on anatase to rutile phase transformation followed by amorphization in NTO films in terms of continuous and discontinuous track formation by SHI irradiation.

  1. On the influence of DC electric fields on the aerosol assisted chemical vapor deposition growth of photoactive titanium dioxide thin films.

    PubMed

    Romero, Luz; Binions, Russell

    2013-11-01

    Titanium dioxide thin films were deposited on fluorine doped tin oxide glass substrate from the electric field assisted aerosol chemical vapor deposition (EACVD) reaction of titanium isopropoxide (TTIP, Ti(OC3H7)4) in toluene on glass substrates at a temperature of 450 °C. DC electric fields were generated by applying a potential difference between the electrodes of the transparent coated oxide coated glass substrates during the deposition. The deposited films were characterized using scanning electron microscopy, X-ray diffraction, atomic force microscopy, Raman spectroscopy, and UV-vis spectroscopy. The photoactivity and hydrophilicity of the deposited films were also analyzed using a dye-ink test and water-contact angle measurements. The characterization work revealed that the incorporation of DC electric fields produced significant reproducible changes in the film microstructure, preferred crystallographic orientation, roughness, and film thickness. Photocatalytic activity was calculated from the half-time (t1/2) or time taken to degrade 50% of the initial resazurin dye concentration. A large improvement in photocatalytic activity was observed for films deposited using an electric field with a strong orientation in the (004) direction (t1/2 17 min) as compared to a film deposited with no electric field (t1/2 40 min). PMID:24160408

  2. A study of structure-property correlation in vanadium pentoxide and titanium dioxide based thin films as functional materials

    NASA Astrophysics Data System (ADS)

    Thapa, Chandra

    The focus of this thesis is to study the structure-property correlation in thin films of V2O5 and TiO2 based transition metal oxides as functional materials. V2O5 is investigated as a cathode material for lithium ion battery and TiO2 as a high-k dielectric material. We studied V2O5 thin films prepared by spin coating using three different types of precursors, MOD precursor, sol-gel organic precursor and sol-gel inorganic precursor. On the basis of structural and electrochemical studies, we find that the capacity is dependent on the degree of non-stoichiometry. We have also studied the effect of addition of Ti. Although Ti doping enhances non-stoichiometry, the capacity was found to increase only in 5% Ti-doped sol-gel film. This means the optimal degree of non-stoichiometry is crucial to enhance the capacity. TiO2 is one of the possible high-k dielectric materials because of its very high dielectric constant. We studied leakage characteristics, the dielectric strength and frequency dependent behavior of dielectric constant of TiO2 thin films prepared by MOD, sputter deposition and annealed at different temperatures. We find dielectric constant increasing with the increase in annealing temperature and leakage current density improvement by almost one order of magnitude with each 100 °C increase in annealing temperature. Since TiO2 possess two distinct thermodynamic phases: anatase and rutile, which dramatically influences the values of dielectric constant and leakage current density, it is crucial to stabilize the phase of TiO2 by doping. We find that 20% Zr-doping completely stabilizes TiO2 phase in its anatase form. The dielectric constant of the films is independent of annealing temperature but the leakage current density improves by one order of magnitude with every 100 °C increase in annealing temperature.

  3. Thin film metrology.

    PubMed

    Nitsch, Gerald; Flinn, Gregory

    2007-10-01

    Thin film metrology is suitable for characterising and performing quality control of a variety of coatings and films used in medical applications. The capabilities of today's systems are described. PMID:18078184

  4. Ceramic Composite Thin Films

    NASA Technical Reports Server (NTRS)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  5. Thin Fluoropolymer Films and Nanoparticle Coatings from the Rapid Expansion of Supercritical Carbon Dioxide Solutions with Electrostatic Collection.

    SciTech Connect

    Fulton, John L.; Deverman, George S.; Yonker, Clement R.; Grate, Jay W.; Deyoung, James; Mcclain, James B.

    2003-03-12

    Application of nanometer thick fluoropolymer films to substrates ranging from microelectronic components to cardiovascular implants is described. In the first step, nanometer-sized polymer particles are generated during the rapid expansion of supercritical fluid solutions. These particles are then charged as they are being formed by application of a high voltage to the expansion nozzle. The charged particles are forced to a solid surface forming uniform coatings with thicknesses from 10?s of nanometers to several micrometers thick. Supercritical carbon dioxide solutions of three different fluoropolymers were used to generate different types of coatings. The method can also be used to generate a solid matrix with nanometer size domains of two chemically diverse solid materials. The size of the particles are so small that they can be deposited to electrically conducting microscopic regions with a spatial resolution better than 50 nm.

  6. Anomalous behavior of B1g mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO) thin films

    NASA Astrophysics Data System (ADS)

    Gautam, Subodh K.; Gautam, Naina; Singh, R. G.; Ojha, S.; Shukla, D. K.; Singh, Fouran

    2015-12-01

    The effect of Niobium doping and size of crystallites on highly transparent nano-crystalline Niobium doped Titanium Dioxide (NTO) thin films with stable anatase phase are reported. The Nb doping concentration is varied within the solubility limit in TiO2 lattice. Films were annealed in controlled environment for improving the crystallinity and size of crystallites. Elemental and thickness analysis were carried out using Rutherford backscattering spectrometry and cross sectional field emission scanning electron microscopy. Structural characteristics reveal a substitutional incorporation of Nb+5 in the TiO2 lattice which inhibits the anatase crystallites growth with increasing the doping percentage. The micro-Raman (MR) spectra of films with small size crystallites shows stiffening of about 4 cm-1 for the Eg(1) mode and is ascribed to phonon confinement and non-stoichiometry. In contrast, B1g mode exhibits a large anomalous softening of 20 cm-1 with asymmetrical broadening; which was not reported for the case of pure TiO2 crystallites. This anomalous behaviour is explained by contraction of the apical Ti-O bonds at the surface upon substitutional Nb5+ doping induced reduction of Ti4+ ions also known as hetero-coordination effect. The proposed hypotheses is manifested through studying the electronic structure and phonon dynamics by performing the near edge x-ray absorption fine structure (NEXAFS) and temperature dependent MR down to liquid nitrogen temperature on pure and 2.5 at.% doped NTO films, respectively.

  7. Carbon thin film thermometry

    NASA Technical Reports Server (NTRS)

    Collier, R. S.; Sparks, L. L.; Strobridge, T. R.

    1973-01-01

    The work concerning carbon thin film thermometry is reported. Optimum film deposition parameters were sought on an empirical basis for maximum stability of the films. One hundred films were fabricated for use at the Marshall Space Flight Center; 10 of these films were given a precise quasi-continuous calibration of temperature vs. resistance with 22 intervals between 5 and 80 K using primary platinum and germanium thermometers. Sensitivity curves were established and the remaining 90 films were given a three point calibration and fitted to the established sensitivity curves. Hydrogen gas-liquid discrimination set points are given for each film.

  8. Microstructure Related Properties of Optical Thin Films.

    NASA Astrophysics Data System (ADS)

    Wharton, John James, Jr.

    Both the optical and physical properties of thin film optical interference coatings depend upon the microstructure of the deposited films. This microstructure is strongly columnar with voids between the columns. Computer simulations of the film growth process indicate that the two most important factors responsible for this columnar growth are a limited mobility of the condensing molecules and self-shadowing by molecules already deposited. During the vacuum deposition of thin films, the microstructure can be influenced by many parameters, such as substrate temperature and vacuum pressure. By controlling these parameters and introducing additional ones, thin film coatings can be improved. In this research, ultraviolet irradiation and ion bombardment were examined as additional parameters. Past studies have shown that post-deposition ultraviolet irradiation can be used to relieve stress and reduce absorption in the far ultraviolet of silicon dioxide films. Ion bombardment has been used to reduce stress, improve packing density, and increase resistance to moisture penetration. Three refractory oxide materials commonly used in thin film coatings were studied; they are silicon dioxide, titanium dioxide, and zirconium dioxide. Both single-layer films and narrowband filters made of these materials were examined. A 1000-watt mercury-xenon lamp was used to provide ultraviolet irradiation. An inverted magnetron ion source was used to produce argon and oxygen ions. Ultraviolet irradiation was found to reduce the absorption and slightly increase the index of refraction in zirconium oxide films. X-ray diffraction analysis revealed that ultraviolet irradiation caused titanium oxide films to become more amorphous; their absorption in the ultraviolet was slightly reduced. No changes were noted in film durability. Ion bombardment enhanced the tetragonal (lll) peak of zirconium oxide but increased the absorption of both zirconium oxide and titanium oxide films. The titanium oxide

  9. Thin film hydrogen sensor

    DOEpatents

    Cheng, Y.T.; Poli, A.A.; Meltser, M.A.

    1999-03-23

    A thin film hydrogen sensor includes a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end. 5 figs.

  10. Biomimetic thin film synthesis

    SciTech Connect

    Graff, G.L.; Campbell, A.A.; Gordon, N.R.

    1995-05-01

    The purpose of this program is to develop a new process for forming thin film coatings and to demonstrate that the biomimetic thin film technology developed at PNL is useful for industrial applications. In the biomimetic process, mineral deposition from aqueous solution is controlled by organic functional groups attached to the underlying substrate surface. The coatings process is simple, benign, inexpensive, energy efficient, and particularly suited for temperature sensitive substrate materials (such as polymers). In addition, biomimetic thin films can be deposited uniformly on complex shaped and porous substrates providing a unique capability over more traditional line-of-sight methods.

  11. Thin film hydrogen sensor

    DOEpatents

    Cheng, Yang-Tse; Poli, Andrea A.; Meltser, Mark Alexander

    1999-01-01

    A thin film hydrogen sensor, includes: a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end.

  12. Effect of the Nd content on the structural and photoluminescence properties of silicon-rich silicon dioxide thin films

    PubMed Central

    2011-01-01

    In this article, the microstructure and photoluminescence (PL) properties of Nd-doped silicon-rich silicon oxide (SRSO) are reported as a function of the annealing temperature and the Nd concentration. The thin films, which were grown on Si substrates by reactive magnetron co-sputtering, contain the same Si excess as determined by Rutherford backscattering spectrometry. Fourier transform infrared (FTIR) spectra show that a phase separation occurs during the annealing because of the condensation of the Si excess resulting in the formation of silicon nanoparticles (Si-np) as detected by high-resolution transmission electron microscopy and X-ray diffraction (XRD) measurements. Under non-resonant excitation at 488 nm, our Nd-doped SRSO films simultaneously exhibited PL from Si-np and Nd3+ demonstrating the efficient energy transfer between Si-np and Nd3+ and the sensitizing effect of Si-np. Upon increasing the Nd concentration from 0.08 to 4.9 at.%, our samples revealed a progressive quenching of the Nd3+ PL which can be correlated with the concomitant increase of disorder within the host matrix as shown by FTIR experiments. Moreover, the presence of Nd-oxide nanocrystals in the highest Nd-doped sample was established by XRD. It is, therefore, suggested that the Nd clustering, as well as disorder, are responsible for the concentration quenching of the PL of Nd3+. PMID:21711673

  13. Multifunctional thin film surface

    SciTech Connect

    Brozik, Susan M.; Harper, Jason C.; Polsky, Ronen; Wheeler, David R.; Arango, Dulce C.; Dirk, Shawn M.

    2015-10-13

    A thin film with multiple binding functionality can be prepared on an electrode surface via consecutive electroreduction of two or more aryl-onium salts with different functional groups. This versatile and simple method for forming multifunctional surfaces provides an effective means for immobilization of diverse molecules at close proximities. The multifunctional thin film has applications in bioelectronics, molecular electronics, clinical diagnostics, and chemical and biological sensing.

  14. Thin film tritium dosimetry

    DOEpatents

    Moran, Paul R.

    1976-01-01

    The present invention provides a method for tritium dosimetry. A dosimeter comprising a thin film of a material having relatively sensitive RITAC-RITAP dosimetry properties is exposed to radiation from tritium, and after the dosimeter has been removed from the source of the radiation, the low energy electron dose deposited in the thin film is determined by radiation-induced, thermally-activated polarization dosimetry techniques.

  15. Evaporated VOx Thin Films

    NASA Astrophysics Data System (ADS)

    Stapinski, Tomasz; Leja, E.

    1989-03-01

    VOx thin films on glass were obtained by thermal evaporation of V205, powder. The structural investigations were carried out with the use of X-ray diffractometer. The electrical properties of the film were examined by means of temperature measurements of resistivity for the samples heat-treated in various conditions. Optical transmission and reflection spectra of VOX films of various composition showed the influence of the heat treatment.

  16. Anomalous behavior of B{sub 1g} mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO) thin films

    SciTech Connect

    Gautam, Subodh K. E-mail: fouran@gmail.com; Ojha, S.; Singh, Fouran E-mail: fouran@gmail.com; Gautam, Naina; Singh, R. G.; Shukla, D. K.

    2015-12-15

    The effect of Niobium doping and size of crystallites on highly transparent nano-crystalline Niobium doped Titanium Dioxide (NTO) thin films with stable anatase phase are reported. The Nb doping concentration is varied within the solubility limit in TiO{sub 2} lattice. Films were annealed in controlled environment for improving the crystallinity and size of crystallites. Elemental and thickness analysis were carried out using Rutherford backscattering spectrometry and cross sectional field emission scanning electron microscopy. Structural characteristics reveal a substitutional incorporation of Nb{sup +5} in the TiO{sub 2} lattice which inhibits the anatase crystallites growth with increasing the doping percentage. The micro-Raman (MR) spectra of films with small size crystallites shows stiffening of about 4 cm{sup −1} for the E{sub g(1)} mode and is ascribed to phonon confinement and non-stoichiometry. In contrast, B{sub 1g} mode exhibits a large anomalous softening of 20 cm{sup −1} with asymmetrical broadening; which was not reported for the case of pure TiO{sub 2} crystallites. This anomalous behaviour is explained by contraction of the apical Ti-O bonds at the surface upon substitutional Nb{sup 5+} doping induced reduction of Ti{sup 4+} ions also known as hetero-coordination effect. The proposed hypotheses is manifested through studying the electronic structure and phonon dynamics by performing the near edge x-ray absorption fine structure (NEXAFS) and temperature dependent MR down to liquid nitrogen temperature on pure and 2.5 at.% doped NTO films, respectively.

  17. Electric field-assisted metal insulator transition in vanadium dioxide (VO2) thin films: optical switching behavior and anomalous far-infrared emissivity variation

    NASA Astrophysics Data System (ADS)

    Crunteanu, Aurelian; Fabert, Marc; Cornette, Julie; Colas, Maggy; Orlianges, Jean-Christophe; Bessaudou, Annie; Cosset, Françoise

    2014-03-01

    We present the vanadium dioxide (VO2) thin films deposition using e-beam evaporation of a vanadium target under oxygen atmosphere on different substrates (sapphire, Si, SiO2/Si…) and we focus on their electrical and optical properties variations as the material undergoes a metal-insulator transition under thermal and electrical stimuli. The phase transition induces extremely abrupt changes in the electronic and optical properties of the material: the electrical resistivity increases up to 5 orders of magnitude while the optical properties (transmission, reflection, refractive index) are drastically modified. We present the integration of these films in simple planar optical devices and we demonstrate electrical-activated optical modulators for visible-infrared signals with high discrimination between the two states. We will highlight a peculiar behavior of the VO2 material in the infrared and far infrared regions (2- 20 μm), namely its anomalous emissivity change under thermal- end electrical activation (negative differential emittance phenomenon) with potential applications in active coatings for thermal regulation, optical limiting or camouflage coatings.

  18. Low-energy electron induced processes in molecular thin films condensed on silicon and titanium dioxide surfaces

    NASA Astrophysics Data System (ADS)

    Lane, Christopher D.

    The focus of the presented experimental research is to examine the fundamental physics and chemistry of electron-stimulated reactions upon adsorbate covered single crystal surfaces. Specifically, condensed SiCl4 on the Si(111) surface and condensed H2O on the TiO2 (110) surface have been studied. By varying adsorbate film thicknesses, the coupling strength of the electron target molecule to the substrate and surrounding media dictates the progression of the electron induced reactions. To investigate the electron interactions with SiCl4 on the Si(111) surface, a multilayer to monolayer approach was taken. Experiments measuring the electron stimulated desorption (ESD) of fragment cations are discussed in Chapter 3. ESD of neutrals was performed on a multilayer (100 ML) coverage of SiCl4 and is discussed in Chapter 4. These experiments remove the influence of the silicon substrate on the electron induced dissociative processes that are monitored via time of flight mass spectrometry (ToF-MS). The results in Chapter 3 and Chapter 4 have been published in Surface Science 593 (2005) 173 and in the Journal of Chemical Physics 124 (2006) 164702, respectively. Results from electron induced reactions within thin films of SiCl4 are presented in Chapter 5. In the low coverage region, the cation and neutral desorption channels are monitored simultaneously, and the adsorbate coupling strength to the silicon substrate is substantially greater. This affects the desorption yields and the autodetachment probability of the transient negative ion (SiCl4-). Chapters 6--8 discuss work that focuses on the electron-stimulated reactions within the H2O/TiO2 system. A discussion of the interactions of H2O with the TiO2(110) surface is presented in Chapter 6. The transition metal oxide surface is comprised of acidic and basic water adsorption sites along with intrinsic surface defects where surface oxygen atoms are missing. These surface defect sites significantly influence the interactions of

  19. The metal-insulator transition in vanadium dioxide: A view at bulk and surface contributions for thin films and the effect of annealing

    SciTech Connect

    Yin, W.; West, K. G.; Lu, J. W.; Pei, Y.; Wolf, S. A.; Reinke, P.; Sun, Y.

    2009-06-01

    Vanadium dioxide is investigated as potential oxide barrier in spin switches, and in order to incorporate VO{sub 2} layers in complex multilayer devices, it is necessary to understand the relation between bulk and surface/interface properties. Highly oriented VO{sub 2} thin films were grown on (0001) sapphire single crystal substrates with reactive bias target ion beam deposition. In the analysis of the VO{sub 2} films, bulk-sensitive methods [x-ray diffraction (XRD) and transport measurements] and surface sensitive techniques [photoelectron spectroscopy (PES) and scanning tunneling microscopy and spectroscopy] were employed. The samples were subjected to heating cycles with annealing temperatures of up to 425 and 525 K. Prior to annealing the VO{sub 2} films exhibit the transition from the monoclinic to the tetragonal phase with the concurrent change in conductivity by more than a factor of 10{sup 3} and their phase purity is confirmed by XRD. Annealing to 425 K and thus cycling across the metal-insulator transition (MIT) temperature has no impact on the bulk properties of the VO{sub 2} film but the surface undergoes irreversible electronic changes. The observation of the valence band with PES during the annealing illustrates that the surface adopts a partially metallic character, which is retained after cooling. Annealing to a higher temperature (525 K) triggers a modification of the bulk, which is evidenced by a considerable reduction in the MIT characteristics, and a degradation in crystallite morphology. The local measurement of the conductivity with scanning tunneling spectroscopy shows the transition of the surface from predominantly semiconducting surface prior to annealing to a surface with an overwhelming contribution from metallic sections afterward. The spatial distribution of metallic regions cannot be linked in a unique manner to the crystallite size or location within the crystallites. The onset of oxygen depletion at the surface is held responsible

  20. Thin film temperature sensor

    NASA Technical Reports Server (NTRS)

    Grant, H. P.; Przybyszewski, J. S.

    1980-01-01

    Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed.

  1. Thin film photovoltaics

    SciTech Connect

    Zweibel, K; Ullal, H S

    1989-05-01

    Thin films are considered a potentially attractive technological approach to making cost-effective electricity by photovoltaics. Over the last twenty years, many have been investigated and some (cadmium telluride, copper indium diselenide, amorphous silicon) have become leading candidates for future large-scale commercialization. This paper surveys the past development of these key thin films and gives their status and future prospects. In all cases, significant progress toward cost-effective PV electricity has been made. If this progress continues, it appears that thin film PV could provide electricity that is competitive for summer daytime peaking power requirements by the middle of the 1990s; and electricity in a range that is competitive with fossil fuel costs (i.e., 6 cents/kilowatt-hour) should be available from PV around the turn of the century. 22 refs., 9 figs.

  2. Thin film ceramic thermocouples

    NASA Technical Reports Server (NTRS)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  3. Thin film photovoltaic device

    DOEpatents

    Catalano, Anthony W.; Bhushan, Manjul

    1982-01-01

    A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids.

  4. Thin film photovoltaic device

    DOEpatents

    Catalano, A.W.; Bhushan, M.

    1982-08-03

    A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids. 5 figs.

  5. Epitaxial thin films

    DOEpatents

    Hunt, Andrew Tye; Deshpande, Girish; Lin, Wen-Yi; Jan, Tzyy-Jiuan

    2006-04-25

    Epitatial thin films for use as buffer layers for high temperature superconductors, electrolytes in solid oxide fuel cells (SOFC), gas separation membranes or dielectric material in electronic devices, are disclosed. By using CCVD, CACVD or any other suitable deposition process, epitaxial films having pore-free, ideal grain boundaries, and dense structure can be formed. Several different types of materials are disclosed for use as buffer layers in high temperature superconductors. In addition, the use of epitaxial thin films for electrolytes and electrode formation in SOFCs results in densification for pore-free and ideal gain boundary/interface microstructure. Gas separation membranes for the production of oxygen and hydrogen are also disclosed. These semipermeable membranes are formed by high-quality, dense, gas-tight, pinhole free sub-micro scale layers of mixed-conducting oxides on porous ceramic substrates. Epitaxial thin films as dielectric material in capacitors are also taught herein. Capacitors are utilized according to their capacitance values which are dependent on their physical structure and dielectric permittivity. The epitaxial thin films of the current invention form low-loss dielectric layers with extremely high permittivity. This high permittivity allows for the formation of capacitors that can have their capacitance adjusted by applying a DC bias between their electrodes.

  6. Thin films for material engineering

    NASA Astrophysics Data System (ADS)

    Wasa, Kiyotaka

    2016-07-01

    Thin films are defined as two-dimensional materials formed by condensing one by one atomic/molecular/ionic species of matter in contrast to bulk three-dimensional sintered ceramics. They are grown through atomic collisional chemical reaction on a substrate surface. Thin film growth processes are fascinating for developing innovative exotic materials. On the basis of my long research on sputtering deposition, this paper firstly describes the kinetic energy effect of sputtered adatoms on thin film growth and discusses on a possibility of room-temperature growth of cubic diamond crystallites and the perovskite thin films of binary compound PbTiO3. Secondly, high-performance sputtered ferroelectric thin films with extraordinary excellent crystallinity compatible with MBE deposited thin films are described in relation to a possible application for thin-film MEMS. Finally, the present thin-film technologies are discussed in terms of a future material science and engineering.

  7. Thin film solar cell workshop

    NASA Technical Reports Server (NTRS)

    Armstrong, Joe; Jeffrey, Frank

    1993-01-01

    A summation of responses to questions posed to the thin-film solar cell workshop and the ensuing discussion is provided. Participants in the workshop included photovoltaic manufacturers (both thin film and crystalline), cell performance investigators, and consumers.

  8. Thin-film optical initiator

    DOEpatents

    Erickson, Kenneth L.

    2001-01-01

    A thin-film optical initiator having an inert, transparent substrate, a reactive thin film, which can be either an explosive or a pyrotechnic, and a reflective thin film. The resultant thin-film optical initiator system also comprises a fiber-optic cable connected to a low-energy laser source, an output charge, and an initiator housing. The reactive thin film, which may contain very thin embedded layers or be a co-deposit of a light-absorbing material such as carbon, absorbs the incident laser light, is volumetrically heated, and explodes against the output charge, imparting about 5 to 20 times more energy than in the incident laser pulse.

  9. Comparative study of water and carbon dioxide adsorption on CuFeO2 and CuFe1-xGaxO2 highly epitaxial thin films

    NASA Astrophysics Data System (ADS)

    Rojas, S.; Joshi, T.; Borisov, P.; Lederman, D.; Cabrera, A. L.

    Thermal programmed desorption (TPD) of CO2 and H2O from a 200 nm thick CuFeO2 and 52 nm thick CuFe1-xGaxO2 delafossite surfaces was performed in a Ultra-high vacuum (UHV) chamber. The thin films with epitaxial quality were grown by Pulsed Laser Deposition (PLD) on Al2O3 (0001) substrates . The adsorption / desorption of CO2 and H2O process was also monitored with X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). Our results revealed that carbon dioxide is preferentially chemisorbed by CuFe1-xGaxO2 over water and we observed the opposite behavior with regard to chemisorption of CO2 and H2O over CuFeO2. Hydroxyls and metal carbonates were formed on the surface due to the chemisorption of H2O and CO2. Arrhenius plots for CO2 and H2O desorption were done and activation energy for desorption were obtained. Supported by FONDECyT 1130372.

  10. NMR characterization of thin films

    DOEpatents

    Gerald II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2010-06-15

    A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

  11. NMR characterization of thin films

    DOEpatents

    Gerald, II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2008-11-25

    A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

  12. Selective inorganic thin films

    SciTech Connect

    Phillips, M.L.F.; Weisenbach, L.A.; Anderson, M.T.

    1995-05-01

    This project is developing inorganic thin films as membranes for gas separation applications, and as discriminating coatings for liquid-phase chemical sensors. Our goal is to synthesize these coatings with tailored porosity and surface chemistry on porous substrates and on acoustic and optical sensors. Molecular sieve films offer the possibility of performing separations involving hydrogen, air, and natural gas constituents at elevated temperatures with very high separation factors. We are focusing on improving permeability and molecular sieve properties of crystalline zeolitic membranes made by hydrothermally reacting layered multicomponent sol-gel films deposited on mesoporous substrates. We also used acoustic plate mode (APM) oscillator and surface plasmon resonance (SPR) sensor elements as substrates for sol-gel films, and have both used these modified sensors to determine physical properties of the films and have determined the sensitivity and selectivity of these sensors to aqueous chemical species.

  13. Thin film photovoltaic cell

    DOEpatents

    Meakin, John D.; Bragagnolo, Julio

    1982-01-01

    A thin film photovoltaic cell having a transparent electrical contact and an opaque electrical contact with a pair of semiconductors therebetween includes utilizing one of the electrical contacts as a substrate and wherein the inner surface thereof is modified by microroughening while being macro-planar.

  14. Thin film scintillators

    NASA Astrophysics Data System (ADS)

    McDonald, Warren; McKinney, George; Tzolov, Marian

    2015-03-01

    Scintillating materials convert energy flux (particles or electromagnetic waves) into light with spectral characteristic matching a subsequent light detector. Commercial scintillators such as yttrium aluminum garnet (YAG) and yttrium aluminum perovskite (YAP) are commonly used. These are inefficient at lower energies due to the conductive coating present on their top surface, which is needed to avoid charging. We hypothesize that nano-structured thin film scintillators will outperform the commercial scintillators at low electron energies. We have developed alternative thin film scintillators, zinc tungstate and zinc oxide, which show promise for higher sensitivity to lower energy electrons since they are inherently conductive. Zinc tungstate films exhibit photoluminescence quantum efficiency of 74%. Cathodoluminescence spectroscopy was applied in transmission and reflection geometries. The comparison between the thin films and the YAG and YAP commercial scintillators shows much higher light output from the zinc tungstate and zinc oxide at electron energies less than 5 keV. Our films were integrated in a backscattered electron detector. This detector delivers better images than an identical detector with commercial YAG scintillator at low electron energies. Dr. Nicholas Barbi from PulseTor LLC, Dr. Anura Goonewardene, NSF Grants: #0806660, #1058829, #0923047.

  15. Optimization of conditions for growth of vanadium dioxide thin films on silicon by pulsed-laser deposition

    SciTech Connect

    Shibuya, Keisuke Sawa, Akihito

    2015-10-15

    We systematically examined the effects of the substrate temperature (T{sub S}) and the oxygen pressure (P{sub O2}) on the structural and optical properties polycrystalline V O{sub 2} films grown directly on Si(100) substrates by pulsed-laser deposition. A rutile-type V O{sub 2} phase was formed at a T{sub S} ≥ 450 °C at P{sub O2} values ranging from 5 to 20 mTorr, whereas other structures of vanadium oxides were stabilized at lower temperatures or higher oxygen pressures. The surface roughness of the V O{sub 2} films significantly increased at growth temperatures of 550 °C or more due to agglomeration of V O{sub 2} on the surface of the silicon substrate. An apparent change in the refractive index across the metal–insulator transition (MIT) temperature was observed in V O{sub 2} films grown at a T{sub S} of 450 °C or more. The difference in the refractive index at a wavelength of 1550 nm above and below the MIT temperature was influenced by both the T{sub S} and P{sub O2}, and was maximal for a V O{sub 2} film grown at 450 °C under 20 mTorr. Based on the results, we derived the P{sub O2} versus 1/T{sub S} phase diagram for the films of vanadium oxides, which will provide a guide to optimizing the conditions for growth of V O{sub 2} films on silicon platforms.

  16. Thin film superconductor magnetic bearings

    DOEpatents

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  17. Thin film superconductor magnetic bearings

    SciTech Connect

    Weinberger, B.R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft that is subject to a load (L) and rotatable around an axis of rotation, a magnet mounted to the shaft, and a stator in proximity to the shaft. The stator has a superconductor thin film assembly positioned to interact with the magnet to produce a levitation force on the shaft that supports the load (L). The thin film assembly includes at least two superconductor thin films and at least one substrate. Each thin film is positioned on a substrate and all the thin films are positioned such that an applied magnetic field from the magnet passes through all the thin films. A similar bearing in which the thin film assembly is mounted on the shaft and the magnet is part of the stator also can be constructed. 8 figs.

  18. Chiral atomically thin films

    NASA Astrophysics Data System (ADS)

    Kim, Cheol-Joo; Sánchez-Castillo, A.; Ziegler, Zack; Ogawa, Yui; Noguez, Cecilia; Park, Jiwoong

    2016-06-01

    Chiral materials possess left- and right-handed counterparts linked by mirror symmetry. These materials are useful for advanced applications in polarization optics, stereochemistry and spintronics. In particular, the realization of spatially uniform chiral films with atomic-scale control of their handedness could provide a powerful means for developing nanodevices with novel chiral properties. However, previous approaches based on natural or grown films, or arrays of fabricated building blocks, could not offer a direct means to program intrinsic chiral properties of the film on the atomic scale. Here, we report a chiral stacking approach, where two-dimensional materials are positioned layer-by-layer with precise control of the interlayer rotation (θ) and polarity, resulting in tunable chiral properties of the final stack. Using this method, we produce left- and right-handed bilayer graphene, that is, a two-atom-thick chiral film. The film displays one of the highest intrinsic ellipticity values (6.5 deg μm–1) ever reported, and a remarkably strong circular dichroism (CD) with the peak energy and sign tuned by θ and polarity. We show that these chiral properties originate from the large in-plane magnetic moment associated with the interlayer optical transition. Furthermore, we show that we can program the chiral properties of atomically thin films layer-by-layer by producing three-layer graphene films with structurally controlled CD spectra.

  19. Chiral atomically thin films.

    PubMed

    Kim, Cheol-Joo; Sánchez-Castillo, A; Ziegler, Zack; Ogawa, Yui; Noguez, Cecilia; Park, Jiwoong

    2016-06-01

    Chiral materials possess left- and right-handed counterparts linked by mirror symmetry. These materials are useful for advanced applications in polarization optics, stereochemistry and spintronics. In particular, the realization of spatially uniform chiral films with atomic-scale control of their handedness could provide a powerful means for developing nanodevices with novel chiral properties. However, previous approaches based on natural or grown films, or arrays of fabricated building blocks, could not offer a direct means to program intrinsic chiral properties of the film on the atomic scale. Here, we report a chiral stacking approach, where two-dimensional materials are positioned layer-by-layer with precise control of the interlayer rotation (θ) and polarity, resulting in tunable chiral properties of the final stack. Using this method, we produce left- and right-handed bilayer graphene, that is, a two-atom-thick chiral film. The film displays one of the highest intrinsic ellipticity values (6.5 deg μm(-1)) ever reported, and a remarkably strong circular dichroism (CD) with the peak energy and sign tuned by θ and polarity. We show that these chiral properties originate from the large in-plane magnetic moment associated with the interlayer optical transition. Furthermore, we show that we can program the chiral properties of atomically thin films layer-by-layer by producing three-layer graphene films with structurally controlled CD spectra. PMID:26900756

  20. Advanced thin film thermocouples

    NASA Astrophysics Data System (ADS)

    Kreider, K. G.; Semancik, S.; Olson, C.

    1984-10-01

    The fabrication, materials characterization, and performance of thin film platinum rhodium thermocouples on gas turbine alloys was investigated. The materials chosen for the study were the turbine blade alloy systems MAR M200+Hf with NiCoCrAlY and FeCrAlY coatings, and vane alloy systems MAR M509 with FeCrAlY. Research was focussed on making improvements in the problem areas of coating substrate stability, adhesion, and insulation reliability and durability. Diffusion profiles between the substrate and coating with and without barrier coatings of Al2O3 are reported. The relationships between fabrication parameters of thermal oxidation and sputtering of the insulator and its characterization and performance are described. The best thin film thermocouples were fabricated with the NiCoCrAlY coatings which were thermally oxidized and sputter coated with Al2O3.

  1. Biomimetic thin film deposition

    SciTech Connect

    Rieke, P.R.; Graff, G.E.; Campbell, A.A.; Bunker, B.C.; Baskaran, S.; Song, L.; Tarasevich, B.J.; Fryxell, G.E.

    1995-09-01

    Biological mineral deposition for the formation of bone, mollusk shell and other hard tissues provides materials scientists with illustrative materials processing strategies. This presentation will review the key features of biomineralization and how these features can be of technical importance. We have adapted existing knowledge of biomineralization to develop a unique method of depositing inorganic thin films and coating. Our approach to thin film deposition is to modify substrate surfaces to imitate the proteins found in nature that are responsible for controlling mineral deposition. These biomimetic surfaces control the nucleation and growth of the mineral from a supersaturated aqueous solution. This has many processing advantages including simple processing equipment, environmentally benign reagents, uniform coating of highly complex shapes, and enhanced adherence of coating. Many different types of metal oxide, hydroxide, sulfide and phosphate materials with useful mechanical, optical, electronic and biomedical properties can be deposited.

  2. Advanced thin film thermocouples

    NASA Technical Reports Server (NTRS)

    Kreider, K. G.; Semancik, S.; Olson, C.

    1984-01-01

    The fabrication, materials characterization, and performance of thin film platinum rhodium thermocouples on gas turbine alloys was investigated. The materials chosen for the study were the turbine blade alloy systems MAR M200+Hf with NiCoCrAlY and FeCrAlY coatings, and vane alloy systems MAR M509 with FeCrAlY. Research was focussed on making improvements in the problem areas of coating substrate stability, adhesion, and insulation reliability and durability. Diffusion profiles between the substrate and coating with and without barrier coatings of Al2O3 are reported. The relationships between fabrication parameters of thermal oxidation and sputtering of the insulator and its characterization and performance are described. The best thin film thermocouples were fabricated with the NiCoCrAlY coatings which were thermally oxidized and sputter coated with Al2O3.

  3. thin films as absorber

    NASA Astrophysics Data System (ADS)

    González, J. O.; Shaji, S.; Avellaneda, D.; Castillo, G. A.; Das Roy, T. K.; Krishnan, B.

    2014-09-01

    Photovoltaic structures were prepared using AgSb(S x Se1- x )2 as absorber and CdS as window layer at various conditions via a hybrid technique of chemical bath deposition and thermal evaporation followed by heat treatments. Silver antimony sulfo selenide thin films [AgSb(S x Se1- x )2] were prepared by heating multilayers of sequentially deposited Sb2S3/Ag dipped in Na2SeSO3 solution, glass/Sb2S3/Ag/Se. For this, Sb2S3 thin films were deposited from a chemical bath containing SbCl3 and Na2S2O3. Then, Ag thin films were thermally evaporated on glass/Sb2S3, followed by selenization by dipping in an acidic solution of Na2SeSO3. The duration of dipping was varied as 3, 4 and 5 h. Two different heat treatments, one at 350 °C for 20 min in vacuum followed by a post-heat treatment at 325 °C for 2 h in Ar, and the other at 350 °C for 1 h in Ar, were applied to the multilayers of different configurations. X-ray diffraction results showed the formation of AgSb(S x Se1- x )2 thin films as the primary phase and AgSb(S,Se)2 and Sb2S3 as secondary phases. Morphology and elemental detection were done by scanning electron microscopy and energy dispersive X-ray analysis. X-ray photoelectron spectroscopic studies showed the depthwise composition of the films. Optical properties were determined by UV-vis-IR transmittance and reflection spectral analysis. AgSb(S x Se1- x )2 formed at different conditions was incorporated in PV structures glass/FTO/CdS/AgSb(S x Se1- x )2/C/Ag. Chemically deposited post-annealed CdS thin films of various thicknesses were used as window layer. J- V characteristics of the cells were measured under dark and AM1.5 illumination. Analysis of the J- V characteristics resulted in the best solar cell parameters of V oc = 520 mV, J sc = 9.70 mA cm-2, FF = 0.50 and η = 2.7 %.

  4. Polycrystalline thin film photovoltaics

    NASA Astrophysics Data System (ADS)

    Zweibel, K.; Ullal, H. S.; Mitchell, R. L.

    Significant progress has recently been made towards improving the efficiencies of polycrystalline thin-film solar cells and modules using CuInSe2 and CdTe. The history of using CuInSe2 and CdTe for solar cells is reviewed. Initial outdoor stability tests of modules are encouraging. Progress in semiconductor deposition techniques has also been substantial. Both CuInSe2 and CdTe are positioned for commercialization during the 1990s. The major participants in developing these materials are described. The US DOE/SERI (Solar Energy Research Institute) program recognizes the rapid progress and important potential of polycrystalline thin films to meet ambitious cost and performance goals. US DOE/SERI is in the process of funding an initiative in this area with the goal of ensuring US leadership in the development of these technologies. The polycrystalline thin-film module development initiative, the modeling and stability of the devices, and health and safety issues are discussed.

  5. Headspace thin-film microextraction coupled with surface-enhanced Raman scattering as a facile method for reproducible and specific detection of sulfur dioxide in wine.

    PubMed

    Deng, Zhuo; Chen, Xuexu; Wang, Yiru; Fang, Enhua; Zhang, Zhigang; Chen, Xi

    2015-01-01

    By coupling thin-film microextraction (TFME) with surface-enhanced Raman scattering (SERS), a facile method was developed for the determination of sulfur dioxide (SO2), the most effective food additive in winemaking technology. The TFME substrate was made by free settling of sea urchin-like ZnO nanomaterials on a glass sheet. The headspace sampling (HS) procedure for SO2 was performed in a simple homemade device, and then the SO2 was determined using SERS after uniformly dropping or spraying a SERS-active substrate (gold nanoparticles, AuNPs) onto the surface of the TFME substrate. A reproducible and strong SERS response of the SO2 absorbed onto the ZnO substrate was obtained. After condition optimization, the SERS signal intensity at a shift of 600 cm(-1) and the SO2 concentration showed a good linearity in the range of 1-200 μg/mL, and the linear correlation coefficient was 0.992. The detection limit for SO2 was found to be 0.1 μg/mL. The HS-TFME-SERS method was applied for the determination of SO2 in wine, and the results obtained agreed very well with those obtained using the traditional distillation and titration method. Analysis of variance and Student t test show that there is no significant difference between the two methods, indicating that the newly developed method is fast, convenient, sensitive and has selective characteristics in the determination of SO2 in wine. PMID:25415770

  6. Electronic structure modification and Fermi level shifting in niobium-doped anatase titanium dioxide thin films: a comparative study of NEXAFS, work function and stiffening of phonons.

    PubMed

    Gautam, Subodh K; Das, Arkaprava; Ojha, S; Shukla, D K; Phase, D M; Singh, Fouran

    2016-02-01

    The electronic structure and tuning of work function (WF) by electronic excitations (EEs) induced by swift heavy ions (SHIs) in anatase niobium-doped titanium dioxide (NTO) thin films is reported. The densities of EEs were varied using 80 MeV O, 130 MeV Ni and 120 MeV Ag ions for irradiation. The EE-induced modifications in electronic structure were studied by O K-edge and Ti L3,2 edge absorption spectra using near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The reduction of hybridized O 2p and Ti 3d unoccupied states in the conduction band with a decrease in energy of the crystal field strength of ∼ 480 meV and the correlated effect on the decrease in the WF value of ∼ 520 meV upon increasing the total energy deposition in the lattice are evident from the study of NEXAFS and scanning Kelvin probe microscopy (SKPM), respectively. The observed stiffening in the low frequency Raman mode (LFRM) of ∼ 9 cm(-1) further validates the electronic structure modification under the influence of EE-induced strain in TiO6 octahedra. The reduction of hybridized valence states, stiffening behavior of LFRM and decrease in WF by nano-crystallization followed by amorphization and defects in NTO lattice are explained in terms of continuous, discontinuous amorphous ion tracks containing intestinally created defects and non-stoichiometry in the lattice. These studies are very appropriate for better insights of electronic structure modification during phase transformation and controlled Fermi level shifting, which plays a crucial role in controlling the charge carrier injection efficiency in opto-electronic applications and also provides a deeper understanding of the involved physical processes. PMID:26752253

  7. New diffusive gradients in a thin film technique for measuring inorganic arsenic and selenium(IV) using a titanium dioxide based adsorbent.

    PubMed

    Bennett, William W; Teasdale, Peter R; Panther, Jared G; Welsh, David T; Jolley, Dianne F

    2010-09-01

    A new diffusive gradients in a thin film (DGT) technique, using a titanium dioxide based adsorbent (Metsorb), has been developed and evaluated for the determination of dissolved inorganic arsenic and selenium. As(III), As(V), and Se(IV) were found to be quantitatively accumulated by the adsorbent (uptake efficiencies of 96.5-100%) and eluted in 1 M NaOH (elution efficiencies of 81.2%, 75.2%, and 88.7%). Se(VI) was not quantitatively accumulated by the adsorbent (<20%). Laboratory DGT validation experiments gave linear mass uptake over time (R(2) >or= 0.998) for As(III), As(V), and Se(IV). Consistent uptake occurred over pH (3.5-8.5) and ionic strength (0.0001-0.75 mol L(-1) NaNO(3)) ranges typical of natural waters, including seawater. Field deployments of DGT probes with various diffusive layer thicknesses confirmed the use of the technique in situ, allowing calculation of the diffusive boundary layers and an accurate measurement of inorganic arsenic. Reproducibility of the technique in field deployments was good (relative standard deviation <8%). Limits of detection (4 day deployments) were 0.01 microg L(-1) for inorganic arsenic and 0.05 microg L(-1) for Se(IV). The results of this study confirmed that DGT with Metsorb was a reliable and robust method for the measurement of inorganic arsenic and the selective measurement of Se(IV) within useful limits of accuracy. PMID:20695441

  8. Thin film mechanics

    NASA Astrophysics Data System (ADS)

    Cooper, Ryan C.

    This doctoral thesis details the methods of determining mechanical properties of two classes of novel thin films suspended two-dimensional crystals and electron beam irradiated microfilms of polydimethylsiloxane (PDMS). Thin films are used in a variety of surface coatings to alter the opto-electronic properties or increase the wear or corrosion resistance and are ideal for micro- and nanoelectromechanical system fabrication. One of the challenges in fabricating thin films is the introduction of strains which can arise due to application techniques, geometrical conformation, or other spurious conditions. Chapters 2-4 focus on two dimensional materials. This is the intrinsic limit of thin films-being constrained to one atomic or molecular unit of thickness. These materials have mechanical, electrical, and optical properties ideal for micro- and nanoelectromechanical systems with truly novel device functionality. As such, the breadth of applications that can benefit from a treatise on two dimensional film mechanics is reason enough for exploration. This study explores the anomylously high strength of two dimensional materials. Furthermore, this work also aims to bridge four main gaps in the understanding of material science: bridging the gap between ab initio calculations and finite element analysis, bridging the gap between ab initio calculations and experimental results, nanoscale to microscale, and microscale to mesoscale. A nonlinear elasticity model is used to determine the necessary elastic constants to define the strain-energy density function for finite strain. Then, ab initio calculations-density functional theory-is used to calculate the nonlinear elastic response. Chapter 2 focuses on validating this methodology with atomic force microscope nanoindentation on molybdenum disulfide. Chapter 3 explores the convergence criteria of three density functional theory solvers to further verify the numerical calculations. Chapter 4 then uses this model to investigate

  9. Dependence of electrophysical properties on structure of vanadium dioxide films

    SciTech Connect

    Aleksandrov, Yu.A.; Baryshnikov, Yu.Yu.; Zakharov, I.L.; Makin, G.I.; Terman, M.Yu.

    1988-02-01

    Among the inorganic materials with a metal-semiconductor phase transition (MSPT), vanadium dioxide attracts much theoretical and practical interest for two reasons. First, the maximum change in the electrical conductivity at the MSPT point is of order of magnitudes, and secondly, since the temperature T/sub P/ at the MSPT point is about 68/sup 0/C, neither high nor low temperature techniques are required for the utilization of VO/sub 2/. We study the mixture and structural-morphological condition of thin films (0.01-2 ..mu..m) of vanadium dioxide as well as the relation between the films and the change in the resistivity in the MSPT temperature range. The resistivity of the vanadium dioxide films was measured by a standard four probe method.

  10. Thin film oxygen partial pressure sensor

    NASA Technical Reports Server (NTRS)

    Wortman, J. J.; Harrison, J. W.; Honbarrier, H. L.; Yen, J.

    1972-01-01

    The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

  11. Polycrystalline thin film photovoltaic technology

    SciTech Connect

    Ullal, H.S.; Zweibel, K.; Mitchell, R.L.; Noufi, R.

    1991-03-01

    Low-cost, high-efficiency thin-film modules are an exciting photovoltaic technology option for generating cost-effective electricity in 1995 and beyond. In this paper we review the significant technical progress made in the following thin films: copper indium diselenide, cadmium telluride, and polycrystalline thin silicon films. Also, the recent US DOE/SERI initiative to commercialize these emerging technologies is discussed. 6 refs., 9 figs.

  12. Center for thin film studies

    NASA Astrophysics Data System (ADS)

    Shannon, Robert P.; Gibson, Ursula J.

    1987-11-01

    This report covers the first year of operation of the URI Thin Film Center (TFC), and describes a diverse array of studies on thin-film materials, substrates, and their processing and analysis. Individual efforts are highlighted in sections on nucleation studies, ion-assisted deposition, Rutherford backscattering spectrometry, Brillouin scattering, a continuum theory of the evolution of structure in thin films, a study of polishing parameters relevant to the preparation of substrates, and the setup of a characterization facility for the Center.

  13. Polycrystalline thin-films

    NASA Astrophysics Data System (ADS)

    Zweibel, K.; Mitchell, R.

    1986-02-01

    This annual report summarizes the status, accomplishments, and projected future research directions of the Polycrystalline Thin Film Task in the Photovoltaic Program Branch of the Solar Energy Research Institute's Solar Electric Research Division. Major subcontracted work in this area has concentrated on development of CuInSe2 and CdTe technologies. During FY 1985, major progress was achieved by subcontractors in: (1) developing a new, low-cost method of fabricating CuInSe2, and (2) improving the efficiency of CuInSe2 devices by about 10% (relative). The report also lists research planned to meet the Department of Energy's goals in these technologies.

  14. Thin film hydrogen sensor

    DOEpatents

    Lauf, Robert J.; Hoffheins, Barbara S.; Fleming, Pamela H.

    1994-01-01

    A hydrogen sensor element comprises an essentially inert, electrically-insulating substrate having a thin-film metallization deposited thereon which forms at least two resistors on the substrate. The metallization comprises a layer of Pd or a Pd alloy for sensing hydrogen and an underlying intermediate metal layer for providing enhanced adhesion of the metallization to the substrate. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors, and at least one of the resistors is left uncovered. The difference in electrical resistances of the covered resistor and the uncovered resistor is related to hydrogen concentration in a gas to which the sensor element is exposed.

  15. Nonlinear optical thin films

    NASA Technical Reports Server (NTRS)

    Leslie, Thomas M.

    1993-01-01

    A focused approach to development and evaluation of organic polymer films for use in optoelectronics is presented. The issues and challenges that are addressed include: (1) material synthesis, purification, and the tailoring of the material properties; (2) deposition of uniform thin films by a variety of methods; (3) characterization of material physical properties (thermal, electrical, optical, and electro-optical); and (4) device fabrication and testing. Photonic materials, devices, and systems were identified as critical technology areas by the Department of Commerce and the Department of Defense. This approach offers strong integration of basic material issues through engineering applications by the development of materials that can be exploited as the active unit in a variety of polymeric thin film devices. Improved materials were developed with unprecedented purity and stability. The absorptive properties can be tailored and controlled to provide significant improvement in propagation losses and nonlinear performance. Furthermore, the materials were incorporated into polymers that are highly compatible with fabrication and patterning processes for integrated optical devices and circuits. By simultaneously addressing the issues of materials development and characterization, keeping device design and fabrication in mind, many obstacles were overcome for implementation of these polymeric materials and devices into systems. We intend to considerably improve the upper use temperature, poling stability, and compatibility with silicon based devices. The principal device application that was targeted is a linear electro-optic modulation etalon. Organic polymers need to be properly designed and coupled with existing integrated circuit technology to create new photonic devices for optical communication, image processing, other laser applications such as harmonic generation, and eventually optical computing. The progression from microscopic sample to a suitable film

  16. An investigation into the optimum thickness of titanium dioxide thin films synthesized by using atmospheric pressure chemical vapour deposition for use in photocatalytic water oxidation.

    PubMed

    Hyett, Geoffrey; Darr, Jawwad A; Mills, Andrew; Parkin, Ivan P

    2010-09-10

    Twenty eight films of titanium dioxide of varying thickness were synthesised by using atmospheric pressure chemical vapour deposition (CVD) of titanium(IV) chloride and ethyl acetate onto glass and titanium substrates. Fixed reaction conditions at a substrate temperature of 660 °C were used for all depositions, with varying deposition times of 5-60 seconds used to control the thickness of the samples. A sacrificial electron acceptor system composed of alkaline sodium persulfate was used to determine the rate at which these films could photo-oxidise water in the presence of 365 nm light. The results of this work showed that the optimum thickness for CVD films on titanium substrates for the purposes of water oxidation was ≈200 nm, and that a platinum coating on the reverse of such samples leads to a five-fold increase in the observed rate of water oxidation. PMID:20645333

  17. Thin film atomic hydrogen detectors

    NASA Technical Reports Server (NTRS)

    Gruber, C. L.

    1977-01-01

    Thin film and bead thermistor atomic surface recombination hydrogen detectors were investigated both experimentally and theoretically. Devices were constructed on a thin Mylar film substrate. Using suitable Wheatstone bridge techniques sensitivities of 80 microvolts/2x10 to the 13th power atoms/sec are attainable with response time constants on the order of 5 seconds.

  18. Polysilicon thin films and interfaces

    SciTech Connect

    Kamins, T. ); Raicu, B. ); Thompson, C.V. )

    1990-01-01

    This volume contains the proceedings of a symposium on polysilicon thin films and interfaces, held as part of the 1990 Materials Research Society Spring Meeting. Topics covered include: crystal grown fo silicon and germanium wafers for photovoltaic devices, microanalysis of tungsten silicide interface, thermal processing of polysilicon thin films, and electrical and optical properties of polysilicon sheets for photovoltaic devices.

  19. Thin film ion conducting coating

    DOEpatents

    Goldner, Ronald B.; Haas, Terry; Wong, Kwok-Keung; Seward, George

    1989-01-01

    Durable thin film ion conducting coatings are formed on a transparent glass substrate by the controlled deposition of the mixed oxides of lithium:tantalum or lithium:niobium. The coatings provide durable ion transport sources for thin film solid state storage batteries and electrochromic energy conservation devices.

  20. Thin film phase transition materials development program

    NASA Astrophysics Data System (ADS)

    Case, W. E.

    1985-04-01

    A number of application concepts have emerged based on the idea that a phase transition thin film such as vanadium dioxide provides a high resolution, two-dimensional format for switching, recording, and processing optical signals. These applications range from high density optical disk recording systems and optical data processing to laser protection devices, infrared FLIRS and seekers, laser radar systems and IR scene simulators. All application candidates have a potential for providing either a totally new capability, an improved performance, a lower cost, or combinations of the three. Probably of greatest significance is the emergence of agile sensor concepts arising out of some of the film's special properties. These are represented by the above FLIRs, seekers and laser radar systems. A three year research program has been completed to advance the state-of-the-art in the preparation and characterization of selected thin film phase transition materials. The objectives of the program were: (1) to expand the data base and improve operational characteristics of Vought prepared vanadium dioxide thin films, (2) to evolve process chemistry and subsequently characterize several new program materials, including rare-earth chalcogenides, organic semiconductor charge complexes, alloys of transition metal oxides, and metal-insulator cermets, and (3) to spin-off new applications and concepts.

  1. Fabrication of mesoporous cerium dioxide films by cathodic electrodeposition.

    PubMed

    Kim, Young-Soo; Lee, Jin-Kyu; Ahn, Jae-Hoon; Park, Eun-Kyung; Kim, Gil-Pyo; Baeck, Sung-Hyeon

    2007-11-01

    Mesoporous cerium dioxide (Ceria, CeO2) thin films have been successfully electrodeposited onto ITO-coated glass substrates from an aqueous solution of cerium nitrate using CTAB (Cetyltrimethylammonium Bromide) as a templating agent. The synthesized films underwent detailed characterizations. The crystallinity of synthesized CeO2 film was confirmed by XRD analysis and HR-TEM analysis, and surface morphology was investigated by SEM analysis. The presence of mesoporosity in fabricated films was confirmed by TEM and small angle X-ray analysis. As-synthesized film was observed from XRD analysis and HR-TEM image to have well-crystallized structure of cubic phase CeO2. Transmission electron microscopy and small angle X-ray analysis revealed the presence of uniform mesoporosity with a well-ordered lamellar phase in the CeO2 films electrodeposited with CTAB templating. PMID:18047150

  2. Polycrystalline thin films

    NASA Astrophysics Data System (ADS)

    Zweibel, K.; Mitchell, R.; Ullal, H.

    1987-02-01

    This annual report for fiscal year 1986 summarizes the status, accomplishments, and projected future research directions of the Polycrystalline Thin Film Task in the Photovoltaic Program Branch of the Solar Energy Research Institute's Solar Electric Research Division. Subcontracted work in this area has concentrated on the development of CuInSe2 and CdTe technologies. During FY 1986, major progress was achieved by subcontractors in (1) achieving 10.5% (SERI-verified) efficiency with CdTe, (2) improving the efficiency of selenized CuInSe2 solar cells to nearly 8%, and (3) developing a transparent contact to CdTe cells for potential use in the top cells of tandem structures.

  3. Polyimide Aerogel Thin Films

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann; Guo, Haiquan

    2012-01-01

    Polyimide aerogels have been crosslinked through multifunctional amines. This invention builds on "Polyimide Aerogels With Three-Dimensional Cross-Linked Structure," and may be considered as a continuation of that invention, which results in a polyimide aerogel with a flexible, formable form. Gels formed from polyamic acid solutions, end-capped with anhydrides, and cross-linked with the multifunctional amines, are chemically imidized and dried using supercritical CO2 extraction to give aerogels having density around 0.1 to 0.3 g/cubic cm. The aerogels are 80 to 95% porous, and have high surface areas (200 to 600 sq m/g) and low thermal conductivity (as low as 14 mW/m-K at room temperature). Notably, the cross-linked polyimide aerogels have higher modulus than polymer-reinforced silica aerogels of similar density, and can be fabricated as both monoliths and thin films.

  4. Ferromagnetic thin films

    DOEpatents

    Krishnan, Kannan M.

    1994-01-01

    A ferromagnetic .delta.-Mn.sub.1-x Ga.sub.x thin film having perpendicular anisotropy is described which comprises: (a) a GaAs substrate, (b) a layer of undoped GaAs overlying said substrate and bonded thereto having a thickness ranging from about 50 to about 100 nanometers, (c) a layer of .delta.-Mn.sub.1-x Ga.sub.x overlying said layer of undoped GaAs and bonded thereto having a thickness ranging from about 20 to about 30 nanometers, and (d) a layer of GaAs overlying said layer of .delta.-Mn.sub.1-x Ga.sub.x and bonded thereto having a thickness ranging from about 2 to about 5 nanometers, wherein x is 0.4 .+-.0.05.

  5. Ferromagnetic thin films

    DOEpatents

    Krishnan, K.M.

    1994-12-20

    A ferromagnetic [delta]-Mn[sub 1[minus]x]Ga[sub x] thin film having perpendicular anisotropy is described which comprises: (a) a GaAs substrate, (b) a layer of undoped GaAs overlying said substrate and bonded thereto having a thickness ranging from about 50 to about 100 nanometers, (c) a layer of [delta]-Mn[sub 1[minus]x]Ga[sub x] overlying said layer of undoped GaAs and bonded thereto having a thickness ranging from about 20 to about 30 nanometers, and (d) a layer of GaAs overlying said layer of [delta]-Mn[sub 1[minus]x]Ga[sub x] and bonded thereto having a thickness ranging from about 2 to about 5 nanometers, wherein x is 0.4[+-]0.05. 7 figures.

  6. Thin-film microextraction.

    PubMed

    Bruheim, Inge; Liu, Xiaochuan; Pawliszyn, Janusz

    2003-02-15

    The properties of a thin sheet of poly(dimethylsiloxane) (PDMS) membrane as an extraction phase were examined and compared to solid-phase microextraction (SPME) PDMS-coated fiber for application to semivolatile analytes in direct and headspace modes. This new PDMS extraction approach showed much higher extraction rates because of the larger surface area to extraction-phase volume ratio of the thin film. Unlike the coated rod formats of SPME using thick coatings, the high extraction rate of the membrane SPME technique allows larger amounts of analytes to be extracted within a short period of time. Therefore, higher extraction efficiency and sensitivity can be achieved without sacrificing analysis time. In direct membrane SPME extraction, a linear relationship was found between the initial rate of extraction and the surface area of the extraction phase. However, for headspace extraction, the rates were somewhat lower because of the resistance to analyte transport at the sample matrix/headspace barrier. It was found that the effect of this barrier could be reduced by increasing either agitation, temperature, or surface area of the sample matrix/headspace interface. A method for the determination of PAHs in spiked lake water samples was developed based on the membrane PDMS extraction coupled with GC/MS. A linearity of 0.9960 and detection limits in the low-ppt level were found. The reproducibility was found to vary from 2.8% to 10.7%. PMID:12622398

  7. Interference Colors in Thin Films.

    ERIC Educational Resources Information Center

    Armstrong, H. L.

    1979-01-01

    Explains interference colors in thin films as being due to the removal, or considerable reduction, of a certain color by destructive inteference that results in the complementary color being seen. (GA)

  8. Thin film cell development workshop report

    NASA Technical Reports Server (NTRS)

    Woodyard, James R.

    1991-01-01

    The Thin Film Development Workshop provided an opportunity for those interested in space applications of thin film cells to debate several topics. The unique characteristics of thin film cells as well as a number of other issues were covered during the discussions. The potential of thin film cells, key research and development issues, manufacturing issues, radiation damage, substrates, and space qualification of thin film cells were discussed.

  9. Thin-Film Power Transformers

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.

    1995-01-01

    Transformer core made of thin layers of insulating material interspersed with thin layers of ferromagnetic material. Flux-linking conductors made of thinner nonferromagnetic-conductor/insulator multilayers wrapped around core. Transformers have geometric features finer than those of transformers made in customary way by machining and mechanical pressing. In addition, some thin-film materials exhibit magnetic-flux-carrying capabilities superior to those of customary bulk transformer materials. Suitable for low-cost, high-yield mass production.

  10. Vapor deposition of thin films

    DOEpatents

    Smith, David C.; Pattillo, Stevan G.; Laia, Jr., Joseph R.; Sattelberger, Alfred P.

    1992-01-01

    A highly pure thin metal film having a nanocrystalline structure and a process of preparing such highly pure thin metal films of, e.g., rhodium, iridium, molybdenum, tungsten, rhenium, platinum, or palladium by plasma assisted chemical vapor deposition of, e.g., rhodium(allyl).sub.3, iridium(allyl).sub.3, molybdenum(allyl).sub.4, tungsten(allyl).sub.4, rhenium(allyl).sub.4, platinum(allyl).sub.2, or palladium(allyl).sub.2 are disclosed. Additionally, a general process of reducing the carbon content of a metallic film prepared from one or more organometallic precursor compounds by plasma assisted chemical vapor deposition is disclosed.

  11. Calorimetry of epitaxial thin films.

    PubMed

    Cooke, David W; Hellman, F; Groves, J R; Clemens, B M; Moyerman, S; Fullerton, E E

    2011-02-01

    Thin film growth allows for the manipulation of material on the nanoscale, making possible the creation of metastable phases not seen in the bulk. Heat capacity provides a direct way of measuring thermodynamic properties of these new materials, but traditional bulk calorimetric techniques are inappropriate for such a small amount of material. Microcalorimetry and nanocalorimetry techniques exist for the measurements of thin films but rely on an amorphous membrane platform, limiting the types of films which can be measured. In the current work, ion-beam-assisted deposition is used to provide a biaxially oriented MgO template on a suspended membrane microcalorimeter in order to measure the specific heat of epitaxial thin films. Synchrotron x-ray diffraction showed the biaxial order of the MgO template. X-ray diffraction was also used to prove the high quality of epitaxy of a film grown onto this MgO template. The contribution of the MgO layer to the total heat capacity was measured to be just 6.5% of the total addenda contribution. The heat capacity of a Fe(.49)Rh(.51) film grown epitaxially onto the device was measured, comparing favorably to literature data on bulk crystals. This shows the viability of the MgO∕SiN(x)-membrane-based microcalorimeter as a way of measuring the thermodynamic properties of epitaxial thin films. PMID:21361612

  12. The Thin Oil Film Equation

    NASA Technical Reports Server (NTRS)

    Brown, James L.; Naughton, Jonathan W.

    1999-01-01

    A thin film of oil on a surface responds primarily to the wall shear stress generated on that surface by a three-dimensional flow. The oil film is also subject to wall pressure gradients, surface tension effects and gravity. The partial differential equation governing the oil film flow is shown to be related to Burgers' equation. Analytical and numerical methods for solving the thin oil film equation are presented. A direct numerical solver is developed where the wall shear stress variation on the surface is known and which solves for the oil film thickness spatial and time variation on the surface. An inverse numerical solver is also developed where the oil film thickness spatial variation over the surface at two discrete times is known and which solves for the wall shear stress variation over the test surface. A One-Time-Level inverse solver is also demonstrated. The inverse numerical solver provides a mathematically rigorous basis for an improved form of a wall shear stress instrument suitable for application to complex three-dimensional flows. To demonstrate the complexity of flows for which these oil film methods are now suitable, extensive examination is accomplished for these analytical and numerical methods as applied to a thin oil film in the vicinity of a three-dimensional saddle of separation.

  13. Thin-film metal hydrides.

    PubMed

    Remhof, Arndt; Borgschulte, Andreas

    2008-12-01

    The goal of the medieval alchemist, the chemical transformation of common metals into nobel metals, will forever be a dream. However, key characteristics of metals, such as their electronic band structure and, consequently, their electric, magnetic and optical properties, can be tailored by controlled hydrogen doping. Due to their morphology and well-defined geometry with flat, coplanar surfaces/interfaces, novel phenomena may be observed in thin films. Prominent examples are the eye-catching hydrogen switchable mirror effect, the visualization of solid-state diffusion and the formation of complex surface morphologies. Thin films do not suffer as much from embrittlement and/or decrepitation as bulk materials, allowing the study of cyclic absorption and desorption. Therefore, thin-metal hydride films are used as model systems to study metal-insulator transitions, for high throughput combinatorial research or they may be used as indicator layers to study hydrogen diffusion. They can be found in technological applications as hydrogen sensors, in electrochromic and thermochromic devices. In this review, we discuss the effect of hydrogen loading of thin niobium and yttrium films as archetypical examples of a transition metal and a rare earth metal, respectively. Our focus thereby lies on the hydrogen induced changes of the electronic structure and the morphology of the thin films, their optical properties, the visualization and the control of hydrogen diffusion and on the study of surface phenomena and catalysis. PMID:18980236

  14. Plasma synthesis of photocatalytic TiO x thin films

    NASA Astrophysics Data System (ADS)

    Sirghi, L.

    2016-06-01

    The development of efficient photocatalytic materials is promising technology for sustainable and green energy production, fabrication of self-cleaning, bactericidal, and super hydrophilic surfaces, CO2 photoreduction, and decomposition of toxic pollutants in air and water. Semiconductors with good photocatalytic activity have been known for four decades and they are regarded as promising candidates for these new technologies. Low-pressure discharge plasma is one of the most versatile technologies being used for the deposition of photocatalytic semiconductor thin films. This article reviews the main results obtained by the author in using low-pressure plasma for synthesis of TiO x thin films with applications in photocatalysis. Titanium dioxide thin films were obtained by radio frequency magnetron sputtering deposition, plasma enhanced chemical vapour deposition, and high power impulse magnetron sputtering deposition. The effects of the plasma deposition method, plasma parameters, film thickness and substrate on the film structure, chemical composition and photocatalytic activity are investigated. The photocatalytic activity of plasma synthesised TiO x thin films was estimated by UV light induced hydrophilicity. Measurements of photocurrent decay in TiO x thin films in vacuum and air showed that the photocatalytic activity is closely connected to the production, recombination and availability for surface reactions of photo-generated charge carriers. The photocatalytic activity of TiO x thin films was investigated at nanoscale by atomic force microscopy. Microscopic regions of different hydrophilicity on UV light irradiated films are discriminated by AFM atomic force microscopy measurements of adhesion and friction force.

  15. Thin film of biocompatible polysaccharides

    NASA Astrophysics Data System (ADS)

    Richert, Ludovic; Lavalle, Philippe; Schaaf, Pierre; Voegel, Jean-Claude; Picart, Catherine

    2003-03-01

    The layer-by-layer deposition method proposed by Decher et al. (1991) is a very simple and versatile method used to build thin films. These films are of interest for bioengineering because of their unique properties and of the possible insertion of bioactive molecules. We present here the peculiar properties of a new kind of film formed with natural biopolymers, namely hyaluronan (HA)and chitosan (CHI). The films may be used as biomimetic substrates to control bacterial and cell adhesion. These polysaccharides are of particular interest because they are biodegradable, non toxic, and can be found in various tissues. Hyaluronan is also a natural ligand for a numerous type of cells through the CD44 receptor. Chitosan has already largely been used for its biological and anti-microbial properties. (CHI/HA) films were built in acidic pH at different ionic strength. The buildup was followed in situ by optical waveguide lightmode spectroscopy (OWLS), quartz crystal microbalance, streaming potential measurements and atomic force microscopy. The kinetics of adsorption and desorption of the polyelectrolytes depended on the ionic strength. Small islands were initially present on the surface which grew by mutual coalescence until becoming a flat film. The films were around 200 nm in thickness. These results suggest that different types of thin films constituted of polysaccharides can be built on any type of surface. These films are currently investigated toward their cell adhesion and bacterial adhesion properties.

  16. (Thin films under chemical stress)

    SciTech Connect

    Not Available

    1990-01-01

    As stated above the purpose of this research is to enable workers in a variety of fields to understand the chemical and physical changes which take place when thin films (primarily organic films) are placed under chemical stress. This stress may occur because the film is being swelled by penetrant entrained in solvent, because interfacial reactions are occurring at one or more boundaries within the film structure, or because some component of the film is responding to an external stimulus (e.g. pH, temperature, electric field, or radiation). These questions are important within the context of our long-term goal of understanding the behavior of composite structures, composed of thin organic polymer films interspersed with Langmuir-Blodgett (LB) and self-assembled monolayers, which might have unique functional properties. In the past year we have concentrated on the following objectives: (1) understanding how the two possible diffusion mechanisms contribute to the swelling of thin films of organic polymers place in solution, (2) identifying systems which are appropriate polymer media for the construction of composite membranes for use in aqueous environments, and (3) understanding the self-assembly process for long chain fatty acids at model surfaces. Progress in meeting each of these objectives will be described in this report. 4 figs.

  17. Strip loaded waveguide on lithium niobate thin films

    NASA Astrophysics Data System (ADS)

    Roussey, Matthieu; Karvinen, Petri; Häyrinen, Markus; Honkanen, Seppo; Kuittinen, Markku

    2016-02-01

    We present the experimental demonstration of a strip loaded waveguide on crystalline lithium niobate thin film. The structure consists in a 1 μm-wide and 200 nm-thick titanium dioxide strip waveguide on a 700 nm lithium niobate slab waveguide. It operates at the telecom wavelength for a TE-polarized light.

  18. Thin-film forces in pseudoemulsion films

    SciTech Connect

    Bergeron, V.; Radke, C.J. |

    1991-06-01

    Use of foam for enhanced oil recovery (EOR) has shown recent success in steam-flooding field applications. Foam can also provide an effective barrier against gas coning in thin oil zones. Both of these applications stem from the unique mobility-control properties a stable foam possesses when it exists in porous media. Unfortunately, oil has a major destabilizing effect on foam. Therefore, it is important for EOR applications to understand how oil destroys foam. Studies all indicate that stabilization of the pseudoemulsion film is critical to maintain foam stability in the presence of oil. Hence, to aid in design of surfactant formulations for foam insensitivity to oil the authors pursue direct measurement of the thin-film or disjoining forces that stabilize pseudoemulsion films. Experimental procedures and preliminary results are described.

  19. Thin films under chemical stress

    SciTech Connect

    Not Available

    1991-01-01

    The goal of work on this project has been develop a set of experimental tools to allow investigators interested in transport, binding, and segregation phenomena in composite thin film structures to study these phenomena in situ. Work to-date has focuses on combining novel spatially-directed optical excitation phenomena, e.g. waveguide eigenmodes in thin dielectric slabs, surface plasmon excitations at metal-dielectric interfaces, with standard spectroscopies to understand dynamic processes in thin films and at interfaces. There have been two main scientific thrusts in the work and an additional technical project. In one thrust we have sought to develop experimental tools which will allow us to understand the chemical and physical changes which take place when thin polymer films are placed under chemical stress. In principle this stress may occur because the film is being swelled by a penetrant entrained in solvent, because interfacial reactions are occurring at one or more boundaries within the film structure, or because some component of the film is responding to an external stimulus (e.g. pH, temperature, electric field, or radiation). However all work to-date has focused on obtaining a clearer understanding penetrant transport phenomena. The other thrust has addressed the kinetics of adsorption of model n-alkanoic acids from organic solvents. Both of these thrusts are important within the context of our long-term goal of understanding the behavior of composite structures, composed of thin organic polymer films interspersed with Langmuir-Blodgett (LB) and self-assembled monolayers. In addition there has been a good deal of work to develop the local technical capability to fabricate grating couplers for optical waveguide excitation. This work, which is subsidiary to the main scientific goals of the project, has been successfully completed and will be detailed as well. 41 refs., 10 figs.

  20. Beryllium thin films for resistor applications

    NASA Technical Reports Server (NTRS)

    Fiet, O.

    1972-01-01

    Beryllium thin films have a protective oxidation resistant property at high temperature and high recrystallization temperature. However, the experimental film has very low temperature coefficient of resistance.

  1. Semiconductor-nanocrystal/conjugated polymer thin films

    DOEpatents

    Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

    2014-06-17

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  2. Thin film-coated polymer webs

    DOEpatents

    Wenz, Robert P.; Weber, Michael F.; Arudi, Ravindra L.

    1992-02-04

    The present invention relates to thin film-coated polymer webs, and more particularly to thin film electronic devices supported upon a polymer web, wherein the polymer web is treated with a purifying amount of electron beam radiation.

  3. Semiconductor-nanocrystal/conjugated polymer thin films

    DOEpatents

    Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

    2010-08-17

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  4. Low work function, stable thin films

    DOEpatents

    Dinh, Long N.; McLean, II, William; Balooch, Mehdi; Fehring, Jr., Edward J.; Schildbach, Marcus A.

    2000-01-01

    Generation of low work function, stable compound thin films by laser ablation. Compound thin films with low work function can be synthesized by simultaneously laser ablating silicon, for example, and thermal evaporating an alkali metal into an oxygen environment. For example, the compound thin film may be composed of Si/Cs/O. The work functions of the thin films can be varied by changing the silicon/alkali metal/oxygen ratio. Low work functions of the compound thin films deposited on silicon substrates were confirmed by ultraviolet photoelectron spectroscopy (UPS). The compound thin films are stable up to 500.degree. C. as measured by x-ray photoelectron spectroscopy (XPS). Tests have established that for certain chemical compositions and annealing temperatures of the compound thin films, negative electron affinity (NEA) was detected. The low work function, stable compound thin films can be utilized in solar cells, field emission flat panel displays, electron guns, and cold cathode electron guns.

  5. Thin film polymeric gel electrolytes

    DOEpatents

    Derzon, D.K.; Arnold, C. Jr.; Delnick, F.M.

    1996-12-31

    Novel hybrid thin film electrolytes, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities {approx_equal}10{sup {minus}3}{Omega}{sup {minus}1} cm{sup {minus}1} are useful as electrolytes for rechargeable lithium batteries. 1 fig.

  6. Thin Film Solid Lubricant Development

    NASA Technical Reports Server (NTRS)

    Benoy, Patricia A.

    1997-01-01

    Tribological coatings for high temperature sliding applications are addressed. A sputter-deposited bilayer coating of gold and chromium is investigated as a potential solid lubricant for protection of alumina substrates during sliding at high temperature. Evaluation of the tribological properties of alumina pins sliding against thin sputtered gold films on alumina substrates is presented.

  7. Hybrid thin-film amplifier

    NASA Technical Reports Server (NTRS)

    Cleveland, G.

    1977-01-01

    Miniature amplifier for bioelectronic instrumentation consumes only about 100 mW and has frequency response flat to within 0.5 dB from 0.14 to 450 Hz. Device consists of five thin film substrates, which contain eight operational amplifiers and seven field-effect transistor dice.

  8. Thin film polymeric gel electrolytes

    DOEpatents

    Derzon, Dora K.; Arnold, Jr., Charles; Delnick, Frank M.

    1996-01-01

    Novel hybrid thin film electrolyte, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities .apprxeq.10.sup.-3 .OMEGA..sup.-1 cm.sup.-1 are useful as electrolytes for rechargeable lithium batteries.

  9. Thin films and uses

    DOEpatents

    Baskaran, Suresh; Graff, Gordon L.; Song, Lin

    1998-01-01

    The invention provides a method for synthesizing a titanium oxide-containing film comprising the following steps: (a) preparing an aqueous solution of a titanium chelate with a titanium molarity in the range of 0.01M to 0.6M. (b) immersing a substrate in the prepared solution, (c) decomposing the titanium chelate to deposit a film on the substrate. The titanium chelate maybe decomposed acid, base, temperature or other means. A preferred method provides for the deposit of adherent titanium oxide films from C2 to C5 hydroxy carboxylic acids. In another aspect the invention is a novel article of manufacture having a titanium coating which protects the substrate against ultraviolet damage. In another aspect the invention provides novel semipermeable gas separation membranes, and a method for producing them.

  10. Polyimide thin-film dielectrics on ferroelectrics

    NASA Technical Reports Server (NTRS)

    Galiardi, R. V.

    1977-01-01

    Conducting layers of multi-layered thin-film ferroelectric device, such as is used in liquid crystal/ferroelectric display, can be electrically isolated using thin-film layer of polyimide. Ease of application and high electrical-breakdown strength allow dependable and economical means of providing dielectric for other thin-film microelectronic devices.

  11. Phase Coarsening in Thin Films

    NASA Astrophysics Data System (ADS)

    Wang, K. G.; Glicksman, M. E.

    2015-08-01

    Phase coarsening (Ostwald ripening) phenomena are ubiquitous in materials growth processes such as thin film formation. The classical theory explaining late-stage phase coarsening phenomena was developed by Lifshitz and Slyozov, and by Wagner in the 1960s. Their theory is valid only for a vanishing volume fraction of the second phase in three dimensions. However, phase coarsening in two-dimensional systems is qualitatively different from that in three dimensions. In this paper, the many-body concept of screening length is reviewed, from which we derive the growth law for a `screened' phase island, and develop diffusion screening theory for phase coarsening in thin films. The coarsening rate constant, maximum size of phase islands in films, and their size distribution function will be derived from diffusion screening theory. A critical comparison will be provided of prior coarsening concepts and improvements derived from screening approaches.

  12. Polycrystalline VO2 thin films via femtosecond laser processing of amorphous VO x

    NASA Astrophysics Data System (ADS)

    Charipar, N. A.; Kim, H.; Breckenfeld, E.; Charipar, K. M.; Mathews, S. A.; Piqué, A.

    2016-05-01

    Femtosecond laser processing of pulsed laser-deposited amorphous vanadium oxide thin films was investigated. Polycrystalline VO2 thin films were achieved by femtosecond laser processing in air at room temperature. The electrical transport properties, crystal structure, surface morphology, and optical properties were characterized. The laser-processed films exhibited a metal-insulator phase transition characteristic of VO2, thus presenting a pathway for the growth of crystalline vanadium dioxide films on low-temperature substrates.

  13. Size-dependent metal-insulator transition in platinum-dispersed silicon dioxide thin film: A candidate for future non-volatile memory

    NASA Astrophysics Data System (ADS)

    Chen, Albert B. K.

    Non-volatile random access memories (NVRAM) are promising data storage and processing devices. Various NVRAM, such as FeRAM and MRAM, have been studied in the past. But resistance switching random access memory (RRAM) has demonstrated the most potential for replacing flash memory in use today. In this dissertation, a novel RRAM material design that relies upon an electronic transition, rather than a phase change (as in chalcogenide Ovonic RRAM) or a structural change (such in oxide and halide filamentary RRAM), is investigated. Since the design is not limited to a single material but applicable to general combinations of metals and insulators, the goal of this study is to use a model material to delineate the intrinsic features of the electronic metal/insulator transition in random systems and to demonstrate their relevance to reliable memory storage and retrieval. We fabricated amorphous SiO2 thin films embedded with randomly dispersed Pt atoms. Macroscopically, this random material exhibits a percolation transition in electric conductivity similar to the one found in various insulator/metal granular materials. However, at Pt concentrations well below the bulk percolation limit, a distinct insulator to metal transition occurs in the thickness direction as the film thickness falls below electron's "diffusion" distance, which is the tunneling distance at 0K. The thickness-triggered metal- to-insulator transition (MIT) can be similarly triggered by other conditions: (a) a changing Pt concentration (a concentration-triggered MIT), (b) a changing voltage/polarity (voltage-triggered MIT), and (c) an UV irradiation (photon-triggered MIT). The resistance switching characteristics of this random material were further investigated in several device configurations under various test conditions. These include: materials for the top and bottom electrodes, fast pulsing, impedance spectroscopy, static stressing, retention, fatigue and temperature from 10K to 448K. The SiO2-Pt

  14. Selective inorganic thin films

    SciTech Connect

    Phillips, M.L.F.; Pohl, P.I.; Brinker, C.J.

    1997-04-01

    Separating light gases using membranes is a technology area for which there exists opportunities for significant energy savings. Examples of industrial needs for gas separation include hydrogen recovery, natural gas purification, and dehydration. A membrane capable of separating H{sub 2} from other gases at high temperatures could recover hydrogen from refinery waste streams, and facilitate catalytic dehydrogenation and the water gas shift (CO + H{sub 2}O {yields} H{sub 2} + CO{sub 2}) reaction. Natural gas purification requires separating CH{sub 4} from mixtures with CO{sub 2}, H{sub 2}S, H{sub 2}O, and higher alkanes. A dehydrating membrane would remove water vapor from gas streams in which water is a byproduct or a contaminant, such as refrigeration systems. Molecular sieve films offer the possibility of performing separations involving hydrogen, natural gas constituents, and water vapor at elevated temperatures with very high separation factors. It is in applications such as these that the authors expect inorganic molecular sieve membranes to compete most effectively with current gas separation technologies. Cryogenic separations are very energy intensive. Polymer membranes do not have the thermal stability appropriate for high temperature hydrogen recovery, and tend to swell in the presence of hydrocarbon natural gas constituents. The authors goal is to develop a family of microporous oxide films that offer permeability and selectivity exceeding those of polymer membranes, allowing gas membranes to compete with cryogenic and adsorption technologies for large-scale gas separation applications.

  15. Thin film buried anode battery

    DOEpatents

    Lee, Se-Hee; Tracy, C. Edwin; Liu, Ping

    2009-12-15

    A reverse configuration, lithium thin film battery (300) having a buried lithium anode layer (305) and process for making the same. The present invention is formed from a precursor composite structure (200) made by depositing electrolyte layer (204) onto substrate (201), followed by sequential depositions of cathode layer (203) and current collector (202) on the electrolyte layer. The precursor is subjected to an activation step, wherein a buried lithium anode layer (305) is formed via electroplating a lithium anode layer at the interface of substrate (201) and electrolyte film (204). The electroplating is accomplished by applying a current between anode current collector (201) and cathode current collector (202).

  16. Thin film concentrator panel development

    NASA Astrophysics Data System (ADS)

    Zimmerman, D. K.

    1982-07-01

    The development and testing of a rigid panel concept that utilizes a thin film reflective surface for application to a low-cost point-focusing solar concentrator is discussed. It is shown that a thin film reflective surface is acceptable for use on solar concentrators, including 1500 F applications. Additionally, it is shown that a formed steel sheet substrate is a good choice for concentrator panels. The panel has good optical properties, acceptable forming tolerances, environmentally resistant substrate and stiffeners, and adaptability to low to mass production rates. Computer simulations of the concentrator optics were run using the selected reflector panel design. Experimentally determined values for reflector surface specularity and reflectivity along with dimensional data were used in the analysis. The simulations provided intercept factor and net energy into the aperture as a function of aperture size for different surface errors and pointing errors. Point source and Sun source optical tests were also performed.

  17. Superconducting UBe 13 thin films

    NASA Astrophysics Data System (ADS)

    Quateman, J. H.; Tedrow, P. M.

    1985-12-01

    Of the known heavy fermion superconductors only UBe 13 can have a low resistivity ratio and still go superconducting. In addition, it is a line compound with a melting temperature of nearly twice that of the constituents. These facts make UBe 13 a promising choice for fabrication in thin film form. We have successfully made 2000 Å UBe 13 films by coevaporation of uranium and beryllium on 700°C substrates which were then heated in situ to 1100°C. These films were polycrystalline as shown by X-ray diffraction and have Tc's of 0.85 K, that of the bulk. The resistivity rise at approximately 2 K and the strong negative magnetoresistance were also of the same magnitude as that of the bulk, as were both the perpendicular and parallel critical fields. Thin films of UBe 13 will make more accessible tunneling and proximity effect experiments which can help elucidate the nature of the superconductivity of this compound.

  18. Zinc oxide thin film acoustic sensor

    SciTech Connect

    Mohammed, Ali Jasim; Salih, Wafaa Mahdi; Hassan, Marwa Abdul Muhsien; Nusseif, Asmaa Deiaa; Kadhum, Haider Abdullah; Mansour, Hazim Louis

    2013-12-16

    This paper reports the implementation of (750 nm) thickness of Zinc Oxide (ZnO) thin film for the piezoelectric pressure sensors. The film was prepared and deposited employing the spray pyrolysis technique. XRD results show that the growth preferred orientation is the (002) plane. A polycrystalline thin film (close to mono crystallite like) was obtained. Depending on the Scanning Electron Microscopy photogram, the film homogeneity and thickness were shown. The resonance frequency measured (about 19 kHz) and the damping coefficient was calculated and its value was found to be about (2.5538), the thin film be haves as homogeneous for under and over damped. The thin film pressure sensing was approximately exponentially related with frequency, the thin film was observed to has a good response for mechanical stresses also it is a good material for the piezoelectric properties.

  19. Zinc oxide thin film acoustic sensor

    NASA Astrophysics Data System (ADS)

    Mohammed, Ali Jasim; Salih, Wafaa Mahdi; Hassan, Marwa Abdul Muhsien; Mansour, Hazim Louis; Nusseif, Asmaa Deiaa; Kadhum, Haider Abdullah

    2013-12-01

    This paper reports the implementation of (750 nm) thickness of Zinc Oxide (ZnO) thin film for the piezoelectric pressure sensors. The film was prepared and deposited employing the spray pyrolysis technique. XRD results show that the growth preferred orientation is the (002) plane. A polycrystalline thin film (close to mono crystallite like) was obtained. Depending on the Scanning Electron Microscopy photogram, the film homogeneity and thickness were shown. The resonance frequency measured (about 19 kHz) and the damping coefficient was calculated and its value was found to be about (2.5538), the thin film be haves as homogeneous for under and over damped. The thin film pressure sensing was approximately exponentially related with frequency, the thin film was observed to has a good response for mechanical stresses also it is a good material for the piezoelectric properties.

  20. Analysis of Hard Thin Film Coating

    NASA Technical Reports Server (NTRS)

    Shen, Dashen

    1998-01-01

    MSFC is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using electron cyclotron resonance chemical vapor deposition (ECRCVD) to deposit hard thin film an stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

  1. Analysis of Hard Thin Film Coating

    NASA Technical Reports Server (NTRS)

    Shen, Dashen

    1998-01-01

    Marshall Space Flight Center (MSFC) is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using Electron Cyclotron Resonance Chemical Vapor Deposition (ECRCVD) to deposit hard thin film on stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

  2. Thin film solar energy collector

    DOEpatents

    Aykan, Kamran; Farrauto, Robert J.; Jefferson, Clinton F.; Lanam, Richard D.

    1983-11-22

    A multi-layer solar energy collector of improved stability comprising: (1) a substrate of quartz, silicate glass, stainless steel or aluminum-containing ferritic alloy; (2) a solar absorptive layer comprising silver, copper oxide, rhodium/rhodium oxide and 0-15% by weight of platinum; (3) an interlayer comprising silver or silver/platinum; and (4) an optional external anti-reflective coating, plus a method for preparing a thermally stable multi-layered solar collector, in which the absorptive layer is undercoated with a thin film of silver or silver/platinum to obtain an improved conductor-dielectric tandem.

  3. Thin film based plasmon nanorulers

    NASA Astrophysics Data System (ADS)

    Taylor, Alexander D.; Lu, Chang; Geyer, Scott; Carroll, D. L.

    2016-07-01

    In this work, isolated metal nanoparticles are supported on a dielectric thin film that is placed on a conducting plane. The optical scattering characteristics of these metal nanoparticles are directly correlated with the localized surface plasmon states of the nanoparticle—image particle dimer, formed in the conducting plane below. Quantification of plasmon resonance shifts can be directly correlated with the application of the plasmon nanoruler equation. This simple geometry shows that direct optical techniques can be used to resolve thickness variations in dielectrics of only a few nanometers.

  4. New devices using ferroelectric thin films

    SciTech Connect

    Land, C.E.; Butler, M.A.; Martin, S.J.

    1989-01-01

    Recent developments in the fabrication technologies of ferroelectric thin films in general and of PZT (lead zirconate titanate) and PLZT (lead lanthanum zirconate titanate) thin films in particular have suggested the feasibility of several new devices. Integrated optical devices for information processing and high-speed switching, high-density optical information processing and storage devices and spatial light modulators are some of the applications currently being investigated for these films. Ongoing studies of the longitudinal electrooptic effects and the photosensitivities of PZT and PLZT thin films have established the feasibility of erasable/rewritable optical memories with fast switching and potentially long lifetimes compared to current magneto-optic thin film devices. Some properties of PZT thin films and of new devices based on those properties are described in this paper. 15 refs., 5 figs., 1 tab.

  5. Thermal Conductivity Measurement of Xe-Implanted Uranium Dioxide Thick Films using Multilayer Laser Flash Analysis

    SciTech Connect

    Nelson, Andrew T.

    2012-08-30

    The Fuel Cycle Research and Development program's Advanced Fuels campaign is currently pursuing use of ion beam assisted deposition to produce uranium dioxide thick films containing xenon in various morphologies. To date, this technique has provided materials of interest for validation of predictive fuel performance codes and to provide insight into the behavior of xenon and other fission gasses under extreme conditions. In addition to the structural data provided by such thick films, it may be possible to couple these materials with multilayer laser flash analysis in order to measure the impact of xenon on thermal transport in uranium dioxide. A number of substrate materials (single crystal silicon carbide, molybdenum, and quartz) containing uranium dioxide films ranging from one to eight microns in thickness were evaluated using multilayer laser flash analysis in order to provide recommendations on the most promising substrates and geometries for further investigation. In general, the uranium dioxide films grown to date using ion beam assisted deposition were all found too thin for accurate measurement. Of the substrates tested, molybdenum performed the best and looks to be the best candidate for further development. Results obtained within this study suggest that the technique does possess the necessary resolution for measurement of uranium dioxide thick films, provided the films are grown in excess of fifty microns. This requirement is congruent with the material needs when viewed from a fundamental standpoint, as this length scale of material is required to adequately sample grain boundaries and possible second phases present in ceramic nuclear fuel.

  6. Fabrication of Thin Film Heat Flux Sensors

    NASA Technical Reports Server (NTRS)

    Will, Herbert A.

    1992-01-01

    Prototype thin film heat flux sensors have been constructed and tested. The sensors can be applied to propulsion system materials and components. The sensors can provide steady state and fast transient heat flux information. Fabrication of the sensor does not require any matching of the mounting surface. Heat flux is proportional to the temperature difference across the upper and lower surfaces of an insulation material. The sensor consists of an array of thermocouples on the upper and lower surfaces of a thin insulating layer. The thermocouples for the sensor are connected in a thermopile arrangement. A 100 thermocouple pair heat flux sensor has been fabricated on silicon wafers. The sensor produced an output voltage of 200-400 microvolts when exposed to a hot air heat gun. A 20 element thermocouple pair heat flux sensor has been fabricated on aluminum oxide sheet. Thermocouples are Pt-Pt/Rh with silicon dioxide as the insulating material. This sensor produced an output of 28 microvolts when exposed to the radiation of a furnace operating at 1000 C. Work is also underway to put this type of heat flux sensor on metal surfaces.

  7. Light-induced characteristic variations in organic thin-film transistors with a poly(vinylphenol-co-methyl methacrylate)/titanium-dioxide nanocomposite gate dielectric

    NASA Astrophysics Data System (ADS)

    Kim, Dongwook; Shin, Hyunji; Park, Sangcheol; Lee, Dokyoung; Choi, Jong Sun; Baang, Sungkeun; Ham, Youngjin; Park, Jaehoon; Piao, Shang Hao; Choi, Hyoung Jin

    2015-11-01

    We investigated the effect of light exposure on the electrical characteristics of organic thinfilm transistors (OTFTs) fabricated with a cross-linked poly(vinylphenol-co-methyl methacrylate) (PVP-co-PMMA)/titanium-dioxide (TiO2) nanocomposite gate dielectric. When illuminated, the off-state drain current increased significantly in the OTFTs containing the TiO2 nanocomposite gate dielectric, but changed negligibly in those containing the pristine PVP-co-PMMA gate dielectric. On the other hand, the dependence of the on-state drain current on the photon energy was similar in both cases. These results can be explained in terms of photogenerated charge carriers in the organic semiconductor and the TiO2 nanoparticles.

  8. Electrostatic thin film chemical and biological sensor

    DOEpatents

    Prelas, Mark A.; Ghosh, Tushar K.; Tompson, Jr., Robert V.; Viswanath, Dabir; Loyalka, Sudarshan K.

    2010-01-19

    A chemical and biological agent sensor includes an electrostatic thin film supported by a substrate. The film includes an electrostatic charged surface to attract predetermined biological and chemical agents of interest. A charge collector associated with said electrostatic thin film collects charge associated with surface defects in the electrostatic film induced by the predetermined biological and chemical agents of interest. A preferred sensing system includes a charge based deep level transient spectroscopy system to read out charges from the film and match responses to data sets regarding the agents of interest. A method for sensing biological and chemical agents includes providing a thin sensing film having a predetermined electrostatic charge. The film is exposed to an environment suspected of containing the biological and chemical agents. Quantum surface effects on the film are measured. Biological and/or chemical agents can be detected, identified and quantified based on the measured quantum surface effects.

  9. Thin films of mixed metal compounds

    DOEpatents

    Mickelsen, Reid A.; Chen, Wen S.

    1985-01-01

    A compositionally uniform thin film of a mixed metal compound is formed by simultaneously evaporating a first metal compound and a second metal compound from independent sources. The mean free path between the vapor particles is reduced by a gas and the mixed vapors are deposited uniformly. The invention finds particular utility in forming thin film heterojunction solar cells.

  10. Characteristics Of Vacuum Deposited Sucrose Thin Films

    NASA Astrophysics Data System (ADS)

    Ungureanu, F.; Predoi, D.; Ghita, R. V.; Vatasescu-Balcan, R. A.; Costache, M.

    Thin films of sucrose (C12H22O11) were deposited on thin cut glass substrates by thermal evaporation technique (p ~ 10-5 torr). The surface morphology was putted into evidence by FT-IR and SEM analysis. The experimental results confirm a uniform deposition of an adherent sucrose layer. The biological tests (e.g., cell morphology and cell viability evaluated by measuring mitochondrial dehydrogenise activity with MTT assay) confirm the properties of sucrose thin films as bioactive material. The human fetal osteoblast system grown on thin sucrose film was used for the determination of cell proliferation, cell viability and cell morphology studies.

  11. Cellulose triacetate, thin film dielectric capacitor

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Jow, T. Richard (Inventor)

    1995-01-01

    Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

  12. Cellulose triacetate, thin film dielectric capacitor

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Jow, T. Richard (Inventor)

    1993-01-01

    Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

  13. Preparation and Characterization of PZT Thin Films

    SciTech Connect

    Bose, A.; Sreemany, M.; Bhattacharyya, D. K.; Sen, Suchitra; Halder, S. K.

    2008-07-29

    In analogy with Piezoelectric Wafer Active Sensors (PWAS), Lead Zirconate Titanate (PZT) thin films also seem to be promising for Structural Health Monitoring (SHM) due to a number of reasons. Firstly, PZT thin films with well oriented domains show enhanced piezoelectric response. Secondly, PWAS requires comparatively large voltage leading to a demand for thin PZT films (<< {mu}m in thickness) for low voltage operation at {<=}10 V. This work focuses on two different aspects: (a) growing oriented PZT thin films in ferroelectric perovskite phase in the range of (80-150) nm thickness on epitaxial Si/Pt without a seed layer and (b) synthesizing perovskite phase in PZT thin films on Corning glass 1737 using a seed layer of TiO{sub x} (TiO{sub x} thickness ranging between 30 nm to 500 nm)

  14. A monolithic thin film electrochromic window

    SciTech Connect

    Goldner, R.B.; Arntz, F.O.; Berera, G.; Haas, T.E.; Wong, K.K. . Electro-Optics Technology Center); Wei, G. ); Yu, P.C. )

    1991-01-01

    Three closely related thin film solid state ionic devices that are potentially important for applications are: electrochromic smart windows, high energy density thin film rechargeable batteries, and thin film electrochemical sensors. Each usually has at least on mixed ion/electron conductor, an electron-blocking ion conductor, and an ion-blocking electron conductor, and many of the technical issues associated with thin film solid state ionics are common to all three devices. Since the electrochromic window has the added technical requirement of electrically-controlled optical modulation, (over the solar spectrum), and since research at the authors' institution has focused primarily on the window structure, this paper will address the electrochromic window, and particularly a monolithic variable reflectivity electrochromic window, as an illustrative example of some of the challenges and opportunities that are confronting the thin film solid state ionics community. 33 refs.

  15. A monolithic thin film electrochromic window

    SciTech Connect

    Goldner, R.B.; Arntz, F.O.; Berera, G.; Haas, T.E.; Wong, K.K.; Wei, G.; Yu, P.C.

    1991-12-31

    Three closely related thin film solid state ionic devices that are potentially important for applications are: electrochromic smart windows, high energy density thin film rechargeable batteries, and thin film electrochemical sensors. Each usually has at least on mixed ion/electron conductor, an electron-blocking ion conductor, and an ion-blocking electron conductor, and many of the technical issues associated with thin film solid state ionics are common to all three devices. Since the electrochromic window has the added technical requirement of electrically-controlled optical modulation, (over the solar spectrum), and since research at the authors` institution has focused primarily on the window structure, this paper will address the electrochromic window, and particularly a monolithic variable reflectivity electrochromic window, as an illustrative example of some of the challenges and opportunities that are confronting the thin film solid state ionics community. 33 refs.

  16. Thin-film optical shutter

    NASA Astrophysics Data System (ADS)

    Matlow, S. L.

    1981-02-01

    The ideal solution to the excessive solar gain problem is an optical shutter, a device which switches from being highly transmissive to solar radiation to being highly reflective to solar radiation when a critical temperature is reached in the enclosure. The switching occurs because one or more materials in the device undergo a phase transition at the critical temperature. A specific embodiment of macroconjugated macromolecules, the poly (p-phenylene)'s, was chosen as the one most likely to meet all of the requirements of the thin film optical shutter project (TFOS). The reason for this choice is explored. In order to be able to make meaningful calculations of the thermodynamic and optical properties of the poly (p-phenylene)'s a quantum mechanical method, the equilibrium bond length (EBL) theory, was developed. Some results of EBL theory are included.

  17. Thin film bioreactors in space

    NASA Technical Reports Server (NTRS)

    Hughes-Fulford, M.; Scheld, H. W.

    1989-01-01

    Studies from the Skylab, SL-3 and D-1 missions have demonstrated that biological organisms grown in microgravity have changes in basic cellular functions such as DNA, mRNA and protein synthesis, cytoskeleton synthesis, glucose utilization, and cellular differentiation. Since microgravity could affect prokaryotic and eukaryotic cells at a subcellular and molecular level, space offers an opportunity to learn more about basic biological systems with one inmportant variable removed. The thin film bioreactor will facilitate the handling of fluids in microgravity, under constant temperature and will allow multiple samples of cells to be grown with variable conditions. Studies on cell cultures grown in microgravity would make it possible to identify and quantify changes in basic biological function in microgravity which are needed to develop new applications of orbital research and future biotechnology.

  18. Wrinkle motifs in thin films

    PubMed Central

    Budrikis, Zoe; Sellerio, Alessandro L.; Bertalan, Zsolt; Zapperi, Stefano

    2015-01-01

    On length scales from nanometres to metres, partial adhesion of thin films with substrates generates a fascinating variety of patterns, such as ‘telephone cord’ buckles, wrinkles, and labyrinth domains. Although these patterns are part of everyday experience and are important in industry, they are not completely understood. Here, we report simulation studies of a previously-overlooked phenomenon in which pairs of wrinkles form avoiding pairs, focusing on the case of graphene over patterned substrates. By nucleating and growing wrinkles in a controlled way, we characterize how their morphology is determined by stress fields in the sheet and friction with the substrate. Our simulations uncover the generic behaviour of avoiding wrinkle pairs that should be valid at all scales. PMID:25758174

  19. BDS thin film damage competition

    SciTech Connect

    Stolz, C J; Thomas, M D; Griffin, A J

    2008-10-24

    A laser damage competition was held at the 2008 Boulder Damage Symposium in order to determine the current status of thin film laser resistance within the private, academic, and government sectors. This damage competition allows a direct comparison of the current state-of-the-art of high laser resistance coatings since they are all tested using the same damage test setup and the same protocol. A normal incidence high reflector multilayer coating was selected at a wavelength of 1064 nm. The substrates were provided by the submitters. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials, and layer count will also be shared.

  20. Dynamic delamination of patterned thin films

    NASA Astrophysics Data System (ADS)

    Kandula, Soma S. V.; Tran, Phuong; Geubelle, Philippe H.; Sottos, Nancy R.

    2008-12-01

    We investigate laser-induced dynamic delamination of a patterned thin film on a substrate. Controlled delamination results from our insertion of a weak adhesion region beneath the film. The inertial forces acting on the weakly bonded portion of the film lead to stable propagation of a crack along the film/substrate interface. Through a simple energy balance, we extract the critical energy for interfacial failure, a quantity that is difficult and sometimes impossible to characterize by more conventional methods for many thin film/substrate combinations.

  1. AES analysis of barium fluoride thin films

    NASA Astrophysics Data System (ADS)

    Kashin, G. N.; Makhnjuk, V. I.; Rumjantseva, S. M.; Shchekochihin, Ju. M.

    1993-06-01

    AES analysis of thin films of metal fluorides is a difficult problem due to charging and decomposition of such films under electron bombardment. We have developed a simple algorithm for a reliable quantitative AES analysis of metal fluoride thin films (BaF 2 in our work). The relative AES sensitivity factors for barium and fluorine were determined from BaF 2 single-crystal samples. We have investigated the dependence of composition and stability of barium fluoride films on the substrate temperature during film growth. We found that the instability of BaF 2 films grown on GaAs substrates at high temperatures (> 525°C) is due to a loss of fluorine. Our results show that, under the optimal electron exposure conditions, AES can be used for a quantitative analysis of metal fluoride thin films.

  2. Infrared radiation of thin plastic films.

    NASA Technical Reports Server (NTRS)

    Tien, C. L.; Chan, C. K.; Cunnington, G. R.

    1972-01-01

    A combined analytical and experimental study is presented for infrared radiation characteristics of thin plastic films with and without a metal substrate. On the basis of the thin-film analysis, a simple analytical technique is developed for determining band-averaged optical constants of thin plastic films from spectral normal transmittance data for two different film thicknesses. Specifically, the band-averaged optical constants of polyethylene terephthalate and polyimide were obtained from transmittance measurements of films with thicknesses in the range of 0.25 to 3 mil. The spectral normal reflectance and total normal emittance of the film side of singly aluminized films are calculated by use of optical constants; the results compare favorably with measured values.

  3. Thin film nitinol microstent for aneurysm occlusion.

    PubMed

    Chun, Youngjae; Levi, Daniel S; Mohanchandra, K P; Vinuela, Fernando; Vinuela, Fernando; Carman, Gregory P

    2009-05-01

    Thin film nitinol produced by sputter deposition was used in the design of microstents intended to treat small vessel aneurysms. Thin film microstents were fabricated by "hot-target" dc sputter deposition. Both stress-strain curves and differential scanning calorimetry curves were generated for the film used to fabricate stents. The films used for stents had an A(f) temperature of approximately 36 degrees C allowing for body activated response from a microcatheter. The 10 microm film was only slightly radio-opaque; thus, a Td marker was attached to the stents to guide fluoroscopic delivery. Thin film microstents were tested in a flow loop with and without nitinol support skeletons to give additional radial support. Stents could be compressed into and easily delivered with <3 Fr catheters. Theoretical frictional and wall drag forces on a thin film nitinol small vessel vascular stent were calculated, and the radial force exerted by thin film stents was evaluated theoretically and experimentally. In vivo studies in swine confirmed that thin film nitinol microstents could be deployed accurately and consistently in the swine cranial vasculature. PMID:19388784

  4. Method of producing thin cellulose nitrate film

    DOEpatents

    Lupica, S.B.

    1975-12-23

    An improved method for forming a thin nitrocellulose film of reproducible thickness is described. The film is a cellulose nitrate film, 10 to 20 microns in thickness, cast from a solution of cellulose nitrate in tetrahydrofuran, said solution containing from 7 to 15 percent, by weight, of dioctyl phthalate, said cellulose nitrate having a nitrogen content of from 10 to 13 percent.

  5. Optical information storage in PLZT thin films

    SciTech Connect

    Land, C.E.

    1989-01-01

    The feasibility of storing and reading high density optical information in lead zirconate titanate (PZT) and in lead lanthanum zirconate titanate (PLZT) thin films depends on both the longitudinal electrooptic coefficients and the photosensitivities of the films. This paper describes the methods used to measure both the longitudinal electrooptic effects and the photosensitivities of the thin films. The results of these measurements were used to evaluate a longitudinal quadratic electrooptic R coefficient, a linear electrooptic r/sub c/ coefficient and the wavelength dependence of the photosensitivity of a composition of PZT polycrystalline thin film. The longitudinal electrooptic R and r/sub c/ coefficients are about an order of magnitude less than the transverse R and R/sub c/ coefficients of the bulk ceramics of similar compositions. This is attributed to clamping of the film by the rigid substrate. The large birefringence after poling (>10/sup /minus/2/) suggests that the optic axes of the films are preferentially oriented normal to the film surface. The techniques used for evaluating the photosensitivities of the thin films are based on measuring the photocurrent generated rather than the reduction in coercive voltage (used previously for bulk ceramics) when the film is exposed to light. The thin film photosensitivities appear to be about three orders of magnitude higher than those of bulk ceramics of similar compositions. 14 refs., 12 figs., 1 tab.

  6. Thin film solar cell module

    SciTech Connect

    Gay, R.R.

    1987-01-20

    A thin film solar cell module is described comprising a first solar cell panel containing an array of solar cells consisting of a TFS semiconductor sandwiched between a transparent conductive zinc oxide layer and a transparent conductive layer selected from the group consisting of tin oxide, indium tin oxide, and zinc oxide deposited upon a transparent superstrate, and a second solar cell panel containing an array of solar cells consisting of a CIS semiconductor layer sandwiched between a zinc oxide semiconductor layer and a conductive metal layer deposited upon an insulating substrate. The zinc oxide semiconductor layer contains a first relatively thin layer of high resistivity zinc oxide adjacent the CIS semiconductor and a second relatively thick layer of low resistivity zinc oxide overlying the high resistivity zinc oxide layer. The transparent conductive zinc oxide layer of the first panel faces the low resistivity zinc oxide layer of the second panel, the first and second panels being positioned optically in series and separated by a transparent insulating layer.

  7. VUV thin films, chapter 7

    NASA Technical Reports Server (NTRS)

    Zukic, Muamer; Torr, Douglas G.

    1993-01-01

    The application of thin film technology to the vacuum ultraviolet (VUV) wavelength region from 120 nm to 230 nm has not been fully exploited in the past because of absorption effects which complicate the accurate determination of the optical functions of dielectric materials. The problem therefore reduces to that of determining the real and imaginary parts of a complex optical function, namely the frequency dependent refractive index n and extinction coefficient k. We discuss techniques for the inverse retrieval of n and k for dielectric materials at VUV wavelengths from measurements of their reflectance and transmittance. Suitable substrate and film materials are identified for application in the VUV. Such applications include coatings for the fabrication of narrow and broadband filters and beamsplitters. The availability of such devices open the VUV regime to high resolution photometry, interferometry and polarimetry both for space based and laboratory applications. This chapter deals with the optics of absorbing multilayers, the determination of the optical functions for several useful materials, and the design of VUV multilayer stacks as applied to the design of narrow and broadband reflection and transmission filters and beamsplitters. Experimental techniques are discussed briefly, and several examples of the optical functions derived for selected materials are presented.

  8. Synthesis of periodic mesoporous silica thin films

    SciTech Connect

    Anderson, M.T.; Martin, J.E.; Odinek, J.G.; Newcomer, P.

    1996-06-01

    We have synthesized periodic mesoporous silica thin films from homogeneous solutions. To synthesize the films, a thin layer of a pH 7 micellar coating solution that contains TMOS (tetramethoxysilane) is dip or spin-coated onto Si wafers, borosilicate glass, or quartz substrates. NH3 gas is diffused into the solution and causes rapid hydrolysis and condensation of the TMOS and the formation of periodic mesoporous thin films within 10 seconds. Combination of homogenous solutions and rapid product formation maximizes the concentration of the desired product and provides a controlled, predictable microstructure. The films have been made continuous and crack-free by optimizing initial silica concentration and film thickness. The films are being evaluated as high surface area, size-selective coatings for surface acoustic wave (SAW) sensors.

  9. Flexible thin metal film thermal sensing system

    NASA Technical Reports Server (NTRS)

    Thomsen, Donald L. (Inventor)

    2010-01-01

    A flexible thin metal film thermal sensing system is provided. A self-metallized polymeric film has a polymeric film region and a metal surface disposed thereon. A layer of electrically-conductive metal is deposited directly onto the self-metallized polymeric film's metal surface. Coupled to at least one of the metal surface and the layer of electrically-conductive metal is a device/system for measuring an electrical characteristic associated therewith as an indication of temperature.

  10. Surface roughness evolution of nanocomposite thin films

    SciTech Connect

    Turkin, A. A.; Pei, Y. T.; Shaha, K. P.; Chen, C. Q.; Vainshtein, D. I.; Hosson, J. Th. M. de

    2009-01-01

    An analysis of dynamic roughening and smoothening mechanisms of thin films grown with pulsed-dc magnetron sputtering is presented. The roughness evolution has been described by a linear stochastic equation, which contains the second- and fourth-order gradient terms. Dynamic smoothening of the growing interface is explained by ballistic effects resulting from impingements of ions to the growing thin film. These ballistic effects are sensitive to the flux and energy of impinging ions. The predictions of the model are compared with experimental data, and it is concluded that the thin film roughness can be further controlled by adjusting waveform, frequency, and width of dc pulses.

  11. Macro stress mapping on thin film buckling

    SciTech Connect

    Goudeau, P.; Villain, P.; Renault, P.-O.; Tamura, N.; Celestre, R.S.; Padmore, H.A.

    2002-11-06

    Thin films deposited by Physical Vapour Deposition techniques on substrates generally exhibit large residual stresses which may be responsible of thin film buckling in the case of compressive stresses. Since the 80's, a lot of theoretical work has been done to develop mechanical models but only a few experimental work has been done on this subject to support these theoretical approaches and nothing concerning local stress measurement mainly because of the small dimension of the buckling (few 10th mm). This paper deals with the application of micro beam X-ray diffraction available on synchrotron radiation sources for stress mapping analysis of gold thin film buckling.

  12. Photonics applications of nanostructured thin films

    NASA Astrophysics Data System (ADS)

    Kennedy, Scott Ronald

    Using an advanced thin film fabrication technique known as Glancing Angle Deposition (GLAD), it is possible to fabricate unique thin film nanostructures with characteristic dimensions on the order of a wavelength of light. By tailoring the morphologies of the films, they can be designed to exhibit particular optical properties that can be customized through advanced substrate motion and highly oblique flux incidence angles. In applications to photonics, controlling the flow of light for a specified task, GLAD thin films can be fabricated to provide the ability to manipulate incident light through controlled interactions of optical frequency electromagnetic radiation with the thin film nanostructures. Tetragonal square spiral photonic band gap crystals, a new class of periodic dielectric material that is characterized by the elimination of the density of states for frequencies lying in the stop gap of the crystal, can be fabricated using GLAD in a virtual single step process. The design and fabrication of these unique devices has been performed and the resultant crystals characterized in terms of optical response with respect to forbidden propagation modes, material properties, and advanced deposition techniques used to improve the overall structure. Chiral or helical thin films deposited using GLAD were also investigated, and have been shown to exhibit optical activity and circular birefringence due to their inherent structural anisotropy. It has been shown that the addition of nematic liquid crystals (LCs) to chiral thin films enhances the overall device performance due to order induced in the LCs by the film structure. This effect was investigated for a variety of materials and film structures. Finally, by developing a modified GLAD technique whereby the deposited film porosity is controlled through the angle of flux incidence, porous broadband antireflection coatings were produced. Using an appropriate effective medium theory to describe the index of refraction

  13. TiO{sub 2} nanotube, nanowire, and rhomboid-shaped particle thin films fixed on a titanium metal plate

    SciTech Connect

    Inoue, Yuko; Noda, Iwao; Torikai, Toshio; Watari, Takanori; Hotokebuchi, Takao; Yada, Mitsunori

    2010-01-15

    Titanium dioxide thin films having various nanostructures could be formed by various treatments on sodium titanate nanotube thin films approximately 5 {mu}m thick fixed on titanium metal plates. Using an aqueous solution with a lower hydrochloric acid concentration (0.01 mol/L) and a higher reaction temperature (90 deg. C) than those previously employed, we obtained a hydrogen titanate nanotube thin film fixed onto a titanium metal plate by H{sup +} ion-exchange treatment of the sodium titanate nanotube thin film. Calcination of hydrogen titanate nanotube thin films yielded porous thin films consisting of anatase nanotubes, anatase nanowires, and anatase nanoparticles grown directly from the titanium metal plate. H{sup +} ion-exchange treatment of sodium titanate nanotube thin films at 140 deg. C resulted in porous thin films consisting of rhomboid-shaped anatase nanoparticles. - Graphical abstract: Titanium dioxide nanotube, nanowire, and rhombic particle thin films could be formed by various treatments on a sodium titanate nanotube thin film fixed on a titanium metal plate.

  14. Passivation Effects in Copper Thin Films

    SciTech Connect

    Wiederhirn, G.; Nucci, J.; Richter, G.; Arzt, E.; Balk, T. J.; Dehm, G.

    2006-02-07

    We studied the influence of a 10 nm AlxOy passivation on the stress-temperature behavior of 100 nm and 1 {mu}m thick Cu films. At low temperatures, the passivation induces a large tensile stress increase in the 100 nm film; however, its effect on the 1 {mu}m film is negligible. At high temperatures, the opposite behavior is observed; while the passivation does not change the 100 nm film behavior, it strengthens the 1 {mu}m film by driving it deeper into compression. These observations are explained in light of a combination of constrained diffusional creep and dislocation dynamics unique to ultra-thin films.

  15. Research on Advanced Thin Film Batteries

    SciTech Connect

    Goldner, Ronald B.

    2003-11-24

    During the past 7 years, the Tufts group has been carrying out research on advanced thin film batteries composed of a thin film LiCo02 cathode (positive electrode), a thin film LiPON (lithium phosphorous oxynitride) solid electrolyte, and a thin film graphitic carbon anode (negative electrode), under grant DE FG02-95ER14578. Prior to 1997, the research had been using an rfsputter deposition process for LiCoOi and LiPON and an electron beam evaporation or a controlled anode arc evaporation method for depositing the carbon layer. The pre-1997 work led to the deposition of a single layer cell that was successfully cycled for more than 400 times [1,2] and the research also led to the deposition of a monolithic double-cell 7 volt battery that was cycled for more than 15 times [3]. Since 1997, the research has been concerned primarily with developing a research-worthy and, possibly, a production-worthy, thin film deposition process, termed IBAD (ion beam assisted deposition) for depositing each ofthe electrodes and the electrolyte of a completely inorganic solid thin film battery. The main focus has been on depositing three materials - graphitic carbon as the negative electrode (anode), lithium cobalt oxide (nominally LiCoCb) as the positive electrode (cathode), and lithium phosphorus oxynitride (LiPON) as the electrolyte. Since 1998, carbon, LiCoOa, and LiPON films have been deposited using the IBAD process with the following results.

  16. Performance Characterization of Monolithic Thin Film Resistors

    NASA Astrophysics Data System (ADS)

    Yin, Rong

    Thin film resistors have a large resistance range and stable performance under high temperature operating condition. Thin film resistors trimmed by laser beam are able to achieve very high precision on resistance value. As a result, thin film resistors have been widely used to improve the performance of integrated circuits such as operational amplifier, analog-to-digital (A/D) and digital -to-analog (D/A) converters, etc. In this dissertation, a new class of thin film resistors, silicon chrome (SiCr) thin film resistors, has been investigated at length. From thin film characterization to aging behavior modelling, we have carried out a series of engineering activities. The characteristics of the SiCr thin film incorporated into three bipolar processes were first determined. After laser trimming, we have measured a couple of physical parameters of the SiCr film in the heat affected zone (HAZ). This is the first time the sheet resistance and the temperature coefficient of resistance (TCR) of thin film in the HAZ have been characterized. Both thermal and d.c. load accelerated aging tests were performed. The test structures were subjected to the aging for 1000 hours. Based on the test data, we not only evaluated the classical thermal aging model for untrimmed thin film resistors, but also established several empirical thermal aging models for trimmed resistors and d.c. load aging models for both trimmed and untrimmed thin film resistors. All the experiments were carried out for both conventional bar resistors and our new Swiss Cheese (SC) resistors. For the first time, the performance of laser trimmed SC resistors, which was experimentally evaluated, shown a clear superiority over that of trimmed bar resistors. Besides these experiments, we have examined different die attach techniques and their effects on thin film resistors. Also, we have developed a number of hardware systems and software tools, such as a temperature controller, d.c. current source, temperature

  17. Permanent laser conditioning of thin film optical materials

    DOEpatents

    Wolfe, C. Robert; Kozlowski, Mark R.; Campbell, John H.; Staggs, Michael; Rainer, Frank

    1995-01-01

    The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold.

  18. Permanent laser conditioning of thin film optical materials

    DOEpatents

    Wolfe, C.R.; Kozlowski, M.R.; Campbell, J.H.; Staggs, M.; Rainer, F.

    1995-12-05

    The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold. 9 figs.

  19. Ferromagnetic properties of fcc Gd thin films

    SciTech Connect

    Bertelli, T. P. Passamani, E. C.; Larica, C.; Nascimento, V. P.; Takeuchi, A. Y.

    2015-05-28

    Magnetic properties of sputtered Gd thin films grown on Si (100) substrates kept at two different temperatures were investigated using X-ray diffraction, ac magnetic susceptibility, and dc magnetization measurements. The obtained Gd thin films have a mixture of hcp and fcc structures, but with their fractions depending on the substrate temperature T{sub S} and film thickness x. Gd fcc samples were obtained when T{sub S} = 763 K and x = 10 nm, while the hcp structure was stabilized for lower T{sub S} (300 K) and thicker film (20 nm). The fcc structure is formed on the Ta buffer layer, while the hcp phase grows on the fcc Gd layer as a consequence of the lattice relaxation process. Spin reorientation phenomenon, commonly found in bulk Gd species, was also observed in the hcp Gd thin film. This phenomenon is assumed to cause the magnetization anomalous increase observed below 50 K in stressed Gd films. Magnetic properties of fcc Gd thin films are: Curie temperature above 300 K, saturation magnetization value of about 175 emu/cm{sup 3}, and coercive field of about 100 Oe at 300 K; features that allow us to classify Gd thin films, with fcc structure, as a soft ferromagnetic material.

  20. Dielectric properties of inorganic fillers filled epoxy thin film

    SciTech Connect

    Norshamira, A. Mariatti, M.

    2015-07-22

    The demand on the small size and high performance electronics has driven changes in the electronic packaging requirements from discrete capacitor to embedded capacitor. Embedded capacitor can improve electrical performance compared with discrete capacitor. This study aimed to achieve high dielectric of epoxy thin film composite that were targeted for application as embedded capacitor. In this study, inorganic fillers such as Calcium Copper Titanate (CCTO), Iron(III) Oxide (Fe{sub 2}O{sub 3}) and Titanium Dioxide (TiO{sub 2}) were loaded in epoxy system at 5 and 20vol%. Morphology and dielectric properties were investigated to identify the effect of fillers loading and types of fillers on the properties of epoxy thin film composite. Based on the study, CCTO with 20vol% loading was found to have good dielectric properties compared to other type of fillers.

  1. Thermally tunable ferroelectric thin film photonic crystals.

    SciTech Connect

    Lin, P. T.; Wessels, B. W.; Imre, A.; Ocola, L. E.; Northwestern Univ.

    2008-01-01

    Thermally tunable PhCs are fabricated from ferroelectric thin films. Photonic band structure and temperature dependent diffraction are calculated by FDTD. 50% intensity modulation is demonstrated experimentally. This device has potential in active ultra-compact optical circuits.

  2. Recent developments in thin film solar cells

    NASA Astrophysics Data System (ADS)

    Dhere, Neelkanth G.

    The present status of the development of thin film solar cells is reviewed, with emphasis on important areas for further research. The following aperture-area efficiencies were measured for thin film modules: a-Si:H, 9.8 percent, 933 sq cm; CuIn(Ga)Se2, 11.1 percent, 938 sq cm; and CdTe, 7.3 percent, 838 sq cm. CuIn(Ga)Se2 cells and modules demonstrated excellent efficiencies and stability. The cost advantage of thin film modules and the higher efficiency and improved stability resulting from multijunctions are shown. Engineering solutions are found to minimize light-induced degradation of a-Si:H solar cells. CdTe cells and modules, and cleaved epitaxial thin film III-V compound cells showed remarkable efficiencies.

  3. Thin film production method and apparatus

    DOEpatents

    Loutfy, Raouf O.; Moravsky, Alexander P.; Hassen, Charles N.

    2010-08-10

    A method for forming a thin film material which comprises depositing solid particles from a flowing suspension or aerosol onto a filter and next adhering the solid particles to a second substrate using an adhesive.

  4. Highly stretchable wrinkled gold thin film wires

    NASA Astrophysics Data System (ADS)

    Kim, Joshua; Park, Sun-Jun; Nguyen, Thao; Chu, Michael; Pegan, Jonathan D.; Khine, Michelle

    2016-02-01

    With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. Conductive wires represent a vital component present in all electronics. Unlike traditional planar and rigid electronics, these new wearable electrical components must conform to curvilinear surfaces, stretch with the body, and remain unobtrusive and low profile. In this paper, the piezoresistive response of shrink induced wrinkled gold thin films under strain demonstrates robust conductive performance in excess of 200% strain. Importantly, the wrinkled metallic thin films displayed negligible change in resistance of up to 100% strain. The wrinkled metallic wires exhibited consistent performance after repetitive strain. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible with roll to roll manufacturing processes. We propose that these wrinkled metal thin film wires are an attractive alternative to conventional wires for wearable applications.

  5. Mechanical Properties of Silicon Carbonitride Thin Films

    NASA Astrophysics Data System (ADS)

    Peng, Xiaofeng; Hu, Xingfang; Wang, Wei; Song, Lixin

    2003-02-01

    Silicon carbonitride thin films were synthesized by reactive rf sputtering a silicon carbide target in nitrogen and argon atmosphere, or sputtering a silicon nitride target in methane and argon atmosphere, respectively. The Nanoindentation technique (Nanoindenter XP system with a continuous stiffness measurement technique) was employed to measure the hardness and elastic modulus of thin films. The effects of sputtering power on the mechanical properties are different for the two SiCN thin films. With increasing sputtering power, the hardness and the elastic modulus decrease for the former but increase for the latter. The tendency is similar to the evolution trend of Si-C bonds in SiCN materials. This reflects that Si-C bonds provide greater hardness for SiCN thin films than Si-N and C-N bonds.

  6. Thin-film reliability and engineering overview

    NASA Technical Reports Server (NTRS)

    Ross, R. G., Jr.

    1984-01-01

    The reliability and engineering technology base required for thin film solar energy conversions modules is discussed. The emphasis is on the integration of amorphous silicon cells into power modules. The effort is being coordinated with SERI's thin film cell research activities as part of DOE's Amorphous Silicon Program. Program concentration is on temperature humidity reliability research, glass breaking strength research, point defect system analysis, hot spot heating assessment, and electrical measurements technology.

  7. Epitaxial thin film growth in outer space

    NASA Technical Reports Server (NTRS)

    Ignatiev, Alex; Chu, C. W.

    1988-01-01

    A new concept for materials processing in space exploits the ultravacuum component of space for thin-film epitaxial growth. The unique LEO space environment is expected to yield 10-ftorr or better pressures, semiinfinite pumping speeds, and large ultravacuum volume (about 100 cu m) without walls. These space ultravacuum properties promise major improvement in the quality, unique nature, and throughput of epitaxially grown materials, including semiconductors, magnetic materials, and thin-film high-temperature superconductors.

  8. Review of CdO thin films

    NASA Astrophysics Data System (ADS)

    Chandiramouli, R.; Jeyaprakash, B. G.

    2013-02-01

    Cadmium Oxide (CdO) thin film is one of the first transparent conducting oxide semiconductors. Its excellent optical and electronic properties have made CdO a promising material for flat panel displays. In this article, we provide a comprehensive review of the state-of-the-art research activities related to the 'preparation-property-application' triangle of CdO thin films.

  9. Advances in CZTS thin films and nanostructured

    NASA Astrophysics Data System (ADS)

    Ali, N.; Ahmed, R.; Bakhtiar-Ul-Haq; Shaari, A.

    2015-06-01

    Already published data for the optical band gap (Eg) of thin films and nanostructured copper zinc tin sulphide (CZTS) have been reviewed and combined. The vacuum (physical) and non-vacuum (chemical) processes are focused in the study for band gap comparison. The results are accumulated for thin films and nanostructured in different tables. It is inferred from the re- view that the nanostructured material has plenty of worth by engineering the band gap for capturing the maximum photons from solar spectrum.

  10. Thin wetting film lensless imaging

    NASA Astrophysics Data System (ADS)

    Allier, C. P.; Poher, V.; Coutard, J. G.; Hiernard, G.; Dinten, J. M.

    2011-03-01

    Lensless imaging has recently attracted a lot of attention as a compact, easy-to-use method to image or detect biological objects like cells, but failed at detecting micron size objects like bacteria that often do not scatter enough light. In order to detect single bacterium, we have developed a method based on a thin wetting film that produces a micro-lens effect. Compared with previously reported results, a large improvement in signal to noise ratio is obtained due to the presence of a micro-lens on top of each bacterium. In these conditions, standard CMOS sensors are able to detect single bacterium, e.g. E.coli, Bacillus subtilis and Bacillus thuringiensis, with a large signal to noise ratio. This paper presents our sensor optimization to enhance the SNR; improve the detection of sub-micron objects; and increase the imaging FOV, from 4.3 mm2 to 12 mm2 to 24 mm2, which allows the detection of bacteria contained in 0.5μl to 4μl to 10μl, respectively.

  11. Microstructural evolution of tungsten oxide thin films

    NASA Astrophysics Data System (ADS)

    Hembram, K. P. S. S.; Thomas, Rajesh; Rao, G. Mohan

    2009-10-01

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 °C were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a "instability wheel" model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  12. Porous Anatase TiO2 Thin Films for NH3 Vapour Sensing

    NASA Astrophysics Data System (ADS)

    Ponnusamy, Dhivya; Madanagurusamy, Sridharan

    2015-12-01

    Anatase titanium dioxide (TiO2) thin films were deposited onto cleaned glass substrates by a direct current (DC) reactive magnetron sputtering technique for different deposition times from 10 min to 40 min, which resulted in films of different thicknesses. Characterization techniques, such as x-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM) were used to characterize the structural and morphological properties of the TiO2 thin films. XRD patterns showed the formation of (101) crystal anatase facets. The grain size values of the film increased with increased deposition time, and the films deposited at 40 min exhibited a porous structure. Anatase TiO2 thin films exhibited excellent sensing response, fast response and recovery time, as well as good stability and selectivity towards ammonia (NH3). The enhanced NH3 sensing behavior of anatase TiO2 films is attributed to the porous morphology and oxygen vacancies.

  13. Photoluminescence of nanocrystalline titanium dioxide films loaded with silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Preclíková, Jana; Galář, Pavel; Trojánek, František; Rezek, Bohuslav; Němcová, Yvonne; Malý, Petr

    2011-04-01

    We report on a systematic study of the photoluminescence properties of nanocrystalline titanium dioxide films loaded with silver nanoparticles under various ambient conditions: in the temperature interval of 10 to 300 K, under different values of ambient air pressure (5 to 105 Pa), and under visible light irradiation that causes the photochromic transformation of the film. Our results enable us to follow the electron transfer from titanium dioxide into silver nanoparticles and to observe the oxidation of silver nanoparticles during the photochromic transformation. We propose a microscopic model explaining the behavior of extinction and photoluminescence of the Ag-TiO2 film under different values of ambient air pressure.

  14. Printable CIGS thin film solar cells

    NASA Astrophysics Data System (ADS)

    Fan, Xiaojuan

    2014-03-01

    Among the various thin film solar cells in the market, CuInGaSe thin film cells have been considered as the most promising alternatives to silicon solar cells because of their high photo-electricity efficiency, reliability, and stability. However, many fabrication of CIGS thin film are based on vacuum processes such as evaporation sputtering techniques which are not cost efficient. This work develops a method using paste or ink liquid spin-coated on glass that would be to conventional ways in terms of cost effective, non-vacuum needed, quick processing. A mixture precursor was prepared by dissolving appropriate amounts of chemicals. After the mixture solution was cooled, a viscous paste prepared and ready for spin-coating process. A slight bluish CIG thin film substrate was then put in a tube furnace with evaporation of metal Se by depositing CdS layer and ZnO nanoparticle thin film coating to a solar cell fabrication. Structure, absorption spectrum, and photo-conversion efficiency for the as-grown CIGS thin film solar cell under study.

  15. Printable CIGS thin film solar cells

    NASA Astrophysics Data System (ADS)

    Fan, Xiaojuan

    2013-03-01

    Among the various thin film solar cells in the market, CuInGaSe thin film solar cells have been considered as the most promising alternatives to crystalline silicon solar cells because of their high photo-electricity conversion efficiency, reliability, and stability. However, many fabrication methods of CIGS thin film are based on vacuum processes such as evaporation and sputtering techniques which are not cost efficient. This work develops a solution method using paste or ink liquid spin-coated on glass that would be competitive to conventional ways in terms of cost effective, non-vacuum needed, and quick processing. A mixture precursor was prepared by dissolving appropriate amounts of composition chemicals. After the mixture solution was cooled, a viscous paste was prepared and ready for spin-coating process. A slight bluish CIG thin film on substrate was then put in a tube furnace with evaporation of metal Se followed by depositing CdS layer and ZnO nanoparticle thin film coating to complete a solar cell fabrication. Structure, absorption spectrum, and photo-electricity conversion efficiency for the as-grown CIGS thin film solar cell are under study.

  16. Carbon Nanotube Thin-Film Antennas.

    PubMed

    Puchades, Ivan; Rossi, Jamie E; Cress, Cory D; Naglich, Eric; Landi, Brian J

    2016-08-17

    Multiwalled carbon nanotube (MWCNT) and single-walled carbon nanotube (SWCNT) dipole antennas have been successfully designed, fabricated, and tested. Antennas of varying lengths were fabricated using flexible bulk MWCNT sheet material and evaluated to confirm the validity of a full-wave antenna design equation. The ∼20× improvement in electrical conductivity provided by chemically doped SWCNT thin films over MWCNT sheets presents an opportunity for the fabrication of thin-film antennas, leading to potentially simplified system integration and optical transparency. The resonance characteristics of a fabricated chlorosulfonic acid-doped SWCNT thin-film antenna demonstrate the feasibility of the technology and indicate that when the sheet resistance of the thin film is >40 ohm/sq no power is absorbed by the antenna and that a sheet resistance of <10 ohm/sq is needed to achieve a 10 dB return loss in the unbalanced antenna. The dependence of the return loss performance on the SWCNT sheet resistance is consistent with unbalanced metal, metal oxide, and other CNT-based thin-film antennas, and it provides a framework for which other thin-film antennas can be designed. PMID:27454334

  17. Laser processing for thin-film photovoltaics

    NASA Astrophysics Data System (ADS)

    Compaan, Alvin D.

    1995-04-01

    Over the past decade major advances have occurred in the field of thin- film photovoltaics (PV) with many of them a direct consequence of the application of laser processing. Improved cell efficiencies have been achieved in crystalline and polycrystalline Si, in hydrogenated amorphous silicon, and in two polycrystalline thin-film materials. The use of lasers in photovoltaics includes laser hole drilling for emitter wrap-through, laser trenching for buried bus lines, and laser texturing of crystalline and polycrystalline Si cells. In thin-film devices, laser scribing is gaining increased importance for module interconnects. Pulsed laser recrystallization of boron-doped hydrogenated amorphous silicon is used to form highly conductive p-layers in p-i-n amorphous silicon cells and in thin-film transistors. Optical beam melting appears to be an attractive method for forming metal semiconductor alloys for contact formation. Finally, pulsed lasers are used for deposition of the entire semiconductor absorber layer in two types of polycrystalline thin-film cells-those based on copper indium diselenide and those based on cadmium telluride. In our lab we have prepared and studied heavily doped polycrystalline silicon thin films and also have used laser physical vapor deposition (LPVD) to prepare 'all-LPVD' CdS/CdTe solar cells on glass with efficiencies tested at NREL at 10.5%. LPVD is highly flexible and ideally suited for prototyping PV cells using ternary or quaternary alloys and for exploring new dopant combinations.

  18. Thin-Film Nanocapacitor and Its Characterization

    ERIC Educational Resources Information Center

    Hunter, David N.; Pickering, Shawn L.; Jia, Dongdong

    2007-01-01

    An undergraduate thin-film nanotechnology laboratory was designed. Nanocapacitors were fabricated on silicon substrates by sputter deposition. A mask was designed to form the shape of the capacitor and its electrodes. Thin metal layers of Au with a 80 nm thickness were deposited and used as two infinitely large parallel plates for a capacitor.…

  19. Atomic layer deposited silicon dioxide films on nanomechanical silicon nitride resonators

    NASA Astrophysics Data System (ADS)

    Waggoner, P. S.; Tan, C. P.; Craighead, H. G.

    2010-06-01

    Thin silicon dioxide films are deposited on nanomechanical resonators using atomic layer deposition (ALD), and their effect on the resonant properties of silicon nitride devices is studied as a function of thickness. We present experimental data and an analytical model for the effect of ALD growth and corroborate the model by studying resonators coated with atomic layer deposited aluminum nitride as well. As thicker films are deposited, device frequency shifts, become nonlinear with thickness, and quality factors drop significantly. Thin silicon dioxide coatings can be deposited on virtually any device surface to support surface chemistries commonly used in biochemical functionalization on glass surfaces. We also demonstrate that the efficiency of silane functionalization improves by 35% when low stress silicon nitride surfaces are coated with only 2.1 nm of atomic layer deposited silicon dioxide. This ALD modification technique should be particularly useful for nanomechanical resonant sensors since a thin, conformal film does not drastically reduce quality factor nor does it add excessive mass that would decrease device sensitivity.

  20. An Extension of Thin Film Optics

    NASA Astrophysics Data System (ADS)

    Apell, P.

    1985-10-01

    The classical McIntyre formula for p-polarized light incident on a thin film on a substrate is extended in general terms to include a realistic description of the interfaces and the possible excitation of plasma waves in the film. An earlier extension is critized and criteria are given for when the classical result is applicable.

  1. Thin films, asphaltenes, and reservoir wettability

    SciTech Connect

    Kaminsky, R.; Bergeron, V.; Radke, C.J. |

    1993-04-01

    Reservoir wettability impacts the success of oil recovery by waterflooding and other methods. To understand wettability and its alteration, thin-film forces in solid-aqueous-oil systems must be elucidated. Upon rupture of thick aqueous films separating the oil and rock phases, asphaltene components in the crude oil adsorb irreversibly on the solid surface, changing it from water-wet to oil-wet. Conditions of wettability alteration can be found by performing adhesion tests, in which an oil droplet is brought into contact with a solid surface. Exceeding a critical capillary pressure destabilizes the film, causing spontaneous film rupture to a molecularly adsorbed layer and oil adhesion accompanied by pinning at the three-phase contact line. The authors conduct adhesion experiments similar to those of Buckley and Morrow and simultaneously examine the state of the underlying thin film using optical microscopy and microinterferometry. Aqueous thin films between an asphaltic Orcutt crude oil and glass surfaces are studied as a function of aqueous pH and salinity. For the first time, they prove experimentally that strongly water-wet to strongly oil-wet wettability alteration and contact-angle pinning occur when thick aqueous films thin to molecularly adsorbed films and when the oil phase contains asphaltene molecules.

  2. Thin transparent films formed from powdered glass

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Glass film less than five mils thick is formed from powdered glass dispersed in an organic liquid, deposited on a substrate, and fused into place. The thin films can be cut and shaped for contact lenses, optical filters and insulating layers.

  3. Liquid phase deposition of electrochromic thin films

    SciTech Connect

    Richardson, Thomas J.; Rubin, Michael D.

    2000-08-18

    Thin films of titanium, zirconium and nickel oxides were deposited on conductive SnO2:F glass substrates by immersion in aqueous solutions. The films are transparent, conformal, of uniform thickness and appearance, and adhere strongly to the substrates. On electrochemical cycling, TiO2, mixed TiO2-ZrO2, and NiOx films exhibited stable electrochromism with high coloration efficiencies. These nickel oxide films were particularly stable compared with films prepared by other non-vacuum techniques. The method is simple, inexpensive, energy efficient, and readily scalable to larger substrates.

  4. Adhesion and friction of thin metal films

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1976-01-01

    Sliding friction experiments were conducted in vacuum with thin films of titanium, chromium, iron, and platinum sputter deposited on quartz or mica substrates. A single crystal hemispherically tipped gold slider was used in contact with the films at loads of 1.0 to 30.0 and at a sliding velocity of 0.7 mm/min at 23 C. Test results indicate that the friction coefficient is dependent on the adhesion of two interfaces, that between the film and its substrate and the slider and the film. There exists a relationship between the percent d bond character of metals in bulk and in thin film form and the friction coefficient. Oxygen can increase adhesive bonding of a metal film (platinum) to a substrate.

  5. Induced electronic anisotropy in bismuth thin films

    SciTech Connect

    Liao, Albert D.; Yao, Mengliang; Opeil, Cyril; Katmis, Ferhat; Moodera, Jagadeesh S.; Li, Mingda; Tang, Shuang; Dresselhaus, Mildred S.

    2014-08-11

    We use magneto-resistance measurements to investigate the effect of texturing in polycrystalline bismuth thin films. Electrical current in bismuth films with texturing such that all grains are oriented with the trigonal axis normal to the film plane is found to flow in an isotropic manner. By contrast, bismuth films with no texture such that not all grains have the same crystallographic orientation exhibit anisotropic current flow, giving rise to preferential current flow pathways in each grain depending on its orientation. Extraction of the mobility and the phase coherence length in both types of films indicates that carrier scattering is not responsible for the observed anisotropic conduction. Evidence from control experiments on antimony thin films suggests that the anisotropy is a result of bismuth's large electron effective mass anisotropy.

  6. Characterization and stability of thin oxide films on plutonium surfaces

    NASA Astrophysics Data System (ADS)

    Flores, H. G. García; Roussel, P.; Moore, D. P.; Pugmire, D. L.

    2011-02-01

    X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were employed to study oxide films on plutonium metal surfaces. Measurements of the relative concentrations of oxygen and plutonium, as well as the resulting oxidation states of the plutonium (Pu) species in the near-surface region are presented. The oxide product of the auto-reduction (AR) of plutonium dioxide films is evaluated and found to be an oxide species which is reduced further than what is expected. The results of this study show a much greater than anticipated extent of auto-reduction and challenge the commonly held notion of the stoichiometric stability of Pu 2O 3 thin-films. The data indicates that a sub-stoichiometric plutonium oxide (Pu 2O 3 - y ) exists at the metal-oxide interface. The level of sub-stoichiometry is shown to depend, in part, on the carbidic contamination of the metal surface.

  7. Flexible Thin Metal Film Thermal Sensing System

    NASA Technical Reports Server (NTRS)

    Thomsen, Donald Laurence (Inventor)

    2012-01-01

    A flexible thin metal film thermal sensing system is provided. A thermally-conductive film made from a thermally-insulating material is doped with thermally-conductive material. At least one layer of electrically-conductive metal is deposited directly onto a surface of the thermally-conductive film. One or more devices are coupled to the layer(s) to measure an electrical characteristic associated therewith as an indication of temperature.

  8. Microcrystalline organic thin-film solar cells.

    PubMed

    Verreet, Bregt; Heremans, Paul; Stesmans, Andre; Rand, Barry P

    2013-10-11

    Microcrystalline organic films with tunable thickness are produced directly on an indium-tin-oxide substrate, by crystallizing a thin amorphous rubrene film followed by its use as a template for subsequent homoepitaxial growth. These films, with exciton diffusion lengths exceeding 200 nm, produce solar cells with increasing photocurrents at thicknesses up to 400 nm with a fill factor >65%, demonstrating significant potential for microcrystalline organic electronic devices. PMID:23939936

  9. Process for making thin film solar cell

    SciTech Connect

    Eberspacher, C.; Ermer, J.H.; Mitchell, K.W.

    1991-09-03

    This paper describes a semiconducting thin film forced on a substrate by the method. It comprises: depositing a composite film of copper and indium on a substrate, the film having an atomic copper to indium ratio of about one, depositing a film of selenium on the composite copper indium film, the selenium film thickness selected to provide an atomic ratio of selenium to copper and indium of less than one, and heating the substrate with the composite copper indium film and the selenium film in the presence of H{sub 2}S gas for a time and at a temperature sufficient to cause interdiffusion of copper, indium, selenium and sulfur to form a semiconductor of the class CuInSe{sub 2{minus}x}S{sub x} where x is less than two.

  10. Thin-film Rechargeable Lithium Batteries

    DOE R&D Accomplishments Database

    Dudney, N. J.; Bates, J. B.; Lubben, D.

    1995-06-01

    Thin film rechargeable lithium batteries using ceramic electrolyte and cathode materials have been fabricated by physical deposition techniques. The lithium phosphorous oxynitride electrolyte has exceptional electrochemical stability and a good lithium conductivity. The lithium insertion reaction of several different intercalation materials, amorphous V{sub 2}O{sub 5}, amorphous LiMn{sub 2}O{sub 4}, and crystalline LiMn{sub 2}O{sub 4} films, have been investigated using the completed cathode/electrolyte/lithium thin film battery.

  11. Thin-film rechargeable lithium batteries

    SciTech Connect

    Dudney, N.J.; Bates, J.B.; Lubben, D.

    1995-06-01

    Thin-film rechargeable lithium batteries using ceramic electrolyte and cathode materials have been fabricated by physical deposition techniques. The lithium phosphorous oxynitride electrolyte has exceptional electrochemical stability and a good lithium conductivity. The lithium insertion reaction of several different intercalation materials, amorphous V{sub 2}O{sub 5}, amorphous LiMn{sub 2}O{sub 4}, and crystalline LiMn{sub 2}O{sub 4} films, have been investigated using the completed cathode/electrolyte/lithium thin-film battery.

  12. Thin Ice Films at Mineral Surfaces.

    PubMed

    Yeşilbaş, Merve; Boily, Jean-François

    2016-07-21

    Ice films formed at mineral surfaces are of widespread occurrence in nature and are involved in numerous atmospheric and terrestrial processes. In this study, we studied thin ice films at surfaces of 19 synthetic and natural mineral samples of varied structure and composition. These thin films were formed by sublimation of thicker hexagonal ice overlayers mostly produced by freezing wet pastes of mineral particles at -10 and -50 °C. Vibration spectroscopy revealed that thin ice films contained smaller populations of strongly hydrogen-bonded water molecules than in hexagonal ice and liquid water. Thin ice films at the surfaces of the majority of minerals considered in this work [i.e., metal (oxy)(hydr)oxides, phyllosilicates, silicates, volcanic ash, Arizona Test Dust] produced intense O-H stretching bands at ∼3400 cm(-1), attenuated bands at ∼3200 cm(-1), and liquid-water-like bending band at ∼1640 cm(-1) irrespective of structure and composition. Illite, a nonexpandable phyllosilicate, is the only mineral that stabilized a form of ice that was strongly resilient to sublimation in temperatures as low as -50 °C. As mineral-bound thin ice films are the substrates upon which ice grows from water vapor or aqueous solutions, this study provides new constraints from which their natural occurrences can be understood. PMID:27377606

  13. The preparation of ACEL thin films

    NASA Astrophysics Data System (ADS)

    Vecht, Aron

    1990-05-01

    Although thin film ACEL devices have become commercially available, the number of companies producing these displays has continued to diminish. The cause of their demise was not display performance, as both sufficient brightness and efficiency has been achieved, but the low return on the heavy capital investment due to the poor yields obtained in production. In order to make ACEL thin film devices more viable, the capital investment needs to be low and/or the production yields high. Opting for relatively expensive sputtering or ALE techniques as the sole methods of fabricating EL structures, is both commercially and scientifically ill-advised. Considerable effort was spent in developing cheaper alternative techniques for thin film deposition. The main objectives of the contract can be summarized as follows: (1) to deposit high quality ZnS thin films by MOCVD, (2) to dope the ZnS thin film with Mn, (3) to deposit high quality dielectric films using a novel spray pyrolysis process, (4) to evaluate optimized insulator/ZnS-Mn/insulator structures, and (5) the fabrication of large area XY matrix ACEL structures.

  14. Thin film absorber for a solar collector

    DOEpatents

    Wilhelm, William G.

    1985-01-01

    This invention pertains to energy absorbers for solar collectors, and more particularly to high performance thin film absorbers. The solar collectors comprising the absorber of this invention overcome several problems seen in current systems, such as excessive hardware, high cost and unreliability. In the preferred form, the apparatus features a substantially rigid planar frame with a thin film window bonded to one planar side of the frame. An absorber in accordance with the present invention is comprised of two thin film layers that are sealed perimetrically. In a preferred embodiment, thin film layers are formed from a metal/plastic laminate. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. The absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

  15. Carrier lifetimes in thin-film photovoltaics

    NASA Astrophysics Data System (ADS)

    Baek, Dohyun

    2015-09-01

    The carrier lifetimes in thin-film solar cells are reviewed and discussed. Shockley-Read-Hall recombination is dominant at low carrier density, Auger recombination is dominant under a high injection condition and high carrier density, and surface recombination is dominant under any conditions. Because the surface photovoltage technique is insensitive to the surface condition, it is useful for bulk lifetime measurements. The photoconductance decay technique measures the effective recombination lifetime. The time-resolved photoluminescence technique is very useful for measuring thin-film semiconductor or solar-cell materials lifetime, because the sample is thin, other techniques are not suitable for measuring the lifetime. Many papers have provided time-resolved photoluminescence (TRPL) lifetimes for copper-indium-gallium-selenide (CIGS) and CdTe thin-film solar cell. The TRPL lifetime strongly depends on open-circuit voltage and conversion efficiency; however, the TRPL life time is insensitive to the short-circuit current.

  16. Adhesive transfer of thin viscoelastic films.

    PubMed

    Shull, Kenneth R; Martin, Elizabeth F; Drzal, Peter L; Hersam, Mark C; Markowitz, Alison R; McSwain, Rachel L

    2005-01-01

    Micellar suspensions of acrylic diblock copolymers are excellent model materials for studying the adhesive transfer of viscoelastic solids. The micellar structure is maintained in films with a variety of thicknesses, giving films with a well-defined structure and viscoelastic character. Thin films were cast onto elastomeric silicone substrates from micellar suspensions in butanol, and the adhesive interactions between these coated elastomeric substrates and a rigid indenter were quantified. By controlling the adhesive properties of the film/indenter and film/substrate interfaces we were able to obtain very clean transfer of the film from the substrate to the portion of the glass indenter with which the film was in contact. Adhesive failure at the film/substrate interface occurs when the film/indenter interface is able to support an applied energy release rate that is sufficient to result in cavity nucleation at the film/substrate interface. Cavity formation is rapidly followed by delamination of the entire region under the indenter. The final stage in the transfer process involves the failure of the film that bridges the indenter and the elastomeric substrate. This film is remarkably robust and is extended to three times its original width prior to failure. Failure of this film occurs at the periphery of the indenter, giving a transferred film that conforms to the original contact area between the indenter and the coated substrate. PMID:15620300

  17. Method for making thin polypropylene film

    DOEpatents

    Behymer, R.D.; Scholten, J.A.

    1985-11-21

    An economical method is provided for making uniform thickness polypropylene film as thin as 100 Angstroms. A solution of polypropylene dissolved in xylene is formed by mixing granular polypropylene and xylene together in a flask at an elevated temperature. A substrate, such as a glass plate or microscope slide is immersed in the solution. When the glass plate is withdrawn from the solution at a uniform rate, a thin polypropylene film forms on a flat surface area of the glass plate as the result of xylene evaporation. The actual thickness of the polypropylene film is functional of the polypropylene in xylene solution concentration, and the particular withdrawal rate of the glass plate from the solution. After formation, the thin polypropylene film is floated from the glass plate onto the surface of water, from which it is picked up with a wire hoop.

  18. Simulated Thin-Film Growth and Imaging

    NASA Astrophysics Data System (ADS)

    Schillaci, Michael

    2001-06-01

    Thin-films have become the cornerstone of the electronics, telecommunications, and broadband markets. A list of potential products includes: computer boards and chips, satellites, cell phones, fuel cells, superconductors, flat panel displays, optical waveguides, building and automotive windows, food and beverage plastic containers, metal foils, pipe plating, vision ware, manufacturing equipment and turbine engines. For all of these reasons a basic understanding of the physical processes involved in both growing and imaging thin-films can provide a wonderful research project for advanced undergraduate and first-year graduate students. After producing rudimentary two- and three-dimensional thin-film models incorporating ballsitic deposition and nearest neighbor Coulomb-type interactions, the QM tunneling equations are used to produce simulated scanning tunneling microscope (SSTM) images of the films. A discussion of computational platforms, languages, and software packages that may be used to accomplish similar results is also given.

  19. Coalescence and percolation in thin metal films

    SciTech Connect

    Yu, X.; Duxbury, P.M.; Jeffers, G.; Dubson, M.A. Center for Fundamental Materials Research, Michigan State University, East Lansing, Michigan 48824-1116 )

    1991-12-15

    Metals thermally evaporated onto warm insulating substrates evolve to the thin-film state via the morphological sequence: compact islands, elongated islands, percolation, hole filling, and finally the thin-film state. The coverage at which the metal percolates ({ital p}{sub {ital c}}) is often considerably higher than that predicted by percolation models, such as inverse swiss cheese or lattice percolation. Using a simple continuum model, we show that high-{ital p}{sub {ital c}}'s arise naturally in thin films that exhibit a crossover from full coalescence of islands at early stages of growth to partial coalescence at later stages. In this interrupted-coalescence model, full coalescence of islands occurs up to a critical island radius {ital R}{sub {ital c}}, after which islands overlap, but do not fully coalesce. We present the morphology of films and the critical area coverages generated by this model.

  20. Tungsten-doped thin film materials

    DOEpatents

    Xiang, Xiao-Dong; Chang, Hauyee; Gao, Chen; Takeuchi, Ichiro; Schultz, Peter G.

    2003-12-09

    A dielectric thin film material for high frequency use, including use as a capacitor, and having a low dielectric loss factor is provided, the film comprising a composition of tungsten-doped barium strontium titanate of the general formula (Ba.sub.x Sr.sub.1-x)TiO.sub.3, where X is between about 0.5 and about 1.0. Also provided is a method for making a dielectric thin film of the general formula (Ba.sub.x Sr.sub.1-x)TiO.sub.3 and doped with W, where X is between about 0.5 and about 1.0, a substrate is provided, TiO.sub.2, the W dopant, Ba, and optionally Sr are deposited on the substrate, and the substrate containing TiO.sub.2, the W dopant, Ba, and optionally Sr is heated to form a low loss dielectric thin film.

  1. Ambient pressure process for preparing aerogel thin films reliquified sols useful in preparing aerogel thin films

    DOEpatents

    Brinker, Charles Jeffrey; Prakash, Sai Sivasankaran

    1999-01-01

    A method for preparing aerogel thin films by an ambient-pressure, continuous process. The method of this invention obviates the use of an autoclave and is amenable to the formation of thin films by operations such as dip coating. The method is less energy intensive and less dangerous than conventional supercritical aerogel processing techniques.

  2. Niobium Thin Film Characterization for Thin Film Technology Used in Superconducting Radiofrequency Cavities

    NASA Astrophysics Data System (ADS)

    Dai, Yishu; Valente-Feliciano, Anne-Marie

    2015-10-01

    Superconducting RadioFrequency (SRF) penetrates about 40-100 nm of the top surface, making thin film technology possible in producing superconducting cavities. Thin film is based on the deposition of a thin Nb layer on top of a good thermal conducting material such as Al or Cu. Thin film allows for better control of the surface and has negligible response to the Earth's magnetic field, eliminating the need for magnetic shielding of the cavities. Thin film superconductivity depends heavily on coating process conditions, involving controllable parameters such as crystal plane orientation, coating temperature, and ion energy. MgO and Al2O3 substrates are used because they offer very smooth surfaces, ideal for studying film growth. Atomic Force Microscopy is used to characterize surface's morphology. It is evident that a lower nucleation energy and a long coating time increases the film quality in the r-plane sapphire crystal orientation. The quality of the film increases with thickness. Nb films coated on r-plane, grow along the (001) plane and yield a much higher RRR compared to the films grown on a- and c-planes. This information allows for further improvement on the research process for thin film technology used in superconducting cavities for the particle accelerators. National Science Foundation, Department of Energy, Jefferson Lab, Old Dominion University.

  3. In situ study of topography, phase and volume changes of titanium dioxide anode in all-solid-state thin film lithium-ion battery by biased scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Zhu, Jing; Feng, Jinkui; Lu, Li; Zeng, Kaiyang

    2012-01-01

    In this study, local cyclic changes of surface topography, phase and volume of TiO2 anode within an all-solid-state thin film Li-ion battery (TiO2/LiPON/LiNi1/3Co1/3Mn1/3O2) at nanoscale are studied. These changes are caused by reversible bias-induced electric field through an in situ scanning probe microscopy (SPM) without external electrochemical attachment. Combining simultaneous measurements of phase and amplitude images, high spatially resolved mapping of “nano-spots” related to Li+ distribution can be obtained, providing new insight into the ionic transport mechanism and diffusion preferred paths in a real all-solid-state thin film lithium ion battery. In addition, the thin film anode shows reversible topographical changes as the volume expansion/contraction is related to the cyclic Li+ insertion/extraction, which are analogues to the charge/discharge behavior observed in electrochemical atomic force microscopy (EC-AFM) studies. The results suggest that the applications of local reversible biases are very useful for modeling the charge/discharge processes of lithium ion batteries.

  4. Optical and morphological properties of sol gel derived titanium dioxide films

    SciTech Connect

    Sharma, A. B.; Sharma, S. K.; M, Vishwas; Rao, K. Narasimha

    2015-08-28

    Titanium oxide (Titania) thin films were synthesized on different substrates via the sol-gel dip-coating method using alkoxide solution. Some selected samples were also prepared with different percentage of Lead (Pb). The influence of Pb addition in precursor sol on the optical properties of titanium dioxide thin films was studied. The optical transmittance in the visible region has increased with increase in weight percentage of lead. The refractive index was slightly decreased with Pb addition. Crystallization of these coatings was achieved through thermal annealing at temperatures above 400 °C. The structural properties and surface morphology of the crystallized coatings were studied by Scanning Electron Microscopy. Increase in average grain size from 250 nm to 350 nm with increase in Pb concentration is observed. Films were appeared to more coarse with increase in Pb addition. An increase in Pb addition resulted increase in average roughness from 12 nm to 25 nm.

  5. Mirrorlike pulsed laser deposited tungsten thin film

    SciTech Connect

    Mostako, A. T. T.; Khare, Alika; Rao, C. V. S.

    2011-01-15

    Mirrorlike tungsten thin films on stainless steel substrate deposited via pulsed laser deposition technique in vacuum (10{sup -5} Torr) is reported, which may find direct application as first mirror in fusion devices. The crystal structure of tungsten film is analyzed using x-ray diffraction pattern, surface morphology of the tungsten films is studied with scanning electron microscope and atomic force microscope. The film composition is identified using energy dispersive x-ray. The specular and diffuse reflectivities with respect to stainless steel substrate of the tungsten films are recorded with FTIR spectra. The thickness and the optical quality of pulsed laser deposition deposited films are tested via interferometric technique. The reflectivity is approaching about that of the bulk for the tungsten film of thickness {approx}782 nm.

  6. Mirrorlike pulsed laser deposited tungsten thin film.

    PubMed

    Mostako, A T T; Rao, C V S; Khare, Alika

    2011-01-01

    Mirrorlike tungsten thin films on stainless steel substrate deposited via pulsed laser deposition technique in vacuum (10(-5) Torr) is reported, which may find direct application as first mirror in fusion devices. The crystal structure of tungsten film is analyzed using x-ray diffraction pattern, surface morphology of the tungsten films is studied with scanning electron microscope and atomic force microscope. The film composition is identified using energy dispersive x-ray. The specular and diffuse reflectivities with respect to stainless steel substrate of the tungsten films are recorded with FTIR spectra. The thickness and the optical quality of pulsed laser deposition deposited films are tested via interferometric technique. The reflectivity is approaching about that of the bulk for the tungsten film of thickness ∼782 nm. PMID:21280810

  7. Corrosion Behaviour of Sputtered Alumina Thin Films

    NASA Astrophysics Data System (ADS)

    Reddy, I. Neelakanta; Dey, Arjun; Sridhara, N.; Anoop, S.; Bera, Parthasarathi; Rani, R. Uma; Anandan, Chinnasamy; Sharma, Anand Kumar

    2015-10-01

    Corrosion studies of sputtered alumina thin films grown on stainless steel (SS) 304 were carried out by linear polarization and electrochemical impedance spectroscopy. Noticeable changes were not observed in morphology and surface roughness of films after carrying out the corrosion test. Corrosion current density (icorr) of alumina coated SS decreased up to 10-10 A cm-2 while icorr value in the range of 10-5-10-6 A cm-2 was observed for bare SS. The direct sputtered film showed superior corrosion resistance behaviour than the reactive sputtered film. This might be attributed to the difference in thickness of the films sputtered by direct and reactive methods. The electronic structure of deposited alumina films was studied both before and after corrosion test by X-ray photoelectron spectroscopy technique which also confirmed no structural changes of alumina film after exposing it to corrosive environment.

  8. Thermochromic properties of Sn, W co-doped VO2 nanostructured thin film deposited by pulsed laser deposition.

    PubMed

    Hur, M G; Masaki, T; Yoon, D H

    2014-12-01

    Tin (Sn) and tungsten (W) co-doped vanadium dioxide (VO2) nanostructured thin films with 50-nm thickness were deposited by pulsed laser deposition (PLD) to reduce the transition temperature and improve the IR transmittance. The crystal structure of the nanostructured thin films and the presence of elements were evaluated by XRD and XPS analysis. The transition temperature (T(c)) of 1 at% Sn-1 at% W co-doped VO2 nanostructured thin film was decreased to about 22 degrees C (from 70.3 to 48.5 degrees C) compared with the undoped VO2 nanostructured thin film. The transmittance width in the IR range of the co-doped nanostructured thin film decreased from 37.5% to 27% compared with the undoped VO2 nanostructured thin film. Also, the width of hysteresis was narrowed by Sn doping. PMID:25970986

  9. A high performance thin film thermoelectric cooler

    SciTech Connect

    Rowe, D.M.; Min, G.; Volklein, F.

    1998-07-01

    Thin film thermoelectric devices with small dimensions have been fabricated using microelectronics technology and operated successfully in the Seebeck mode as sensors or generators. However, they do not operate successfully in the Peltier mode as coolers, because of the thermal bypass provided by the relatively thick substrate upon which the thermoelectric device is fabricated. In this paper a processing sequence is described which dramatically reduces this thermal bypass and facilitates the fabrication of high performance integrated thin film thermoelectric coolers. In the processing sequence a very thin amorphous SiC (or SiO{sub 2}SiN{sub 4}) film is deposited on a silicon substrate using conventional thin film deposition and a membrane formed by removing the silicon substrate over a desired region using chemical etching or micro-machining. Thermoelements are deposited on the membrane using conventional thin film deposition and patterning techniques and configured so that the region which is to be cooled is abutted to the cold junctions of the Peltier thermoelements while the hot junctions are located at the outer peripheral area which rests on the silicon substrate rim. Heat is pumped laterally from the cooled region to the silicon substrate rim and then dissipated vertically through it to an external heat sink. Theoretical calculations of the performance of a cooler described above indicate that a maximum temperature difference of about 40--50K can be achieved with a maximum heat pumping capacity of around 10 milliwatts.

  10. Ion beam-based characterization of multicomponent oxide thin films and thin film layered structures

    SciTech Connect

    Krauss, A.R.; Rangaswamy, M.; Lin, Yuping; Gruen, D.M.; Schultz, J.A.; Schmidt, H.K.; Chang, R.P.H.

    1992-11-01

    Fabrication of thin film layered structures of multi-component materials such as high temperature superconductors, ferroelectric and electro-optic materials, and alloy semiconductors, and the development of hybrid materials requires understanding of film growth and interface properties. For High Temperature Superconductors, the superconducting coherence length is extremely short (5--15 {Angstrom}), and fabrication of reliable devices will require control of film properties at extremely sharp interfaces; it will be necessary to verify the integrity of thin layers and layered structure devices over thicknesses comparable to the atomic layer spacing. Analytical techniques which probe the first 1--2 atomic layers are therefore necessary for in-situ characterization of relevant thin film growth processes. However, most surface-analytical techniques are sensitive to a region within 10--40 {Angstrom} of the surface and are physically incompatible with thin film deposition and are typically restricted to ultra high vacuum conditions. A review of ion beam-based analytical methods for the characterization of thin film and multi-layered thin film structures incorporating layers of multicomponent oxides is presented. Particular attention will be paid to the use of time-of-flight techniques based on the use of 1- 15 key ion beams which show potential for use as nondestructive, real-time, in-situ surface diagnostics for the growth of multicomponent metal and metal oxide thin films.

  11. Thin film dielectric composite materials

    DOEpatents

    Jia, Quanxi; Gibbons, Brady J.; Findikoglu, Alp T.; Park, Bae Ho

    2002-01-01

    A dielectric composite material comprising at least two crystal phases of different components with TiO.sub.2 as a first component and a material selected from the group consisting of Ba.sub.1-x Sr.sub.x TiO.sub.3 where x is from 0.3 to 0.7, Pb.sub.1-x Ca.sub.x TiO.sub.3 where x is from 0.4 to 0.7, Sr.sub.1-x Pb.sub.x TiO.sub.3 where x is from 0.2 to 0.4, Ba.sub.1-x Cd.sub.x TiO.sub.3 where x is from 0.02 to 0.1, BaTi.sub.1-x Zr.sub.x O.sub.3 where x is from 0.2 to 0.3, BaTi.sub.1-x Sn.sub.x O.sub.3 where x is from 0.15 to 0.3, BaTi.sub.1-x Hf.sub.x O.sub.3 where x is from 0.24 to 0.3, Pb.sub.1-1.3x La.sub.x TiO.sub.3+0.2x where x is from 0.23 to 0.3, (BaTiO.sub.3).sub.x (PbFeo.sub.0.5 Nb.sub.0.5 O.sub.3).sub.1-x where x is from 0.75 to 0.9, (PbTiO.sub.3).sub.- (PbCo.sub.0.5 W.sub.0.5 O.sub.3).sub.1-x where x is from 0.1 to 0.45, (PbTiO.sub.3).sub.x (PbMg.sub.0.5 W.sub.0.5 O.sub.3).sub.1-x where x is from 0.2 to 0.4, and (PbTiO.sub.3).sub.x (PbFe.sub.0.5 Ta.sub.0.5 O.sub.3).sub.1-x where x is from 0 to 0.2, as the second component is described. The dielectric composite material can be formed as a thin film upon suitable substrates.

  12. Crystallization of zirconia based thin films.

    PubMed

    Stender, D; Frison, R; Conder, K; Rupp, J L M; Scherrer, B; Martynczuk, J M; Gauckler, L J; Schneider, C W; Lippert, T; Wokaun, A

    2015-07-28

    The crystallization kinetics of amorphous 3 and 8 mol% yttria stabilized zirconia (3YSZ and 8YSZ) thin films grown by pulsed laser deposition (PLD), spray pyrolysis and dc-magnetron sputtering are explored. The deposited films were heat treated up to 1000 °C ex situ and in situ in an X-ray diffractometer. A minimum temperature of 275 °C was determined at which as-deposited amorphous PLD grown 3YSZ films fully crystallize within five hours. Above 325 °C these films transform nearly instantaneously with a high degree of micro-strain when crystallized below 500 °C. In these films the t'' phase crystallizes which transforms at T > 600 °C to the t' phase upon relaxation of the micro-strain. Furthermore, the crystallization of 8YSZ thin films grown by PLD, spray pyrolysis and dc-sputtering are characterized by in situ XRD measurements. At a constant heating rate of 2.4 K min(-1) crystallization is accomplished after reaching 800 °C, while PLD grown thin films were completely crystallized already at ca. 300 °C. PMID:26119755

  13. Surface Structure and Photocatalytic Activity of Nano-TiO2 Thin Film

    EPA Science Inventory

    Controlled titanium dioxide (TiO2) thin films were deposited on stainless steel surfaces using flame aerosol synthetic technique, which is a one-step coating process, that doesn’t require further calcination. Solid state characterization of the coatings was conducted by different...

  14. Capillary stress in microporous thin films

    SciTech Connect

    Samuel, J.; Hurd, A.J.; Frink, L.J.D.; Swol, F. van; Brinker, C.J. |; Raman, N.K.

    1996-06-01

    Development of capillary stress in porous xerogels, although ubiquitous, has not been systematically studied. The authors have used the beam bending technique to measure stress isotherms of microporous thin films prepared by a sol-gel route. The thin films were prepared on deformable silicon substrates which were then placed in a vacuum system. The automated measurement was carried out by monitoring the deflection of a laser reflected off the substrate while changing the overlying relative pressure of various solvents. The magnitude of the macroscopic bending stress was found to reach a value of 180 MPa at a relative pressure of methanol, P/Po = 0.001. The observed stress is determined by the pore size distribution and is an order of magnitude smaller in mesoporous thin films. Density Functional Theory (DFT) indicates that for the microporous materials, the stress at saturation is compressive and drops as the relative pressure is reduced.

  15. Vibration welding system with thin film sensor

    DOEpatents

    Cai, Wayne W; Abell, Jeffrey A; Li, Xiaochun; Choi, Hongseok; Zhao, Jingzhou

    2014-03-18

    A vibration welding system includes an anvil, a welding horn, a thin film sensor, and a process controller. The anvil and horn include working surfaces that contact a work piece during the welding process. The sensor measures a control value at the working surface. The measured control value is transmitted to the controller, which controls the system in part using the measured control value. The thin film sensor may include a plurality of thermopiles and thermocouples which collectively measure temperature and heat flux at the working surface. A method includes providing a welder device with a slot adjacent to a working surface of the welder device, inserting the thin film sensor into the slot, and using the sensor to measure a control value at the working surface. A process controller then controls the vibration welding system in part using the measured control value.

  16. Thin film ferroelectric electro-optic memory

    NASA Technical Reports Server (NTRS)

    Thakoor, Sarita (Inventor); Thakoor, Anilkumar P. (Inventor)

    1993-01-01

    An electrically programmable, optically readable data or memory cell is configured from a thin film of ferroelectric material, such as PZT, sandwiched between a transparent top electrode and a bottom electrode. The output photoresponse, which may be a photocurrent or photo-emf, is a function of the product of the remanent polarization from a previously applied polarization voltage and the incident light intensity. The cell is useful for analog and digital data storage as well as opto-electric computing. The optical read operation is non-destructive of the remanent polarization. The cell provides a method for computing the product of stored data and incident optical data by applying an electrical signal to store data by polarizing the thin film ferroelectric material, and then applying an intensity modulated optical signal incident onto the thin film material to generate a photoresponse therein related to the product of the electrical and optical signals.

  17. Mesoscale morphologies in polymer thin films.

    SciTech Connect

    Ramanathan, M.; Darling, S. B.

    2011-06-01

    In the midst of an exciting era of polymer nanoscience, where the development of materials and understanding of properties at the nanoscale remain a major R&D endeavor, there are several exciting phenomena that have been reported at the mesoscale (approximately an order of magnitude larger than the nanoscale). In this review article, we focus on mesoscale morphologies in polymer thin films from the viewpoint of origination of structure formation, structure development and the interaction forces that govern these morphologies. Mesoscale morphologies, including dendrites, holes, spherulites, fractals and honeycomb structures have been observed in thin films of homopolymer, copolymer, blends and composites. Following a largely phenomenological level of description, we review the kinetic and thermodynamic aspects of mesostructure formation outlining some of the key mechanisms at play. We also discuss various strategies to direct, limit, or inhibit the appearance of mesostructures in polymer thin films as well as an outlook toward potential areas of growth in this field of research.

  18. Thin Film Transistors On Plastic Substrates

    DOEpatents

    Carey, Paul G.; Smith, Patrick M.; Sigmon, Thomas W.; Aceves, Randy C.

    2004-01-20

    A process for formation of thin film transistors (TFTs) on plastic substrates replaces standard thin film transistor fabrication techniques, and uses sufficiently lower processing temperatures so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The silicon based thin film transistor produced by the process includes a low temperature substrate incapable of withstanding sustained processing temperatures greater than about 250.degree. C., an insulating layer on the substrate, a layer of silicon on the insulating layer having sections of doped silicon, undoped silicon, and poly-silicon, a gate dielectric layer on the layer of silicon, a layer of gate metal on the dielectric layer, a layer of oxide on sections of the layer of silicon and the layer of gate metal, and metal contacts on sections of the layer of silicon and layer of gate metal defining source, gate, and drain contacts, and interconnects.

  19. Method for synthesizing thin film electrodes

    DOEpatents

    Boyle, Timothy J.

    2007-03-13

    A method for making a thin-film electrode, either an anode or a cathode, by preparing a precursor solution using an alkoxide reactant, depositing multiple thin film layers with each layer approximately 500 1000 .ANG. in thickness, and heating the layers to above 600.degree. C. to achieve a material with electrochemical properties suitable for use in a thin film battery. The preparation of the anode precursor solution uses Sn(OCH.sub.2C(CH.sub.3).sub.3).sub.2 dissolved in a solvent in the presence of HO.sub.2CCH.sub.3 and the cathode precursor solution is formed by dissolving a mixture of (Li(OCH.sub.2C(CH.sub.3).sub.3)).sub.8 and Co(O.sub.2CCH.sub.3).H.sub.2O in at least one polar solvent.

  20. Trends in gas sensors with tunable thin films

    NASA Astrophysics Data System (ADS)

    Domash, Lawrence; Cohen, Mitchell; Wagner, Matthias

    2004-10-01

    A new family of miniature nano-tunable narrowband infrared filters has been developed based on the thermo-optic properties of thin film semiconductors. Originally developed for fiber optic telecommunications networks at 1.5 μm, the technology has now been extended to the 3-5 μm range, leading to very compact tunable filters with passbands on the order of 0.5% of center wavelength and tuning ranges up to 4% of center wavelength. Two applications are described. First, a prototype carbon monoxide sensor testbed based on a 4550-4650 nm tunable filter is shown to be capable of detecting less than 20 ppm of CO. Second, we show how nano-tunable thin film filters can be integrated with miniature blackbody sources to create a new family of ultra low cost integrated tunable IR emitters, which we have named Firefly. Packaged in TO cans, Firefly devices enable precision detection of gases including carbon dioxide, carbon monoxide, sulphur dioxide, hydrogen cyanide, water vapor, nitric oxide or methane.

  1. Memory switches based on metal oxide thin films

    NASA Technical Reports Server (NTRS)

    Ramesham, Rajeshuni (Inventor); Thakoor, Anilkumar P. (Inventor); Lambe, John J. (Inventor)

    1990-01-01

    MnO.sub.2-x thin films (12) exhibit irreversible memory switching (28) with an OFF/ON resistance ratio of at least about 10.sup.3 and the tailorability of ON state (20) resistance. Such films are potentially extremely useful as a connection element in a variety of microelectronic circuits and arrays (24). Such films provide a pre-tailored, finite, non-volatile resistive element at a desired place in an electric circuit, which can be electrically turned OFF (22) or disconnected as desired, by application of an electrical pulse. Microswitch structures (10) constitute the thin film element, contacted by a pair of separate electrodes (16a, 16b) and have a finite, pre-selected ON resistance which is ideally suited, for example, as a programmable binary synaptic connection for electronic implementation of neural network architectures. The MnO.sub.2-x microswitch is non-volatile, patternable, insensitive to ultraviolet light, and adherent to a variety of insulating substrates (14), such as glass and silicon dioxide-coated silicon substrates.

  2. Solid-state thin-film supercapacitor with ruthenium oxide and solid electrolyte thin films

    NASA Astrophysics Data System (ADS)

    Yoon, Y. S.; Cho, W. I.; Lim, J. H.; Choi, D. J.

    Direct current reactive sputtering deposition of ruthenium oxide thin films (bottom and top electrodes) at 400°C are performed to produce a solid-state thin-film supercapacitor (TFSC). The supercapacitor has a cell structure of RuO 2/Li 2.94PO 2.37N 0.75 (Lipon)/RuO 2/Pt. Radio frequency, reactive sputtering deposition of an Li 2.94PO 2.37N 0.75 electrolyte film is performed on the bottom RuO 2 film at room temperature to separate the bottom and top RuO 2 electrodes electrically. The stoichiometry of the RuO 2 thin film is investigated by Rutherford back-scattering spectrometry (RBS). X-ray diffraction (XRD) shows that the as-deposited RuO 2 thin film is an amorphous phase. Scanning electron microscopy (SEM) measurements reveal that the RuO 2/Lipon/RuO 2 hetero-interfaces have no inter-diffusion problems. Charge-discharge measurements with constant current at room temperature clearly reveal typical supercapacitor behaviour for a RuO 2/Lipon/RuO 2/Pt cell structure. Since the electrolyte thin film has low ionic mobility, the capacity and cycle performance are inferior to those of a bulk type of supercapacitor. These results indicate that a high performance, TFSC can be fabricated by a solid electrolyte thin film with high ionic conductivity.

  3. Feasibility Study of Thin Film Thermocouple Piles

    NASA Technical Reports Server (NTRS)

    Sisk, R. C.

    2001-01-01

    Historically, thermopile detectors, generators, and refrigerators based on bulk materials have been used to measure temperature, generate power for spacecraft, and cool sensors for scientific investigations. New potential uses of small, low-power, thin film thermopiles are in the area of microelectromechanical systems since power requirements decrease as electrical and mechanical machines shrink in size. In this research activity, thin film thermopile devices are fabricated utilizing radio frequency sputter coating and photoresist lift-off techniques. Electrical characterizations are performed on two designs in order to investigate the feasibility of generating small amounts of power, utilizing any available waste heat as the energy source.

  4. Borocarbide thin films and tunneling measurements.

    SciTech Connect

    Iavarone, M.; Andreone, A.; Cassinese, A.; Dicapual, R.; giannil, L.; Vagliol, R.; DeWilde, Y.; Crabtree, G. W.

    2000-06-15

    The results obtained by their group in thin film fabrication and STM tunneling on superconducting borocarbides YNi{sub 2}B{sub 2}C have been be briefly reviewed. Results concerning the microwave surface impedance and the S/N planar junctions on LuNi{sub 2}B{sub 2}C thin films have been also presented and analyzed. These new data unambiguously confirm the full BCS nature of the superconducting gap in borocarbides and the absence of significant pair-breaking effects in LuNi{sub 2}B{sub 2}C.

  5. Emittance Theory for Thin Film Selective Emitter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Lowe, Roland A.; Good, Brian S.

    1994-01-01

    Thin films of high temperature garnet materials such as yttrium aluminum garnet (YAG) doped with rare earths are currently being investigated as selective emitters. This paper presents a radiative transfer analysis of the thin film emitter. From this analysis the emitter efficiency and power density are calculated. Results based on measured extinction coefficients for erbium-YAG and holmium-YAG are presented. These results indicated that emitter efficiencies of 50 percent and power densities of several watts/sq cm are attainable at moderate temperatures (less than 1750 K).

  6. Annealed CVD molybdenum thin film surface

    DOEpatents

    Carver, Gary E.; Seraphin, Bernhard O.

    1984-01-01

    Molybdenum thin films deposited by pyrolytic decomposition of Mo(CO).sub.6 attain, after anneal in a reducing atmosphere at temperatures greater than 700.degree. C., infrared reflectance values greater than reflectance of supersmooth bulk molybdenum. Black molybdenum films deposited under oxidizing conditions and annealed, when covered with an anti-reflecting coating, approach the ideal solar collector characteristic of visible light absorber and infrared energy reflector.

  7. Dynamics of liquid films and thin jets

    NASA Technical Reports Server (NTRS)

    Zak, M.

    1979-01-01

    The theory of liquid films and thin jets as one- and two-dimensional continuums is examined. The equations of motion have led to solutions for the characteristic speeds of wave propagation for the parameters characterizing the shape. The formal analogy with a compressible fluid indicates the possibility of shock wave generation in films and jets and the formal analogy to the theory of threads and membranes leads to the discovery of some new dynamic effects. The theory is illustrated by examples.

  8. Superconducting thin films on potassium tantalate substrates

    DOEpatents

    Feenstra, Roeland; Boatner, Lynn A.

    1992-01-01

    A superconductive system for the lossless transmission of electrical current comprising a thin film of superconducting material Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.7-x epitaxially deposited upon a KTaO.sub.3 substrate. The KTaO.sub.3 is an improved substrate over those of the prior art since the it exhibits small lattice constant mismatch and does not chemically react with the superconducting film.

  9. Microstructure and properties of manganese dioxide films prepared by electrodeposition

    NASA Astrophysics Data System (ADS)

    Jacob, G. Moses; Zhitomirsky, I.

    2008-08-01

    Nanostructured manganese dioxide films were obtained by galvanostatic, pulse and reverse pulse electrodeposition from 0.01 to 0.1 M KMnO 4 solutions. The deposition yield was investigated by in situ monitoring the deposit mass using a quartz crystal microbalance (QCM). Obtained films were studied by electron microscopy, X-ray diffraction analysis, energy dispersive spectroscopy, thermogravimetric and differential thermal analysis. The QCM and electron microscopy data were utilized for the investigation of deposition kinetics and film formation mechanism. It was shown that the deposition rate and film microstructure could be changed by variation of deposition conditions. The method allowed the fabrication of dense or porous films. The thickness of dense films was limited to ˜0.1 μm due to the insulating properties of manganese dioxide and film cracking, attributed to drying shrinkage. Porous and crack-free 1-2 μm films were obtained using galvanostatic or reverse pulse deposition from 0.02 M KMnO 4 solutions. It was shown that film porosity is beneficial for the charge transfer during deposition and crack prevention in thick films. Moreover, porous nanostructured films showed good capacitive behavior for applications in electrochemical supercapacitors. The porous nanostructured films prepared in the reverse pulse regime showed higher specific capacitance (SC) compared to the SC of the galvanostatic films. The highest SC of 279 F/g in a voltage window of 1 V was obtained in 0.1 M Na 2SO 4 solutions at a scan rate of 2 mV/s.

  10. Hydrogenated nanocrystalline silicon germanium thin films

    NASA Astrophysics Data System (ADS)

    Yusoff, A. R. M.; Syahrul, M. N.; Henkel, K.

    2007-08-01

    Hydrogenated nanocrystalline silicon germanium thin films (nc-SiGe:H) is an interesting alternative material to replace hydrogenated nanocrystalline silicon (nc-Si:H) as the narrow bandgap absorber in an a-Si/a-SiGe/nc-SiGe(nc-Si) triple-junction solar cell due to its higher optical absorption in the wavelength range of interest. In this paper, we present results of optical, structural investigations and electrical characterization of nc-SiGe:H thin films made by hot-wire chemical vapor deposition (HWCVD) with a coil-shaped tungsten filament and with a disilane/germane/hydrogen gas mixture. The optical band gaps of a-SiGe:H and nc-SiGe:H thin-films, which are deposited with the same disilane/germane/hydrogen gas mixture ratio of 3.4:1.7:7, are about 1.58 eV and 2.1 eV, respectively. The nc-SiGe:H thin film exhibits a larger optical absorption coefficient of about 2-4 in the 600-900 nm range when compared to nc-Si:H thin film. Therefore, a thinner nc-SiGe:H layer of sim500 nm thickness may be sufficient for the narrow bandgap absorber in an a-Si based multiple-junction solar cell. We enhanced the transport properties as measured by the photoconductivity frequency mixing technique. These improved alloys do not necessarily show an improvement in the degree of structural heterogeneity on the nanometer scale as measured by small-angle X-ray scattering. Decreasing both the filament temperature and substrate temperature produced a film with relatively low structural heterogeneity while photoluminescence showed an order of magnitude increase in defect density for a similar change in the process.

  11. Oriented thin films of perylenetetracarboxylic diimide on frictiontransferred polymer films

    NASA Astrophysics Data System (ADS)

    Tanigaki, Nobutaka; Heck, Claire; Mizokuro, Toshiko

    Perylenetetracarboxylic diimide (PTCDI) is a promising material for application in organic electronics. In this study we report on the preparation of oriented thin films of PTCDI on the surface of oriented polymer substrates, which were prepared by friction transfer method. Two polymers, poly(tetrafluoroethylene) (PTFE) and poly(p-phenylene) (PPP) were used as the orienting substrate for PTCDI for comparison studies. Characterization by polarized UV-vis absorption shows that the orienting ability of PPP is larger than that of PTFE substrate. Furthermore, polarization-sensitive photoelectric conversion devices were fabricated by using the oriented PTCDI thin film on the PPP substrate.

  12. Gas adsorption on microporous carbon thin films

    SciTech Connect

    O'Shea, S.; Pailthorpe, B.A.; Collins, R.E.; Furlong, D.N. )

    1992-05-01

    A gas adsorption study was performed on amorphous hydrogenated carbon thin films which are deposited by reactive magnetron sputtering using acetylene gas. It is found that the films are highly microporous. Annealing significantly increases the adsorption capacity of the films and decreases the effects of low-pressure hysteresis in the adsorption isotherms. The general gas adsorption behavior closely resembles that of powdered activated carbons. The Dubinin-Radushkevich equation can be used to model the submonolayer adsorption isotherm for a variety of gases. 38 refs., 9 figs., 3 tabs.

  13. Study of iron mononitride thin films

    SciTech Connect

    Tayal, Akhil Gupta, Mukul Phase, D. M. Reddy, V. R. Gupta, Ajay

    2014-04-24

    In this work we have studied the crystal structural and local ordering of iron and nitrogen in iron mononitride thin films prepared using dc magnetron sputtering at sputtering power of 100W and 500W. The films were sputtered using pure nitrogen to enhance the reactivity of nitrogen with iron. The x-ray diffraction (XRD), conversion electron Mössbauer spectroscopy (CEMS) and soft x-ray absorption spectroscopy (SXAS) studies shows that the film crystallizes in ZnS-type crystal structure.

  14. Growth Induced Magnetic Anisotropy in Crystalline and Amorphous Thin Films

    SciTech Connect

    Hellman, Frances

    1998-10-03

    OAK B204 Growth Induced Magnetic Anisotropy in Crystalline and Amorphous Thin Films. The work in the past 6 months has involved three areas of magnetic thin films: (1) amorphous rare earth-transition metal alloys, (2) epitaxial Co-Pt and hTi-Pt alloy thin films, and (3) collaborative work on heat capacity measurements of magnetic thin films, including nanoparticles and CMR materials.

  15. Microstructural characterization in nanocrystalline ceramic thin films

    NASA Astrophysics Data System (ADS)

    Kim, Hakkwan

    The primary objective of this research is to investigate the effects of process variables on microstructure in several fluoride and oxide thin films prepared by vapor deposition, in order to predict the properties and behaviors of nanocrystalline thin film materials. There are three distinct stages of this research. The first stage focuses on measuring of the porosity in polycrystalline thin films of a variety of fluorides as a function of the substrate temperature during deposition, and discussing the mechanism by which the porosity varies as a function of the process variables. We have measured the porosity in thin films of lithium fluoride (LiF), magnesium fluoride (MgF2), barium fluoride (BaF 2) and calcium fluoride (CaF2) using an atomic force microscope (AFM) and a quartz crystal thickness monitor. The porosity is very sensitive to the substrate temperature and decreases as the substrate temperature increases. Consistent behavior is observed among all of the materials in this study. The second stage is to understand the film microstructure including grain growth and texture development, because these factors are known to influence the behavior and stability of polycrystalline thin films. This study focuses on grain growth and texture development in polycrystalline lithium fluoride thin films using dark field (DF) transmission electron microscopy (TEM). It is demonstrated that we can isolate the size distribution of <111> surface normal grains from the overall size distribution, based on simple and plausible assumptions about the texture. The {111} texture formation and surface morphology were also observed by x-ray diffraction (XRD) and AFM, respectively. The grain size distributions become clearly bimodal as the annealing time increases, and we deduce that the short-time size distributions are also a sum of two overlapping peaks. The smaller grain-size peak in the distribution corresponds to the {111}-oriented grains which do not grow significantly, while

  16. Rim instability of bursting thin smectic films

    NASA Astrophysics Data System (ADS)

    Trittel, Torsten; John, Thomas; Tsuji, Kinko; Stannarius, Ralf

    2013-05-01

    The rupture of thin smectic bubbles is studied by means of high speed video imaging. Bubbles of centimeter diameter and film thicknesses in the nanometer range are pierced, and the instabilities of the moving rim around the opening hole are described. Scaling laws describe the relation between film thickness and features of the filamentation process of the rim. A flapping motion of the retracting smectic film is assumed as the origin of the observed filamentation instability. A comparison with similar phenomena in soap bubbles is made. The present experiments extend studies on soap films [H. Lhuissier and E. Villermaux, Phys. Rev. Lett. 103, 054501 (2009), 10.1103/PhysRevLett.103.054501] to much thinner, uniform films of thermotropic liquid crystals.

  17. Residual stress measurement in YBCO thin films.

    SciTech Connect

    Cheon, J. H.; Singh, J. P.

    2002-05-13

    Residual stress in YBCO films on Ag and Hastelloy C substrates was determined by using 3-D optical interferometry and laser scanning to measure the change in curvature radius before and after film deposition. The residual stress was obtained by appropriate analysis of curvature measurements. Consistent with residual thermal stress calculations based on the thermal expansion coefficient mismatch between the substrates and YBCO film, the measured residual stress in the YBCO film on Hastelloy C substrate was tensile, while it was compressive on the Ag substrate. The stress values measured by the two techniques were generally in good agreement, suggesting that optical interferometry and laser scanning have promise for measuring residual stresses in thin films.

  18. Thin film thermocouples for high temperature measurement

    NASA Astrophysics Data System (ADS)

    Kreider, Kenneth G.

    1989-05-01

    Thin film thermocouples have unique capabilities for measuring surface temperatures at high temperatures (above 800 K) under harsh conditions. Their low mass, approximately 2 x 10(-5) g/mm permits very rapid response and very little disturbance of heat transfer to the surface being measured. This has led to applications inside gas turbine engines and diesel engines measuring the surface temperature of first stage turbine blades and vanes and ceramic liners in diesel cylinders. The most successful high temperature (up to 1300 K) thin film thermocouples are sputter deposited from platinum and platinum-10 percent rhodium targets although results using base metal alloys, gold, and platinel will also be presented. The fabrication techniques used to form the thermocouples, approaches used to solve the high temperature insulation and adherence problems, current applications, and test results using the thin film thermocouples are reviewed. In addition a discussion will be presented on the current problems and future trends related to applications of thin film thermocouples at higher temperatures up to 1900 K.

  19. US polycrystalline thin film solar cells program

    SciTech Connect

    Ullal, H.S.; Zweibel, K.; Mitchell, R.L. )

    1989-11-01

    The Polycrystalline Thin Film Solar Cells Program, part of the United States National Photovoltaic Program, performs R D on copper indium diselenide and cadmium telluride thin films. The objective of the Program is to support research to develop cells and modules that meet the US Department of Energy's long-term goals by achieving high efficiencies (15%-20%), low-cost ($50/m{sup 2}), and long-time reliability (30 years). The importance of work in this area is due to the fact that the polycrystalline thin-film CuInSe{sub 2} and CdTe solar cells and modules have made rapid advances. They have become the leading thin films for PV in terms of efficiency and stability. The US Department of Energy has increased its funding through an initiative through the Solar Energy Research Institute in CuInSe{sub 2} and CdTe with subcontracts to start in Spring 1990. 23 refs., 5 figs.

  20. New techniques for producing thin boron films

    SciTech Connect

    Thomas, G.E.

    1988-01-01

    A review will be presented of methods for producing thin boron films using an electron gun. Previous papers have had the problem of spattering of the boron source during the evaporation. Methods for reducing this problem will also be presented. 12 refs., 4 figs.

  1. Microwave-enhanced thin-film deposition

    NASA Technical Reports Server (NTRS)

    Chitre, S.

    1984-01-01

    The deposition of semiconducting and insulating thin films at low temperatures using microwave technology was explored. The method of plasma formations, selection of a power source, the design of the microwave plasma cavity, the microwave circuitry, impedance matching, plasma diagnostics, the deposition chamber and the vacuum system were studied.

  2. Semiconductor cooling by thin-film thermocouples

    NASA Technical Reports Server (NTRS)

    Tick, P. A.; Vilcans, J.

    1970-01-01

    Thin-film, metal alloy thermocouple junctions do not rectify, change circuit impedance only slightly, and require very little increase in space. Although they are less efficient cooling devices than semiconductor junctions, they may be applied to assist conventional cooling techniques for electronic devices.

  3. Refracting boundaries in thin film glass lightguides

    NASA Astrophysics Data System (ADS)

    Turner, A. F.; Browning, S. D.

    1980-02-01

    The paper describes experimental studies of refraction at a straightline boundary between evaporated glass lightguides and evaporated thin film overlays of SbO3 with index 2.10. Attention is given to sample preparation, measurement procedures, and computations. It is noted that Snell's law gives the total change of mode indices on each side of the boundary are used.

  4. US Polycrystalline Thin Film Solar Cells Program

    NASA Astrophysics Data System (ADS)

    Ullal, Harin S.; Zweibel, Kenneth; Mitchell, Richard L.

    1989-11-01

    The Polycrystalline Thin Film Solar Cells Program, part of the United States National Photovoltaic Program, performs R and D on copper indium diselenide and cadmium telluride thin films. The objective of the program is to support research to develop cells and modules that meet the U.S. Department of Energy's long-term goals by achieving high efficiencies (15 to 20 percent), low-cost ($50/m(sup 2)), and long-time reliability (30 years). The importance of work in this area is due to the fact that the polycrystalline thin-film CuInSe2 and CdTe solar cells and modules have made rapid advances. They have become the leading thin films for PV in terms of efficiency and stability. The U.S. Department of Energy has increased its funding through an initiative through the Solar Energy Research Institute in CuInSe2 and CdTe with subcontracts to start in spring 1990.

  5. Thin film hydrous metal oxide catalysts

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.

    1995-01-01

    Thin film (<100 nm) hydrous metal oxide catalysts are prepared by 1) synthesis of a hydrous metal oxide, 2) deposition of the hydrous metal oxide upon an inert support surface, 3) ion exchange with catalytically active metals, and 4) activating the hydrous metal oxide catalysts.

  6. Flexoelectricity in barium strontium titanate thin film

    SciTech Connect

    Kwon, Seol Ryung; Huang, Wenbin; Yuan, Fuh-Gwo; Jiang, Xiaoning; Shu, Longlong; Maria, Jon-Paul

    2014-10-06

    Flexoelectricity, the linear coupling between the strain gradient and the induced electric polarization, has been intensively studied as an alternative to piezoelectricity. Especially, it is of interest to develop flexoelectric devices on micro/nano scales due to the inherent scaling effect of flexoelectric effect. Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} thin film with a thickness of 130 nm was fabricated on a silicon wafer using a RF magnetron sputtering process. The flexoelectric coefficients of the prepared thin films were determined experimentally. It was revealed that the thin films possessed a transverse flexoelectric coefficient of 24.5 μC/m at Curie temperature (∼28 °C) and 17.44 μC/m at 41 °C. The measured flexoelectric coefficients are comparable to that of bulk BST ceramics, which are reported to be 10–100 μC/m. This result suggests that the flexoelectric thin film structures can be effectively used for micro/nano-sensing devices.

  7. UV absorption control of thin film growth

    DOEpatents

    Biefeld, Robert M.; Hebner, Gregory A.; Killeen, Kevin P.; Zuhoski, Steven P.

    1991-01-01

    A system for monitoring and controlling the rate of growth of thin films in an atmosphere of reactant gases measures the UV absorbance of the atmosphere and calculates the partial pressure of the gases. The flow of reactant gases is controlled in response to the partial pressure.

  8. Thin-Film Solid Oxide Fuel Cells

    NASA Technical Reports Server (NTRS)

    Chen, Xin; Wu, Nai-Juan; Ignatiev, Alex

    2009-01-01

    The development of thin-film solid oxide fuel cells (TFSOFCs) and a method of fabricating them have progressed to the prototype stage. This can result in the reduction of mass, volume, and the cost of materials for a given power level.

  9. Rechargeable Thin-film Lithium Batteries

    DOE R&D Accomplishments Database

    Bates, J. B.; Gruzalski, G. R.; Dudney, N. J.; Luck, C. F.; Yu, Xiaohua

    1993-08-01

    Rechargeable thin film batteries consisting of lithium metal anodes, an amorphous inorganic electrolyte, and cathodes of lithium intercalation compounds have recently been developed. The batteries, which are typically less than 6 {mu}m thick, can be fabricated to any specified size, large or small, onto a variety of substrates including ceramics, semiconductors, and plastics. The cells that have been investigated include Li TiS{sub 2}, Li V{sub 2}O{sub 5}, and Li Li{sub x}Mn{sub 2}O{sub 4}, with open circuit voltages at full charge of about 2.5, 3.6, and 4.2, respectively. The development of these batteries would not have been possible without the discovery of a new thin film lithium electrolyte, lithium phosphorus oxynitride, that is stable in contact with metallic lithium at these potentials. Deposited by rf magnetron sputtering of Li{sub 3}PO{sub 4} in N{sub 2}, this material has a typical composition of Li{sub 2.9}PO{sub 3.3}N{sub 0.46} and a conductivity at 25{degrees}C of 2 {mu}S/cm. The maximum practical current density obtained from the thin film cells is limited to about 100 {mu}A/cm{sup 2} due to a low diffusivity of Li{sup +} ions in the cathodes. In this work, the authors present a short review of their work on rechargeable thin film lithium batteries.

  10. Layered TiO2 :PVK nano-composite thin films for photovoltaic applications. TiO2 :PVK nano-composite thin films

    NASA Astrophysics Data System (ADS)

    Kaune, G.; Wang, W.; Metwalli, E.; Ruderer, M.; Roßner, R.; Roth, S. V.; Müller-Buschbaum, P.

    2008-05-01

    The influence of the solvent used for spin-coating on the homogeneity of poly(N-vinylcarbazole) (PVK) films is investigated. Homogenous films are obtained only by the use of toluene, solution in tetrahydrofuran (THF) and chloroform results in radially oriented inhomogeneities and films prepared by use of N-methylpyrrolidone and dimethylacetamide show particle formation during spin-coating. Layered nano-composite thin films are prepared by spin-coating a PVK film on top of a nano-structured titanium dioxide ( TiO2 layer. The TiO2 thin films are prepared by a sol-gel process using an amphiphilic copolymer as structure-directing agent. Structural characterisation of the TiO2 :PVK nano-composite films is done by field emission scanning electron microscopy (FESEM) and grazing-incidence small-angle scattering (GISAXS). Bare TiO2 films are probed for comparison. Light is basically only absorbed in the ultraviolet regime and absorption slightly increases upon addition of PVK, which makes the layered TiO2 :PVK nano-composite thin films good candidates for UV photovoltaic devices. Furthermore, absorption remains stable over a period of several days.

  11. Growth induced magnetic anisotropy in crystalline and amorphous thin films

    SciTech Connect

    Hellman, F.

    1998-07-20

    The work in the past 6 months has involved three areas of magnetic thin films: (1) amorphous rare earth-transition metal alloys, (2) epitaxial Co-Pt and Ni-Pt alloy thin films, and (3) collaborative work on heat capacity measurements of magnetic thin films, including nanoparticles and CMR materials. A brief summary of work done in each area is given.

  12. Influence of molecular structure and microstructure on device performance of polycrystalline pentacene thin-film transistors

    NASA Astrophysics Data System (ADS)

    Cheng, Horng-Long; Mai, Yu-Shen; Chou, Wei-Yang; Chang, Li-Ren

    2007-04-01

    The authors have fabricated the pentacene thin films on polymethylmethacrylate (PMMA) and on silicon dioxide dielectric surfaces featuring similar surface energy and surface roughness. On both surfaces the pentacene films displayed high crystal quality from x-ray diffraction scans, although the film on PMMA had significantly smaller grain size. The pentacene transistors with PMMA exhibited excellent electrical characteristics, including high mobility of above 1.1cm2/Vs, on/off ratio above 106, and sharp subthreshold slope below 1V/decade. The analysis of molecular microstructure of the pentacene films provided a reasonable explanation for the high performance using resonance micro-Raman spectroscopy.

  13. Electrochromic TiO2 Thin Film Prepared by Dip-Coating Technique

    NASA Astrophysics Data System (ADS)

    Suriani, S.; Kamisah, M. M.

    2002-12-01

    Titanium dioxide (TiO2) thin films were prepared by using sol-gel dip coating technique. The coating solutions were prepared by reacting titanium isopropoxide as precursors and ethanol as solvent. The films were formed on transparent ITO-coated glass by a dip coating technique and final dried at various temperatures up to 600 °C for 30 minutes. The films were characterized with the UV-Vis-NIR Spectrometer, Scanning Electron Microscopy (SEM) and X-ray diffractometer (XRD). XRD results show that the films dried at 600 °C form anatase structure. From the spectroscopic studies, the sample shows electrochromic property.

  14. Deuterium storage in nanocrystalline magnesium thin films

    NASA Astrophysics Data System (ADS)

    Checchetto, R.; Bazzanella, N.; Miotello, A.; Brusa, R. S.; Zecca, A.; Mengucci, A.

    2004-02-01

    Nanocrystalline magnesium deuteride thin films with the β-MgD2 structure were prepared by vacuum evaporation of hexagonal magnesium (h-Mg) samples and thermal annealing in 0.15 MPa D2 atmosphere at 373 K. Thermal desorption spectroscopy analysis indicated that the rate-limiting step in the deuterium desorption was given by the thermal decomposition of the deuteride phase. The activation energy Δg of the β-MgD2→h-Mg+D2 reaction scaled from 1.13±0.03 eV in 650-nm-thick films to 1.01±0.02 eV in 75-nm-thick films most likely as consequence of different stress and defect level. Positron annihilation spectroscopy analysis of the thin-film samples submitted to deuterium absorption and desorption cycles reveal the presence of a high concentration of void-like defects in the h-Mg layers after the very first decomposition of the β-MgD2 phase, the presence of these open volume defects reduces the D2 absorption capacity of the h-Mg thin film.

  15. Surface photovoltage spectroscopy of thin films

    NASA Astrophysics Data System (ADS)

    Leibovitch, M.; Kronik, L.; Fefer, E.; Burstein, L.; Korobov, V.; Shapira, Yoram

    1996-06-01

    The surface photovoltage (SPV) spectrum due to subband-gap illumination of thin films is theoretically studied. It is shown that this SPV is inherently sensitive to buried interfaces just as it is sensitive to the external semiconductor surface. The different contributions to the SPV from all the optically active gap states present within a sample, consisting of a bulk substrate covered by a thin film, are analyzed. Analytical expressions are obtained in the low illumination intensity and the depletion approximation regime. The evolution of the SPV spectrum with film thickness is examined and is found to depend on both site and population of the gap states. Three modes of evolution are found, according to the relative importance of gap state population changes with film thickness. These modes are confirmed by a numerical simulation of a thin film of pseudomorphic InAlAs on InP substrates and by experiments conducted on the same system. The approach is also applied to the InP/In2O3 system, revealing gap state formation, followed by filling with electrons, thereby explaining previous observations of nearly ideal I-V behavior at this junction.

  16. MISSE 5 Thin Films Space Exposure Experiment

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.; Kinard, William H.; Jones, James L.

    2007-01-01

    The Materials International Space Station Experiment (MISSE) is a set of space exposure experiments using the International Space Station (ISS) as the flight platform. MISSE 5 is a co-operative endeavor by NASA-LaRC, United Stated Naval Academy, Naval Center for Space Technology (NCST), NASA-GRC, NASA-MSFC, Boeing, AZ Technology, MURE, and Team Cooperative. The primary experiment is performance measurement and monitoring of high performance solar cells for U.S. Navy research and development. A secondary experiment is the telemetry of this data to ground stations. A third experiment is the measurement of low-Earth-orbit (LEO) low-Sun-exposure space effects on thin film materials. Thin films can provide extremely efficacious thermal control, designation, and propulsion functions in space to name a few applications. Solar ultraviolet radiation and atomic oxygen are major degradation mechanisms in LEO. This paper is an engineering report of the MISSE 5 thm films 13 months space exposure experiment.

  17. Hematite thin films: growth and characterization

    NASA Astrophysics Data System (ADS)

    Uribe, J. D.; Osorio, J.; Barrero, C. A.; Giratá, D.; Morales, A. L.; Devia, A.; Gómez, M. E.; Ramirez, J. G.; Gancedo, J. R.

    2006-04-01

    We have grown hematite (α Fe 2 O 3) thin films on stainless steel and (001)-silicon single-crystal substrates by RF magnetron sputtering process in argon atmosphere at substrate temperatures from 400 to 800°C. Conversion Electron Mössbauer (CEM) spectra of the sample grown on stainless steel at 400°C exhibit values for hyperfine parameter characteristic of bulk hematite phase in the weak ferromagnetic state. Also, the relative line intensity ratio suggests that the magnetization vector of the polycrystalline film is aligned preferentially parallel to the surface. The X-ray diffraction (XRD) pattern of the polycrystalline thin film grown on steel substrates also corresponds to α Fe 2 O 3. The samples were also analyzed by Atomic Force Microscopy (AFM), those grown on stainless steel reveal a morphology consisting of columnar grains with random orientation, given the inhomogeneity of the substrate surface.

  18. Hematite thin films: growth and characterization

    NASA Astrophysics Data System (ADS)

    Uribe, J. D.; Osorio, J.; Barrero, C. A.; Giratá, D.; Morales, A. L.; Devia, A.; Gómez, M. E.; Ramirez, J. G.; Gancedo, J. R.

    We have grown hematite (α - Fe 2 O 3) thin films on stainless steel and (001)-silicon single-crystal substrates by RF magnetron sputtering process in argon atmosphere at substrate temperatures from 400 to 800°C. Conversion Electron Mössbauer (CEM) spectra of the sample grown on stainless steel at 400°C exhibit values for hyperfine parameter characteristic of bulk hematite phase in the weak ferromagnetic state. Also, the relative line intensity ratio suggests that the magnetization vector of the polycrystalline film is aligned preferentially parallel to the surface. The X-ray diffraction (XRD) pattern of the polycrystalline thin film grown on steel substrates also corresponds to α - Fe 2O3. The samples were also analyzed by Atomic Force Microscopy (AFM), those grown on stainless steel reveal a morphology consisting of columnar grains with random orientation, given the inhomogeneity of the substrate surface.

  19. Nonreciprocal switching of VO2 thin films on microstructured surfaces

    NASA Astrophysics Data System (ADS)

    Adams, Charles; Karakurt, Ismail; Leiderer, Paul; Boneberg, Johannes; Haglund, Richard

    2010-10-01

    Vanadium dioxide is a strongly correlated electron material that undergoes an insulator-to-metal transition at approximately 340 K, with a corresponding large change in its optical and electronic properties. By depositing a VO2 thin film on a planar hexagonal close-packed array of 1.54 μm diameter silica microspheres, we constructed a laser-triggered thin film optical switch that exhibits different fluence thresholds for the insulator-metal transition (IMT) depending on the direction of illumination. The IMT was triggered by a ns Nd:YAG laser (532 nm) from two directions normal to the substrate while monitoring the transmission with a near-IR diode laser. Due to the focusing effects of the microspheres, the fluence required for switching the VO2 was 2.4 times higher when the switching laser was incident from the film (top) side of the array than from the microsphere (bottom) side. Through both the experiments and simulations, we find evidence for strong nonlinear near-field absorption in the VO2.

  20. A magnetron sputtering system for the preparation of patterned thin films and in situ thin film electrical resistance measurements

    SciTech Connect

    Arnalds, U. B.; Agustsson, J. S.; Ingason, A. S.; Eriksson, A. K.; Gylfason, K. B.; Gudmundsson, J. T.; Olafsson, S.

    2007-10-15

    We describe a versatile three gun magnetron sputtering system with a custom made sample holder for in situ electrical resistance measurements, both during film growth and ambient changes on film electrical properties. The sample holder allows for the preparation of patterned thin film structures, using up to five different shadow masks without breaking vacuum. We show how the system is used to monitor the electrical resistance of thin metallic films during growth and to study the thermodynamics of hydrogen uptake in metallic thin films. Furthermore, we demonstrate the growth of thin film capacitors, where patterned films are created using shadow masks.

  1. A magnetron sputtering system for the preparation of patterned thin films and in situ thin film electrical resistance measurements.

    PubMed

    Arnalds, U B; Agustsson, J S; Ingason, A S; Eriksson, A K; Gylfason, K B; Gudmundsson, J T; Olafsson, S

    2007-10-01

    We describe a versatile three gun magnetron sputtering system with a custom made sample holder for in situ electrical resistance measurements, both during film growth and ambient changes on film electrical properties. The sample holder allows for the preparation of patterned thin film structures, using up to five different shadow masks without breaking vacuum. We show how the system is used to monitor the electrical resistance of thin metallic films during growth and to study the thermodynamics of hydrogen uptake in metallic thin films. Furthermore, we demonstrate the growth of thin film capacitors, where patterned films are created using shadow masks. PMID:17979429

  2. Thin blend films of cellulose and polyacrylonitrile

    NASA Astrophysics Data System (ADS)

    Lu, Rui; Zhang, Xin; Mao, Yimin; Briber, Robert; Wang, Howard

    Cellulose is the most abundant renewable, biocompatible and biodegradable natural polymer. Cellulose exhibits excellent chemical and mechanical stability, which makes it useful for applications such as construction, filtration, bio-scaffolding and packaging. To further expand the potential applications of cellulose materials, their alloying with synthetic polymers has been investigated. In this study, thin films of cotton linter cellulose (CLC) and polyacrylonitrile (PAN) blends with various compositions spanning the entire range from neat CLC to neat PAN were spun cast on silicon wafers from common solutions in dimethyl sulfoxide / ionic liquid mixtures. The morphologies of thin films were characterized using optical microscopy, atomic force microscopy, scanning electron microscopy and X-ray reflectivity. Morphologies of as-cast films are highly sensitive to the film preparation conditions; they vary from featureless smooth films to self-organized ordered nano-patterns to hierarchical structures spanning over multiple length scales from nanometers to tens of microns. By selectively removing the PAN-rich phase, the structures of blend films were studied to gain insights in their very high stability in hot water, acid and salt solutions.

  3. Electrochromism in oxyfluoride thin films

    SciTech Connect

    Azens, A.; Gutarra, A.; Stjerna, B.; Granqvist, C.G.; Gabrusenoks, J.; Lusis, A.

    1994-12-31

    Oxyfluoride films based on W and Ti were prepared by reactive sputtering in plasmas containing O{sub 2} + CF{sub 4}. The deposition rate was large, particularly when chemical sputtering was promoted by heating the target. The films could show large charge insertion/extraction, high coloration efficiency, and good cycling durability. Electrochromic devices have several potential and practical applications in contemporary technology. Among the foremost of these one notes smart windows with variable throughput of radiant energy, anti-dazzling rear-view mirrors for cars and trucks, elements for non-emissive information display, and surfaces for variable thermal emittance. Smart windows technology, that is presently emerging, may have a pervasive and benign influence on building design and management.

  4. Borides in Thin Film Technology

    NASA Astrophysics Data System (ADS)

    Mitterer, Christian

    1997-10-01

    The borides of transition and rare-earth metals are considered for application as wear- and corrosion-resistant, decorative or thermionic coatings. After a review of physical vapor deposition (PVD) techniques used for the deposition of these coatings, a survey of investigations to apply these coatings is given. As a result of the strong directionality of covalent boron-boron bonds, boride coatings show an increasing tendency to amorphous film growth with increasing B/Meatomic ratio and, for rare-earth hexaborides, with decreasing metallic radius of the rare-earth metal. Mechanical and optical properties are strongly influenced by the crystallographic structure of the boride phase. Because of their high hardness combined with good adhesion, crystalline films based on the diborides of transition metals seem to be promising candidates for wear resistant coatings on cutting tools. Alloying of these films with nitrogen by reactive PVD processes results in the formation of extremely fine-grained multiphase hard coatings with excellent tribological and corrosion behavior, thus offering new applications in the coating of engineering components. Because of their distinct colorations, some of the hexaborides of rare-earth elements may be used as decorative coatings on consumer products like wristwatch casings or eyeglass frames. Another promising field is the development of thermionic coatings based on rare-earth hexaborides, which may offer the possibility of the production of inexpensive and simple high emission filaments.

  5. Optical characterization of polysilazane based silica thin films on silicon substrates

    NASA Astrophysics Data System (ADS)

    Ricci, Pier Carlo; Gulleri, Gianluca; Fumagalli, Francesco; Carbonaro, Carlo Maria; Corpino, Riccardo

    2013-01-01

    In this work polysilazane based silica thin films grown on multilayer structures of different ultra-thin barriers (UTBs) on silicon substrates were studied. The silica thin films were obtained by polysilazane spin coating deposition (also called SOD, spin-on dielectrics) upon different UTB liners (silicon nitride or silicon dioxide). By curing the SOD with thermal treatments the polysilazane is converted into silica thin films. The degree of conversion to SiO2 was analyzed and the oxide local structure was studied in terms of Sisbnd Osbnd Si bridges by FTIR spectroscopy. Steady state and time resolved luminescence were applied to further characterize the oxide structure, the substrate-silica interfaces and the presence of defects. The analysis revealed the presence of dioxasilirane, dbnd Si(O2), and silylene, dbnd Si:, defect centers in the samples grown on silicon nitride UTB, while these defects are not observed in samples grown on silicon oxide UTB.

  6. Thin film bismuth iron oxides useful for piezoelectric devices

    DOEpatents

    Zeches, Robert J.; Martin, Lane W.; Ramesh, Ramamoorthy

    2016-05-31

    The present invention provides for a composition comprising a thin film of BiFeO.sub.3 having a thickness ranging from 20 nm to 300 nm, a first electrode in contact with the BiFeO.sub.3 thin film, and a second electrode in contact with the BiFeO.sub.3 thin film; wherein the first and second electrodes are in electrical communication. The composition is free or essentially free of lead (Pb). The BFO thin film is has the piezoelectric property of changing its volume and/or shape when an electric field is applied to the BFO thin film.

  7. Giant nonlinear response of terahertz nanoresonators on VO2 thin film.

    PubMed

    Kyoung, Jisoo; Seo, Minah; Park, Hyeongryeol; Koo, Sukmo; Kim, Hyun-sun; Park, Youngmi; Kim, Bong-Jun; Ahn, Kwangjun; Park, Namkyoo; Kim, Hyun-Tak; Kim, Dai-Sik

    2010-08-01

    We report on an order of magnitude enhanced nonlinear response of vanadium dioxide thin film patterned with nanoresonators--nano slot antennas fabricated on the gold film. Transmission of terahertz radiation, little affected by an optical pumping for the case of bulk thin film, can now be completely switched-off: DeltaT/T approximately -0.9999 by the same optical pumping power. This unprecedentedly large optical pump-terahertz probe nonlinearity originates from the insulator-to-metal phase transition drastically reducing the antenna cross sections of the nanoresonators. Our scheme enables nanoscale-thin film technology to be used for all-optical switching of long wavelength light. PMID:20721032

  8. Polycrystalline thin film materials and devices

    SciTech Connect

    Baron, B.N.; Birkmire, R.W.; Phillips, J.E.; Shafarman, W.N.; Hegedus, S.S.; McCandless, B.E. . Inst. of Energy Conversion)

    1992-10-01

    Results of Phase II of a research program on polycrystalline thin film heterojunction solar cells are presented. Relations between processing, materials properties and device performance were studied. The analysis of these solar cells explains how minority carrier recombination at the interface and at grain boundaries can be reduced by doping of windows and absorber layers, such as in high efficiency CdTe and CuInSe{sub 2} based solar cells. The additional geometric dimension introduced by the polycrystallinity must be taken into consideration. The solar cells are limited by the diode current, caused by recombination in the space charge region. J-V characteristics of CuInSe{sub 2}/(CdZn)S cells were analyzed. Current-voltage and spectral response measurements were also made on high efficiency CdTe/CdS thin film solar cells prepared by vacuum evaporation. Cu-In bilayers were reacted with Se and H{sub 2}Se gas to form CuInSe{sub 2} films; the reaction pathways and the precursor were studied. Several approaches to fabrication of these thin film solar cells in a superstrate configuration were explored. A self-consistent picture of the effects of processing on the evolution of CdTe cells was developed.

  9. Thin-film cadmium telluride solar cells

    NASA Astrophysics Data System (ADS)

    Chu, T. L.

    1987-10-01

    Cadmium telluride, with a room-temperature band-gap energy of 1.5 eV, is a promising thin-film photovoltaic material. The major objective of this research has been to demonstrate thin-film CdTe heterojunction solar cells with a total area greater than 1 sq cm and photovoltaic efficiencies of 13 percent or more. Thin-film p-CdTe/CdS/SnO2:F/glass solar cells with an AM1.5 efficiency of 10.5 percent have been reported previously. This report contains results of work done on: (1) the deposition, resistivity control, and characterization of p-CdTe films by the close-spaced sublimation process; (2) the deposition of large-band-gap window materials; (3) the electrical properties of CdS/CdTe heterojunctions; (4) the formation of stable, reproducible, ohmic contacts (such as p-HgTe) to p-CdTe; and (5) the preparation and evaluation of heterojunction solar cells.

  10. Thin-film cadmium telluride solar cells

    NASA Astrophysics Data System (ADS)

    1986-09-01

    This is the final technical progress report of a research program entitled Thin-Film Cadmium Telluride Solar Cells. The major objective was to demonstrate chemical vapor deposition (CVD)-grown CdTe devices with a photovoltaic efficiency of at least 10%. The work included: (1) CVD and characterization of p-CdTe films of controlled resistivity; (2) deposition and characterization of heterojunction partners; (3) surface passivation of CdTe; and (4) preparation and characterization of thin-film solar cells. The CVD of p-CdTe was optimized with emphasis on resistivity control through nonstoichiometry and extrinsic doping. Both carbon and oxygen were identified as acceptors. The use of thermal oxidation for surface passivation of CdTe was investigated using capacitance-voltage measurement. Device-quality thermal oxide can be prepared by hydrogen annealing of CdTe before oxidation. Deposition and characterization of CdS, CdO, and ZnO:In were also carried out. The best thin-film cell to date had a conversion efficiency near 9%.

  11. Deformation behavior of metallic glass thin films

    NASA Astrophysics Data System (ADS)

    Liu, Y. H.; Zhao, F.; Li, Y. L.; Chen, M. W.

    2012-09-01

    We report room-temperature deformation behavior of damage-free metallic glass films characterized by nanoindentation and atomic force microscopy. The glass films with thicknesses ranging from 5 μm down to ˜60 nm plastically deform by shear bands when subjected to both spherical and sharp Berkovich indenters. Importantly, we found that gallium contamination from focus ion beam (FIB) milling significantly suppresses shear band formation, indicating that the absence of shear bands in FIB milled samples may be caused by gallium irradiation damage, rather than sample size effect. Finite element simulation reveals that a high stress gradient at the film/substrate interface promotes the plastic deformation of the thin films but does not give rise to significant strain inhomogeneity.

  12. Study on a terahertz modulator based on metamaterial with photoinduced vanadium dioxide film

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Jiang, Ping; Xu, Xian-feng

    2016-06-01

    Applying the photoexcitation characteristics of vanadium dioxide (VO2), a dynamic resonant terahertz (THz) modulation with the combination of a VO2 film and a metamaterial was suggested to realize THz wave active manipulation. The designed metamaterial with structured copper rings arrays can realize a passband from 0.776 to 1.045 THz. When insulator-metal phase transition in VO2 thin film, which is deposited on the other surface of the metamaterial substrate, is induced by optical pumping, the metamaterial/VO2 film hybrid structure behaves as an absorber with absorption rates of 90% at 0.88 THz and the transmission energy decrease to less than 3%. Therefore, about 78% modulation depth and more than 250 GHz modulation bandwidth have been reached under the photoinducing. The simulation results illustrate the promise of using phase transition materials for efficient broadband fast response modulators for THz waves.

  13. Dynamics of polymer thin films and surfaces

    NASA Astrophysics Data System (ADS)

    Fakhraai, Zahra

    2007-12-01

    The dynamics of thin polymer films display many differences from the bulk dynamics. Different modes of motions in polymers are affected by confinement in different ways. The enhancement in the dynamics of some modes of motion can cause anomalies in the glass transition temperature (Tg) of thin films, while other modes of motion such as diffusion can be substantially slowed down due to the confinement effects. In this thesis, different modes of dynamics are probed using different techniques. The interface healing of two identical polymer surfaces is used as a probe of segmental motion in the direction normal to the plane of the films and it is shown that this mode of motion is slowed down at temperatures above bulk glass transition, while the glass transition itself is decreased indicating that the type of motion responsible for the glass transition is enhanced. The glass transition measurements at different cooling rates indicate that this enhancement only happens at temperatures close to or below bulk glass transition temperature and it is not expected to be detected at higher temperatures where the system is in the melt state. It is shown that the sample preparation technique is not a factor in observing this enhanced dynamics, while the existence of the free surface can be important in observed reductions in the glass transition temperature. The dynamics near the free surface is further studied using a novel nano-deformation technique, and it is shown that the dynamics near the free surface is in fact enhanced compared to the bulk dynamics and this enhancement is increased as the temperature is decreased further below Tg. It is also shown that this mode of relaxation is much different from the bulk modes of relaxations, and a direct relationship between this enhanced motion and Tg reduction in thin films can be established. The results presented in this thesis can lead to a possible universal picture that can resolve the behavior of different modes of motions in

  14. Thin Film...Large Payoff

    NASA Technical Reports Server (NTRS)

    1998-01-01

    SRS Technologies is currently the only company licensed by Langley Research Center to produce colorless polyimides. They currently produce two polyimides, the LaRC-CP1 and LaRC-CP2 developed by Langley Research Center. These polyimides offer many advantages over other commercially available materials including excellent thermal stability, radiation resistance, solubility, and transparency. The SRS polyimides can be used in laminates, films, molded parts, and stock shapes. The polyimide technology has also helped the company further their development of solar arrays.

  15. Effect of the nanocrystalline structure type on the optical properties of TiO2:Nd (1 at.%) thin films

    NASA Astrophysics Data System (ADS)

    Mazur, Michal; Wojcieszak, Damian; Kaczmarek, Danuta; Domaradzki, Jaroslaw; Zatryb, Grzegorz; Misiewicz, Jan; Morgiel, Jerzy

    2015-04-01

    Titanium dioxide thin films, each doped with the same amount of neodymium (1 at.%) were deposited by Low Pressure Hot Target Reactive Sputtering and High Energy Reactive Magnetron Sputtering processes in order to obtain anatase and rutile thin film structures respectively. The microstructure and phase composition were analyzed using the transmission electron microscopy method including high resolution electron microscopy imaging. The measurements of the optical properties showed, that both prepared thin films were transparent in the visible light range and had a low extinction coefficient of ca. 3 ṡ 10-3. The thin film with the anatase structure had a lower cut-off wavelength and refractive index and a higher value of optical energy band gap as-compared to the TiO2:Nd coating with the rutile structure. Simultaneously, more efficient photoluminescence emission was observed for the rutile thin films.

  16. Temperature dependence of LRE-HRE-TM thin films

    NASA Astrophysics Data System (ADS)

    Li, Zuoyi; Cheng, Xiaomin; Lin, Gengqi; Li, Zhen; Huang, Zhixin; Jin, Fang; Wang, Xianran; Yang, Xiaofei

    2003-04-01

    Temperature dependence of the properties of RE-TM thin films is very important for MO recording. In this paper, we studied the temperature dependence of the magnetic and magneto-optical properties of the amorphous LRE-HRE-TM single layer thin films and LRE-HRE-TM/HRE-TM couple-bilayered thin films. For LRE-HRE-TM single layer thin films, the temperature dependence of the magnetization was investigated by using the mean field theory. The experimental and theoretical results matched very well. With the LRE substitution in HRE-TM thin film, the compensation temperature Tcomp decreased and the curie temperature Tc remained unchanged. Kerr rotation angle became larger and the saturation magnetization Ms at room temperature increased. For LRE-HRE-TM/HRE-TM couple-bilayered thin films, comparisons of the temperature dependences of the coercivities and Kerr rotation angles were made between isolated sublayers and couple-bilayered thin film.

  17. Growth of solid and hollow gold particles through the thermal annealing of nanoscale patterned thin films

    SciTech Connect

    Lin, Junhao; He, Weidong; Vilayur Ganapathy, Subramanian; Peppernick, Samuel J.; Wang, Bin; Palepu, Sandeep; Remec, Miroslav; Hess, Wayne P.; Hmelo, Anthony B.; Pantelides, Sokrates T.; Dickerson, James

    2013-11-27

    Through thermally annealing well-arrayed, circular, nanoscale thin films of gold, deposited onto [111] silicon/silicon dioxide substrates, both solid and hollow gold particles of different morphologies with controllable sizes were obtained. The thin film could form individual particle or clusters of particles by tuning the diameter of it. Hollow gold particles were featured by their large size whose diameter was larger than 500 nm and confirmed by a cross-section view. Hollow gold particles show greater plasmonic field enhancement under photoemission electron microscopy. Potential growth mechanisms for these structures are explored

  18. Thermal conductivities of thin, sputtered optical films

    SciTech Connect

    Henager, C.H. Jr.; Pawlewicz, W.T.

    1991-05-01

    The normal component of the thin film thermal conductivity has been measured for the first time for several advanced sputtered optical materials. Included are data for single layers of boron nitride (BN), aluminum nitride (AIN), silicon aluminum nitride (Si-Al-N), silicon aluminum oxynitride (Si-Al-O-N), silicon carbide (SiC), and for dielectric-enhanced metal reflectors of the form Al(SiO{sub 2}/Si{sub 3}N{sub 4}){sup n} and Al(Al{sub 2}O{sub 3}/AIN){sup n}. Sputtered films of more conventional materials like SiO{sub 2}, Al{sub 2}O{sub 3}, Ta{sub 2}O{sub 5}, Ti, and Si have also been measured. The data show that thin film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or very fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film/substrate interface contribution is presented.

  19. Electrohydrodynamic instabilities in thin liquid trilayer films

    SciTech Connect

    Roberts, Scott A.; Kumar, Satish

    2010-12-09

    Experiments by Dickey and Leach show that novel pillar shapes can be generated from electrohydrodynamic instabilities at the interfaces of thin polymer/polymer/air trilayer films. In this paper, we use linear stability analysis to investigate the effect of free charge and ac electric fields on the stability of trilayer systems. Our work is also motivated by our recent theoretical study which demonstrates how ac electric fields can be used to increase control over the pillar formation process in thin liquid bilayer films. For perfect dielectric films, the effect of an AC electric field can be understood by considering an equivalent DC field. Leaky dielectric films yield pillar configurations that are drastically different from perfect dielectric films, and AC fields can be used to control the location of free charge within the trilayer system. This can alter the pillar instability modes and generate smaller diameter pillars when conductivities are mismatched. The results presented may be of interest for the creation of complex topographical patterns on polymer coatings and in microelectronics.

  20. Electrohydrodynamic instabilities in thin liquid trilayer films

    DOE PAGESBeta

    Roberts, Scott A.; Kumar, Satish

    2010-12-09

    Experiments by Dickey and Leach show that novel pillar shapes can be generated from electrohydrodynamic instabilities at the interfaces of thin polymer/polymer/air trilayer films. In this paper, we use linear stability analysis to investigate the effect of free charge and ac electric fields on the stability of trilayer systems. Our work is also motivated by our recent theoretical study which demonstrates how ac electric fields can be used to increase control over the pillar formation process in thin liquid bilayer films. For perfect dielectric films, the effect of an AC electric field can be understood by considering an equivalent DCmore » field. Leaky dielectric films yield pillar configurations that are drastically different from perfect dielectric films, and AC fields can be used to control the location of free charge within the trilayer system. This can alter the pillar instability modes and generate smaller diameter pillars when conductivities are mismatched. The results presented may be of interest for the creation of complex topographical patterns on polymer coatings and in microelectronics.« less

  1. Nonlinear viscoelastic characterization of thin polyethylene film

    NASA Technical Reports Server (NTRS)

    Wilbeck, J. S.

    1981-01-01

    In order to understand the state of stress and strain in a typical balloon fabricated from thin polyethylene film, experiment data in the literature reviewed. It was determined that the film behaves as a nonlinear viscoelasticity material and should be characterized accordingly. A simple uniaxial, nonlinear viscoelastic model was developed for predicting stress given a certain strain history. The simple model showed good qualitative agreement with results of constant rate, uniaxial accurately predicting stresses for cyclic strain histories typical of balloon flights. A program was outlined which will result in the development of a more complex nonlinear viscoelastic model.

  2. Electrochromism in copper oxide thin films

    SciTech Connect

    Richardson, T.J.; Slack, J.L.; Rubin, M.D.

    2000-08-15

    Transparent thin films of copper(I) oxide prepared on conductive SnO2:F glass substrates by anodic oxidation of sputtered copper films or by direct electrodeposition of Cu2O transformed reversibly to opaque metallic copper films when reduced in alkaline electrolyte. In addition, the same Cu2O films transform reversibly to black copper(II) oxide when cycled at more anodic potentials. Copper oxide-to-copper switching covered a large dynamic range, from 85% and 10% photopic transmittance, with a coloration efficiency of about 32 cm2/C. Gradual deterioration of the switching range occurred over 20 to 100 cycles. This is tentatively ascribed to coarsening of the film and contact degradation caused by the 65% volume change on conversion of Cu to Cu2O. Switching between the two copper oxides (which have similar volumes) was more stable and more efficient (CE = 60 cm2/C), but covered a smaller transmittance range (60% to 44% T). Due to their large electrochemical storage capacity and tolerance for alkaline electrolytes, these cathodically coloring films may be useful as counter electrodes for anodically coloring electrode films such as nickel oxide or metal hydrides.

  3. Thin film cadmium telluride solar cells

    NASA Astrophysics Data System (ADS)

    Chu, T. L.; Chu, Shirley S.; Ang, S. T.; Mantravadi, M. K.

    1987-08-01

    Thin-film p-CdTe/CdS/SnO2:F/glass solar cells of the inverted configuration were prepared by the deposition of p-type CdTe films onto CdS/SnO2:F/glass substrates using CVD or close-spaced sublimation (CSS) techniques based on the procedures of Chu et al. (1983) and Nicholl (1963), respectively. The deposition rates of p-CdTe films deposited by CSS were higher than those deposited by the CVD technique (4-5 min were sufficient), and the efficiencies higher than 10 percent were obtained. However, the resistivity of films prepared by CSS was not as readily controlled as that of the CVD films. The simplest technique to reduce the resistivity of the CSS p-CdTe films was to incorporate a dopant, such as As or Sb, into the reaction mixture during the preparation of the source material. The films with resistivities in the range of 500-1000 ohm cm were deposited in this manner.

  4. Nitrogen doped zinc oxide thin film

    SciTech Connect

    Li, Sonny X.

    2003-12-15

    To summarize, polycrystalline ZnO thin films were grown by reactive sputtering. Nitrogen was introduced into the films by reactive sputtering in an NO{sub 2} plasma or by N{sup +} implantation. All ZnO films grown show n-type conductivity. In unintentionally doped ZnO films, the n-type conductivities are attributed to Zn{sub i}, a native shallow donor. In NO{sub 2}-grown ZnO films, the n-type conductivity is attributed to (N{sub 2}){sub O}, a shallow double donor. In NO{sub 2}-grown ZnO films, 0.3 atomic % nitrogen was found to exist in the form of N{sub 2}O and N{sub 2}. Upon annealing, N{sub 2}O decomposes into N{sub 2} and O{sub 2}. In furnace-annealed samples N{sub 2} redistributes diffusively and forms gaseous N{sub 2} bubbles in the films. Unintentionally doped ZnO films were grown at different oxygen partial pressures. Zni was found to form even at oxygen-rich condition and led to n-type conductivity. N{sup +} implantation into unintentionally doped ZnO film deteriorates the crystallinity and optical properties and leads to higher electron concentration. The free electrons in the implanted films are attributed to the defects introduced by implantation and formation of (N{sub 2}){sub O} and Zni. Although today there is still no reliable means to produce good quality, stable p-type ZnO material, ZnO remains an attractive material with potential for high performance short wavelength optoelectronic devices. One may argue that gallium nitride was in a similar situation a decade ago. Although we did not obtain any p-type conductivity, we hope our research will provide a valuable reference to the literature.

  5. Study of microstructure and electroluminescence of zinc sulfide thin film

    NASA Astrophysics Data System (ADS)

    Zhao-hong, Liu; Yu-jiang, Wang; Mou-zhi, Chen; Zhen-xiang, Chen; Shu-nong, Sun; Mei-chun, Huang

    1998-03-01

    The electroluminscent zinc sulfide thin film doped with erbium, fabricated by thermal evaporation with two boats, are examined. The surface and internal electronic states of ZnS thin film are measured by means of x-ray diffraction and x-ray photoemission spectroscopy. The information on the relations between electroluminescent characteristics and internal electronic states of the film is obtained. And the effects of the microstructure of thin film doped with rare earth erbium on electroluminescence are discussed as well.

  6. Domain switching of fatigued ferroelectric thin films

    SciTech Connect

    Tak Lim, Yun; Yeog Son, Jong E-mail: hoponpop@ulsan.ac.kr; Shin, Young-Han E-mail: hoponpop@ulsan.ac.kr

    2014-05-12

    We investigate the domain wall speed of a ferroelectric PbZr{sub 0.48}Ti{sub 0.52}O{sub 3} (PZT) thin film using an atomic force microscope incorporated with a mercury-probe system to control the degree of electrical fatigue. The depolarization field in the PZT thin film decreases with increasing the degree of electrical fatigue. We find that the wide-range activation field previously reported in ferroelectric domains result from the change of the depolarization field caused by the electrical fatigue. Domain wall speed exhibits universal behavior to the effective electric field (defined by an applied electric field minus the depolarization field), regardless of the degree of the electrical fatigue.

  7. Techniques for Connecting Superconducting Thin Films

    NASA Technical Reports Server (NTRS)

    Mester, John; Gwo, Dz-Hung

    2006-01-01

    Several improved techniques for connecting superconducting thin films on substrates have been developed. The techniques afford some versatility for tailoring the electronic and mechanical characteristics of junctions between superconductors in experimental electronic devices. The techniques are particularly useful for making superconducting or alternatively normally conductive junctions (e.g., Josephson junctions) between patterned superconducting thin films in order to exploit electron quantum-tunneling effects. The techniques are applicable to both low-Tc and high-Tc superconductors (where Tc represents the superconducting- transition temperature of a given material), offering different advantages for each. Most low-Tc superconductors are metallic, and heretofore, connections among them have been made by spot welding. Most high-Tc superconductors are nonmetallic and cannot be spot welded. These techniques offer alternatives to spot welding of most low-Tc superconductors and additional solutions to problems of connecting most high-Tc superconductors.

  8. Polycrystalline thin films FY 1992 project report

    SciTech Connect

    Zweibel, K.

    1993-01-01

    This report summarizes the activities and results of the Polycrystalline Thin Film Project during FY 1992. The purpose of the DOE/NREL PV (photovoltaic) Program is to facilitate the development of PV that can be used on a large enough scale to produce a significant amount of energy in the US and worldwide. The PV technologies under the Polycrystalline Thin Film project are among the most exciting next-generation'' options for achieving this goal. Over the last 15 years, cell-level progress has been steady, with laboratory cell efficiencies reaching levels of 15 to 16%. This progress, combined with potentially inexpensive manufacturing methods, has attracted significant commercial interest from US and international companies. The NREL/DOE program is designed to support the efforts of US companies through cost-shared subcontracts (called government/industry partnerships'') that we manage and fund and through collaborative technology development work among industry, universities, and our laboratory.

  9. Nanoporous piezo- and ferroelectric thin films.

    PubMed

    Ferreira, Paula; Hou, Ru Z; Wu, Aiying; Willinger, Marc-Georg; Vilarinho, Paula M; Mosa, Jadra; Laberty-Robert, Christel; Boissière, Cédric; Grosso, David; Sanchez, Clément

    2012-02-01

    Nanoporous barium titanate and lead titanate thin films (∼100 nm calculated from ellipsometric data) are prepared starting from sol-gel solutions modified with a commercially available block-copolymer and evaporation-induced self-assembly methodology. The tuning of the thermal treatment followed by in situ ellipsometry allows the decomposition of the organic components and of the structuring agent leading to the formation of porous tetragonal crystalline perovskite structures as observed by XRD, HRTEM, SEM, and ellipsoporosimetry. Both nanoporous barium titanate and lead titanate thin films present local piezoelectric and ferroelectric behavior measured by piezoresponse force microscopy (PFM), being promising platforms for the preparation of the generation of new multifunctional systems. PMID:22206407

  10. Thin film strain gage development program

    NASA Technical Reports Server (NTRS)

    Grant, H. P.; Przybyszewski, J. S.; Anderson, W. L.; Claing, R. G.

    1983-01-01

    Sputtered thin-film dynamic strain gages of 2 millimeter (0.08 in) gage length and 10 micrometer (0.0004 in) thickness were fabricated on turbojet engine blades and tested in a simulated compressor environment. Four designs were developed, two for service to 600 K (600 F) and two for service to 900 K (1200 F). The program included a detailed study of guidelines for formulating strain-gage alloys to achieve superior dynamic and static gage performance. The tests included gage factor, fatigue, temperature cycling, spin to 100,000 G, and erosion. Since the installations are 30 times thinner than conventional wire strain gage installations, and any alteration of the aerodynamic, thermal, or structural performance of the blade is correspondingly reduced, dynamic strain measurement accuracy higher than that attained with conventional gages is expected. The low profile and good adherence of the thin film elements is expected to result in improved durability over conventional gage elements in engine tests.

  11. Multiferroic oxide thin films and heterostructures

    SciTech Connect

    Lu, Chengliang E-mail: Tao.Wu@kaust.edu.sa; Hu, Weijin; Wu, Tom E-mail: Tao.Wu@kaust.edu.sa; Tian, Yufeng

    2015-06-15

    Multiferroic materials promise a tantalizing perspective of novel applications in next-generation electronic, memory, and energy harvesting technologies, and at the same time they also represent a grand scientific challenge on understanding complex solid state systems with strong correlations between multiple degrees of freedom. In this review, we highlight the opportunities and obstacles in growing multiferroic thin films with chemical and structural integrity and integrating them in functional devices. Besides the magnetoelectric effect, multiferroics exhibit excellent resistant switching and photovoltaic properties, and there are plenty opportunities for them to integrate with other ferromagnetic and superconducting materials. The challenges include, but not limited, defect-related leakage in thin films, weak magnetism, and poor control on interface coupling. Although our focuses are Bi-based perovskites and rare earth manganites, the insights are also applicable to other multiferroic materials. We will also review some examples of multiferroic applications in spintronics, memory, and photovoltaic devices.

  12. Polycrystalline thin films FY 1992 project report

    SciTech Connect

    Zweibel, K.

    1993-01-01

    This report summarizes the activities and results of the Polycrystalline Thin Film Project during FY 1992. The purpose of the DOE/NREL PV (photovoltaic) Program is to facilitate the development of PV that can be used on a large enough scale to produce a significant amount of energy in the US and worldwide. The PV technologies under the Polycrystalline Thin Film project are among the most exciting ``next-generation`` options for achieving this goal. Over the last 15 years, cell-level progress has been steady, with laboratory cell efficiencies reaching levels of 15 to 16%. This progress, combined with potentially inexpensive manufacturing methods, has attracted significant commercial interest from US and international companies. The NREL/DOE program is designed to support the efforts of US companies through cost-shared subcontracts (called ``government/industry partnerships``) that we manage and fund and through collaborative technology development work among industry, universities, and our laboratory.

  13. Substrate heater for thin film deposition

    DOEpatents

    Foltyn, Steve R.

    1996-01-01

    A substrate heater for thin film deposition of metallic oxides upon a target substrate configured as a disk including means for supporting in a predetermined location a target substrate configured as a disk, means for rotating the target substrate within the support means, means for heating the target substrate within the support means, the heating means about the support means and including a pair of heating elements with one heater element situated on each side of the predetermined location for the target substrate, with one heater element defining an opening through which desired coating material can enter for thin film deposition and with the heating means including an opening slot through which the target substrate can be entered into the support means, and, optionally a means for thermal shielding of the heating means from surrounding environment is disclosed.

  14. Superconducting thin films on potassium tantalate substrates

    SciTech Connect

    Feenstra, R.; Boatner, L.A.

    1992-05-05

    This patent describes a composition for the lossless transmission of electrical current, it comprises: a superconducting thin film epitaxially deposited on a oriented surface of a single crystal KTa{sub 1{minus}z}Nb{sub 2}O{sub 3} substrate, where z is 0 to 1, wherein the superconducting thin film is selected from the group consisting of YBa{sub 2{minus}}Cu{sub 3}O{sub 7}, Y{sub 2}Ba{sub 4}Cu{sub 8}O{sub 20}, a compound wherein a trivalent rare earth element replaces yttrium in compound YBa{sub 2}Cu{sub 3}O{sub 7}, and a compound wherein scandium replaces yttrium in the compound YBa{sub 2}Cu{sub 3}O{sub 7}.

  15. Radiation effects on thin film solar cells

    SciTech Connect

    Gay, C.F.; Anspaugh, B.E.; Potter, R.R.; Tanner, D.P.

    1984-05-01

    A study has been undertaken to assess the effects of 1 MeV electron radiation on two types of thin film solar cells, thin-film silicon:hydrogen alloy (TFS) and copper indium diselenide (CIS). Using TFS devices with efficiencies between 8-9% AM 0 (9-10% AM 1.5), and CIS devices with efficiencies between 7-8% AM 0 (8-9% AM 1.5), the results show the devices are more stable to electron radiation than the typical crystalline silicon aerospace cells. In fact the CIS showed no degradation at all and with low temperature annealing the TFS could be restored to within 97% of initial power output.

  16. Generalized Ellipsometry on Ferromagnetic Sculptured Thin Films.

    NASA Astrophysics Data System (ADS)

    Schmidt, Daniel; Hofmann, Tino; Mok, Kah; Schmidt, Heidemarie; Skomski, Ralf; Schubert, Eva; Schubert, Mathias

    2011-03-01

    We present and discuss generalized ellipsometry and generalized vector-magneto-optic ellipsometry investigations on cobalt nanostructured thin films with slanted, highly-spatially coherent, columnar arrangement. The samples were prepared by glancing angle deposition. The thin films are highly transparent and reveal strong form-induced birefringence. We observe giant Kerr rotation in the visible spectral region, tunable by choice of the nanostructure geometry. Spatial magnetization orientation hysteresis and magnetization magnitude hysteresis properties are studied using a 3-dimensional Helmholtz coil arrangement allowing for arbitrary magnetic field direction at the sample position for field strengths up to 0.4 Tesla. Analysis of data obtained within this novel vector-magneto-optic setup reveals magnetization anisotropy of the Co slanted nanocolumns supported by mean-field theory modeling.

  17. Electrostatic Discharge Effects on Thin Film Resistors

    NASA Technical Reports Server (NTRS)

    Sampson, Michael J.; Hull, Scott M.

    1999-01-01

    Recently, open circuit failures of individual elements in thin film resistor networks have been attributed to electrostatic discharge (ESD) effects. This paper will discuss the investigation that came to this conclusion and subsequent experimentation intended to characterize design factors that affect the sensitivity of resistor elements to ESD. The ESD testing was performed using the standard human body model simulation. Some of the design elements to be evaluated were: trace width, trace length (and thus width to length ratio), specific resistivity of the trace (ohms per square) and resistance value. However, once the experiments were in progress, it was realized that the ESD sensitivity of most of the complex patterns under evaluation was determined by other design and process factors such as trace shape and termination pad spacing. This paper includes pictorial examples of representative ESD failure sites, and provides some options for designing thin film resistors that are ESD resistant. The risks of ESD damage are assessed and handling precautions suggested.

  18. Thin film photovoltaic panel and method

    DOEpatents

    Ackerman, Bruce; Albright, Scot P.; Jordan, John F.

    1991-06-11

    A thin film photovoltaic panel includes a backcap for protecting the active components of the photovoltaic cells from adverse environmental elements. A spacing between the backcap and a top electrode layer is preferably filled with a desiccant to further reduce water vapor contamination of the environment surrounding the photovoltaic cells. The contamination of the spacing between the backcap and the cells may be further reduced by passing a selected gas through the spacing subsequent to sealing the backcap to the base of the photovoltaic panels, and once purged this spacing may be filled with an inert gas. The techniques of the present invention are preferably applied to thin film photovoltaic panels each formed from a plurality of photovoltaic cells arranged on a vitreous substrate. The stability of photovoltaic conversion efficiency remains relatively high during the life of the photovoltaic panel, and the cost of manufacturing highly efficient panels with such improved stability is significantly reduced.

  19. Silver nanowire composite thin films as transparent electrodes for Cu(In,Ga)Se₂/ZnS thin film solar cells.

    PubMed

    Tan, Xiao-Hui; Chen, Yu; Liu, Ye-Xiang

    2014-05-20

    Solution processed silver nanowire indium-tin oxide nanoparticle (AgNW-ITONP) composite thin films were successfully applied as the transparent electrodes for Cu(In,Ga)Se₂ (CIGS) thin film solar cells with ZnS buffer layers. Properties of the AgNW-ITONP thin film and its effects on performance of CIGS/ZnS thin film solar cells were studied. Compared with the traditional sputtered ITO electrodes, the AgNW-ITONP thin films show comparable optical transmittance and electrical conductivity. Furthermore, the AgNW-ITONP thin film causes no physical damage to the adjacent surface layer and does not need high temperature annealing, which makes it very suitable to use as transparent conductive layers for heat or sputtering damage-sensitive optoelectronic devices. By using AgNW-ITONP electrodes, the required thickness of the ZnS buffer layers for CIGS thin film solar cells was greatly decreased. PMID:24922214

  20. Thin-film optical shutter. Final report

    SciTech Connect

    Matlow, S.L.

    1981-02-01

    A specific embodiment of macroconjugated macromolecules, the poly (p-phenylene)'s, has been chosen as the one most likely to meet all of the requirements of the Thin Film Optical Shutter project (TFOS). The reason for this choice is included. In order to be able to make meaningful calculations of the thermodynamic and optical properties of the poly (p-phenylene)'s a new quantum mechanical method was developed - Equilibrium Bond Length (EBL) Theory. Some results of EBL Theory are included.

  1. Large-area thin-film modules

    NASA Technical Reports Server (NTRS)

    Tyan, Y. S.; Perez-Albuerne, E. A.

    1985-01-01

    The low cost potential of thin film solar cells can only be fully realized if large area modules can be made economically with good production yields. This paper deals with two of the critical challenges. A scheme is presented which allows the simple, economical realization of the long recognized, preferred module structure of monolithic integration. Another scheme reduces the impact of shorting defects and, as a result, increases the production yields. Analytical results demonstrating the utilization and advantages of such schemes are discussed.

  2. Packaging material for thin film lithium batteries

    DOEpatents

    Bates, John B.; Dudney, Nancy J.; Weatherspoon, Kim A.

    1996-01-01

    A thin film battery including components which are capable of reacting upon exposure to air and water vapor incorporates a packaging system which provides a barrier against the penetration of air and water vapor. The packaging system includes a protective sheath overlying and coating the battery components and can be comprised of an overlayer including metal, ceramic, a ceramic-metal combination, a parylene-metal combination, a parylene-ceramic combination or a parylene-metal-ceramic combination.

  3. Structures for dense, crack free thin films

    DOEpatents

    Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    2011-03-08

    The process described herein provides a simple and cost effective method for making crack free, high density thin ceramic film. The steps involve depositing a layer of a ceramic material on a porous or dense substrate. The deposited layer is compacted and then the resultant laminate is sintered to achieve a higher density than would have been possible without the pre-firing compaction step.

  4. Thin Film Sensors for Surface Measurements

    NASA Technical Reports Server (NTRS)

    Martin, Lisa C.; Wrbanek, John D.; Fralick, Gustave C.

    2001-01-01

    Advanced thin film sensors that can provide accurate surface temperature, strain, and heat flux measurements have been developed at NASA Glenn Research Center. These sensors provide minimally intrusive characterization of advanced propulsion materials and components in hostile, high-temperature environments as well as validation of propulsion system design codes. The sensors are designed for applications on different material systems and engine components for testing in engine simulation facilities. Thin film thermocouples and strain gauges for the measurement of surface temperature and strain have been demonstrated on metals, ceramics and advanced ceramic-based composites of various component configurations. Test environments have included both air-breathing and space propulsion-based engine and burner rig environments at surface temperatures up to 1100 C and under high gas flow and pressure conditions. The technologies developed for these sensors as well as for a thin film heat flux gauge have been integrated into a single multifunctional gauge for the simultaneous real-time measurement of surface temperature, strain, and heat flux. This is the first step toward the development of smart sensors with integrated signal conditioning and high temperature electronics that would have the capability to provide feedback to the operating system in real-time. A description of the fabrication process for the thin film sensors and multifunctional gauge will be provided. In addition, the material systems on which the sensors have been demonstrated, the test facilities and the results of the tests to-date will be described. Finally, the results will be provided of the current effort to demonstrate the capabilities of the multifunctional gauge.

  5. Stable localized patterns in thin liquid films

    NASA Technical Reports Server (NTRS)

    Deissler, Robert J.; Oron, Alexander

    1991-01-01

    We study a 2-D nonlinear evolution equation which describes the 3-D spatiotemporal behavior of the air-liquid interface of a thin liquid film lying on the underside of a cooled horizontal plate. We show that the Marangoni effect can stabilize the destabilizing effect of gravity (the Rayleigh-Taylor instability) allowing for the existence of stable localized axisymmetric solutions for a wide range of parameter values. Various properties of these structures are discussed.

  6. Molecular theory of liquid crystal thin films

    NASA Astrophysics Data System (ADS)

    Meng, Shihong

    A molecular theory has been developed to describe the isotropic-nematic transitoon of model nematogens in bulk and in thin films. The surfaces of thin films can be hard surfaces or coated with surfactant monolayers. The theory only includes hard body interactions between all molecule species: solvent, nematogens and surfactants. We have studied the influence of the separation between confining walls, concentration of nematogens, as well as the surface anchoring and areal density of surfactant at the interface upon the phases of nematogens. We have explained the possible existence of planar degenerate phase through entropic pictures and have confirmed close to the bulk isotropic-nematic transition point, the order of the phases of nematogens from isotropic to nematic then back to isotropic when varying the areal density of surfactant monolayers at interfaces. From the results obtained, we believe that we have captured the main competing interactions between surfactants and nematogens and our molecular level theory is capable of describing these two interactions of different natures. Our results can provide a guideline for molecular design of biosensors. We have modeled the molecular systems with as much simplification as possible while retaining the main features. The thesis is arranged into introduction, results on bulk, thin films confined between hard walls and between surfactant monolayers.

  7. Thermochromic vanadium oxide thin films: Electronic and optical properties

    NASA Astrophysics Data System (ADS)

    Niklasson, G. A.; Li, S.-Y.; Granqvist, C. G.

    2014-11-01

    Vanadium dioxide, VO2, is a widely studied thermochromic material with potential applications in energy efficient window technology. It undergoes a first-order metal-to- insulator transition, accompanied by a crystal structure transformation from monoclinic to tetragonal rutile, at a critical temperature of 68 °C. Below this temperature, VO2 is semiconducting and infrared transmitting whereas it is metallic and infrared reflecting above the transition temperature. However, in order to achieve significant thermochromic switching, the luminous transmittance of thin films will typically be less than 50%. Here we report on recent research to improve the luminous transmittance as well as the transmittance change at the transition temperature. We systematically evaluate the effect of antireflection coatings, doping with Mg and the performance of coatings comprising thermochromic nanoparticles in a transparent matrix. The last option is shown to give the best performance and holds great promise for practical applications.

  8. Hydrothermal epitaxy of perovskite thin films

    NASA Astrophysics Data System (ADS)

    Chien, Allen T.

    1998-12-01

    This work details the discovery and study of a new process for the growth of epitaxial single crystal thin films which we call hydrothermal epitaxy. Hydrothermal epitaxy is a low temperature solution route for producing heteroepitaxial thin films through the use of solution chemistry and structurally similar substrates. The application of this synthesis route has led to the growth of a variety of epitaxial perovskite (BaTiOsb3, SrTiOsb3, and Pb(Zr,Ti)Osb3 (PZT)) thin films which provides a simple processing pathway for the formation of other materials of technological interest. BaTiOsb3 and PZT heteroepitaxial thin films and powders were produced by the hydrothermal method at 90-200sp°C using various alkali bases. XRD and TEM analysis shows that, in each case, the films and powders form epitaxially with a composition nearly identical to that of the starting precursors. Sequential growth experiments show that film formation initiates by the nucleation of submicron faceted islands at the step edges of the SrTiOsb3 substrates followed by coalescence after longer growth periods. A Ba-rich interfacial layer between the BaTiOsb3 islands and the SrTiOsb3 surface is seen by cross-section TEM during early growth periods. Electrophoretic and Basp{2+} adsorption data provide a chemical basis for the existence of the interfacial layer. Homoepitaxial growth of SrTiOsb3 on SrTiOsb3 also occurs by island growth, suggesting that the growth mode may be a consequence of the aqueous surface chemistry inherent in the process. Film formation is shown to be affected by any number of factors including type of base, pH, temperature, and substrate pretreatments. Different cation bases (Na-, K-, Rb-, Cs-, TMA-OH) demonstrated pronounced changes in powder and film morphology. For example, smaller cation bases (e.g., NaOH, KOH and RbOH) resulted the formation of 1.5 mum \\{100\\} faceted perovskite PbTiOsb3 blocks while larger cation bases (e.g., CsOH and TMA-OH) produced 500 nm sized

  9. Oriented lead zirconate titanate thin films: Characterization of film crystallization

    SciTech Connect

    Voigt, J.A.; Tuttle, B.A.; Headley, T.J.; Eatough, M.O.; Lamppa, D.L.; Goodnow, D.

    1993-11-01

    Film processing temperature and time was varied to characterize the pyrochlore-to-perovskite crystallization of solution-derived PZT 20/80 thin films. 3000 {Angstrom} thick films were prepared by spin deposition using <100> single crystal MgO as substrate. By controlled rapid thermal processing, films at different stages in the perovskite crystallization process were prepared with the tetragonal PZT 20/80 phase being <100>/<001> oriented relative to the MgO surface. An activation energy for the conversion process of 326 kJ/mole was determined by use of an Arrhenius expression using rate constants found by application of the method of Avrami. Activation energy for formation of the PZT 20/80 perovskite phase of the solution-derived films compared favorably with that calculated from data by Kwok and Desu for sputter-deposited 3500 {Angstrom} thick PZT 55/45 films. Similarity in activation energies indicates that the energetics of the conversion process are not strongly dependent on the method used for film deposition.

  10. Thin Dielectric Films Containing Tb{sup 3+} Ions For Application In Thin Film Solar Cells

    SciTech Connect

    Sendova-Vassileva, M.; Angelov, O.; Dimova-Malmovska, D.; Baumgartner, K.; Carius, R.; Hollaender, B.

    2010-01-21

    Thin transparent dielectric films containing Tb{sup 3+} are developed for application as spectral converters of the solar spectrum in thin film silicon solar cells. The results on the deposition and characterization of thin SiO{sub 2} and Al{sub 2}O{sub 3} films containing Tb{sup 3+} ions are presented. The films are prepared by RF magnetron co-sputtering, a well established technique for large area coatings. Photoluminescence (PL) is measured at room temperature, using the 488 nm line of an Ar laser and a nitrogen-cooled CCD camera attached to a monochromator. The dependence of the PL intensity on the concentration of Tb in the film is studied. It is found that the intensity exhibits a maximum at about 1 at.%. Annealing studies are performed on SiO{sub 2}:Tb with two different methods to improve the PL intensity. In both regimes of annealing, the best results for thin SiO{sub 2}:Tb films are obtained in the temperature range of 650-700 deg. C. After treatment at this temperature the Tb PL increases 2.5-3 times.

  11. Thin Dielectric Films Containing Tb3+ Ions For Application In Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Sendova-Vassileva, M.; Baumgartner, K.; Angelov, O.; Holländer, B.; Dimova-Malmovska, D.; Carius, R.

    2010-01-01

    Thin transparent dielectric films containing Tb3+ are developed for application as spectral converters of the solar spectrum in thin film silicon solar cells. The results on the deposition and characterization of thin SiO2 and Al2O3 films containing Tb3+ ions are presented. The films are prepared by RF magnetron co-sputtering, a well established technique for large area coatings. Photoluminescence (PL) is measured at room temperature, using the 488 nm line of an Ar laser and a nitrogen-cooled CCD camera attached to a monochromator. The dependence of the PL intensity on the concentration of Tb in the film is studied. It is found that the intensity exhibits a maximum at about 1 at.%. Annealing studies are performed on SiO2:Tb with two different methods to improve the PL intensity. In both regimes of annealing, the best results for thin SiO2:Tb films are obtained in the temperature range of 650-700° C. After treatment at this temperature the Tb PL increases 2.5-3 times.

  12. Effect of film thickness on the structural, optical and electrical properties of SnO2: F thin films prepared by spray ultrasonic for solar cells applications

    NASA Astrophysics Data System (ADS)

    Benhaoua, Boubaker; Abbas, Soumaia; Rahal, Achour; Benhaoua, Atmane; Aida, M. S.

    2015-07-01

    In this work, undoped tin dioxide (SnO2) and fluorine doped tin dioxide (SnO2: F) thin films were deposited on 480 °C heated glass using spray ultrasonic technique. SnCl2 and NH4F were used as sources of SnO2 and fluorine doping respectively. Effects of films thickness on the optical, structural and opto-electrical properties of undoped and 6 wt.% fluorine doped SnO2 (FTO) thin films were investigated. Optical transmittance spectra of the films showed high transparency of about 76-84% in visible region. The optical gap, for SnO2 and 6 wt.% F doped SnO2 thin films, were found to be in 3.77-3.93 eV range. X-ray diffraction (XRD) patterns showed that both SnO2 and SnO2: F films were polycrystalline with cassiterite tetragonal crystal structure. The preferential orientation for undoped SnO2 was along (2 1 1) plane whereas F doped SnO2 preferential orientations were along (2 0 0) planes. The calculated grain sizes were in 25.63-33.53 nm average. Figure of merit for FTO thin films revealed maximum value about 9.04 × 10-3 (Ω-1) at λ = 800 nm. The high conducting and transparent elaborated FTO thin films are promising to be used as window layer in solar cells.

  13. Bauschinger effect in unpassivated freestanding thin films

    NASA Astrophysics Data System (ADS)

    Shishvan, Siamak Soleymani; Nicola, Lucia; Van der Giessen, Erik

    2010-05-01

    Two-dimensional (2D) discrete dislocation plasticity simulations are carried out to investigate the Bauschinger effect (BE) in freestanding thin films. The BE in plastic flow of polycrystalline materials is generally understood to be caused by inhomogeneous deformation during loading, leading to residual stress upon unloading. This inhomogeneity can be caused by dislocation pile-ups, variations in texture, grain orientations, and grain size. To study the BE, columnar-grained films as well as films with multiple grains across the thickness are considered. The film is modeled in a 2D framework by a unit cell consisting of an array of grains with different orientation. In order to capture the interaction among grains, we motivate and explore the use of an affine deformation assumption on the grain level to mimic the three-dimensional geometry in this framework. It is shown that the dispersion of grain size in a film together with the size-dependence of yield strength leads to significant BEs in bare films. Quantitative comparison of simulations with experimental data is provided.

  14. Evaporated CaS thin films for AC electroluminescence devices

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Tanaka, S.; Shanker, V.; Shiiki, M.; Deguchi, H.

    1985-08-01

    The growth behavior of evaporated CaS thin films has been investigated to achieve bright electroluminescence. The crystallinity of CaS films is improved with substrate temperature and for temperatures higher than 300°C, the films orient to the (200) plane. Sulfur coevaporation further helps to form a more perfect film even at lower temperatures. A CaS: Ce,Cl electroluminescent thin film device has been fabricated with a brightness of 650 cd/m 2.

  15. Electrohydrodynamic processing and characterisation of titanium dioxide films

    NASA Astrophysics Data System (ADS)

    Mahalingam, Suntharavathanan

    The research in this thesis demonstrates a novel electrohydrodynamic preparation of titanium dioxide (TiC>2) films. In this process, a liquid breaks up into spray droplets under influence of an electric field. This process is influenced by many factors properties of the liquid - surface tension, electrical conductivity, relative permittivity, viscosity, density and liquid flow rate and applied voltage. This technique has unique advantage like simple set-up and economical way to formulate the films. Many modes of processing were identified by drawing the mode-selection map for various applied voltage and flow rate using a titania sol. For a fixed flow rate, changing the applied voltage changed the processing mode. For a fixed applied voltage, changing the flow rate changed the shape of the liquid filament at the end of the needle. The stable cone-jet mode processing produced a near mono-disperse of droplets. The stable cone-jet processing of TiC>2 films showed anatase phase and converted to rutile phase at higher annealing temperature. The morphological characterisation revealed the dense and crack free surfaces of the TiC>2 films. The dielectric constant of the electrohydrodynamically processed TiC>2 films was 7. The increase in annealing temperature reduced the dielectric constant of the films. The leakage current density of the films was improved by post deposition annealing. The optical characterisation of the films showed a good transparency in the visible light region. The transmission in the visible range varied between 70-90%. The annealing temperature influenced the transmittance of the films. The energy bandgap is -3.50 eV for indirect transition. The larger coverage area nitrogen doped titanium dioxide films were obtained by using a metal clamped needle - ground electrode set-up for the first time. Metal clamping the needle lowered the stable cone-jet operating voltage window. The nitrogen doping in TiC>2 films retarded the phase formation however, showed

  16. Thin film cadmium telluride photovoltaic cells

    SciTech Connect

    Compaan, A.; Bohn, R. )

    1992-04-01

    This report describes research to develop to vacuum-based growth techniques for CdTe thin-film solar cells: (1) laser-driven physical vapor deposition (LDPVD) and (2) radio-frequency (rf) sputtering. The LDPVD process was successfully used to deposit thin films of CdS, CdTe, and CdCl{sub 2}, as well as related alloys and doped semiconductor materials. The laser-driven deposition process readily permits the use of several target materials in the same vacuum chamber and, thus, complete solar cell structures were fabricated on SnO{sub 2}-coated glass using LDPVD. The rf sputtering process for film growth became operational, and progress was made in implementing it. Time was also devoted to enhancing or implementing a variety of film characterization systems and device testing facilities. A new system for transient spectroscopy on the ablation plume provided important new information on the physical mechanisms of LDPVD. The measurements show that, e.g., Cd is predominantly in the neutral atomic state in the plume but with a fraction that is highly excited internally ({ge} 6 eV), and that the typical neutral Cd translational kinetic energies perpendicular to the target are 20 eV and greater. 19 refs.

  17. Active superconducting devices formed of thin films

    DOEpatents

    Martens, Jon S.; Beyer, James B.; Nordman, James E.; Hohenwarter, Gert K. G.

    1991-05-28

    Active superconducting devices are formed of thin films of superconductor which include a main conduction channel which has an active weak link region. The weak link region is composed of an array of links of thin film superconductor spaced from one another by voids and selected in size and thickness such that magnetic flux can propagate across the weak link region when it is superconducting. Magnetic flux applied to the weak link region will propagate across the array of links causing localized loss of superconductivity in the links and changing the effective resistance across the links. The magnetic flux can be applied from a control line formed of a superconducting film deposited coplanar with the main conduction channel and weak link region on a substrate. The devices can be formed of any type to superconductor but are particularly well suited to the high temperature superconductors since the devices can be entirely formed from coplanar films with no overlying regions. The devices can be utilized for a variety of electrical components, including switching circuits, amplifiers, oscillators and modulators, and are well suited to microwave frequency applications.

  18. Dynamic Characterization of Thin Film Magnetic Materials

    NASA Astrophysics Data System (ADS)

    Gu, Wei

    A broadband dynamic method for characterizing thin film magnetic material is presented. The method is designed to extract the permeability and linewidth of thin magnetic films from measuring the reflection coefficient (S11) of a house-made and short-circuited strip line testing fixture with or without samples loaded. An adaptive de-embedding method is applied to remove the parasitic noise of the housing. The measurements were carried out with frequency up to 10GHz and biasing magnetic fields up to 600 Gauss. Particular measurement setup and 3-step experimental procedures are described in detail. The complex permeability of a 330nm thick continuous FeGaB, 435nm thick laminated FeGaB film and a 100nm thick NiFe film will be induced dynamically in frequency-biasing magnetic field spectra and compared with a theoretical model based on Landau-Lifshitz-Gilbert (LLG) equations and eddy current theories. The ferromagnetic resonance (FMR) phenomenon can be observed among these three magnetic materials investigated in this thesis.

  19. Nanocrystalline silicon based thin film solar cells

    NASA Astrophysics Data System (ADS)

    Ray, Swati

    2012-06-01

    Amorphous silicon solar cells and panels on glass and flexible substrate are commercially available. Since last few years nanocrystalline silicon thin film has attracted remarkable attention due to its stability under light and ability to absorb longer wavelength portion of solar spectrum. For amorphous silicon/ nanocrystalline silicon double junction solar cell 14.7% efficiency has been achieved in small area and 13.5% for large area modules internationally. The device quality nanocrystalline silicon films have been fabricated by RF and VHF PECVD methods at IACS. Detailed characterizations of the materials have been done. Nanocrystalline films with low defect density and high stability have been developed and used as absorber layer of solar cells.

  20. Supramolecular structure of electroactive polymer thin films

    NASA Astrophysics Data System (ADS)

    Kornilov, V. M.; Lachinov, A. N.; Karamov, D. D.; Nabiullin, I. R.; Kul'velis, Yu. V.

    2016-05-01

    This paper presents the results of an experimental investigation of the supramolecular structure of polydiphenylenephthalide thin films that exhibit effects of resistive switching. The supramolecular structure of the polymer has been investigated using small-angle neutron scattering in conjunction with atomic force microscopy. It has been found that the internal structure of polymer films consists of structural elements in the form of spheroids. The sizes of the structural elements, which were obtained from the neutron scattering data and analysis of the atomic force microscopy images, correlate well with each other. A model of the formation of polymer layers has been proposed. The observed structural elements in polymer films are formed due to the association of macromolecules in the initial polymer solution.

  1. Electrohydrodynamic instabilities in thin trilayer liquid films.

    SciTech Connect

    Roberts, Scott A.; Kumar, Satish

    2010-11-01

    When DC or AC electric fields are applied to a thin liquid film, the interface may become unstable and form a series of pillars. We examine how the presence of a second liquid interface influences pillar dynamics and morphologies. For perfect dielectric films, linear stability analysis of a lubrication-approximation-based model shows that the root mean square voltage governs the pillar behavior. For leaky dielectric films, Floquet theory is applied to carry out the linear stability analysis, and reveals that the accumulation of free charge at each interface depends on the conductivities in the adjoining phases and that high frequencies of the AC electric field may be used to control this accumulation at each interface independently. The results presented here may of interest for the controlled creation of surface topographical features in applications such as patterned coatings and microelectronics.

  2. Magnetization relaxation in sputtered thin permalloy films

    NASA Astrophysics Data System (ADS)

    Oliveira, R. C.; Rodríguez-Suárez, R. L.; Aguiar, F. M. De; Rezende, S. M.; Fermin, J. R.; Azevedo, A.

    2004-05-01

    In order to understand the underlying phenomena of magnetization damping in metallic thin films, samples of permalloy films were grown by magnetron sputtering, and their 8.6-GHz ferromagnetic resonance linewidth ΔH has been measured as a function of the Permalloy (Py) film thickness t, at room temperature. We made samples of Py(t)/Si(001) and X/Py(t)/X/Si(001), with X=Pd (40Å), and Cr (25Å), with 20Å < t < 200Å. While ΔH scales with t-2 in the bare Py/Si series, it is shown that the damping behavior strongly depends on X in the sandwich samples.

  3. Preface: Thin films of molecular organic materials

    NASA Astrophysics Data System (ADS)

    Fraxedas, J.

    2008-03-01

    This special issue is devoted to thin films of molecular organic materials and its aim is to assemble numerous different aspects of this topic in order to reach a wide scientific audience. Under the term 'thin films', structures with thicknesses spanning from one monolayer or less up to several micrometers are included. In order to narrow down this relaxed definition (how thin is thin?) I suggest joining the stream that makes a distinction according to the length scale involved, separating nanometer-thick films from micrometer-thick films. While the physical properties of micrometer-thick films tend to mimic those of bulk materials, in the low nanometer regime new structures (e.g., crystallographic and substrate-induced phases) and properties are found. However, one has to bear in mind that some properties of micrometer-thick films are really confined to the film/substrate interface (e.g. charge injection), and are thus of nanometer nature. Supported in this dimensionality framework, this issue covers the most ideal and model 0D case, a single molecule on a surface, through to the more application-oriented 3D case, placing special emphasis on the fascinating 2D domain that is monolayer assembly. Thus, many aspects will be reviewed, such as single molecules, self-organization, monolayer regime, chirality, growth, physical properties and applications. This issue has been intentionally restricted to small molecules, thus leaving out polymers and biomolecules, because for small molecules it is easier to establish structure--property relationships. Traditionally, the preparation of thin films of molecular organic materials has been considered as a secondary, lower-ranked part of the more general field of this class of materials. The coating of diverse surfaces such as silicon, inorganic and organic single crystals, chemically modified substrates, polymers, etc., with interesting molecules was driven by the potential applications of such molecular materials

  4. The formation and analysis of thin film high temperature superconductors

    SciTech Connect

    Nastasi, M.; Muenchausen, R.E.; Arendt, P.N.

    1989-01-01

    Thin films of high temperature superconductors have been fabricated using a variety of physical vapor deposition techniques. Recent results of HTS thin films produced by coevaporation, sputtering and laser deposition will be briefly reviewed. In addition some examples of the utility of high energy ion backscattering for the analysis of film stoichiometry will be given. 34 refs., 6 figs.

  5. The formation and analysis of thin film high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Nastasi, Michael; Muenchausen, Ross E.; Arendt, Paul N.

    Thin films of high temperature superconductors have been fabricated using a variety of physical vapor deposition techniques. Recent results of HTS thin films produced by coevaporation, sputtering and laser deposition will be briefly reviewed. In addition some examples of the utility of high energy ion backscattering for the analysis of film stoichiometry will be given.

  6. Dynamics of Bimodal Growth in Pentacene Thin Films

    SciTech Connect

    Mayer, Alex C.; Malliaras, George G.; Kazimirov, Alexander

    2006-09-08

    Previous studies have established that pentacene films deposited on silicon oxide consist of a substrate-induced 'thin-film' phase, with the bulk phase of pentacene detected in thicker films only. We show that the bulk phase nucleates as early as the first monolayer, and continues to nucleate as film growth progresses, shadowing the growth of the thin-film phase. Moreover, we find that the transition between the 'thin-film' and the bulk phase is not a continuous one, as observed in heteroepitaxial systems, but rather the two phases nucleate and grow independently.

  7. The characteristics of Au:VO2 nanocomposite thin film for photo-electricity applications

    NASA Astrophysics Data System (ADS)

    Zhu, Yabin; Na, Jie; He, Fan; Zhou, Yueliang

    2013-08-01

    Au nanoparticles have been fabricated on normal glass substrates using nanosphere lithography (NSL) method. Vanadium dioxide has been deposited on Au/glass by reactive radio frequency (rf) magnetron sputtering. The structure and composition were determined by X-ray diffraction and X-ray photoelectron spectroscope. Electrical and optical properties of bare VO2 and Au:VO2 nanocomposite thin films were measured. Typical hysteresis behavior and sharp phase transition were observed. Nanopartical Au could effectively reduce the transition temperature to 40 °C. The transmittance spectrum for both Au:VO2 nanocomposite thin film shows high transmittance under transition temperature and low transmittance above transition temperature. The characteristics present the Au:VO2 nanocomposite thin film can be used for applications, such as “smart window” or “laser protector”.

  8. Optical switching properties of VOx thin films deposited on Si3N4 substrates using ion beam sputtering

    NASA Astrophysics Data System (ADS)

    Lu, Jianing; Hu, Ming; Liang, Jiran; Chen, Tao; Tan, Lei

    2009-07-01

    Vanadium dioxide (VO2) thin films, for their property of metal-insulator transition (MIT), have drawn many researchers' attention on optical devices study. Nowadays it is complicated to fabricate single-phase VO2) thin films. Ion beam sputtering is adopted to deposit VOx thin films (main component is VO2) ) on Si3N4, while sputtering power, substrate temperature and partial oxygen pressure of VOx are adjusted. Then annealing technology is utilized to improve the parameter property of VOx thin films. The thin films are tested by AFM, XPS, XRD, Fourier transform infrared spectrometry, tunable semiconductor laser and optical power meter. Both temperature-driven phasetransition and photoexcitation phasetransition of VOx thin films are applied. The samples are heated from 20°C to 80°C, discovering that the phasetransition temperature is about 59°C and the value of resistance before the phasetransition is two orders of magnitude over the value of resistance after the phasetransition. At the wavelength of 1550 nm, the transmission is from 32% to 1%. Besides, the extinction ratio of the thin films sample is obtained. The optical properties show that the VOx thin films have an apparent switching effect in the optical communication fields.

  9. LiMn2O4-based cathode thin films for Li thin-film batteries

    NASA Astrophysics Data System (ADS)

    Yim, Haena; Shin, Dong-Wook; Choi, Ji-Won

    2016-01-01

    Substitution methods for Mn3+ in a spinel lithium manganese oxide with other cations have been used to prevent capacity degradation during the electrochemical charge and discharge of Li-batteries by increasing the average valence of Mn. In particular, in this review we outlin the effects of Sn substitution on the cycling performance of LiMn2O4 thin films that can be used as positive electrode in Li-batteries. The thin films were prepared by using pulsed laser deposition and solution deposition with regard to the structural and the electro-chemical characteristics.

  10. Properties of silicon dioxide films deposited at low temperatures by microwave plasma enhanced decomposition of tetraethylorthosilicate

    SciTech Connect

    Ray, S.K.; Maiti, C.K.; Lahiri, S.K.; Chakrabarti, N.B.

    1992-05-01

    Silicon dioxide films have been deposited at low temperatures (200-250{degrees}C) by microwave plasma enhanced decomposition of tetraethylorthosilicate (TEOS). The effects of the presence of oxygen in the discharge in film deposition rate, mechanism, and the physical properties of the films have been investigated. Structural characterization of the deposited films has been carried out by etch rate measurements, infrared transmission spectra, x-ray photoelectron spectroscopy, Auger, and secondary ion mass spectrometry analyses. Films deposited using TEOS and oxygen have confirmed a density comparable to standard silane-based low-pressure chemical vapor deposited and plasma enhanced chemical vapor deposited oxides, nearly perfect stoichiometry, extremely low sodium and carbon content, and the absence of many undesirable hydrogen related bonds. Various electrical properties, viz., resistivity, breakdown strength, fixed oxide charge density, interface state density, and trapping behavior have been evaluated by the characterization of metal-oxide-semiconductor capacitors fabricated using deposited oxides. Deposited films on thin native oxides grown by either in situ plasma oxidation or a low temperature thermal oxidation exhibited excellent electrical properties. 32 refs., 16 figs., 2 tabs.

  11. Immersion Deposition of Metal Films on Silicon and Germanium Substrates in Supercritical Carbon Dioxide

    SciTech Connect

    Ye, Xiang-Rong; Wai, Chien M.; Zhang, Daqing; Kranov, Yanko; Mcilroy, David; Lin, Yuehe; Engelhard, Mark H.

    2003-01-29

    A low temperature carbon dioxide based on immersion deposition technology (SFID) has been developed for producing palladium, copper, silver, and other metal films on silicon-based substrates in supercritical CO2. The reaction is initiated by oxidation of elemental silicon to SiF4 or H2SiF6 by HF with the release of electrons that cause the reduction of metal ions in an organometallic precursor to the metallic form on silicon surface in CO2. Only the substrate surfaces are coated with metals using this method. Based on surface analysis of the films and spectroscopic analysis of the reaction products, the mechanism of metal film deposition is discussed. The metal films (Pd, Cu, and Ag) formed on silicon surfaces by the SFID method exhibit good coverage, smooth and dense texture, high purity and a metallic behavior. Similarly, metal films can also be deposited onto geranium substrates using SFID. The gas-like properties and the high pressure of the supercritical fluids, combined with the low reaction temperature, make this SFID method potentially useful for depositing thin metal films in small features, which are difficult to accomplish by conventional CVD methods.

  12. Metallic Thin-Film Bonding and Alloy Generation

    NASA Technical Reports Server (NTRS)

    Fryer, Jack Merrill (Inventor); Campbell, Geoff (Inventor); Peotter, Brian S. (Inventor); Droppers, Lloyd (Inventor)

    2016-01-01

    Diffusion bonding a stack of aluminum thin films is particularly challenging due to a stable aluminum oxide coating that rapidly forms on the aluminum thin films when they are exposed to atmosphere and the relatively low meting temperature of aluminum. By plating the individual aluminum thin films with a metal that does not rapidly form a stable oxide coating, the individual aluminum thin films may be readily diffusion bonded together using heat and pressure. The resulting diffusion bonded structure can be an alloy of choice through the use of a carefully selected base and plating metals. The aluminum thin films may also be etched with distinct patterns that form a microfluidic fluid flow path through the stack of aluminum thin films when diffusion bonded together.

  13. Low-Cost Detection of Thin Film Stress during Fabrication

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy A.

    2015-01-01

    NASA's Marshall Space Flight Center has developed a simple, cost-effective optical method for thin film stress measurements during growth and/or subsequent annealing processes. Stress arising in thin film fabrication presents production challenges for electronic devices, sensors, and optical coatings; it can lead to substrate distortion and deformation, impacting the performance of thin film products. NASA's technique measures in-situ stress using a simple, noncontact fiber optic probe in the thin film vacuum deposition chamber. This enables real-time monitoring of stress during the fabrication process and allows for efficient control of deposition process parameters. By modifying process parameters in real time during fabrication, thin film stress can be optimized or controlled, improving thin film product performance.

  14. Investigating the interfacial dynamics of thin films

    NASA Astrophysics Data System (ADS)

    Rosenbaum, Aaron W.

    This thesis probes the interfacial dynamics and associated phenomena of thin films. Surface specific tools were used to study the self-assembly of alkanethiols, the mono- and bilayer dynamics of SF6, and the surface motion of poly(methyl methacrylate). Non-pertubative helium atom scattering was the principal technique used to investigate these systems. A variety of other complementary tools, including scanning tunneling microscopy, electron diffraction, Auger spectroscopy, atomic force microscopy, and ellipsometry were used in tandem with the neutral atom scattering studies. Controlling the spontaneous assembly of alkanethiols on Au(111) requires a better fundamental understanding of the adsorbate-adsorbate and substrate-adsorbate interactions. Our characterization focused on two key components, the surface structure and adsorbate vibrations. The study indicates that the Au(111) reconstruction plays a larger role than anticipated in the low-density phase of alkanethiol monolayers. A new structure is proposed for the 1-decanethiol monolayer that impacts the low-energy vibrational mode. Varying the alkane chain lengths imparts insight into the assembly process via characterization of a dispersionless phonon mode. Studies of SF6 physisorbed on Au(111) bridge surface research on rare gas adsorbates with complicated dynamical organic thin films. Mono- and bilayer coverages of SF6/Au(111) were studied at cryogenic temperatures. Our experiments probed the surface properties of SF6 yielding insights into substrate and coverage effects. The study discovered a dispersionless Einstein oscillation with multiple harmonic overtones. A second layer of SF6 softened the mode, but did not show any indications of bulk or cooperative interactions. The vibrational properties of SF 6 showed both striking similarities and differences when compared with physisorbed rare gases. Lastly, this thesis will discuss studies of thin film poly(methyl methacrylate) on Si. The non-pertubative and

  15. Electrical and optical properties of sputtered amorphous vanadium oxide thin films

    NASA Astrophysics Data System (ADS)

    Podraza, N. J.; Gauntt, B. D.; Motyka, M. A.; Dickey, E. C.; Horn, M. W.

    2012-04-01

    Amorphous vanadium oxide (VOx) is a component found in composite nanocrystalline VOx thin films. These types of composite films are used as thermistors in pulsed biased uncooled infrared imaging devices when containing face centered cubic vanadium monoxide phase crystallites, and substantial fractions of amorphous material in the composite are necessary to optimize device electrical properties. Similarly, optoelectronic devices exploiting the metal-to-semiconductor transition contain the room-temperature monoclinic or high-temperature (>68 °C) rutile vanadium dioxide phase. Thin films of VOx exhibiting the metal-to-semiconductor transition are typically polycrystalline or nanocrystalline, implying that significant amounts of disordered, amorphous material is present at grain boundaries or surrounding the crystallites and can impact the overall optical or electronic properties of the film. The performance of thin film material for either application depends on both the nature of the crystalline and amorphous components, and in this work we seek to isolate and study amorphous VOx. VOx thin films were deposited by pulsed dc reactive magnetron sputtering to produce amorphous materials with oxygen contents ≥2, which were characterized electrically by temperature dependent current-voltage measurements and optically characterized by spectroscopic ellipsometry. Film resistivity, thermal activation energy, and complex dielectric function spectra from 0.75 to 6.0 eV were used to identify the impact of microstructural variations including composition and density.

  16. Pulsed laser deposition of pepsin thin films

    NASA Astrophysics Data System (ADS)

    Kecskeméti, G.; Kresz, N.; Smausz, T.; Hopp, B.; Nógrádi, A.

    2005-07-01

    Pulsed laser deposition (PLD) of organic and biological thin films has been extensively studied due to its importance in medical applications among others. Our investigations and results on PLD of a digestion catalyzing enzyme, pepsin, are presented. Targets pressed from pepsin powder were ablated with pulses of an ArF excimer laser ( λ = 193 nm, FWHM = 30 ns), the applied fluence was varied between 0.24 and 5.1 J/cm 2. The pressure in the PLD chamber was 2.7 × 10 -3 Pa. The thin layers were deposited onto glass and KBr substrates. Our IR spectroscopic measurements proved that the chemical composition of deposited thin films is similar to that of the target material deposited at 0.5 and 1.3 J/cm 2. The protein digesting capacity of the transferred pepsin was tested by adapting a modified "protein cube" method. Dissolution of the ovalbumin sections proved that the deposited layers consisted of catalytically active pepsin.

  17. Nano crystalline TiO2 thin films as negative electrodes for lithium ion batteries.

    PubMed

    Aslan, Serdar; Guler, Mehmet Oguz; Cevher, Ozgur; Akbulut, Hatem

    2012-12-01

    In this study, rutile (tetragonal, P42/mnm), anatase (tetragonal, I41/amd) polymorphs of titanium dioxide films were synthesized successfully magnetron sputtering of titanium films on stainless steel substrates followed by in situ direct current plasma oxidation. The as-prepared titanium dioxide thin films were oxidized at 75 W, 100 W and 125 W plasma powers in order to optimize the system with best electrochemical performance. The mean grain sizes of the deposited films were found to be in the range of 14.2-12.9 nm as revealed by the scanning electron microscopy and X-ray diffractometer studies. The electrochemical studies were performed with pure metallic lithium foil cathode with the best performing nano structured titanium dioxide as anode. The specific capacity of the nanocrystalline titanium dioxide films oxidized at 125 W direct current was 207 mA h g(-1) even after 20 cycles in the 0.02-2 V region, indicating excellent cycling stability and reversibility. PMID:23447985

  18. Influence of Heat Treatment Conditions on the Properties of Vanadium Oxide Thin Films for Thermochromic Applications.

    PubMed

    Kim, Donguk; Kwon, Samyoung; Park, Young; Boo, Jin-Hyo; Nam, Sang-Hun; Joo, Yang Tae; Kim, Minha; Lee, Jaehyeong

    2016-05-01

    In present work, the effects of the heat treatment on the structural, optical, and thermochromic properties of vanadium oxide films were investigated. Vanadium dioxide (VO2) thin films were deposited on glass substrate by reactive pulsed DC magnetron sputtering from a vanadium metal target in mixture atmosphere of argon and oxygen gas. Various heat treatment conditions were applied in order to evaluate their influence on the crystal phases formed, surface morphology, and optical properties. The films were characterized by an X-ray diffraction (XRD) in order to investigate the crystal structure and identify the phase change as post-annealing temperature of 500-600 degrees C for 5 minutes. Surface conditions of the obtained VO2(M) films were analyzed by field emission scanning electron microscopy (FE-SEM) and the semiconductor-metal transition (SMT) characteristics of the VO2 films were evaluate by optical spectrophotometry in the UV-VIS-NIR, controlling temperature of the films. PMID:27483853

  19. Physical Properties of Thin Film Semiconducting Materials

    NASA Astrophysics Data System (ADS)

    Bouras, N.; Djebbouri, M.; Outemzabet, R.; Sali, S.; Zerrouki, H.; Zouaoui, A.; Kesri, N.

    2005-10-01

    The physics and chemistry of semiconducting materials is a continuous question of debate. We can find a large stock of well-known properties but at the same time, many things are not understood. In recent years, porous silicon (PS-Si), diselenide of copper and indium (CuInSe2 or CIS) and metal oxide semiconductors like tin oxide (SnO2) and zinc oxide (ZnO) have been subjected to extensive studies because of the rising interest their potential applications in fields such as electronic components, solar panels, catalysis, gas sensors, in biocompatible materials, in Li-based batteries, in new generation of MOSFETS. Bulk structure and surface and interface properties play important roles in all of these applications. A deeper understanding of these fundamental properties would impact largely on technological application performances. In our laboratory, thin films of undoped and antimony-doped films of tin oxide have been deposited by chemical vapor deposition. Spray pyrolysis was used for ZnO. CIS was prepared by flash evaporation or close-space vapor transport. Some of the deposition parameters have been varied, such as substrate temperature, time of deposition (or anodization), and molar concentration of bath preparation. For some samples, thermal annealing was carried out under oxygen (or air), under nitrogen gas and under vacuum. Deposition and post-deposition parameters are known to strongly influence film structure and electrical resistivity. We investigated the influence of film thickness and thermal annealing on structural optical and electrical properties of the films. Examination of SnO2 by x-ray diffraction showed that the main films are polycrystalline with rutile structure. The x-ray spectra of ZnO indicated a hexagonal wurtzite structure. Characterizations of CIS films with compositional analysis, x-ray diffraction, scanning microscopy, spectrophotometry, and photoluminescence were carried out.

  20. High- Tc thin-film magnetometer

    SciTech Connect

    Miklich, A.H.; Wellstood, F.C.; Kingston, J.J.; Clarke, J. ); Colclough, M.S. ); Cardona, A.H.; Bourne, L.C.; Olson, W.L.; Eddy, M.M. )

    1990-09-01

    We have constructed and tested high-{Tc} magnetometers by coupling a high-{Tc} thin-film Superconducting QUantum Interference Device (SQUID) to two different high-{Tc} thin-film flux transformers. The SQUID was made from Tl{sub 2}CaBa{sub 2}Cu{sub 2}O{sub 8+y} films grown on MgO, with junctions consisting of native grain boundaries. The flux transformers were made from YBa{sub 2}Cu{sub 3}O{sub 7-x}, and each had 10-turn input coils and a single-turn pickup loop. The first transformer, which was patterned with a combination of shadow masks and photolithography, yielded a magnetic field gain of about {minus}7.5, functioned up to 79 K, and gave a magnetic field sensitivity B{sub N} (10 Hz) {approx} 3.1 pT Hz{sup {minus}1/2}at 38 K. The second transformer, which was patterned entirely by photolithography, yielded a gain of about {minus}8.7, functioned up to 25 K, and had a sensitivity B{sub N} (10 Hz) {approx} 3.5 pT Hz{sup {minus}1/2} at 4.2 K. In both cases, the limiting noise arose in the SQUID. 10 refs., 5 figs., 1 tab.

  1. Strain Tuning of Ferroelectric Thin Films *

    NASA Astrophysics Data System (ADS)

    Schlom, Darrell G.; Chen, Long-Qing; Eom, Chang-Beom; Rabe, Karin M.; Streiffer, Stephen K.; Triscone, Jean-Marc

    2007-08-01

    Predictions and measurements of the effect of biaxial strain on the properties of epitaxial ferroelectric thin films and superlattices are reviewed. Results for single-layer ferroelectric films of biaxially strained SrTiO3, BaTiO3, and PbTiO3 as well as PbTiO3/SrTiO3 and BaTiO3/SrTiO3 superlattices are described. Theoretical approaches, including first principles, thermodynamic analysis, and phase-field models, are applied to these biaxially strained materials, the assumptions and limitations of each technique are explained, and the predictions are compared. Measurements of the effect of biaxial strain on the paraelectric-to-ferroelectric transition temperature (TC) are shown, demonstrating the ability of percent-level strains to shift TC by hundreds of degrees in agreement with the predictions that predated such experiments. Along the way, important experimental techniques for characterizing the properties of strained ferroelectric thin films and superlattices, as well as appropriate substrates on which to grow them, are mentioned.

  2. Thin-film cadmium telluride solar cells

    NASA Astrophysics Data System (ADS)

    Chu, T. L.

    1986-08-01

    The major objective of this work was to demonstrate CdTe devices grown by chemical vapor deposition (CVD) with a total area greater than 1 cm2 and photovoltic efficiencies of at least 13%. During the period covered, various processing steps were investigated for the preparation of thin-film CdTe heterojunction solar cells of the inverted configuration. Glass coated with fluorine-doped tin oxide was used as the substrate. Thin-film heterojunction solar cells were prepared by depositing p-CdTe films on substrates using CVD and close-spaced sublimation (CSS). Cells prepared from CSS CdTe usually have a higher conversion efficiency than those prepared from CVD CdTe, presumably due to the chemical interaction between CdS and CdTe at the interface during the CVD process. The best cell, about 1.2 sq cm in area, had an AM 1.5 (global) efficiency of 10.5%, and further improvements are expected by optimizing the process parameters.

  3. PZT Thin Film Piezoelectric Traveling Wave Motor

    NASA Technical Reports Server (NTRS)

    Shen, Dexin; Zhang, Baoan; Yang, Genqing; Jiao, Jiwei; Lu, Jianguo; Wang, Weiyuan

    1995-01-01

    With the development of micro-electro-mechanical systems (MEMS), its various applications are attracting more and more attention. Among MEMS, micro motors, electrostatic and electromagnetic, are the typical and important ones. As an alternative approach, the piezoelectric traveling wave micro motor, based on thin film material and integrated circuit technologies, circumvents many of the drawbacks of the above mentioned two types of motors and displays distinct advantages. In this paper we report on a lead-zirconate-titanate (PZT) piezoelectric thin film traveling wave motor. The PZT film with a thickness of 150 micrometers and a diameter of 8 mm was first deposited onto a metal substrate as the stator material. Then, eight sections were patterned to form the stator electrodes. The rotor had an 8 kHz frequency power supply. The rotation speed of the motor is 100 rpm. The relationship of the friction between the stator and the rotor and the structure of the rotor on rotation were also studied.

  4. Orthogonal Thin Film Photovoltaics on Vertical Nanostructures.

    PubMed

    Ahnood, Arman; Zhou, H; Suzuki, Y; Sliz, R; Fabritius, T; Nathan, Arokia; Amaratunga, G A J

    2015-12-01

    Decoupling paths of carrier collection and illumination within photovoltaic devices is one promising approach for improving their efficiency by simultaneously increasing light absorption and carrier collection efficiency. Orthogonal photovoltaic devices are core-shell type structures consisting of thin film photovoltaic stack on vertical nanopillar scaffolds. These types of devices allow charge collection to take place in the radial direction, perpendicular to the path of light in the vertical direction. This approach addresses the inherently high recombination rate of disordered thin films, by allowing semiconductor films with minimal thicknesses to be used in photovoltaic devices, without performance degradation associated with incomplete light absorption. This work considers effects which influence the performance of orthogonal photovoltaic devices. Illumination non-uniformity as light travels across the depth of the pillars, electric field enhancement due to the nanoscale size and shape of the pillars, and series resistance due to the additional surface structure created through the use of pillars are considered. All of these effects influence the operation of orthogonal solar cells and should be considered in the design of vertically nanostructured orthogonal photovoltaics. PMID:26676997

  5. Orthogonal Thin Film Photovoltaics on Vertical Nanostructures

    NASA Astrophysics Data System (ADS)

    Ahnood, Arman; Zhou, H.; Suzuki, Y.; Sliz, R.; Fabritius, T.; Nathan, Arokia; Amaratunga, G. A. J.

    2015-12-01

    Decoupling paths of carrier collection and illumination within photovoltaic devices is one promising approach for improving their efficiency by simultaneously increasing light absorption and carrier collection efficiency. Orthogonal photovoltaic devices are core-shell type structures consisting of thin film photovoltaic stack on vertical nanopillar scaffolds. These types of devices allow charge collection to take place in the radial direction, perpendicular to the path of light in the vertical direction. This approach addresses the inherently high recombination rate of disordered thin films, by allowing semiconductor films with minimal thicknesses to be used in photovoltaic devices, without performance degradation associated with incomplete light absorption. This work considers effects which influence the performance of orthogonal photovoltaic devices. Illumination non-uniformity as light travels across the depth of the pillars, electric field enhancement due to the nanoscale size and shape of the pillars, and series resistance due to the additional surface structure created through the use of pillars are considered. All of these effects influence the operation of orthogonal solar cells and should be considered in the design of vertically nanostructured orthogonal photovoltaics.

  6. thin films by an hybrid deposition configuration: pulsed laser deposition and thermal evaporation

    NASA Astrophysics Data System (ADS)

    Escobar-Alarcón, L.; Solís-Casados, D. A.; Perez-Alvarez, J.; Romero, S.; Morales-Mendez, J. G.; Haro-Poniatowski, E.

    2014-10-01

    The aim of this work was to report the application of an hybrid deposition configuration to deposit Titanium dioxide (TiO2) thin films modified with different amounts of bismuth (Bi:TiO2). The samples were synthesized combining a TiO2 laser ablation plasma with a flux of vapor of bismuth produced by thermal evaporation. By varying the deposition rate of Bi it was possible to control the amount of Bi incorporated in the film and consequently the film properties. A detailed compositional, structural, and optical characterization by XPS, RBS, Raman spectroscopy, and UV-Vis spectrometry techniques is discussed. Photocatalytic response of the deposited thin films was studied through the degradation of a malachite green solution.

  7. Porous Organic Cage Thin Films and Molecular-Sieving Membranes.

    PubMed

    Song, Qilei; Jiang, Shan; Hasell, Tom; Liu, Ming; Sun, Shijing; Cheetham, Anthony K; Sivaniah, Easan; Cooper, Andrew I

    2016-04-01

    Porous organic cage molecules are fabricated into thin films and molecular-sieving membranes. Cage molecules are solution cast on various substrates to form amorphous thin films, with the structures tuned by tailoring the cage chemistry and processing conditions. For the first time, uniform and pinhole-free microporous cage thin films are formed and demonstrated as molecular-sieving membranes for selective gas separation. PMID:26800019

  8. Overview and Challenges of Thin Film Solar Electric Technologies

    SciTech Connect

    Ullal, H. S.

    2008-12-01

    In this paper, we report on the significant progress made worldwide by thin-film solar cells, namely, amorphous silicon (a-Si), cadmium telluride (CdTe), and copper indium gallium diselenide (CIGS). Thin-film photovoltaic (PV) technology status is also discussed in detail. In addition, R&D and technology challenges in all three areas are elucidated. The worldwide estimated projection for thin-film PV technology production capacity announcements are estimated at more than 5000 MW by 2010.

  9. Form Birefringence in Thin Films with Oblique Columnar Structures

    NASA Astrophysics Data System (ADS)

    Wang, Jian-Guo; Shao, Jian-Da; Wang, Su-Mei; He, Hong-Bo; Fan, Zheng-Xiu

    2005-08-01

    Effective medium theory is useful for designing optical elements with form birefringent subwavelength structures. Thin films fabricated by oblique deposition are similar to the two-dimensional surface relief subwavelength gratings. We use the effective medium theory to calculate the anisotropic optical properties of the thin films with oblique columnar structures. The effective refractive indices and the directions are calculated from effective medium theory. It is shown that optical thin films with predetermined refractive indices and birefringence may be engineered.

  10. Durable thin film coatings for reflectors used in low earth orbit

    NASA Technical Reports Server (NTRS)

    Mcclure, Donald J.

    1989-01-01

    This paper discusses the properties of thin film coatings used to provide a durable reflective surface for solar concentrators used in the solar dynamic system designed for the Space Station. The material system to be used consists of an adhesion promotion layer, a silver reflective layer, and a protective layer of aluminum oxide and silicon dioxide. The performance characteristics of this system are described and compared to those of several alternative systems which use aluminum as the reflective layer.

  11. Polycrystalline-thin-film thermophotovoltaic cells

    NASA Astrophysics Data System (ADS)

    Dhere, Neelkanth G.

    1996-02-01

    Thermophotovoltaic (TPV) cells convert thermal energy to electricity. Modularity, portability, silent operation, absence of moving parts, reduced air pollution, rapid start-up, high power densities, potentially high conversion efficiencies, choice of a wide range of heat sources employing fossil fuels, biomass, and even solar radiation are key advantages of TPV cells in comparison with fuel cells, thermionic and thermoelectric convertors, and heat engines. The potential applications of TPV systems include: remote electricity supplies, transportation, co-generation, electric-grid independent appliances, and space, aerospace, and military power applications. The range of bandgaps for achieving high conversion efficiencies using low temperature (1000-2000 K) black-body or selective radiators is in the 0.5-0.75 eV range. Present high efficiency convertors are based on single crystalline materials such as In1-xGaxAs, GaSb, and Ga1-xInxSb. Several polycrystalline thin films such as Hg1-xCdxTe, Sn1-xCd2xTe2, and Pb1-xCdxTe, etc., have great potential for economic large-scale applications. A small fraction of the high concentration of charge carriers generated at high fluences effectively saturates the large density of defects in polycrystalline thin films. Photovoltaic conversion efficiencies of polycrystalline thin films and PV solar cells are comparable to single crystalline Si solar cells, e.g., 17.1% for CuIn1-xGaxSe2 and 15.8% for CdTe. The best recombination-state density Nt is in the range of 10-15-10-16 cm-3 acceptable for TPV applications. Higher efficiencies may be achieved because of the higher fluences, possibility of bandgap tailoring, and use of selective emitters such as rare earth oxides (erbia, holmia, yttria) and rare earth-yttrium aluminium garnets. As compared to higher bandgap semiconductors such as CdTe, it is easier to dope the lower bandgap semiconductors. TPV cell development can benefit from the more mature PV solar cell and opto

  12. Fluorination of amorphous thin-film materials with xenon fluoride

    DOEpatents

    Weil, R.B.

    1987-05-01

    A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

  13. Fluorination of amorphous thin-film materials with xenon fluoride

    DOEpatents

    Weil, Raoul B.

    1988-01-01

    A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

  14. Dye-Sensitization Of Nanocrystalline ZnO Thin Films

    NASA Astrophysics Data System (ADS)

    Ajimsha, R. S.; Tyagi, M.; Das, A. K.; Misra, P.; Kukreja, L. M.

    2010-12-01

    Nannocrystalline and nanoporus thin films of ZnO were synthesized on glass substrates by using wet chemical drop casting method. X-ray diffraction measurements on these samples confirmed the formation of ZnO nanocrystallites in hexagonal wurtzite phase with mean size of ˜20 nm. Photo sensitization of these nanostructured ZnO thin films was carried out using three types of dyes Rhodamine 6 G, Chlorophyll and cocktail of Rhodamine 6 G and Chlorophyll in 1:1 ratio. Dye sensitized ZnO thin films showed enhanced optical absorption in visible spectral region compared to the pristine ZnO thin films.

  15. Uncooled thin film pyroelectric IR detector with aerogel thermal isolation

    DOEpatents

    Ruffner, Judith A.; Bullington, Jeff A.; Clem, Paul G.; Warren, William L.; Brinker, C. Jeffrey; Tuttle, Bruce A.; Schwartz, Robert W.

    1999-01-01

    A monolithic infrared detector structure which allows integration of pyroelectric thin films atop low thermal conductivity aerogel thin films. The structure comprises, from bottom to top, a substrate, an aerogel insulating layer, a lower electrode, a pyroelectric layer, and an upper electrode layer capped by a blacking layer. The aerogel can offer thermal conductivity less than that of air, while providing a much stronger monolithic alternative to cantilevered or suspended air-gap structures for pyroelectric thin film pixel arrays. Pb(Zr.sub.0.4 Ti.sub.0.6)O.sub.3 thin films deposited on these structures displayed viable pyroelectric properties, while processed at 550.degree. C.

  16. Applications of thin-film photovoltaics for space

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Hepp, Aloysius F.

    1991-01-01

    The authors discuss the potential applications of thin-film polycrystalline and amorphous cells for space. There have been great advances in thin-film solar cells for terrestrial applications. Transfer of this technology to space applications could result in ultra low-weight solar arrays with potentially large gains in specific power. Recent advances in thin-film solar cells are reviewed, including polycrystalline copper indium selenide and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon arrays. The possibility of using thin-film multi-bandgap cascade solar cells is discussed.

  17. Thin-Film Photovoltaics: Status and Applications to Space Power

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Hepp, Aloysius F.

    1991-01-01

    The potential applications of thin film polycrystalline and amorphous cells for space are discussed. There have been great advances in thin film solar cells for terrestrial applications; transfer of this technology to space applications could result in ultra low weight solar arrays with potentially large gains in specific power. Recent advances in thin film solar cells are reviewed, including polycrystalline copper iridium selenide and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon alloys. The possibility of thin film multi bandgap cascade solar cells is discussed.

  18. Structural characterization of impurified zinc oxide thin films

    SciTech Connect

    Trinca, L. M.; Galca, A. C. Stancu, V. Chirila, C. Pintilie, L.

    2014-11-05

    Europium doped zinc oxide (Eu:ZnO) thin films have been obtained by pulsed laser deposition (PLD). 002 textured thin films were achieved on glass and silicon substrates, while hetero-epilayers and homo-epilayers have been attained on single crystal SrTiO{sub 3} and ZnO, respectively. X-ray Diffraction (XRD) was employed to characterize the Eu:ZnO thin films. Extended XRD studies confirmed the different thin film structural properties as function of chosen substrates.

  19. Piezoelectric thin films and their applications for electronics

    NASA Astrophysics Data System (ADS)

    Yoshino, Yukio

    2009-03-01

    ZnO and AlN piezoelectric thin films have been studied for applications in bulk acoustic wave (BAW) resonator. This article introduces methods of forming ZnO and AlN piezoelectric thin films by radio frequency sputtering and applications of BAW resonators considering the relationship between the crystallinity of piezoelectric thin films and the characteristics of the BAW resonators. Using ZnO thin films, BAW resonators were fabricated for a contour mode at 3.58 MHz and thickness modes from 200 MHz to 5 GHz. The ZnO thin films were combined with various materials, substrates, and thin films to minimize the temperature coefficient of frequency (TCF). The minimum TCF of BAW resonators was approximately 2 ppm/°C in the range -20 to 80 °C. The electromechanical coupling coefficient (k2) in a 1.9 GHz BAW resonator was 6.9%. Using AlN thin films, 5-20 GHz BAW resonators with an ultrathin membrane were realized. The membrane thickness of a 20 GHz BAW resonator was about 200 nm, k2 was 6.1%, and the quality factor (Q) was about 280. Q decreased with increasing resonant frequency. The value of k2 is almost the same for 5-20 GHz resonators. This result could be obtained by improving the thickness uniformity, by controlling internal stress of thin films, and by controlling the crystallinity of AlN piezoelectric thin film.

  20. Dye-Sensitization Of Nanocrystalline ZnO Thin Films

    SciTech Connect

    Ajimsha, R. S.; Tyagi, M.; Das, A. K.; Misra, P.; Kukreja, L. M.

    2010-12-01

    Nannocrystalline and nanoporus thin films of ZnO were synthesized on glass substrates by using wet chemical drop casting method. X-ray diffraction measurements on these samples confirmed the formation of ZnO nanocrystallites in hexagonal wurtzite phase with mean size of {approx}20 nm. Photo sensitization of these nanostructured ZnO thin films was carried out using three types of dyes Rhodamine 6 G, Chlorophyll and cocktail of Rhodamine 6 G and Chlorophyll in 1:1 ratio. Dye sensitized ZnO thin films showed enhanced optical absorption in visible spectral region compared to the pristine ZnO thin films.

  1. Rechargeable thin film battery and method for making the same

    DOEpatents

    Goldner, Ronald B.; Liu, Te-Yang; Goldner, Mark A.; Gerouki, Alexandra; Haas, Terry E.

    2006-01-03

    A rechargeable, stackable, thin film, solid-state lithium electrochemical cell, thin film lithium battery and method for making the same is disclosed. The cell and battery provide for a variety configurations, voltage and current capacities. An innovative low temperature ion beam assisted deposition method for fabricating thin film, solid-state anodes, cathodes and electrolytes is disclosed wherein a source of energetic ions and evaporants combine to form thin film cell components having preferred crystallinity, structure and orientation. The disclosed batteries are particularly useful as power sources for portable electronic devices and electric vehicle applications where high energy density, high reversible charge capacity, high discharge current and long battery lifetimes are required.

  2. Role of asphaltenes in stabilizing thin liquid emulsion films.

    PubMed

    Tchoukov, Plamen; Yang, Fan; Xu, Zhenghe; Dabros, Tadeusz; Czarnecki, Jan; Sjöblom, Johan

    2014-03-25

    Drainage kinetics, thickness, and stability of water-in-oil thin liquid emulsion films obtained from asphaltenes, heavy oil (bitumen), and deasphalted heavy oil (maltenes) diluted in toluene are studied. The results show that asphaltenes stabilize thin organic liquid films at much lower concentrations than maltenes and bitumen. The drainage of thin organic liquid films containing asphaltenes is significantly slower than the drainage of the films containing maltenes and bitumen. The films stabilized by asphaltenes are much thicker (40-90 nm) than those stabilized by maltenes (∼10 nm). Such significant variation in the film properties points to different stabilization mechanisms of thin organic liquid films. Apparent aging effects, including gradual increase of film thickness, rigidity of oil/water interface, and formation of submicrometer size aggregates, were observed for thin organic liquid films containing asphaltenes. No aging effects were observed for films containing maltenes and bitumen in toluene. The increasing stability and lower drainage dynamics of asphaltene-containing thin liquid films are attributed to specific ability of asphaltenes to self-assemble and form 3D network in the film. The characteristic length of stable films is well beyond the size of single asphaltene molecules, nanoaggregates, or even clusters of nanoaggregates reported in the literature. Buildup of such 3D structure modifies the rheological properties of the liquid film to be non-Newtonian with yield stress (gel like). Formation of such network structure appears to be responsible for the slower drainage of thin asphaltenes in toluene liquid films. The yield stress of liquid film as small as ∼10(-2) Pa is sufficient to stop the drainage before the film reaches the critical thickness at which film rupture occurs. PMID:24564447

  3. Rechargeable thin-film electrochemical generator

    DOEpatents

    Rouillard, Roger; Domroese, Michael K.; Hoffman, Joseph A.; Lindeman, David D.; Noel, Joseph-Robert-Gaetan; Radewald, Vern E.; Ranger, Michel; Sudano, Anthony; Trice, Jennifer L.; Turgeon, Thomas A.

    2000-09-15

    An improved electrochemical generator is disclosed. The electrochemical generator includes a thin-film electrochemical cell which is maintained in a state of compression through use of an internal or an external pressure apparatus. A thermal conductor, which is connected to at least one of the positive or negative contacts of the cell, conducts current into and out of the cell and also conducts thermal energy between the cell and thermally conductive, electrically resistive material disposed on a vessel wall adjacent the conductor. The thermally conductive, electrically resistive material may include an anodized coating or a thin sheet of a plastic, mineral-based material or conductive polymer material. The thermal conductor is fabricated to include a resilient portion which expands and contracts to maintain mechanical contact between the cell and the thermally conductive material in the presence of relative movement between the cell and the wall structure. The electrochemical generator may be disposed in a hermetically sealed housing.

  4. Levan nanostructured thin films by MAPLE assembling.

    PubMed

    Sima, Felix; Mutlu, Esra Cansever; Eroglu, Mehmet S; Sima, Livia E; Serban, Natalia; Ristoscu, Carmen; Petrescu, Stefana M; Oner, Ebru Toksoy; Mihailescu, Ion N

    2011-06-13

    Synthesis of nanostructured thin films of pure and oxidized levan exopolysaccharide by matrix-assisted pulsed laser evaporation is reported. Solutions of pure exopolysaccharides in dimethyl sulfoxide were frozen in liquid nitrogen to obtain solid cryogenic pellets that have been used as targets in pulsed laser evaporation experiments with a KrF* excimer source. The expulsed material was collected and assembled onto glass slides and Si wafers. The contact angle studies evidenced a higher hydrophilic behavior in the case of oxidized levan structures because of the presence of acidic aldehyde-hydrogen bonds of the coating formed after oxidation. The obtained films preserved the base material composition as confirmed by Fourier transform infrared spectroscopy. They were compact with high specific surface areas, as demonstrated by scanning electron and atomic force microscopy investigations. In vitro colorimetric assays revealed a high potential for cell proliferation for all coatings with certain predominance for oxidized levan. PMID:21520921

  5. Galvanostatic Ion Detrapping Rejuvenates Oxide Thin Films.

    PubMed

    Arvizu, Miguel A; Wen, Rui-Tao; Primetzhofer, Daniel; Klemberg-Sapieha, Jolanta E; Martinu, Ludvik; Niklasson, Gunnar A; Granqvist, Claes G

    2015-12-01

    Ion trapping under charge insertion-extraction is well-known to degrade the electrochemical performance of oxides. Galvanostatic treatment was recently shown capable to rejuvenate the oxide, but the detailed mechanism remained uncertain. Here we report on amorphous electrochromic (EC) WO3 thin films prepared by sputtering and electrochemically cycled in a lithium-containing electrolyte under conditions leading to severe loss of charge exchange capacity and optical modulation span. Time-of-flight elastic recoil detection analysis (ToF-ERDA) documented pronounced Li(+) trapping associated with the degradation of the EC properties and, importantly, that Li(+) detrapping, caused by a weak constant current drawn through the film for some time, could recover the original EC performance. Thus, ToF-ERDA provided direct and unambiguous evidence for Li(+) detrapping. PMID:26599729

  6. Electron impinging on metallic thin film targets

    NASA Astrophysics Data System (ADS)

    Rouabah, Z.; Bouarissa, N.; Champion, C.

    2010-03-01

    Based on the Vicanek and Urbassek theory [M. Vicanek, H.M. Urbassek, Phys. Rev. B 44 (1991) 7234] combined to a home-made Monte Carlo simulation, the present work deals with backscattering coefficients, mean penetration depths and stopping profiles for 1-4 keV electrons normally incident impinging on Al and Cu thin film targets. The cross-sections used to describe the electron transport are calculated via the appropriate analytical expression given by Jablonski [A. Jablonski, Phys. Rev. B 58 (1998) 16470] whose new improved version has been recently given [Z. Rouabah, N. Bouarissa, C. Champion, N. Bouaouadja, Appl. Surf. Sci. 255 (2009) 6217]. The behavior of the backscattering coefficient, mean penetration depth and stopping profiles versus the metallic film thickness at the nanometric scale and beyond is here analyzed and discussed.

  7. Exchange stiffness in thin film Co alloys

    NASA Astrophysics Data System (ADS)

    Eyrich, C.; Huttema, W.; Arora, M.; Montoya, E.; Rashidi, F.; Burrowes, C.; Kardasz, B.; Girt, E.; Heinrich, B.; Mryasov, O. N.; From, M.; Karis, O.

    2012-04-01

    The exchange stiffness (Aex) is one of the key parameters controlling magnetization reversal in magnetic materials. We used a method based on the spin spiral formation in two ferromagnetic films antiferromagnetically coupled across a non-magnetic spacer layer and Brillouin scattering to measure Aex for a series of Co1-δXδ (X = Cr, Ni, Ru, Pd, Pt) thin film alloys. The results show that Aex of Co alloys does not necessarily scale with Ms; Aex approximately decreases at the rate of 1.1%, 1.5%, 2.1%, 3.5%, and 5.6%, while Ms decreases at the rate of 1.1%, 0.5%, 1.1%, 3.7%, and 2.5% per addition of 1 at % of Pt, Ni, Pd, Cr, and Ru, respectively.

  8. Thermoviscoelastic models for polyethylene thin films

    NASA Astrophysics Data System (ADS)

    Li, Jun; Kwok, Kawai; Pellegrino, Sergio

    2016-02-01

    This paper presents a constitutive thermoviscoelastic model for thin films of linear low-density polyethylene subject to strains up to yielding. The model is based on the free volume theory of nonlinear thermoviscoelasticity, extended to orthotropic membranes. An ingredient of the present approach is that the experimentally inaccessible out-of-plane material properties are determined by fitting the model predictions to the measured nonlinear behavior of the film. Creep tests, uniaxial tension tests, and biaxial bubble tests are used to determine the material parameters. The model has been validated experimentally, against data obtained from uniaxial tension tests and biaxial cylindrical tests at a wide range of temperatures and strain rates spanning two orders of magnitude.

  9. Process for making dense thin films

    DOEpatents

    Jacobson, Craig P.; Visco, Steven J.; DeJonghe, Lutgard C.

    2005-07-26

    Provided are low-cost, mechanically strong, highly electronically conductive porous substrates and associated structures for solid-state electrochemical devices, techniques for forming these structures, and devices incorporating the structures. The invention provides solid state electrochemical device substrates of novel composition and techniques for forming thin electrode/membrane/electrolyte coatings on the novel or more conventional substrates. In particular, in one embodiment the invention provides techniques for firing of device substrate to form densified electrolyte/membrane films 5 to 20 microns thick. In another embodiment, densified electrolyte/membrane films 5 to 20 microns thick may be formed on a pre-sintered substrate by a constrained sintering process. In some cases, the substrate may be a porous metal, alloy, or non-nickel cermet incorporating one or more of the transition metals Cr, Fe, Cu and Ag, or alloys thereof.

  10. High Performance Airbrushed Organic Thin Film Transistors

    SciTech Connect

    Chan, C.; Richter, L; Dinardo, B; Jaye, C; Conrad, B; Ro, H; Germack, D; Fischer, D; DeLongchamp, D; Gunlach, D

    2010-01-01

    Spray-deposited poly-3-hexylthiophene (P3HT) transistors were characterized using electrical and structural methods. Thin-film transistors with octyltrichlorosilane treated gate dielectrics and spray-deposited P3HT active layers exhibited a saturation regime mobility as high as 0.1 cm{sup 2} V{sup -1} s{sup -1}, which is comparable to the best mobilities observed in high molecular mass P3HT transistors prepared using other methods. Optical and atomic force microscopy showed the presence of individual droplets with an average diameter of 20 {micro}m and appreciable large-scale film inhomogeneities. Despite these inhomogeneities, near-edge x-ray absorption fine structure spectroscopy of the device-relevant channel interface indicated excellent orientation of the P3HT.

  11. Interface Effects in Perovskite Thin Films

    NASA Astrophysics Data System (ADS)

    Lepetit, Marie-Bernadette; Mercey, Bernard; Simon, Charles

    2012-02-01

    The control of matter properties (transport, magnetic, dielectric,…) using synthesis as thin films is strongly hindered by the lack of reliable theories, able to guide the design of new systems, through the understanding of the interface effects and of the way the substrate constraints are imposed on the material. The present Letter analyzes the energetic contributions at the interfaces, and proposes a model describing the microscopic mechanisms governing the interactions at an epitaxial interface between a manganite and another transition metal oxide in perovskite structure (as for instance SrTiO3). The model is checked against experimental results and literature analysis.

  12. Nanostructured thin films and their macrobehaviors

    NASA Astrophysics Data System (ADS)

    Lo, Mei-Ling; Liao, Shih-Fang; Lee, Cheng-Chung

    2014-08-01

    The iridescence green band and cyan tail of the wing on Papilio blumei butterfly were investigated. The bi-color phenomenon on the scales of butterfly wings was found and analyzed. The spectral change with thickness of chitin-air layers, width of air hole, total layer numbers and incident angle of light were simulated by FDTD method. 2D photonic-crystal model was applied to explain the change of reflectance spectra and color with angle. The replica of structural color and nanostructured thin films for Papilio blumei butterflies was fabricated successfully by three main techniques, PS spheres bedding, electron-beam gun evaporation and ICP etching.

  13. Robust, Thin Optical Films for Extreme Environments

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The environment of space presents scientists and engineers with the challenges of a harsh, unforgiving laboratory in which to conduct their scientific research. Solar astronomy and X-ray astronomy are two of the more challenging areas into which NASA scientists delve, as the optics for this high-tech work must be extremely sensitive and accurate, yet also be able to withstand the battering dished out by radiation, extreme temperature swings, and flying debris. Recent NASA work on this rugged equipment has led to the development of a strong, thin film for both space and laboratory use.

  14. Thin film photovoltaic device with multilayer substrate

    DOEpatents

    Catalano, Anthony W.; Bhushan, Manjul

    1984-01-01

    A thin film photovoltaic device which utilizes at least one compound semiconductor layer chosen from Groups IIB and VA of the Periodic Table is formed on a multilayer substrate The substrate includes a lowermost support layer on which all of the other layers of the device are formed. Additionally, an uppermost carbide or silicon layer is adjacent to the semiconductor layer. Below the carbide or silicon layer is a metal layer of high conductivity and expansion coefficient equal to or slightly greater than that of the semiconductor layer.

  15. Polydiacetylene thin films for nonlinear optical applications

    NASA Technical Reports Server (NTRS)

    Paley, Mark S.

    1993-01-01

    One very promising class of organic compounds for nonlinear optical (NLO) applications are polydiacetylenes, which are novel in that they are highly conjugated polymers which can also be crystalline. Polydiacetylenes offer several advantages over other organic materials: because of their highly conjugated electronic structures, they are capable of possessing large optical nonlinearities with fast response times; because they are crystalline, they can be highly ordered, which is essential for optimizing their NLO properties; and, last, because they are polymeric, they can be formed as thin films, which are useful for device fabrication. We have actively been carrying out ground-based research on several compounds of interest.

  16. Articles including thin film monolayers and multilayers

    SciTech Connect

    Li, DeQuan; Swanson, B.I.

    1992-12-31

    This invention pertains to thin film assemblies or devices useful as sensors, nonlinear optical materials, and trace material scavengers. It claims a base substrate having an oxide surface layer, and a multidentate ligand, capable of binding a metal ion, attached to the oxide surface layer of the base substrate. A metal species may be provided attached to the ligand, and a multifunctional organic ligand may be provided attached to the metal species. A second metal species may be provided attached to the multifunctional ligand.

  17. Thin film dielectric microstrip kinetic inductance detectors

    NASA Astrophysics Data System (ADS)

    Mazin, Benjamin A.; Sank, Daniel; McHugh, Sean; Lucero, Erik A.; Merrill, Andrew; Gao, Jiansong; Pappas, David; Moore, David; Zmuidzinas, Jonas

    2010-03-01

    Microwave kinetic inductance detectors, or MKIDs, are a type of low temperature detector that exhibit intrinsic frequency domain multiplexing at microwave frequencies. We present the first theory and measurements on a MKID based on a microstrip transmission line resonator. A complete characterization of the dielectric loss and noise properties of these resonators is performed, and agrees well with the derived theory. A competitive noise equivalent power of 5×10-17 W Hz-1/2 at 10 Hz has been demonstrated. The resonators exhibit the highest quality factors known in a microstrip resonator with a deposited thin film dielectric.

  18. Thin-Film Photovoltaic Device Fabrication

    NASA Technical Reports Server (NTRS)

    Scofield, John H.

    2003-01-01

    This project will primarily involve the fabrication and characterization of thin films and devices for photovoltaic applications. The materials involved include Il-VI materials such as zinc oxide, cadmium sulfide, and doped analogs. The equipment ot be used will be sputtering and physical evaporations. The types of characterization includes electrical, XRD, SEM and CV and related measurements to establish the efficiency of the devices. The faculty fellow will be involved in a research team composed of NASA and University researchers as well as students and other junior researchers.

  19. Effective dynamics for ferromagnetic thin films

    SciTech Connect

    Garcia-Cervera, Carlos J.; E, Weinan

    2001-07-01

    In a ferromagnetic material, the dynamics of the relaxation process are affected by the presence of a strong shape or material anisotropy. In this article, we systematically explore this fact to derive the effective dynamical equation for a soft ferromagnetic thin film. We show that, as a consequence of the interplay between shape anisotropy and damping, the gyromagnetic term is effectively also a damping term for the in-plane components of the magnetization distribution. We validate our result through numerical simulation of the original Landau{endash}Lifshitz equation and our effective equation. {copyright} 2001 American Institute of Physics.

  20. Sensitive detection of NMR for thin films.

    PubMed

    Lee, Soonchil

    2015-10-01

    NMR can provide valuable information about thin films, but its relatively low sensitivity allows data acquisition only from bulk samples. The sensitivity problem is circumvented by detection schemes with higher sensitivity and/or enhanced polarization. In most of these ingenious techniques, electrons play a central role through hyperfine interactions with the nuclei of interest or the conversion of the spin orientation to an electric charge. The state of the art in NMR is the control of a single nuclear spin state, the complete form of which is one of the ultimate goals of nanotechnology. PMID:26549846

  1. Stable localized patterns in thin liquid films

    NASA Technical Reports Server (NTRS)

    Deissler, Robert J.; Oron, Alexander

    1992-01-01

    A two-dimensional nonlinear evolution equation is studied which describes the three-dimensional spatiotemporal behavior of the air-liquid interface of a thin liquid film lying on the underside of a cooled horizontal plate. It is shown that the equation has a Liapunov functional, and this fact is exploited to demonstrate that the Marangoni effect can stabilize the destabilizing effect of gravity (the Rayleigh-Taylor instability), allowing for the existence of stable localized axisymmetric solutions for a wide range of parameter values. Various properties of these structures are discussed.

  2. Directed Assembly of Nanofilled Polymer Thin Films

    NASA Astrophysics Data System (ADS)

    Karim, Alamgir

    Facile directed self-assembly (DSA) of multicomponent thin films is important for potential technological applications. This requires a fine control of a complex interplay of processing parameters that need to be properly optimized for different organized structures. This talk will discuss some of our recent success towards realizing tunable DSA of soft matter multicomponent systems involving a dispersion of polymer-grafted nanoparticles in block copolymer or homopolymer matrices. DSA methods for such multicomponent films will be discussed. These include the use of zone-annealing with soft-shear to create highly anisotropic nanoparticle arrays, while direct immersion annealing (DIA) has been used to order nanoparticle filled films by dipping the films into controlled solvent quality solvent mixtures. A recently observed phenomena of confinement driven entropic order and phase segregation of polymer grafted nanoparticles in similar and dissimilar polymer matrices in melt state will be discussed. A high density of nano particles of different types ranging from metallic to inorganic to organic were patterned almost exclusively into channels via topographical soft confinement using entropic forces. Enthalpic interactions between the nanoparticle grafted layer and the polymer matrix could be used as a further handle to tune the directed assembly of the nanoparticles. The phenomena will be discussed in terms of confinement parameters, partition coefficient, free energy gain and entropic versus enthalpic interactions.

  3. Initial Steps of Rubicene Film Growth on Silicon Dioxide

    PubMed Central

    2013-01-01

    The film growth of the conjugated organic molecule rubicene on silicon dioxide was studied in detail. Since no structural data of the condensed material were available, we first produced high quality single crystals from solution and determined the crystal structure. This high purity material was used to prepare ultrathin films under ultrahigh vacuum conditions, by physical vapor deposition. Thermal desorption spectroscopy (TDS) was applied to delineate the adsorption and desorption kinetics. It could be shown that the initial sticking coefficient is only 0.2 ± 0.05, but the sticking coefficient increases with increasing coverage. TDS further revealed that first a closed, weakly bound bilayer develops (wetting layer), which dewets after further deposition of rubicene, leading to an island-like layer. These islands are crystalline and exhibit the same structure as the solution grown crystals. The orientation of the crystallites is with the (001) plane parallel to the substrate. A dewetting of the closed bilayer was also observed when the film was exposed to air. Furthermore, Ostwald ripening of the island-like film takes place under ambient conditions, leading to films composed of few, large crystallites. From TDS, we determined the heat of evaporation from the multilayer islands to be 1.47 eV, whereas the desorption energy from the first layer is only 1.25 eV. PMID:23476720

  4. Guided-mode-resonance-enhanced measurement of thin-film absorption.

    PubMed

    Wang, Yifei; Huang, Yin; Sun, Jingxuan; Pandey, Santosh; Lu, Meng

    2015-11-01

    We present a numerical and experimental study of a guided-mode-resonance (GMR) device for detecting surface-bound light-absorbing thin films. The GMR device functions as an optical resonator at the wavelength strongly absorbed by the thin film. The GMR mode produces an evanescent field that results in enhanced optical absorption by the thin film. For a 100-nm-thick lossy thin film, the GMR device enhances its absorption coefficients over 26 × compared to a conventional glass substrate. Simulations show the clear quenching effect of the GMR when the extinction coefficient is greater than 0.01. At the resonant wavelength, the reflectance of the GMR surface correlates well with the degree of optical absorption. GMR devices are fabricated on a glass substrate using a surface-relief grating and a titanium-dioxide coating. To analyze a visible absorbing dye, the reflection coefficient of dye-coated GMR devices was measured. The GMR-based method was also applied to detecting acid gases, such as hydrochloric vapor, by monitoring the change in absorption in a thin film composed of a pH indicator, bromocresol green. This technique potentially allows absorption analysis in the visible and infrared ranges using inexpensive equipment. PMID:26561126

  5. Organic thin films. Rational synthesis of organic thin films with exceptional long-range structural integrity.

    PubMed

    Seiki, Noriya; Shoji, Yoshiaki; Kajitani, Takashi; Ishiwari, Fumitaka; Kosaka, Atsuko; Hikima, Takaaki; Takata, Masaki; Someya, Takao; Fukushima, Takanori

    2015-06-01

    Highly oriented, domain-boundary-free organic thin films could find use in various high-performance organic materials and devices. However, even with state-of-the-art supramolecular chemistry, it is difficult to construct organic thin films with structural integrity in a size regime beyond the micrometer length scale. We show that a space-filling design, relying on the two-dimensional (2D) nested hexagonal packing of a particular type of triptycene, enables the formation of large-area molecular films with long-range 2D structural integrity up to the centimeter length scale by vacuum evaporation, spin-coating, and cooling from the isotropic liquid of the triptycene. X-ray diffraction analysis and microscopic observations reveal that triptycene molecules form a completely oriented 2D (hexagonal triptycene array) + 1D (layer stacking) structure, which is key for the long-range propagation of structural order. PMID:26045433

  6. Electrodeposited CulnSe2 Thin Film Junctions

    NASA Technical Reports Server (NTRS)

    Raffaelle, R. P.; Mantovani, J. G.; Bailey, S. G.; Hepp, A. F.; Gordon, E. M.; Haraway, R.

    1998-01-01

    We have investigated thin films and junctions based on copper indium diselenide (CIS) which have been grown by electrochemical deposition. CIS is a leading candidate for use in polycrystalline thin film photovoltaic solar cells. Electrodeposition is a cost-effective method for producing thin-film CIS. We have produced both p and n type CIS thin films from the same aqueous solution by simply varying the deposition potential. A CIS pn junction was deposited using a step-function potential. Stoichiometry of the single layer films was determined by energy dispersive spectroscopy. Carrier densities of these films increased with deviation from stoichiometry, as determined by the capacitance versus voltage dependence of Schottky contacts. Optical bandgaps for the single layer films as determined by transmission spectroscopy were also found to increase with deviation from stoichiometry. Rectifying current versus voltage characteristics were demonstrated for the Schottky barriers and for the pn junction.

  7. Electrodeposited CuInSe2 Thin Film Junctions

    NASA Technical Reports Server (NTRS)

    Raffaelle, R. P.; Mantovani, J. G.; Bailey, S. G.; Hepp, A. F.; Gordon, E. M.; Haraway, R.

    1997-01-01

    We have investigated thin films and junctions based on copper indium diselenide (CIS) which have been grown by electrochemical deposition. CIS is a leading candidate for use in polycrystalline thin film photovoltaic solar cells. Electrodeposition is a cost-effective method for producing thin-film CIS. We have produced both p and n type CIS thin films from the same aqueous solution by simply varying the deposition potential. A CIS pn junction was deposited using a step-function potential. Stoichiometry of the single layer films was determined by energy dispersive spectroscopy. Carrier densities of these films increased with deviation from stoichiometry, as determined by the capacitance versus voltage dependence of Schottky contacts. Optical bandgaps for the single layer films as determined by transmission spectroscopy were also found to increase with deviation from stoichiometry. Rectifying current versus voltage characteristics were demonstrated for the Schottky barriers and for the pn junction.

  8. Studies of Niobium Thin Film Produced by Energetic Vacuum Deposition

    SciTech Connect

    Genfa Wu; Anne-Marie Valente; H. Phillips; Haipeng Wang; Andy Wu; T. J. Renk; P Provencio

    2004-05-01

    An energetic vacuum deposition system has been used to study deposition energy effects on the properties of niobium thin films on copper and sapphire substrates. The absence of working gas avoids the gaseous inclusions commonly seen with sputtering deposition. A biased substrate holder controls the deposition energy. Transition temperature and residual resistivity ratio of the niobium thin films at several deposition energies are obtained together with surface morphology and crystal orientation measurements by AFM inspection, XRD and TEM analysis. The results show that niobium thin films on sapphire substrate exhibit the best cryogenic properties at deposition energy around 123 eV. The TEM analysis revealed that epitaxial growth of film was evident when deposition energy reaches 163 eV for sapphire substrate. Similarly, niobium thin film on copper substrate shows that film grows more oriented with higher deposition energy and grain size reaches the scale of the film thickness at the deposition energy around 153 eV.

  9. Antimony selenide thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Zeng, Kai; Xue, Ding-Jiang; Tang, Jiang

    2016-06-01

    Due to their promising applications in low-cost, flexible and high-efficiency photovoltaics, there has been a booming exploration of thin-film solar cells using new absorber materials such as Sb2Se3, SnS, FeS2, CuSbS2 and CuSbSe2. Among them, Sb2Se3-based solar cells are a viable prospect because of their suitable band gap, high absorption coefficient, excellent electronic properties, non-toxicity, low cost, earth-abundant constituents, and intrinsically benign grain boundaries, if suitably oriented. This review surveys the recent development of Sb2Se3-based solar cells with special emphasis on the material and optoelectronic properties of Sb2Se3, the solution-based and vacuum-based fabrication process and the recent progress of Sb2Se3-sensitized and Sb2Se3 thin-film solar cells. A brief overview further addresses some of the future challenges to achieve low-cost, environmentally-friendly and high-efficiency Sb2Se3 solar cells.

  10. Micromagnetic studies of thin metallic films (invited)

    NASA Astrophysics Data System (ADS)

    Zhu, Jian-Gang; Bertram, H. Neal

    1988-04-01

    A computer simulation model has been developed to conduct micromagnetic studies of thin magnetic films. Thin-film media are modeled as a planar hexagonal array of hexagonally shaped grains. Each grain is a single domain particle whose magnetization reverses by coherent rotation. The computation utilizes coupled gyromagnetic dynamic equations with phenomenological Landau-Lifshitz damping. In particular, the effects of particle interactions are investigated. The effect of media microstructure on magnetic hysteresis is examined as well as the effect of intergranular exchange coupling. The difference between planar and completely random orientation of the crystalline anisotropy axes is discussed. Recorded transitions are simulated by allowing a pair of perfect transitions to relax. With no intergranular exchange coupling, the transitions show profound irregularity and zig-zag structure. Intergranular exchange coupling produces more uniform transitions with increased zig-zag structure amplitude. For a closely spaced transition pair, the equilibrium configuration yields percolated transition boundaries with stable reverse island domains. The effect of gyromagnetic precession also has been examined.

  11. thin films toward less leakage currents

    NASA Astrophysics Data System (ADS)

    Yao, Zhao; Wang, Cong; Li, Yang; Kim, Hong-Ki; Kim, Nam-Young

    2014-08-01

    To prepare high-density integrated capacitors with low leakage currents, 0.2-μm-thick BaTiO3 thin films were successfully deposited on integrated semiconductor substrates at room temperature by the aerosol deposition (AD) method. In this study, the effects of starting powder size were considered in an effort to remove macroscopic defects. A surface morphology of 25.3 nm and an interface roughness of less than 50 nm were obtained using BT-03B starting powder. The nano-crystalline thin films achieved after deposition were annealed at various temperatures to promote crystallization and densification. Moreover, the influence of rapid thermal annealing process on the surface morphology and crystal growth was evaluated. As the annealing temperature increased from room temperature to 650°C, the root mean square (RMS) roughness decreased from 25.3 to 14.3 nm. However, the surface was transformed into rough performance at 750°C, which agreed well with the surface microstructure trend. Moreover, the crystal growth also reveals the changes in surface morphology via surface energy analysis.

  12. Thin-film Rechargeable Lithium Batteries

    DOE R&D Accomplishments Database

    Bates, J. B.; Gruzalski, G. R.; Dudney, N. J.; Luck, C. F.; Yu, X.

    1993-11-01

    Rechargeable thin films batteries with lithium metal anodes, an amorphous inorganic electrolyte, and cathodes of lithium intercalation compounds have been fabricated and characterized. The cathodes include TiS{sub 2}, the {omega} phase of V{sub 2}O{sub 5}, and the cubic spinel Li{sub x}Mn{sub 2}O{sub 4} with open circuit voltages at full charge of about 2.5 V, 3.7 V, and 4.2 V, respectively. The development of these robust cells, which can be cycled thousands of times, was possible because of the stability of the amorphous lithium electrolyte, lithium phosphorus oxynitride. This material has a typical composition of Li{sub 2.9}PO{sub 3.3}N{sub 0.46} and a conductivity at 25 C of 2 {mu}S/cm. Thin film cells have been cycled at 100% depth of discharge using current densities of 2 to 100 {mu}A/cm{sup 2}. The polarization resistance of the cells is due to the slow insertion rate of Li{sup +} ions into the cathode. Chemical diffusion coefficients for Li{sup +} ions in the three types of cathodes have been estimated from the analysis of ac impedance measurements.

  13. Dynamic interfaces in an organic thin film

    PubMed Central

    Tao, Chenggang; Liu, Qiang; Riddick, Blake C.; Cullen, William G.; Reutt-Robey, Janice; Weeks, John D.; Williams, Ellen D.

    2008-01-01

    Low-dimensional boundaries between phases and domains in organic thin films are important in charge transport and recombination. Here, fluctuations of interfacial boundaries in an organic thin film, acridine-9-carboxylic acid on Ag(111), have been visualized in real time and measured quantitatively using scanning tunneling microscopy. The boundaries fluctuate via molecular exchange with exchange time constants of 10–30 ms at room temperature, with length-mode fluctuations that should yield characteristic f−1/2 signatures for frequencies less than ≈100 Hz. Although acridine-9-carboxylic acid has highly anisotropic intermolecular interactions, it forms islands that are compact in shape with crystallographically distinct boundaries that have essentially identical thermodynamic and kinetic properties. The physical basis of the modified symmetry is shown to arise from significantly different substrate interactions induced by alternating orientations of successive molecules in the condensed phase. Incorporating this additional set of interactions in a lattice–gas model leads to effective multicomponent behavior, as in the Blume–Emery–Griffiths model, and can straightforwardly reproduce the experimentally observed isotropic behavior. The general multicomponent description allows the domain shapes and boundary fluctuations to be tuned from isotropic to highly anisotropic in terms of the balance between intermolecular interactions and molecule–substrate interactions. PMID:18765797

  14. Optical thin film metrology for optoelectronics

    NASA Astrophysics Data System (ADS)

    Petrik, Peter

    2012-12-01

    The manufacturing of optoelectronic thin films is of key importance, because it underpins a significant number of industries. The aim of the European joint research project for optoelectronic thin film characterization (IND07) in the European Metrology Research Programme of EURAMET is to develop optical and X-ray metrologies for the assessment of quality as well as key parameters of relevant materials and layer systems. This work is intended to be a step towards the establishment of validated reference metrologies for the reliable characterization, and the development of calibrated reference samples with well-defined and controlled parameters. In a recent comprehensive study (including XPS, AES, GD-OES, GD-MS, SNMS, SIMS, Raman, SE, RBS, ERDA, GIXRD), Abou-Ras et al. (Microscopy and Microanalysis 17 [2011] 728) demonstrated that most characterization techniques have limitations and bottle-necks, and the agreement of the measurement results in terms of accurate, absolute values is not as perfect as one would expect. This paper focuses on optical characterization techniques, laying emphasis on hardware and model development, which determine the kind and number of parameters that can be measured, as well as their accuracy. Some examples will be discussed including optical techniques and materials for photovoltaics, biosensors and waveguides.

  15. Apparatus for laser assisted thin film deposition

    DOEpatents

    Warner, Bruce E.; McLean, II, William

    1996-01-01

    A pulsed laser deposition apparatus uses fiber optics to deliver visible output beams. One or more optical fibers are coupled to one or more laser sources, and delivers visible output beams to a single chamber, to multiple targets in the chamber or to multiple chambers. The laser can run uninterrupted if one of the deposition chambers ceases to operate because other chambers can continue their laser deposition processes. The laser source can be positioned at a remote location relative to the deposition chamber. The use of fiber optics permits multi-plexing. A pulsed visible laser beam is directed at a generally non-perpendicular angle upon the target in the chamber, generating a plume of ions and energetic neutral species. A portion of the plume is deposited on a substrate as a thin film. A pulsed visible output beam with a high pulse repetition frequency is used. The high pulse repetition frequency is greater than 500 Hz, and more preferably, greater than about 1000 Hz. Diamond-like-carbon (DLC) is one of the thin films produced using the apparatus.

  16. Apparatus for laser assisted thin film deposition

    DOEpatents

    Warner, B.E.; McLean, W. II

    1996-02-13

    A pulsed laser deposition apparatus uses fiber optics to deliver visible output beams. One or more optical fibers are coupled to one or more laser sources, and delivers visible output beams to a single chamber, to multiple targets in the chamber or to multiple chambers. The laser can run uninterrupted if one of the deposition chambers ceases to operate because other chambers can continue their laser deposition processes. The laser source can be positioned at a remote location relative to the deposition chamber. The use of fiber optics permits multi-plexing. A pulsed visible laser beam is directed at a generally non-perpendicular angle upon the target in the chamber, generating a plume of ions and energetic neutral species. A portion of the plume is deposited on a substrate as a thin film. A pulsed visible output beam with a high pulse repetition frequency is used. The high pulse repetition frequency is greater than 500 Hz, and more preferably, greater than about 1000 Hz. Diamond-like-carbon (DLC) is one of the thin films produced using the apparatus. 9 figs.

  17. ``Verso'' laser cleaning of mechanically thin films

    NASA Astrophysics Data System (ADS)

    Barone, Alberto; Bloisi, Francesco; Vicari, Luciano

    2003-03-01

    In usual dry laser cleaning of opaque samples, short laser pulses are projected onto the sample surface to be cleaned. Energy transferred from light ejects extraneous particles away from the surface. Laser beam fluence is limited by the damage reached by high temperature that the sample surface can produce. We have experimentally shown that for thin samples, the thermo-elastic wave propagates within the whole sample thickness, thus also the rear surface, while temperature effects are limited to the front surface. Therefore, the proposed "verso" laser cleaning technique (the pulsed laser beam impinges on rear sample surface) can be applied to any opaque "mechanically thin" film and is useful for samples having delicate treatments on the surface to be cleaned (e.g. written paper, painted tiles, magnetic films). We have applied our technique to paper sheets showing that it is possible to efficiently clean the surface without damaging ink marks on it. Using a probe beam deflection (PBD) technique in both direct and reverse configuration we have shown that the "verso" cleaning effect is due to the higher penetration depth of the thermo-elastic wave with respect to the temperature profile propagation.

  18. Ti-Cr-Al-O Thin Film Resistors

    SciTech Connect

    Jankowski, A F; Hayes, J P

    2002-03-21

    Thin films of Ti-Cr-Al-O are produced for use as an electrical resistor material. The films are rf sputter deposited from ceramic targets using a reactive working gas mixture of Ar and O{sub 2}. Vertical resistivity values from 10{sup 4} to 10{sup 10} Ohm-cm are measured for Ti-Cr-Al-O films. The film resistivity can be design selected through control of the target composition and the deposition parameters. The Ti-Cr-Al-O thin film resistor is found to be thermally stable unlike other metal-oxide films.

  19. Method of improving field emission characteristics of diamond thin films

    DOEpatents

    Krauss, Alan R.; Gruen, Dieter M.

    1999-01-01

    A method of preparing diamond thin films with improved field emission properties. The method includes preparing a diamond thin film on a substrate, such as Mo, W, Si and Ni. An atmosphere of hydrogen (molecular or atomic) can be provided above the already deposited film to form absorbed hydrogen to reduce the work function and enhance field emission properties of the diamond film. In addition, hydrogen can be absorbed on intergranular surfaces to enhance electrical conductivity of the diamond film. The treated diamond film can be part of a microtip array in a flat panel display.

  20. The role of microstructural phenomena in magnetic thin films

    SciTech Connect

    Laughlin, D.E.; Lambeth, D.N.

    1992-12-31

    The subject is germane to magnetic recording media. Results during the first 2 years are presented under the following headings: atomic resolution TEM of CoNiCr films; CoNiCr and CoCrTa thin films; development of texture; and CoSm/Cr thin films. The HREM results showed that defects in Co-based films may be responsible for higher coercivity. Findings are presented on the effects of Cr interlayers on the microstructure of the second Co-based film in Co/Cr/Co/Cr multilayer films. Proposed research plans are outlined.

  1. The role of microstructural phenomena in magnetic thin films

    SciTech Connect

    Laughlin, D.E.; Lambeth, D.N.

    1992-01-01

    The subject is germane to magnetic recording media. Results during the first 2 years are presented under the following headings: atomic resolution TEM of CoNiCr films; CoNiCr and CoCrTa thin films; development of texture; and CoSm/Cr thin films. The HREM results showed that defects in Co-based films may be responsible for higher coercivity. Findings are presented on the effects of Cr interlayers on the microstructure of the second Co-based film in Co/Cr/Co/Cr multilayer films. Proposed research plans are outlined.

  2. Method of improving field emission characteristics of diamond thin films

    DOEpatents

    Krauss, A.R.; Gruen, D.M.

    1999-05-11

    A method of preparing diamond thin films with improved field emission properties is disclosed. The method includes preparing a diamond thin film on a substrate, such as Mo, W, Si and Ni. An atmosphere of hydrogen (molecular or atomic) can be provided above the already deposited film to form absorbed hydrogen to reduce the work function and enhance field emission properties of the diamond film. In addition, hydrogen can be absorbed on intergranular surfaces to enhance electrical conductivity of the diamond film. The treated diamond film can be part of a microtip array in a flat panel display. 3 figs.

  3. The role of microstructural phenomena in magnetic thin films

    NASA Astrophysics Data System (ADS)

    Laughlin, D. E.; Lambeth, D. N.

    Magnetic recording media is studied. Results during the first 2 years are presented under the following headings: atomic resolution transmission electron microscopy (TEM) of CoNiCr films; CoNiCr and CoCrTa thin films; development of texture; and CoSm/Cr thin films. The high resolution electron microscopy (HREM) results showed that defects in Co-based films may be responsible for higher coercivity. Findings are presented on the effects of Cr interlayers on the microstructure of the second Co-based film in Co/Cr/Co/Cr multilayer films. Proposed research plans are outlined.

  4. Nanocomposite thin films exhibiting high mechanical and optical flexibility

    NASA Astrophysics Data System (ADS)

    Druffel, Thad; Buazza, Omar; Lattis, Matt; Farmer, Scott

    2008-08-01

    Nanocomposites are created by doping host polymers with nanoparticles that typically have higher or lower refractive indices. The ability to tailor the mechanical and optical performance of these composites has led to their increased use in transparent materials. Nanocomposites maintain the elastic properties of the binding polymers and exhibit infinite refractive index tunability between the limits of the system. These unique properties provide distinct benefits for multilayer, thin-film optical filters. Because the nanoparticles are dispersed in a fluid or bound in a polymer matrix in use, toxicity risks that may be associated with raw particles are reduced. Using a stable dispersion of titanium dioxide nanoparticles and a UV curable monomer, we were able to design and produce several quarter-wave filters that demonstrate control of the height and width of the passband through adjustment of the organic/inorganic ratio and layer count. The volume loading of the metal oxides can be adjusted from zero to near the theoretical packing density of spheres, allowing refractive index to be controlled over a large range. Because metal oxide particles exhibit high UV absorption, these additives provide UV protection to the host polymer and the filter's substrate. Additionally, significant improvements in abrasion resistance are often observed in films loaded with nanoparticles at the concentrations of interest.

  5. Properties of VO 2 thin film prepared with precursor VO(acac) 2

    NASA Astrophysics Data System (ADS)

    Pan, Mei; Zhong, Hongmei; Wang, Shaowei; Liu, Jie; Li, Zhifeng; Chen, Xiaoshuang; Lu, Wei

    2004-04-01

    Both pure and tungsten (W)- or chromium (Cr)-doped vanadium dioxide (VO 2) thin films have been deposited by the sol-gel method on Si substrate using VO(acac) 2 as a precursor. XRD, Raman and atomic force microscopy (AFM) measurements showed the high (1 1 0) orientation of the films. It was found that the temperature coefficient of resistivity (TCR) values of the films around room temperature could be adjusted by impurity doping. Compared with the un-doped VO 2 films, the W-doping leads to larger TCR values, while the Cr-doping leads to smaller ones. The TCR value is linearly dependent on the impurity at room temperature. The largest TCR value of 5.2/% K -1 was obtained for 20/at% W-doped VO 2 film.

  6. Study of the optical properties of SiOxNy thin films by effective medium theories

    NASA Astrophysics Data System (ADS)

    Tan, X.; Wojcik, J.; Mascher, P.

    2004-07-01

    Silicon oxynitride (SiOxNy) films were deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) and covered the entire composition range from silicon dioxide to silicon nitride. The composition of the films was determined by Rutherford backscattering spectroscopy (RBS), nuclear reaction analysis (NRA), and elastic recoil detection (ERD). These techniques provide the absolute areal concentrations of all elements, including silicon, oxygen, nitrogen, and hydrogen. Additionally, Fourier transform infrared (FTIR) spectroscopy and ellipsometry measurements were performed for the optical characterization of the thin films. Effective medium theories (EMT) were used to model the optical and compositional properties of the SiOxNy films. The refractive index measured by ellipsometry was compared with theoretical calculations using Maxwell-Garnett and Bruggeman equations. The experimental results agree quite well with model data. It is also shown that the concentration of hydrogen in the films has a major influence on the quality of the agreement. .

  7. Microstructural and mechanical characteristics of Ni–Cr thin films

    SciTech Connect

    Petley, Vijay; Sathishkumar, S.; Thulasi Raman, K.H.; Rao, G.Mohan; Chandrasekhar, U.

    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 texture 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.

  8. Use of thin films in high-temperature superconducting bearings.

    SciTech Connect

    Hull, J. R.; Cansiz, A.

    1999-09-30

    In a PM/HTS bearing, locating a thin-film HTS above a bulk HTS was expected to maintain the large levitation force provided by the bulk with a lower rotational drag provided by the very high current density of the film. For low drag to be achieved, the thin film must shield the bulk from inhomogeneous magnetic fields. Measurement of rotational drag of a PM/HTS bearing that used a combination of bulk and film HTS showed that the thin film is not effective in reducing the rotational drag. Subsequent experiments, in which an AC coil was placed above the thin-film HTS and the magnetic field on the other side of the film was measured, showed that the thin film provides good shielding when the coil axis is perpendicular to the film surface but poor shielding when the coil axis is parallel to the surface. This is consistent with the lack of reduction in rotational drag being due to a horizontal magnetic moment of the permanent magnet. The poor shielding with the coil axis parallel to the film surface is attributed to the aspect ratio of the film and the three-dimensional nature of the current flow in the film for this coil orientation.

  9. Reactive thin film flows over spinning discs

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Wray, Alex; Yang, Junfeng; Matar, Omar

    2015-11-01

    We consider the dynamics of a thin film flowing over a spinning disc in the presence of a chemical reaction, and associated heat and mass transfer. We use a boundary-layer approximation in conjunction with the Karman-Polhausen approximation for the velocity distribution in the film to derive a set of coupled one-dimensional evolution equations for the film thickness, radial and azimuthal flow rates, concentration of the reagents and products, and temperature. These highly nonlinear partial differential equations are solved numerically to reveal the formation of large-amplitude waves that travel from the disc inlet to its periphery. The influence of these waves on the concentration and temperature profiles is analysed for a wide range of system parameters: the Damkohler and Schmidt numbers, the thermal Peclet numbers, and the dimensionless disc radius (a surrogate for the Eckman number). It is shown that these waves lead to significant enhancement of the rates of heat and mass transfer associated with the reactive flow; these are measured by tracking the temporal evolution of local and spatially-averaged Nusselt and Sherwood numbers, respectively. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  10. Controlled nanostructuration of polycrystalline tungsten thin films

    SciTech Connect

    Girault, B.; Eyidi, D.; Goudeau, P.; Guerin, P.; Bourhis, E. Le; Renault, P.-O.; Sauvage, T.

    2013-05-07

    Nanostructured tungsten thin films have been obtained by ion beam sputtering technique stopping periodically the growing. The total thickness was maintained constant while nanostructure control was obtained using different stopping periods in order to induce film stratification. The effect of tungsten sublayers' thicknesses on film composition, residual stresses, and crystalline texture evolution has been established. Our study reveals that tungsten crystallizes in both stable {alpha}- and metastable {beta}-phases and that volume proportions evolve with deposited sublayers' thicknesses. {alpha}-W phase shows original fiber texture development with two major preferential crystallographic orientations, namely, {alpha}-W<110> and unexpectedly {alpha}-W<111> texture components. The partial pressure of oxygen and presence of carbon have been identified as critical parameters for the growth of metastable {beta}-W phase. Moreover, the texture development of {alpha}-W phase with two texture components is shown to be the result of a competition between crystallographic planes energy minimization and crystallographic orientation channeling effect maximization. Controlled grain size can be achieved for the {alpha}-W phase structure over 3 nm stratification step. Below, the {beta}-W phase structure becomes predominant.

  11. Vertically aligned biaxially textured molybdenum thin films

    SciTech Connect

    Krishnan, Rahul; Riley, Michael; Lee, Sabrina; Lu, Toh-Ming

    2011-09-15

    Vertically aligned, biaxially textured molybdenum nanorods were deposited using dc magnetron sputtering with glancing flux incidence (alpha = 85 degrees with respect to the substrate normal) and a two-step substrate-rotation mode. These nanorods were identified with a body-centered cubic crystal structure. The formation of a vertically aligned biaxial texture with a [110] out-of-plane orientation was combined with a [-110] in-plane orientation. The kinetics of the growth process was found to be highly sensitive to an optimum rest time of 35 seconds for the two-step substrate rotation mode. At all other rest times, the nanorods possessed two separate biaxial textures each tilted toward one flux direction. While the in-plane texture for the vertical nanorods maintains maximum flux capture area, inclined Mo nanorods deposited at alpha = 85 degrees without substrate rotation display a [-1-1-4] in-plane texture that does not comply with the maximum flux capture area argument. Finally, an in situ capping film was deposited with normal flux incidence over the biaxially textured vertical nanorods resulting in a thin film over the porous nanorods. This capping film possessed the same biaxial texture as the nanorods and could serve as an effective substrate for the epitaxial growth of other functional materials.

  12. Amorphous molybdenum silicon superconducting thin films

    SciTech Connect

    Bosworth, D. Sahonta, S.-L.; Barber, Z. H.; Hadfield, R. H.

    2015-08-15

    Amorphous superconductors have become attractive candidate materials for superconducting nanowire single-photon detectors due to their ease of growth, homogeneity and competitive superconducting properties. To date the majority of devices have been fabricated using W{sub x}Si{sub 1−x}, though other amorphous superconductors such as molybdenum silicide (Mo{sub x}Si{sub 1−x}) offer increased transition temperature. This study focuses on the properties of MoSi thin films grown by magnetron sputtering. We examine how the composition and growth conditions affect film properties. For 100 nm film thickness, we report that the superconducting transition temperature (Tc) reaches a maximum of 7.6 K at a composition of Mo{sub 83}Si{sub 17}. The transition temperature and amorphous character can be improved by cooling of the substrate during growth which inhibits formation of a crystalline phase. X-ray diffraction and transmission electron microscopy studies confirm the absence of long range order. We observe that for a range of 6 common substrates (silicon, thermally oxidized silicon, R- and C-plane sapphire, x-plane lithium niobate and quartz), there is no variation in superconducting transition temperature, making MoSi an excellent candidate material for SNSPDs.

  13. Oxynitride Thin Film Barriers for PV Packaging

    SciTech Connect

    Glick, S. H.; delCueto, J. A.; Terwilliger, K. M.; Jorgensen, G. J.; Pankow, J. W.; Keyes, B. M.; Gedvilas, L. M.; Pern, F. J.

    2005-11-01

    Dielectric thin-film barrier and adhesion-promoting layers consisting of silicon oxynitride materials (SiOxNy, with various stoichiometry) were investigated. For process development, films were applied to glass (TCO, conductive SnO2:F; or soda-lime), polymer (PET, polyethylene terephthalate), aluminized soda-lime glass, or PV cell (a-Si, CIGS) substrates. Design strategy employed de-minimus hazard criteria to facilitate industrial adoption and reduce implementation costs for PV manufacturers or suppliers. A restricted process window was explored using dilute compressed gases (3% silane, 14% nitrous oxide, 23% oxygen) in nitrogen (or former mixtures, and 11.45% oxygen mix in helium and/or 99.999% helium dilution) with a worst-case flammable and non-corrosive hazard classification. Method employed low radio frequency (RF) power, less than or equal to 3 milliwatts per cm2, and low substrate temperatures, less than or equal to 100 deg C, over deposition areas less than or equal to 1000 cm2. Select material properties for barrier film thickness (profilometer), composition (XPS/FTIR), optical (refractive index, %T and %R), mechanical peel strength and WVTR barrier performance are presented.

  14. Pressureless Bonding Using Sputtered Ag Thin Films

    NASA Astrophysics Data System (ADS)

    Oh, Chulmin; Nagao, Shijo; Suganuma, Katsuaki

    2014-12-01

    To improve the performance and reliability of power electronic devices, particularly those built around next-generation wide-bandgap semiconductors such as SiC and GaN, the bonding method used for packaging must change from soldering to solderless technology. Because traditional solders are problematic in the harsh operating conditions expected for emerging high-temperature power devices, we propose a new bonding method in this paper, namely a pressureless, low-temperature bonding process in air, using abnormal grain growth on sputtered Ag thin films to realize extremely high temperature resistance. To investigate the mechanisms of this bonding process, we characterized the microstructural changes in the Ag films over various bonding temperatures and times. We measured the bonding properties of the specimens by a die-shear strength test, as well as by x-ray diffraction measurements of the residual stress in the Ag films to show how the microstructural developments were essential to the bonding technology. Sound bonds with high die strength can be achieved only with abnormal grain growth at optimum bonding temperature and time. Pressureless bonding allows for production of reliable high-temperature power devices for a wide variety of industrial, energy, and environmental applications.

  15. Eutectic bonds on wafer scale by thin film multilayers

    NASA Astrophysics Data System (ADS)

    Christensen, Carsten; Bouwstra, Siebe

    1996-09-01

    The use of gold based thin film multilayer systems for forming eutectic bonds on wafer scale is investigated and preliminary results will be presented. On polished 4 inch wafers different multilayer systems are developed using thin film techniques and bonded afterwards under reactive atmospheres and different bonding temperatures and forces. Pull tests are performed to extract the bonding strengths.

  16. Applications of Thin Film Thermocouples for Surface Temperature Measurement

    NASA Technical Reports Server (NTRS)

    Martin, Lisa C.; Holanda, Raymond

    1994-01-01

    Thin film thermocouples provide a minimally intrusive means of measuring surface temperature in hostile, high temperature environments. Unlike wire thermocouples, thin films do not necessitate any machining of the surface, therefore leaving intact its structural integrity. Thin films are many orders of magnitude thinner than wire, resulting in less disruption to the gas flow and thermal patterns that exist in the operating environment. Thin film thermocouples have been developed for surface temperature measurement on a variety of engine materials. The sensors are fabricated in the NASA Lewis Research Center's Thin Film Sensor Lab, which is a class 1000 clean room. The thermocouples are platinum-13 percent rhodium versus platinum and are fabricated by the sputtering process. Thin film-to-leadwire connections are made using the parallel-gap welding process. Thermocouples have been developed for use on superalloys, ceramics and ceramic composites, and intermetallics. Some applications of thin film thermocouples are: temperature measurement of space shuttle main engine turbine blade materials, temperature measurement in gas turbine engine testing of advanced materials, and temperature and heat flux measurements in a diesel engine. Fabrication of thin film thermocouples is described. Sensor durability, drift rate, and maximum temperature capabilities are addressed.

  17. Tools to Synthesize the Learning of Thin Films

    ERIC Educational Resources Information Center

    Rojas, Roberto; Fuster, Gonzalo; Slusarenko, Viktor

    2011-01-01

    After a review of textbooks written for undergraduate courses in physics, we have found that discussions on thin films are mostly incomplete. They consider the reflected and not the transmitted light for two instead of the four types of thin films. In this work, we complement the discussion in elementary textbooks, by analysing the phase…

  18. Progress in polycrystalline thin-film solar cells

    SciTech Connect

    Zweibel, K; Hermann, A; Mitchell, R

    1983-07-01

    Photovoltaic devices based on several polycrystalline thin-film materials have reached near and above 10% sunlight-to-electricity conversion efficiencies. This paper examines the various polycrystalline thin-film PV materials including CuInSe/sub 2/ and CdTe in terms of their material properties, fabrication techniques, problems, and potentials.

  19. Semipermeable thin-film membranes comprising siloxane, alkoxysilyl and aryloxysilyl oligomers and copolymers

    DOEpatents

    Babcock, Walter C.; Friesen, Dwayne T.

    1988-01-01

    Novel semiperimeable membranes and thin film composite (TFC) gas separation membranes useful in the separation of oxygen, nitrogen, hydrogen, water vapor, methane, carbon dioxide, hydrogen sulfide, lower hydrocarbons, and other gases are disclosed. The novel semipermeable membranes comprise the polycondensation reaction product of two complementary polyfunctional compounds, each having at least two functional groups that are mutually reactive in a condensation polymerization reaction, and at least one of which is selected from siloxanes, alkoxsilyls and aryloxysilyls. The TFC membrane comprises a microporous polymeric support, the surface of which has the novel semipermeable film formed thereon, preferably by interfacial polymerization.

  20. Semipermeable thin-film membranes comprising siloxane, alkoxysilyl and aryloxysilyl oligomers and copolymers

    DOEpatents

    Babcock, W.C.; Friesen, D.T.

    1988-11-01

    Novel semipermeable membranes and thin film composite (TFC) gas separation membranes useful in the separation of oxygen, nitrogen, hydrogen, water vapor, methane, carbon dioxide, hydrogen sulfide, lower hydrocarbons, and other gases are disclosed. The novel semipermeable membranes comprise the polycondensation reaction product of two complementary polyfunctional compounds, each having at least two functional groups that are mutually reactive in a condensation polymerization reaction, and at least one of which is selected from siloxanes, alkoxsilyls and aryloxysilyls. The TFC membrane comprises a microporous polymeric support, the surface of which has the novel semipermeable film formed thereon, preferably by interfacial polymerization.