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Sample records for oxide film obta

  1. Structural conformation in a poly (ethylene oxide) film obta inedfrom X-ray emission spectroscopy (XES)

    SciTech Connect

    Kashtanov, S.; Zhuang, G.V.; Augustsson, A.; Guo, J.-H.; Nordgren, J.; Luo, Y.; Ross, P.N.

    2007-03-16

    The electronic structure of poly(ethylene oxide) (PEO) in a thin (< 1 {micro}) film sample was experimentally probed by X-ray emission spectroscopy. The emission spectra from this film were much sharper with more resolved fine structure than the spectra from the bulk polymer from which it was cast. Both non-resonant and resonant X-ray emission spectra were simulated using density functional theory (DFT) applied to four different models representing different conformations in the polymer. Calculated spectra were compared with experimental results for the PEO film. It was found that the best fit was obtained with the polymer conformation in PEO electrolytes from which the salt (LiMF6, M=P, As, or Sb) had been removed. This conformation is different from that in the crystalline bulk polymer and implies that film casting, commonly used to form electrolytes for Li polymer batteries, induces the same conformation in the polymer with or without the salt present.

  2. Stabilized chromium oxide film

    DOEpatents

    Garwin, Edward L.; Nyaiesh, Ali R.

    1988-01-01

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150.ANG. are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

  3. Stabilized chromium oxide film

    DOEpatents

    Nyaiesh, A.R.; Garwin, E.L.

    1986-08-04

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150A are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

  4. Metal oxide films on metal

    DOEpatents

    Wu, Xin D.; Tiwari, Prabhat

    1995-01-01

    A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

  5. Electrochromism in nickel oxide films

    SciTech Connect

    Wruck, D.A.

    1991-01-01

    Optical absorption in a thin-film nickel oxide electrode depends on the state of charge of the electrode; the effect has been called electrochromism, and it may have practical applications in low-speed light modulation devices. In this dissertation, the physical and chemical processes which lead to the change in optical properties are investigated. Preparation of NiO film electrodes by reactive sputtering of a Ni target in an Ar + O[sub 2] gas mixture is described, and the electrochromic response is correlated to film growth conditions. Structural, electronic, and electrochemical properties of the NiO films are characterized by x-ray diffraction, infrared absorption, x-ray photoemission, optical absorption, electrical conductivity, and electrochemical measurements. It is proposed that the electrochromism results from the adsorption and desorption of protons at the oxygen-rich surface of a granular and porous NiO film. The surface electronic levels are then modified by the presence or absence of the O-H bonds, and the effect on the film electronic properties is discussed. A general discussion is also given of the current-limiting processes at the NiO film electrodes.

  6. Process for fabrication of metal oxide films

    SciTech Connect

    Tracy, C.E.; Benson, D.; Svensson, S.

    1990-07-17

    This invention is comprised of a method of fabricating metal oxide films from a plurality of reactants by inducing a reaction by plasma deposition among the reactants. The plasma reaction is effective for consolidating the reactants and producing thin films of metal oxides, e.g. electro-optically active transition metal oxides, at a high deposition rate. The presence of hydrogen during the plasma reaction enhances the deposition rate of the metal oxide. Various types of metal oxide films can be produced.

  7. 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.

  8. Silicon oxide films grown in microwave discharge

    NASA Technical Reports Server (NTRS)

    Kraitchman, J.

    1968-01-01

    Silicon oxide films thicker than 1000 angstrom are produced in the dense plasma of a microwave discharge. The oxide growth is characterized by a rate limiting diffusion process modified by sputtering effects produced by the discharge. Silicon is rapidly oxidized at temperatures estimated to be 500 degrees C or lower.

  9. 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.

  10. CVD diamond film oxidation resistance research

    NASA Astrophysics Data System (ADS)

    Jing, Longwei; Wang, Xiaoping; Wang, Lijun; Pan, Xiufang; Sun, Yiqing; Wang, Jinye; Sun, Hongtao

    2013-12-01

    Diamond films were deposited on a silicon substrate by microwave plasma chemical vapor deposition system, and its oxidation experiments were carried out in atmospheric environmental condition by using a muffle furnace. Inatmospheric environment (the temperature is from 400°C to 900°C) the oxidation resistance of diamond thin films was investigated. The results indicate that under the atmospheric environment diamond thin film surface morphology did not change after 6 hours at 400°C. Diamond thin film surface morphology began to change after 2 hours at 600°C, and when time was extended to 4 hours, the diamond thin film surface morphology changed significantly. The surface morphology of diamond films began to change after 15 minutes at a 700°C condition and when time was extended to 6 hours diamond films were all destroyed. All the diamond films on the silicon substrate disappeared completely in 20 minutes at 900°C. The intact crystal face is the reason that natural diamond has stable chemical property. The crystal face of synthetic diamond film has a lot of defects, especially on the side. Oxidation of the diamond films begin with the grain boundary and defects.

  11. High quality oxide films on substrates

    DOEpatents

    Ruckman, Mark W.; Strongin, Myron; Gao, Yong L.

    1994-01-01

    A method for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material.

  12. High quality oxide films on substrates

    DOEpatents

    Ruckman, M.W.; Strongin, M.; Gao, Y.L.

    1994-02-01

    A method is described for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material. 4 figures.

  13. 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.

  14. 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.

  15. Oxidation behavior of titanium nitride films

    NASA Astrophysics Data System (ADS)

    Chen, Hong-Ying; Lu, Fu-Hsing

    2005-07-01

    The oxidation behavior of titanium nitride (TiN) films has been investigated by using x-ray diffraction, Raman scattering spectroscopy, and field emission scanning electron microscopy. TiN films were deposited onto Si substrates by using cathodic arc plasma deposition technique. After that, the films were annealed in the air at 500-800 °C for 2 h. The x-ray diffraction spectra showed that rutile-TiO2 appeared above 600 °C. The relative intensity of TiO2 rapidly increased with temperatures. Only rutile-TiO2 was detected above 700 °C. Raman scattering spectra indicated the presence of rutile-TiO2 signals above 500 °C. Meanwhile an additional Si peak appeared at 700 °C in Raman spectra, above which only Si peak appeared. Many nano pores were found on the surface of films annealed at temperatures between 600 and 700 °C in field emission scanning electron microscopy, while the granular structure existed at 800 °C. The as-deposited TiN films had an apparent columnar structure. The thin and dense oxide overlayer appeared at 500 °C, and thicker oxide layer existed above 600 °C. The elongated grain structure with many voids existed in the film at 800 °C. These pores-voids might result from the nitrogen release during the oxidation of the nitride. The oxide layer obviously grows inward indicating the oxidation of TiN films belongs to an inward oxidation. The pre-exponential factor and the activation energy of the oxidation were evaluated by Arrhenius-type relation. These values were 2.2×10-6 cm2/s and 110+/-10 kJ/mol, which are consistent with those reports in the literature.

  16. 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.

  17. Electro-deposition of superconductor oxide films

    DOEpatents

    Bhattacharya, Raghu N.

    2001-01-01

    Methods for preparing high quality superconducting oxide precursors which are well suited for further oxidation and annealing to form superconducting oxide films. The method comprises forming a multilayered superconducting precursor on a substrate by providing an electrodeposition bath comprising an electrolyte medium and a substrate electrode, and providing to the bath a plurality of precursor metal salts which are capable of exhibiting superconducting properties upon subsequent treatment. The superconducting precursor is then formed by electrodepositing a first electrodeposited (ED) layer onto the substrate electrode, followed by depositing a layer of silver onto the first electrodeposited (ED) layer, and then electrodepositing a second electrodeposited (ED) layer onto the Ag layer. The multilayered superconducting precursor is suitable for oxidation at a sufficient annealing temperature in air or an oxygen-containing atmosphere to form a crystalline superconducting oxide film.

  18. Graphene oxide film as solid lubricant.

    PubMed

    Liang, Hongyu; Bu, Yongfeng; Zhang, Junyan; Cao, Zhongyue; Liang, Aimin

    2013-07-10

    As a layered material, graphene oxide (GO) film is a good candidate for improving friction and antiwear performance of silicon-based MEMS devices. Via a green electrophoretic deposition (EPD) approach, GO films with tunable thickness in nanoscale are fabricated onto silicon wafer in a water solution. The morphology, microstructure, and mechanical properties as well as the friction coefficient and wear resistance of the films were investigated. The results indicated that the friction coefficient of silicon wafer was reduced to 1/6 its value, and the wear volume was reduced to 1/24 when using GO film as solid lubricant. These distinguished tribology performances suggest that GO films are expected to be good solid lubricants for silicon-based MEMS/NEMS devices. PMID:23786494

  19. High quality transparent conducting oxide thin films

    DOEpatents

    Gessert, Timothy A.; Duenow, Joel N.; Barnes, Teresa; Coutts, Timothy J.

    2012-08-28

    A transparent conducting oxide (TCO) film comprising: a TCO layer, and dopants selected from the elements consisting of Vanadium, Molybdenum, Tantalum, Niobium, Antimony, Titanium, Zirconium, and Hafnium, wherein the elements are n-type dopants; and wherein the transparent conducting oxide is characterized by an improved electron mobility of about 42 cm.sup.2/V-sec while simultaneously maintaining a high carrier density of .about.4.4e.times.10.sup.20 cm.sup.-3.

  20. Patterning of Indium Tin Oxide Films

    NASA Technical Reports Server (NTRS)

    Immer, Christopher

    2008-01-01

    A relatively rapid, economical process has been devised for patterning a thin film of indium tin oxide (ITO) that has been deposited on a polyester film. ITO is a transparent, electrically conductive substance made from a mixture of indium oxide and tin oxide that is commonly used in touch panels, liquid-crystal and plasma display devices, gas sensors, and solar photovoltaic panels. In a typical application, the ITO film must be patterned to form electrodes, current collectors, and the like. Heretofore it has been common practice to pattern an ITO film by means of either a laser ablation process or a photolithography/etching process. The laser ablation process includes the use of expensive equipment to precisely position and focus a laser. The photolithography/etching process is time-consuming. The present process is a variant of the direct toner process an inexpensive but often highly effective process for patterning conductors for printed circuits. Relative to a conventional photolithography/ etching process, this process is simpler, takes less time, and is less expensive. This process involves equipment that costs less than $500 (at 2005 prices) and enables patterning of an ITO film in a process time of less than about a half hour.

  1. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  2. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus_minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus_minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  3. 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.

  4. Metal current collect protected by oxide film

    DOEpatents

    Jacobson, Craig P.; Visco, Steven J.; DeJonghe, Lutgard C.

    2004-05-25

    Provided are low-cost, mechanically strong, highly electronically conductive current collects and associated structures for solid-state electrochemical devices, techniques for forming these structures, and devices incorporating the structures. The invention provides solid state electrochemical devices having as current interconnects a ferritic steel felt or screen coated with a protective oxide film.

  5. Interfacial Assembly of Graphene Oxide Films

    NASA Astrophysics Data System (ADS)

    Valtierrez, Cain; Ismail, Issam; Macosko, Christopher; Stottrup, Benjamin

    Controlled assembly of monolayer graphene-oxide (GO) films at the air/water interface is of interest for the development of transparent conductive thin films of chemically-derived graphene. We present experimental results from investigations of the assembly of polydisperse GO sheets at the air-water interface. GO nanosheets with lateral dimensions of greater than 10 microns were created using a modified Tour synthesis (Dimiev and Tour, 2014). GO films were generated with conventional Langmuir trough techniques to control lateral packing density. Film morphology was characterized in situ with Brewster angle microscopy. Films were transferred unto a substrate via the Langmuir-Blodgett deposition technique and imaged with fluorescence quenching microscopy. Through pH modulation of the aqueous subphase, it was found that GO's intrinsic surface activity to the interface increased with increasing subphase acidity. Finally, we found a dominant elastic contribution during uniaxial film deformation as measured by anisotropic pressure measurements. A. M. Dimiev, and J. M. Tour, ``Mechanism of GO Formation,'' ACS Nano, 8, (2014)

  6. Influence of doping with third group oxides on properties of zinc oxide thin films

    SciTech Connect

    Palimar, Sowmya Bangera, Kasturi V.; Shivakumar, G. K.

    2013-03-15

    The study of modifications in structural, optical and electrical properties of vacuum evaporated zinc oxide thin films on doping with III group oxides namely aluminum oxide, gallium oxide and indium oxide are reported. It was observed that all the films have transmittance ranging from 85 to 95%. The variation in optical properties with dopants is discussed. On doping the film with III group oxides, the conductivity of the films showed an excellent improvement of the order of 10{sup 3} {Omega}{sup -1} cm{sup -1}. The measurements of activation energy showed that all three oxide doped films have 2 donor levels below the conduction band.

  7. Porous Nickel Oxide Film Sensor for Formaldehyde

    NASA Astrophysics Data System (ADS)

    Cindemir, U.; Topalian, Z.; Österlund, L.; Granqvist, C. G.; Niklasson, G. A.

    2014-11-01

    Formaldehyde is a volatile organic compound and a harmful indoor pollutant contributing to the "sick building syndrome". We used advanced gas deposition to fabricate highly porous nickel oxide (NiO) thin films for formaldehyde sensing. The films were deposited on Al2O3 substrates with prefabricated comb-structured electrodes and a resistive heater at the opposite face. The morphology and structure of the films were investigated with scanning electron microscopy and X-ray diffraction. Porosity was determined by nitrogen adsorption isotherms with the Brunauer-Emmett-Teller method. Gas sensing measurements were performed to demonstrate the resistive response of the sensors with respect to different concentrations of formaldehyde at 150 °C.

  8. 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

  9. Metallic oxide switches using thick film technology

    NASA Technical Reports Server (NTRS)

    Patel, D. N.; Williams, L., Jr.

    1974-01-01

    Metallic oxide thick film switches were processed on alumina substrates using thick film technology. Vanadium pentoxide in powder form was mixed with other oxides e.g., barium, strontium copper and glass frit, ground to a fine powder. Pastes and screen printable inks were made using commercial conductive vehicles and appropriate thinners. Some switching devices were processed by conventional screen printing and firing of the inks and commercial cermet conductor terminals on 96% alumina substrates while others were made by applying small beads or dots of the pastes between platinum wires. Static, and dynamic volt-ampere, and pulse tests indicate that the switching and self-oscillatory characteristics of these devices could make them useful in memory element, oscillator, and automatic control applications.

  10. Plasma deposition of aluminum oxide films

    NASA Astrophysics Data System (ADS)

    Catherine, Y.; Talebian, A.

    1988-03-01

    A plasma deposition technique for amorphous aluminum oxide films is discussed. A 450 kHz or 13.56 MHz power supply was used to generate the plasma and the deposition of the film was achieved at low plasma power using trimethyl-aluminum and carbon dioxide reactant sources. It has been found that for the low frequency plasma the growth is strongly dependent upon TMA concentration, indicating that the growth process is mass transport limited. On the other hand using the 13.56 MHz discharge results in a surface controlled growth rate. An increase in the deposition temperature up to 300° C makes the films more dense and lowers their etching rate. FTIR and ESCA measurements showed that oxidation is only completed with high CO2 concentrations and a deposition temperature above 250° C. The dielectric films were found to have a dielectric constant in the range 7.3=2-9 and a refractive index between 1.5 1.8 depending upon deposition conditions.

  11. Pulsed Laser Deposition of Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Brodoceanu, D.; Scarisoreanu, N. D.; Filipescu, M. (Morar); Epurescu, G. N.; Matei, D. G.; Verardi, P.; Craciun, F.; Dinescu, M.

    2004-10-01

    Pulsed Laser Deposition (PLD) emerged as an attractive technique for growth of thin films with different properties as metals, semiconductors, ferroelectrics, biocompatibles, polymers, etc., due to its important advantages: (i) the stoichiometric transfer of a complex composition from target to film and film crystallization at lower substrate temperature respect to other techniques (due to the high energy of species in the laser plasma); (ii) single step process, synthesis and deposition; (iii) creation in plasma of species impossible to be obtained by other processes; (iv) possibility of "in situ" heterostructure deposition using a multi-target system, etc. Simple or complex oxides are between the materials widely studied for their applications. PMN is the most known relaxor ferroelectric material: it exhibits a high dielectric constant value around the (diffuse) maximum phase transition temperature, of more than 35 000 in bulk form. Other oxides as lead zirconate titanate, Pb(ZrxTi1-x)O3 simple or La doped exhibit exceptional properties as large remanent polarization, high dielectric permittivity, high piezoelectric coefficient. SrBi2Ta2O9 (SBT) is characterized by a high "fatigue resistance" (constant remanent polarization until 1012 switching cycles), low imprint, and low leakage current. The physical properties of zirconium oxide (or zirconia) -- high strength, stability at high temperatures -- make it useful for applications involving gas sensors, corrosion or heat resistant mechanical parts, high refractive index optical coatings. Of particular interest is its use as an alternative gate dielectric in metal-oxide-semiconductor (MOS) devices or capacitor in dynamic random access memory (DRAM) chips. All these oxides have been deposited by laser ablation in oxygen reactive atmosphere and some of their properties will be presented in this paper.

  12. Investigation of photoelectrochemical-oxidized p-GaSb films

    NASA Astrophysics Data System (ADS)

    Lee, Hsin-Ying; Huang, Hung-Lin; Lee, Ching-Ting; Petrovich Pchelyakov, Oleg; Andreevich Pakhanov, Nikolay

    2012-12-01

    GaSb oxide films were directly formed on the p-GaSb films using the bias-assisted photoelectrochemical (PEC) oxidation method. X-ray photoelectron spectroscopy analysis indicated that the resulting GaSb oxide films consisted of Ga2O3, Sb2O3, and Sb2O5. Different from the non-PEC oxides, the PEC derived oxide contained much more Sb2O5 than Sb2O3. Besides, the interface state density between the PEC oxide and p-GaSb was lower than that of the ordinary oxide/p-GaSb interface. The high quality of the PEC-oxidized GaSb films was attributed to the increase of the stable Sb2O5 content and decrease of the elemental Sb content in the films.

  13. Copper oxide thin films for ethanol sensing

    NASA Astrophysics Data System (ADS)

    Lamri Zeggar, M.; Bourfaa, F.; Adjimi, A.; Aida, M. S.; Attaf, N.

    2016-03-01

    The present is a study of a new active layer for ethanol (C2H5OH) vapour sensing devices based on copper oxide (CuO). CuO films were prepared by spray ultrasonic pyrolysis at a substrate temperature of 350 °C. Films microstructure was examined by X-ray diffraction and atomic force microscopy. Vapour-sensing testing was conducted using static vapour-sensing system, at different operating temperatures in the range of 100°C to 175°C for the vapour concentration of 300 ppm. The results show a high response of 45% at relatively low operating temperatures of 150°C towards ethanol vapour.

  14. Thin zinc oxide and cuprous oxide films for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Jeong, Seongho

    Metal oxide semiconductors and heterojunctions made from thin films of metal oxide semiconductors have broad range of functional properties and high potential in optical, electrical and magnetic devices such as light emitting diodes, spintronic devices and solar cells. Among the oxide semiconductors, zinc oxide (ZnO) and cuprous oxide (Cu2O) are attractive because they are inexpensive, abundant and nontoxic. As synthesized ZnO is usually an intrinsic n - type semiconductor with wide band gap (3.4 eV) and can be used as the transparent conducting window layer in solar cells. As synthesized Cu2O is usually a p - type semiconductor with a band gap of 2.17 eV and has been considered as a potential material for the light absorbing layer in solar cells. I used various techniques including metal organic chemical vapor deposition, magnetron sputtering and atomic layer deposition to grow thin films of ZnO and Cu2O and fabricated Cu2O/ZnO heterojunctions. I specifically investigated the optical and electrical properties of Cu 2O thin films deposited on ZnO by MOCVD and showed that Cu2O thin films grow as single phase with [110] axis aligned perpendicular to the ZnO surface which is (0001) plane and with in-plane rotational alignment due to (220) Cu2O || (0002)ZnO; [001]Cu2O || [12¯10]ZnO epitaxy. Moreover, I fabricated solar cells based on these Cu2O/ZnO heterojunctions and characterized them. Electrical characterization of these solar cells as a function of temperature between 100 K and 300 K under illumination revealed that interface recombination and tunneling at the interface are the factors that limit the solar cell performance. To date solar cells based on Cu2O/ZnO heterojunctions had low open circuit voltages (~ 0.3V) even though the expected value is around 1V. I achieved open circuit voltages approaching 1V at low temperature (~ 100 K) and showed that if interfacial recombination is reduced these cells can achieve their predicted potential.

  15. Oxidation resistance of Pb-Te-Se optical recording film

    NASA Astrophysics Data System (ADS)

    Terao, Motoyasu; Horigome, Shinkichi; Shigematsu, Kazuo; Miyauchi, Yasushi; Nakazawa, Masatoshi

    1987-08-01

    The dependence of oxidation resistance of metal-Te-Se optical recording films on film composition is investigated, as well as the effects of oxidation on laser beam recorded hole shape. The films are deposited by vacuum evaporation on substrates with a glass/UV light curing resin/cellulose nitrate structure. The role of Se in the film is to inhibit the oxidation. With at least 14% Se addition, film oxidation is completely inhibited even at 60 °C, relative humidity 95%. Depth profiles of elements in the recording films are analyzed by Auger electron and x-ray photoelectron spectroscopy to clarify the mechanisms of oxidation inhibition by Se addition. A selenium condensed layer is found at the inner part of an oxidized surface layer. The surface Te oxide layer and the Se-rich layer should inhibit the film inside from oxidizing. The role of the metallic elements In, Pb, Sn, Bi, and Sb in the film is to inhibit cracking and to decrease noise in reproduced signals by decreasing the size of crystal grains. Lead is found to be the best among these metallic elements, because the recorded hole shape is clean even when recorded after 15 days accelerated oxidation at 60 °C, relative humidity 95%. A very long storage life is expected for the Pb-Te-Se optical recording film.

  16. Electrochromism: from oxide thin films to devices

    NASA Astrophysics Data System (ADS)

    Rougier, A.; Danine, A.; Faure, C.; Buffière, S.

    2014-03-01

    In respect of their adaptability and performance, electrochromic devices, ECDs, which are able to change their optical properties under an applied voltage, have received significant attention. Target applications are multifold both in the visible region (automotive sunroofs, smart windows, ophthalmic lenses, and domestic appliances (oven, fridge…)) and in the infrared region (Satellites Thermal Control, IR furtivity). In our group, focusing on oxide thin films grown preferentially at room temperature, optimization of ECDs performances have been achieved by tuning the microstructure, the stoichiometry and the cationic composition of the various layers. Herein, our approach for optimized ECDs is illustrated through the example of WO3 electrochromic layer in the visible and in the IR domain as well as ZnO based transparent conducting oxide layer. Targeting the field of printed electronics, simplification of the device architecture for low power ECDs is also reported.

  17. Transparent Conductive Oxides in Thin Film Photovoltaics

    NASA Astrophysics Data System (ADS)

    Hamelmann, Frank U.

    2014-11-01

    This paper show results from the development of transparent conductive oxides (TCO's) on large areas for the use as front electrode in thin film silicon solar modules. It is focused on two types of zinc oxide, which are cheap to produce and scalable to a substrate size up to 6 m2. Low pressure CVD with temperatures below 200°C can be used for the deposition of boron doped ZnO with a native surface texture for good light scattering, while sputtered aluminum doped ZnO needs a post deposition treatment in an acid bath for a rough surface. The paper presents optical and electrical characterization of large area samples, and also results about long term stability of the ZnO samples with respect to the so called TCO corrosion.

  18. Oxidizing annealing effects on VO2 films with different microstructures

    NASA Astrophysics Data System (ADS)

    Dou, Yan-Kun; Li, Jing-Bo; Cao, Mao-Sheng; Su, De-Zhi; Rehman, Fida; Zhang, Jia-Song; Jin, Hai-Bo

    2015-08-01

    Vanadium dioxide (VO2) films have been prepared by direct-current magnetron sputter deposition on m-, a-, and r-plane sapphire substrates. The obtained VO2 films display different microstructures depending on the orientation of sapphire substrates, i.e. mixed microstructure of striped grains and equiaxed grains on m-sapphire, big equiaxed grains on a-sapphire and fine-grained microstructure on r-sapphire. The VO2 films were treated by the processes of oxidation in air. The electric resistance and infrared transmittance of the oxidized films were characterized to examine performance characteristics of VO2 films with different microstructures in oxidation environment. The oxidized VO2 films on m-sapphire exhibit better electrical performance than the other two films. After air oxidization for 600 s at 450 °C, the VO2 films on m-sapphire show a resistance change of 4 orders of magnitude over the semiconductor-to-metal transition. The oxidized VO2 films on a-sapphire have the highest optical modulation efficiency in infrared region compared to other samples. The different performance characteristics of VO2 films are understood in terms of microstructures, i.e. grain size, grain shape, and oxygen vacancies. The findings reveal the correlation of microstructures and performances of VO2 films, and provide useful knowledge for the design of VO2 materials to different applications.

  19. Dysprosium oxide and dysprosium-oxide-doped titanium oxide thin films grown by atomic layer deposition

    SciTech Connect

    Tamm, Aile Kozlova, Jekaterina; Aarik, Lauri; Aarik, Jaan; Kukli, Kaupo; Link, Joosep; Stern, Raivo

    2015-01-15

    Dysprosium oxide and dysprosium-oxide-doped titanium oxide thin films were grown by atomic layer deposition on silicon substrates. For depositing dysprosium and titanium oxides Dy(thd){sub 3}-O{sub 3} and TiCl{sub 4}-O{sub 3} were used as precursors combinations. Appropriate parameters for Dy(thd){sub 3}-O{sub 3} growth process were obtained by using a quartz crystal microbalance system. The Dy{sub 2}O{sub 3} films were deposited on planar substrates and on three-dimensional substrates with aspect ratio 1:20. The Dy/Ti ratio of Dy{sub 2}O{sub 3}-doped TiO{sub 2} films deposited on a planar silicon substrate ranged from 0.04 to 0.06. Magnetometry studies revealed that saturation of magnetization could not be observed in planar Dy{sub 2}O{sub 3} films, but it was observable in Dy{sub 2}O{sub 3} films on 3D substrates and in doped TiO{sub 2} films with a Dy/Ti atomic ratio of 0.06. The latter films exhibited saturation magnetization 10{sup −6} A cm{sup 2} and coercivity 11 kA/m at room temperature.

  20. High carrier concentration p-type transparent conducting oxide films

    DOEpatents

    Yan, Yanfa; Zhang, Shengbai

    2005-06-21

    A p-type transparent conducting oxide film is provided which is consisting essentially of, the transparent conducting oxide and a molecular doping source, the oxide and doping source grown under conditions sufficient to deliver the doping source intact onto the oxide.

  1. p-type conduction in sputtered indium oxide films

    SciTech Connect

    Stankiewicz, Jolanta; Alcala, Rafael; Villuendas, Francisco

    2010-05-10

    We report p-type conductivity in intrinsic indium oxide (IO) films deposited by magnetron sputtering on fused quartz substrates under oxygen-rich ambient. Highly oriented (111) films were studied by x-ray diffraction, optical absorption, and Hall effect measurements. We fabricated p-n homojunctions on these films.

  2. Polymer-assisted aqueous deposition of metal oxide films

    DOEpatents

    Li, DeQuan; Jia, Quanxi

    2003-07-08

    An organic solvent-free process for deposition of metal oxide thin films is presented. The process includes aqueous solutions of necessary metal precursors and an aqueous solution of a water-soluble polymer. After a coating operation, the resultant coating is fired at high temperatures to yield optical quality metal oxide thin films.

  3. Method of producing solution-derived metal oxide thin films

    DOEpatents

    Boyle, Timothy J.; Ingersoll, David

    2000-01-01

    A method of preparing metal oxide thin films by a solution method. A .beta.-metal .beta.-diketonate or carboxylate compound, where the metal is selected from groups 8, 9, 10, 11, and 12 of the Periodic Table, is solubilized in a strong Lewis base to form a homogeneous solution. This precursor solution forms within minutes and can be deposited on a substrate in a single layer or a multiple layers to form a metal oxide thin film. The substrate with the deposited thin film is heated to change the film from an amorphous phase to a ceramic metal oxide and cooled.

  4. Effects of oxidative treatments on human hair keratin films.

    PubMed

    Fujii, T; Ito, Y; Watanabe, T; Kawasoe, T

    2012-01-01

    The effects of hydrogen peroxide and commercial bleach on hair and human hair keratin films were examined by protein solubility, scanning electron microscopy (SEM), immunofluorescence microscopy, immunoblotting, and Fourier-transform infrared spectroscopy. Protein solubility in solutions containing urea decreased when the keratin films were treated with hydrogen peroxide or bleach. Oxidative treatments promoted the urea-dependent morphological change by turning films from opaque to transparent in appearance. Immunofluorescence microscopy and immunoblotting showed that the oxidation of amino acids and proteins occurred due to the oxidative treatments, and such occurrence was more evident in the bleach-treated films than in the hydrogen peroxide-treated films. Compared with hair samples, the formation of cysteic acid was more clearly observed in the keratin films after the oxidative treatments. PMID:22487448

  5. Crystalline state and acoustic properties of zinc oxide films

    SciTech Connect

    Kal'naya, G.I.; Pryadko, I.F.; Yarovoi, Yu.A.

    1988-08-01

    We study the effect of the crystalline state of zinc oxide films, prepared by magnetron sputtering, on the efficiency of SAW transducers based on the layered system textured ZnO film-interdigital transducer (IDT)-fused quartz substrate. The crystalline perfection of the ZnO films was studied by the x-ray method using a DRON-2.0 diffractometer. The acoustic properties of the layered system fused quartz substrate-IDT-zinc oxide film were evaluated based on the squared electromechanical coupling constant K/sup 2/ for strip filters. It was found that K/sup 2/ depends on the magnitude of the mechanical stresses. When zinc oxide films are deposited by the method of magnetron deposition on fused quartz substrates, depending on the process conditions limitations can arise on the rate of deposition owing to mechanical stresses, which significantly degrade the efficiency of SAW transducers based on them, in the ZnO films.

  6. Resputtering of zinc oxide films prepared by radical assisted sputtering

    SciTech Connect

    Song Qiuming; Jiang Yousong; Song Yizhou

    2009-02-15

    Sputtering losses of zinc oxide films prepared by radical assisted sputtering were studied. It was found that the sputtering loss can be very severe in oxygenous sputtering processes of zinc oxide films. In general, resputtering caused by negative oxygen ions dominates the sputtering loss, while diffuse deposition plays a minor role. Resputtering is strongly correlated with the sputtering threshold energy of the deposited films and the concentration of O{sup -} in the sputtering zone. The balance between the oxygen concentration in the sputtering zone and the oxidation degree of the growing films depends on the sputtering rate. Our research suggests that a lower oxygen concentration in the sputtering zone and a higher oxidation degree of the growing films are favorable for reducing the resputtering losses. The sputtering loss mechanisms discussed in this work are also helpful for understanding the deposition processes of other magnetron sputtering systems.

  7. Amorphous tin-cadmium oxide films and the production thereof

    DOEpatents

    Li, Xiaonan; Gessert, Timothy A

    2013-10-29

    A tin-cadmium oxide film having an amorphous structure and a ratio of tin atoms to cadmium atoms of between 1:1 and 3:1. The tin-cadmium oxide film may have an optical band gap of between 2.7 eV and 3.35 eV. The film may also have a charge carrier concentration of between 1.times.10.sup.20 cm.sup.-3 and 2.times.10.sup.20 cm.sup.-3. The tin cadmium oxide film may also exhibit a Hall mobility of between 40 cm.sup.2V.sup.-1 s.sup.-1 and 60 cm.sup.2V.sup.-1 s.sup.-1. Also disclosed is a method of producing an amorphous tin-cadmium oxide film as described and devices using same.

  8. Rapid Deposition of Titanium Oxide and Zinc Oxide Films by Solution Precursor Plasma Spray

    NASA Astrophysics Data System (ADS)

    Ando, Yasutaka

    In order to develop a high rate atmospheric film deposition process for functional films, as a basic study, deposition of titanium oxide film and zinc oxide film by solution precursor plasma spray (SPPS) was conducted in open air. Consequently, in the case of titanium oxide film deposition, anantase film and amorphous film as well as rutile film could be deposited by varying the deposition distance. In the case of anatase dominant film, photo-catalytic properties of the films could be confirmed by wettability test. In addition, the dye sensitized sollar cell (DSC) using the TiO2 film deposited by this SPPS technique as photo voltaic device generates 49mV in OCV. On the other hand, in the case of zinc oxide film deposition, it was proved that well crystallized ZnO films with photo catalytic properties could be deposited. From these results, this process was found to have high potential for high rate functional film deposition process conducted in the air.

  9. Films based on oxidized starch and cellulose from barley.

    PubMed

    El Halal, Shanise Lisie Mello; Colussi, Rosana; Deon, Vinícius Gonçalves; Pinto, Vânia Zanella; Villanova, Franciene Almeida; Carreño, Neftali Lenin Villarreal; Dias, Alvaro Renato Guerra; Zavareze, Elessandra da Rosa

    2015-11-20

    Starch and cellulose fibers were isolated from grains and the husk from barley, respectively. Biodegradable films of native starch or oxidized starches and glycerol with different concentrations of cellulose fibers (0%, 10% and 20%) were prepared. The films were characterized by morphological, mechanical, barrier, and thermal properties. Cellulose fibers isolated from the barley husk were obtained with 75% purity and high crystallinity. The morphology of the films of the oxidized starches, regardless of the fiber addition, was more homogeneous as compared to the film of the native starch. The addition of cellulose fibers in the films increased the tensile strength and decreased elongation. The water vapor permeability of the film of oxidized starch with 20% of cellulose fibers was lower than the without fibers. However the films with cellulose fibers had the highest decomposition with the initial temperature and thermal stability. The oxidized starch and cellulose fibers from barley have a good potential for use in packaging. The addition of cellulose fibers in starch films can contribute to the development of films more resistant that can be applied in food systems to maintain its integrity. PMID:26344323

  10. 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.

  11. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, Kevin C.; Kodas, Toivo T.

    1994-01-01

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said FIELD OF THE INVENTION The present invention relates to the field of film coating deposition techniques, and more particularly to the deposition of multicomponent metal oxide films by aerosol chemical vapor deposition. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

  12. Low reflectance sputtered vanadium oxide thin films on silicon

    NASA Astrophysics Data System (ADS)

    Esther, A. Carmel Mary; Dey, Arjun; Rangappa, Dinesh; Sharma, Anand Kumar

    2016-07-01

    Vanadium oxide thin films on silicon (Si) substrate are grown by pulsed radio frequency (RF) magnetron sputtering technique at RF power in the range of 100-700 W at room temperature. Deposited thin films are characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques to investigate microstructural, phase, electronic structure and oxide state characteristics. The reflectance and transmittance spectra of the films and the Si substrate are recorded at the solar region (200-2300 nm) of the spectral window. Substantial reduction in reflectance and increase in transmittance is observed for the films grown beyond 200 W. Further, optical constants viz. absorption coefficient, refractive index and extinction coefficient of the deposited vanadium oxide films are evaluated.

  13. Method for producing high quality oxide films on substrates

    DOEpatents

    Ruckman, M.W.; Strongin, M.; Gao, Y.L.

    1993-11-23

    A method is described for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material. 4 figures.

  14. Method for producing high quality oxide films on substrates

    DOEpatents

    Ruckman, Mark W.; Strongin, Myron; Gao, Yong L.

    1993-01-01

    A method for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material.

  15. Altering properties of cerium oxide thin films by Rh doping

    SciTech Connect

    Ševčíková, Klára; Nehasil, Václav; Vorokhta, Mykhailo; Haviar, Stanislav; Matolín, Vladimír; and others

    2015-07-15

    Highlights: • Thin films of ceria doped by rhodium deposited by RF magnetron sputtering. • Concentration of rhodium has great impact on properties of Rh–CeO{sub x} thin films. • Intensive oxygen migration in films with low concentration of rhodium. • Oxygen migration suppressed in films with high amount of Rh dopants. - Abstract: Ceria containing highly dispersed ions of rhodium is a promising material for catalytic applications. The Rh–CeO{sub x} thin films with different concentrations of rhodium were deposited by RF magnetron sputtering and were studied by soft and hard X-ray photoelectron spectroscopies, Temperature programmed reaction and X-ray powder diffraction techniques. The sputtered films consist of rhodium–cerium mixed oxide where cerium exhibits a mixed valency of Ce{sup 4+} and Ce{sup 3+} and rhodium occurs in two oxidation states, Rh{sup 3+} and Rh{sup n+}. We show that the concentration of rhodium has a great influence on the chemical composition, structure and reducibility of the Rh–CeO{sub x} thin films. The films with low concentrations of rhodium are polycrystalline, while the films with higher amount of Rh dopants are amorphous. The morphology of the films strongly influences the mobility of oxygen in the material. Therefore, varying the concentration of rhodium in Rh–CeO{sub x} thin films leads to preparing materials with different properties.

  16. Unidirectional oxide hetero-interface thin-film diode

    SciTech Connect

    Park, Youngmin; Lee, Eungkyu; Lee, Jinwon; Lim, Keon-Hee; Kim, Youn Sang

    2015-10-05

    The unidirectional thin-film diode based on oxide hetero-interface, which is well compatible with conventional thin-film fabrication process, is presented. With the metal anode/electron-transporting oxide (ETO)/electron-injecting oxide (EIO)/metal cathode structure, it exhibits that electrical currents ohmically flow at the ETO/EIO hetero-interfaces for only positive voltages showing current density (J)-rectifying ratio of ∼10{sup 5} at 5 V. The electrical properties (ex, current levels, and working device yields) of the thin-film diode (TFD) are systematically controlled by changing oxide layer thickness. Moreover, we show that the oxide hetero-interface TFD clearly rectifies an AC input within frequency (f) range of 10{sup 2} Hz < f < 10{sup 6} Hz, providing a high feasibility for practical applications.

  17. Unidirectional oxide hetero-interface thin-film diode

    NASA Astrophysics Data System (ADS)

    Park, Youngmin; Lee, Eungkyu; Lee, Jinwon; Lim, Keon-Hee; Kim, Youn Sang

    2015-10-01

    The unidirectional thin-film diode based on oxide hetero-interface, which is well compatible with conventional thin-film fabrication process, is presented. With the metal anode/electron-transporting oxide (ETO)/electron-injecting oxide (EIO)/metal cathode structure, it exhibits that electrical currents ohmically flow at the ETO/EIO hetero-interfaces for only positive voltages showing current density (J)-rectifying ratio of ˜105 at 5 V. The electrical properties (ex, current levels, and working device yields) of the thin-film diode (TFD) are systematically controlled by changing oxide layer thickness. Moreover, we show that the oxide hetero-interface TFD clearly rectifies an AC input within frequency (f) range of 102 Hz < f < 106 Hz, providing a high feasibility for practical applications.

  18. Morphological instability leading to formation of porous anodic oxide films

    NASA Astrophysics Data System (ADS)

    Hebert, Kurt R.; Albu, Sergiu P.; Paramasivam, Indhumati; Schmuki, Patrik

    2012-02-01

    Electrochemical oxidation of metals, in solutions where the oxide is somewhat soluble, produces anodic oxides with highly regular arrangements of pores. Although porous aluminium and titanium oxides have found extensive use in functional nanostructures, pore initiation and self-ordering are not yet understood. Here we present an analysis that examines the roles of oxide dissolution and ionic conduction in the morphological stability of anodic films. We show that patterns of pores with a minimum spacing are possible only within a narrow range of the oxide formation efficiency (the fraction of oxidized metal atoms retained in the film), which should exist when the metal ion charge exceeds two. Experimentally measured efficiencies, over diverse anodizing conditions on both aluminium and titanium, lie within the different ranges predicted for each metal. On the basis of these results, the relationship between dissolution chemistry and the conditions for pore initiation can now be understood in quantitative terms.

  19. Morphological instability leading to formation of porous anodic oxide films.

    PubMed

    Hebert, Kurt R; Albu, Sergiu P; Paramasivam, Indhumati; Schmuki, Patrik

    2012-02-01

    Electrochemical oxidation of metals, in solutions where the oxide is somewhat soluble, produces anodic oxides with highly regular arrangements of pores. Although porous aluminium and titanium oxides have found extensive use in functional nanostructures, pore initiation and self-ordering are not yet understood. Here we present an analysis that examines the roles of oxide dissolution and ionic conduction in the morphological stability of anodic films. We show that patterns of pores with a minimum spacing are possible only within a narrow range of the oxide formation efficiency (the fraction of oxidized metal atoms retained in the film), which should exist when the metal ion charge exceeds two. Experimentally measured efficiencies, over diverse anodizing conditions on both aluminium and titanium, lie within the different ranges predicted for each metal. On the basis of these results, the relationship between dissolution chemistry and the conditions for pore initiation can now be understood in quantitative terms. PMID:22138790

  20. Structural, electronic and chemical properties of metal/oxide and oxide/oxide interfaces and thin film structures

    SciTech Connect

    Lad, Robert J.

    1999-12-14

    This project focused on three different aspects of oxide thin film systems: (1) Model metal/oxide and oxide/oxide interface studies were carried out by depositing ultra-thin metal (Al, K, Mg) and oxide (MgO, AlO{sub x}) films on TiO{sub 2}, NiO and {alpha}-Al{sub 2}O{sub 3} single crystal oxide substrates. (2) Electron cyclotron resonance (ECR) oxygen plasma deposition was used to fabricate AlO{sub 3} and ZrO{sub 2} films on sapphire substrates, and film growth mechanisms and structural characteristics were investigated. (3) The friction and wear characteristics of ZrO{sub 2} films on sapphire substrates in unlubricated sliding contact were studied and correlated with film microstructure. In these studies, thin film and interfacial regions were characterized using diffraction (RHEED, LEED, XRD), electron spectroscopies (XPS, UPS, AES), microscopy (AFM) and tribology instruments (pin-on-disk, friction microprobe, and scratch tester). By precise control of thin film microstructure, an increased understanding of the structural and chemical stability of interface regions and tribological performance of ultra-thin oxide films was achieved in these important ceramic systems.

  1. Depression of melting point for protective aluminum oxide films

    NASA Astrophysics Data System (ADS)

    Dreizin, E. L.; Allen, D. J.; Glumac, N. G.

    2015-01-01

    The protective aluminum oxide film naturally formed on a surface of aluminum has a thickness in the range of 3-5 nm. Its melting causes loss of its continuity, which may significantly affect the ignition and combustion processes and their relative time scales. Melting of the alumina film also plays an important role when aluminum powders are used to prepare composites and/or being sintered. This letter quantifies depression of the melting point of an alumina film based on its nano-meter thickness. A theoretical estimate is supported by experiments relying on a detected change in the optical properties of naturally oxidized aluminum particles heated in an inert environment.

  2. Influence of film thickness on laser ablation threshold of transparent conducting oxide thin-films

    NASA Astrophysics Data System (ADS)

    Rung, S.; Christiansen, A.; Hellmann, R.

    2014-06-01

    We report on a comprehensive study of the laser ablation threshold of transparent conductive oxide thin films. The ablation threshold is determined for both indium tin oxide and gallium zinc oxide as a function of film thickness and for different laser wavelengths. By using a pulsed diode pumped solid state laser at 1064 nm, 532 nm, 355 nm and 266 nm, respectively, the relationship between optical absorption length and film thickness is studied. We find that the ablation threshold decreases with increasing film thickness in a regime where the absorption length is larger than the film thickness. In turn, the ablation threshold increases in case the absorption length is smaller than the film thickness. In particular, we observe a minimum of the ablation threshold in a region where the film thickness is comparable to the absorption length. To the best of our knowledge, this behaviour previously predicted for thin metal films, has been unreported for all three regimes in case of transparent conductive oxides, yet. For industrial laser scribing processes, these results imply that the efficiency can be optimized by using a laser where the optical absorption length is close to the film thickness.

  3. Lithium cobalt oxide thin film and its electrochromism

    NASA Astrophysics Data System (ADS)

    Wei, Guang; Haas, Terry E.; Goldner, Ronald B.

    1989-06-01

    Thin films of lithium cobalt oxide have been prepared by RF-sputtering from powdered LiCoO2. These films permit reversible electrolytic removal of lithium ions upon application of an anodic voltage in a propylene carbonate-lithium perchlorate electrolyte, the films changing in color from a pale amber transparent state to a dark brown. A polycrystalline columnar film structure was revealed with SEM and TEM. X ray examination of the films suggests that the layered rhombohedral LiCoO2 structure is the major crystalline phase present. Oxidation-reduction titration and atomic absorption were used for the determination of the film stoichiometry. The results show that the as deposited-films on glass slides are lithium deficient (relative to the starting material) and show a high average cobalt oxidation state near +3.5. The measurements of dc conductivity suggest a band to band conduction at high temperature (300 to 430 K) and hopping conduction in localized states at low temperature (4 to 270 K). The thermoelectric power data show that the films behave as p-type semiconductors. Transmission and reflectance measurements from 400 nm to 2500 nm show significant near-IR reflectivity.

  4. Understanding organic film behavior on alloy and metal oxides.

    PubMed

    Raman, Aparna; Quiñones, Rosalynn; Barriger, Lisa; Eastman, Rachel; Parsi, Arash; Gawalt, Ellen S

    2010-02-01

    Native oxide surfaces of stainless steel 316L and Nitinol alloys and their constituent metal oxides, namely nickel, chromium, molybdenum, manganese, iron, and titanium, were modified with long chain organic acids to better understand organic film formation. The adhesion and stability of films of octadecylphosphonic acid, octadecylhydroxamic acid, octadecylcarboxylic acid, and octadecylsulfonic acid on these substrates were examined in this study. The films formed on these surfaces were analyzed by diffuse reflectance infrared Fourier transform spectroscopy, contact angle goniometry, atomic force microscopy, and matrix-assisted laser desorption ionization mass spectrometry. The effect of the acidity of the organic moiety and substrate composition on the film characteristics and stability is discussed. Interestingly, on the alloy surfaces, the presence of less reactive metal sites does not inhibit film formation. PMID:20039608

  5. Understanding Organic Film Behavior on Alloy and Metal Oxides

    PubMed Central

    Raman, Aparna; Quiñones, Rosalynn; Barriger, Lisa; Eastman, Rachel; Parsi, Arash

    2010-01-01

    Native oxide surfaces of stainless steel 316L and Nitinol alloys and their constituent metal oxides namely, nickel, chromium, molybdenum, manganese, iron and titanium were modified with long chain organic acids to better understand organic film formation. The adhesion and stability of films of octadecylphosphonic acid, octadecylhydroxamic acid, octadecylcarboxylic acid and octadecylsulfonic acid on these substrates was examined in this study. The films formed on these surfaces were analyzed by diffuse reflectance infrared Fourier transform spectroscopy, contact angle goniometry, atomic force microscopy and matrix assisted laser desorption ionization mass spectrometry. The effect of the acidity of the organic moiety and substrate composition on the film characteristics and stability is discussed. Interestingly, on the alloy surfaces, the presence of less reactive metal sites does not inhibit film formation. PMID:20039608

  6. 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.

  7. Study of indium tin oxide films exposed to atomic axygen

    NASA Technical Reports Server (NTRS)

    Snyder, Paul G.; De, Bhola N.; Woollam, John A.; Coutts, T. J.; Li, X.

    1989-01-01

    A qualitative simulation of the effects of atomic oxygen has been conducted on indium tin oxide (ITO) films prepared by dc sputtering onto room-temperature substrates, by exposing them to an RF-excited oxygen plasma and characterizing the resulting changes in optical, electrical, and structural properties as functions of exposure time with ellipsometry, spectrophotometry, resistivity, and X-ray measurements. While the films thus exposed exhibit reduced resistivity and optical transmission; both of these effects, as well as partial crystallization of the films, may be due to sample heating by the plasma. Film resistivity is found to stabilize after a period of exposure.

  8. High temperature coefficient of resistance molybdenum oxide and nickel oxide thin films for microbolometer applications

    NASA Astrophysics Data System (ADS)

    Jin, Yao O.; John, David Saint; Podraza, Nikolas J.; Jackson, Thomas N.; Horn, Mark W.

    2015-03-01

    Molybdenum oxide (MoOx) and nickel oxide (NiOx) thin films were deposited by reactive biased target ion beam deposition. MoOx thin film resistivity varied from 3 to 2000 Ω.cm with a temperature coefficient of resistance (TCR) from -1.7% to -3.2%/K, and NiOx thin film resistivity varied from 1 to 300 Ω.cm with a TCR from -2.2% to -3.3%/K, both easily controlled by varying the oxygen partial pressure. Biased target ion beam deposited high TCR MoOx and NiOx thin films are polycrystalline semiconductors and have good stability in air. Compared with commonly used vanadium oxide thin films, MoOx or NiOx thin films offer improved process control for resistive temperature sensors.

  9. Determination of oxygen diffusion kinetics during thin film ruthenium oxidation

    SciTech Connect

    Coloma Ribera, R. Kruijs, R. W. E. van de; Yakshin, A. E.; Bijkerk, F.

    2015-08-07

    In situ X-ray reflectivity was used to reveal oxygen diffusion kinetics for thermal oxidation of polycrystalline ruthenium thin films and accurate determination of activation energies for this process. Diffusion rates in nanometer thin RuO{sub 2} films were found to show Arrhenius behaviour. However, a gradual decrease in diffusion rates was observed with oxide growth, with the activation energy increasing from about 2.1 to 2.4 eV. Further exploration of the Arrhenius pre-exponential factor for diffusion process revealed that oxidation of polycrystalline ruthenium joins the class of materials that obey the Meyer-Neldel rule.

  10. NEXAFS Study of Air Oxidation for Mg Nanoparticle Thin Film

    NASA Astrophysics Data System (ADS)

    Ogawa, S.; Murakami, S.; Shirai, K.; Nakanishi, K.; Ohta, T.; Yagi, S.

    2013-03-01

    The air oxidation reaction of Mg nanoparticle thin film has been investigated by Mg K-edge NEXAFS technique. It is revealed that MgO is formed on the Mg nanoparticle surfaces at the early stage of the air oxidation for Mg nanoparticle thin film. The simulation of NEXAFS spectrum using standard spectra indicates the existence of complex magnesium carbonates (x(MgCO3).yMg(OH2).z(H2O)) in addition to MgO at the early stage of the air oxidation.

  11. High stability mechanisms of quinary indium gallium zinc aluminum oxide multicomponent oxide films and thin film transistors

    SciTech Connect

    Lee, Ching-Ting Lin, Yung-Hao; Lin, Jhong-Ham

    2015-01-28

    Quinary indium gallium zinc aluminum oxide (IGZAO) multicomponent oxide films were deposited using indium gallium zinc oxide (IGZO) target and Al target by radio frequency magnetron cosputtering system. An extra carrier transport pathway could be provided by the 3 s orbitals of Al cations to improve the electrical properties of the IGZO films, and the oxygen instability could be stabilized by the strong Al-O bonds in the IGZAO films. The electron concentration change and the electron mobility change of the IGZAO films for aging time of 10 days under an air environment at 40 °C and 75% humidity were 20.1% and 2.4%, respectively. The experimental results verified the performance stability of the IGZAO films. Compared with the thin film transistors (TFTs) using conventional IGZO channel layer, in conducting the stability of TFTs with IGZAO channel layer, the transconductance g{sub m} change, threshold voltage V{sub T} change, and the subthreshold swing S value change under the same aging condition were improved to 7.9%, 10.5%, and 14.8%, respectively. Furthermore, the stable performances of the IGZAO TFTs were also verified by the positive gate bias stress. In this research, the quinary IGZAO multicomponent oxide films and that applied in TFTs were the first studied in the literature.

  12. High stability mechanisms of quinary indium gallium zinc aluminum oxide multicomponent oxide films and thin film transistors

    NASA Astrophysics Data System (ADS)

    Lee, Ching-Ting; Lin, Yung-Hao; Lin, Jhong-Ham

    2015-01-01

    Quinary indium gallium zinc aluminum oxide (IGZAO) multicomponent oxide films were deposited using indium gallium zinc oxide (IGZO) target and Al target by radio frequency magnetron cosputtering system. An extra carrier transport pathway could be provided by the 3 s orbitals of Al cations to improve the electrical properties of the IGZO films, and the oxygen instability could be stabilized by the strong Al-O bonds in the IGZAO films. The electron concentration change and the electron mobility change of the IGZAO films for aging time of 10 days under an air environment at 40 °C and 75% humidity were 20.1% and 2.4%, respectively. The experimental results verified the performance stability of the IGZAO films. Compared with the thin film transistors (TFTs) using conventional IGZO channel layer, in conducting the stability of TFTs with IGZAO channel layer, the transconductance gm change, threshold voltage VT change, and the subthreshold swing S value change under the same aging condition were improved to 7.9%, 10.5%, and 14.8%, respectively. Furthermore, the stable performances of the IGZAO TFTs were also verified by the positive gate bias stress. In this research, the quinary IGZAO multicomponent oxide films and that applied in TFTs were the first studied in the literature.

  13. Growth of Epitaxial Oxide Thin Films on Graphene

    PubMed Central

    Zou, Bin; Walker, Clementine; Wang, Kai; Tileli, Vasiliki; Shaforost, Olena; Harrison, Nicholas M.; Klein, Norbert; Alford, Neil M.; Petrov, Peter K.

    2016-01-01

    The transfer process of graphene onto the surface of oxide substrates is well known. However, for many devices, we require high quality oxide thin films on the surface of graphene. This step is not understood. It is not clear why the oxide should adopt the epitaxy of the underlying oxide layer when it is deposited on graphene where there is no lattice match. To date there has been no explanation or suggestion of mechanisms which clarify this step. Here we show a mechanism, supported by first principles simulation and structural characterisation results, for the growth of oxide thin films on graphene. We describe the growth of epitaxial SrTiO3 (STO) thin films on a graphene and show that local defects in the graphene layer (e.g. grain boundaries) act as bridge-pillar spots that enable the epitaxial growth of STO thin films on the surface of the graphene layer. This study, and in particular the suggestion of a mechanism for epitaxial growth of oxides on graphene, offers new directions to exploit the development of oxide/graphene multilayer structures and devices. PMID:27515496

  14. Growth of Epitaxial Oxide Thin Films on Graphene.

    PubMed

    Zou, Bin; Walker, Clementine; Wang, Kai; Tileli, Vasiliki; Shaforost, Olena; Harrison, Nicholas M; Klein, Norbert; Alford, Neil M; Petrov, Peter K

    2016-01-01

    The transfer process of graphene onto the surface of oxide substrates is well known. However, for many devices, we require high quality oxide thin films on the surface of graphene. This step is not understood. It is not clear why the oxide should adopt the epitaxy of the underlying oxide layer when it is deposited on graphene where there is no lattice match. To date there has been no explanation or suggestion of mechanisms which clarify this step. Here we show a mechanism, supported by first principles simulation and structural characterisation results, for the growth of oxide thin films on graphene. We describe the growth of epitaxial SrTiO3 (STO) thin films on a graphene and show that local defects in the graphene layer (e.g. grain boundaries) act as bridge-pillar spots that enable the epitaxial growth of STO thin films on the surface of the graphene layer. This study, and in particular the suggestion of a mechanism for epitaxial growth of oxides on graphene, offers new directions to exploit the development of oxide/graphene multilayer structures and devices. PMID:27515496

  15. 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.

  16. Synthesis and Oxidation Resistance of h-BN Thin Films

    NASA Astrophysics Data System (ADS)

    Stewart, David; Meulenberg, Robert; Lad, Robert

    Hexagonal boron nitride (h-BN) is an exciting 2D material for use in sensors and other electronic devices that operate in harsh, high temperature environments. Not only is h-BN a wide band gap material with excellent wear resistance and high temperature stability, but recent reports indicate that h-BN can prevent metallic substrates from oxidizing above 600°C in low O2 pressures. However, the PVD of highly crystalline h-BN films required for this oxidation protection has proven challenging. In this work, we have explored the growth of h-BN thin films by reactive RF magnetron sputtering from an elemental B target in an Ar/N2 atmosphere. The film growth rate is extremely slow and the resulting films are atomically smooth and homogeneous. Using DC biasing during deposition and high temperature annealing treatments, the degree of film crystallinity can be controlled. The oxidation resistance of h-BN films deposited on inert sapphire and reactive metal substrates such as Zr and ZrB2 has been examined by techniques such as XPS, XRD, and SEM after oxidation between 600 and 1200°C under varying oxygen pressures. The success of h-BN as a passivation layer for metallic substrates in harsh environments is shown to depend greatly on its crystalline quality and defects. Supported by the NSF SusChEM program.

  17. Growth control of the oxidation state in vanadium oxide thin films

    SciTech Connect

    Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Lee, Ho Nyung

    2014-12-05

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research, but also technological applications that utilize the subtle change in the physical properties originating from the metalinsulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V₂⁺²O₃, V⁺⁴O₂, and V₂⁺⁵O₅. A well pronounced MIT was only observed in VO₂ films grown in a very narrow range of oxygen partial pressure P(O₂). The films grown either in lower (< 10 mTorr) or higher P(O₂) (> 25 mTorr) result in V₂O₃ and V₂O₅ phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO₂ thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an 3 improved MIT behavior.

  18. Growth control of the oxidation state in vanadium oxide thin films

    DOE PAGESBeta

    Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Lee, Ho Nyung

    2014-12-05

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research, but also technological applications that utilize the subtle change in the physical properties originating from the metalinsulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase puremore » epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V₂⁺²O₃, V⁺⁴O₂, and V₂⁺⁵O₅. A well pronounced MIT was only observed in VO₂ films grown in a very narrow range of oxygen partial pressure P(O₂). The films grown either in lower (< 10 mTorr) or higher P(O₂) (> 25 mTorr) result in V₂O₃ and V₂O₅ phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO₂ thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an 3 improved MIT behavior.« less

  19. Growth control of the oxidation state in vanadium oxide thin films

    NASA Astrophysics Data System (ADS)

    Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

    2014-12-01

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V2 + 3 O 3 , V + 4 O 2 , and V2 + 5 O 5 . A well pronounced MIT was only observed in VO2 films grown in a very narrow range of oxygen partial pressure P(O2). The films grown either in lower (<10 mTorr) or higher P(O2) (>25 mTorr) result in V2O3 and V2O5 phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO2 thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.

  20. Growth control of the oxidation state in vanadium oxide thin films

    SciTech Connect

    Lee, Shinbuhm; Meyer, Tricia L.; Lee, Ho Nyung; Park, Sungkyun; Egami, Takeshi

    2014-12-01

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V{sub 2}{sup +3}O{sub 3}, V{sup +4}O{sub 2}, and V{sub 2}{sup +5}O{sub 5}. A well pronounced MIT was only observed in VO{sub 2} films grown in a very narrow range of oxygen partial pressure P(O{sub 2}). The films grown either in lower (<10 mTorr) or higher P(O{sub 2}) (>25 mTorr) result in V{sub 2}O{sub 3} and V{sub 2}O{sub 5} phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO{sub 2} thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.

  1. Simultaneous Electrochemical Reduction and Delamination of Graphene Oxide Films.

    PubMed

    Wang, Xiaohan; Kholmanov, Iskandar; Chou, Harry; Ruoff, Rodney S

    2015-09-22

    Here we report an electrochemical method to simultaneously reduce and delaminate graphene oxide (G-O) thin films deposited on metal (Al and Au) substrates. During the electrochemical reaction, interface charge transfer between the G-O thin film and the electrode surface was found to be important in eliminating oxygen-containing groups, yielding highly reduced graphene oxide (rG-O). In the meantime, hydrogen bubbles were electrochemically generated at the rG-O film/electrode interface, propagating the film delamination. Unlike other metal-based G-O reduction methods, the metal used here was either not etched at all (for Au) or etched a small amount (for Al), thus making it possible to reuse the substrate and lower production costs. The delaminated rG-O film exhibits a thickness-dependent degree of reduction: greater reduction is achieved in thinner films. The thin rG-O films having an optical transmittance of 90% (λ = 550 nm) had a sheet resistance of 6390 ± 447 Ω/□ (ohms per square). rG-O-based stretchable transparent conducting films were also demonstrated. PMID:26257072

  2. Stress and phase transformation phenomena in oxide films

    SciTech Connect

    Exarhos, G.J.; Hess, N.J.

    1992-04-01

    In situ optical methods are reviewed for characterization of phase transformation processes and evaluation of residual stress in solution- deposited metastable oxide films. Such low density films most often are deposited as disordered phases making them prone to crystallization and attendant densification when subjected to increased temperature and/or applied pressure. Inherent stress imparted during film deposition and its evolution during the transformation are evaluated from phonon frequency shifts seen in Raman spectra (TiO{sub 2}) or from changes in the laser-induced fluorescence emission spectra for films containing rare earth (Sm{sup +3}:Y{sub 3}Al{sub 5}O{sub 12}) or transition metal (Cr{sup +3}:Al{sub 2}O{sub 3}) dopants. The data in combination with measured increases in line intensities intrinsic to the evolving phase are used to follow crystallization processes in thin films. In general, film deposition parameters are found to influence the crystallite ingrowth kinetics and the magnitude of stress and stress relaxation in the film during the transformation. The utility of these methods to probe crystallization phenomena in oxide films will be addressed.

  3. Submicron fabrication by local anodic oxidation of germanium thin films

    NASA Astrophysics Data System (ADS)

    Oliveira, A. B.; Medeiros-Ribeiro, G.; Azevedo, A.

    2009-08-01

    Here we describe a lithography scheme based on the local anodic oxidation of germanium film by a scanning atomic force microscope in a humidity-controlled atmosphere. The oxidation kinetics of the Ge film were investigated by a tapping mode, in which a pulsed bias voltage was synchronized and applied with the resonance frequency of the cantilever, and by a contact mode, in which a continuous voltage was applied. In the tapping mode we clearly identified two regimes of oxidation as a function of the applied voltage: the trench width increased linearly during the vertical growth and increased exponentially during the lateral growth. Both regimes of growth were interpreted taking into consideration the Cabrera-Mott mechanism of oxidation applied to the oxide/Ge interface. We also show the feasibility of the bottom-up fabrication process presented in this work by showing a Cu nanowire fabricated on top of a silicon substrate.

  4. Multifunctional oxide thin films for magnetoelectric and electromechanical applications

    NASA Astrophysics Data System (ADS)

    Baek, Seung Hyub

    Epitaxial multifunctional oxide thin films have been extensively researched to understand and exploit a variety of their physical properties. In order to integrate such versatile properties into real devices, there are several critical issues: (1) high-quality thin film growth, (2) fundamental understanding on reliable performance, and (3) device fabrication process preserving functionality of oxides. We have investigated all these issues, employing two different materials: multiferroic BiFeO3 and piezoelectric Pb(Mg1/3 Nb2/3)O3-PbTiO3 (PMN-PT) epitaxial thin films. For the high-quality thin film growth, we have chosen both BiFeO 3 and PMN-PT thin films as a model system. Bi2O3and PbO are the volatile species in these oxides, which makes it hard to grow phase-pure stoichiometric thin films. Because the properties of oxides are sensitive to stoichiometry and defects, it is highly required to fix such volatile elements during thin film growth. We have grown high-quality epitaxial thin films using a fast-rate off-axis sputtering method and vicinal substrates. In addition, we were able to control domain structures of BiFeO3 thin films using vicinal substrates. For the study on the reliability issues in oxides, we have used BiFeO 3 thin films within the framework of magnetoelectric device applications. For reliable magnetoelectric performance of BiFeO3, polarization switching path has to be (1) deterministic, and to be retained along with (2) time---retention, and (3) cycles--- fatigue. We have used monodomain BiFeO3 thin films as a model system. Based on theoretical predictions, we have studied polarization switching paths, and achieved both selective polarization switching and retention problems using island BiFeO3 structure. We have also investigated polarization fatigue, dependent on switching path. For the demonstration of working devices preserving the original functionality of oxides, we have fabricated micro-cantilevers using PMN-PT heterostructure on Si. The

  5. Thermal stability of sputtered iridium oxide films

    SciTech Connect

    Sanjines, R.; Aruchamy, A.; Levy, F. )

    1989-06-01

    Dry and partially hydrated films of IrO/sub 2/ were prepared by reactive sputtering. The authors discuss their thermal stability investigated by means of XPS, x-ray diffraction, and resistivity measurements. Dry films decomposed at about 400{sup 0}C iin air and at 200{sup 0}C in vacuum (10/sup -2/ Pa), whereas partially hydrated films decomposed at 350{sup 0} and 150{sup 0}C, respectively. After electrochemical treatments of the films mounted as electrochromic electrodes in an electrolytic cell, the decomposition occurred at different temperatures. In particular, the bleached state was found to have the relatively low decomposition temperature of about 100{sup 0}C in air.

  6. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, K.C.; Kodas, T.T.

    1994-01-11

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said substrate.

  7. In-situ spectroscopic studies of electrochromic tungsten oxide films

    NASA Astrophysics Data System (ADS)

    Ozer, Nilgun; Demirbas, Muharrem; Ozyurt, Secuk

    2001-11-01

    Tungsten oxide thin films were prepared using an ethanolic solution of tungsten hexachloride (WCl6) by sol-gel spin coating. The films were spin coated on indium tin oxide (ITO) coated glass substrate at temperatures in the range of 100 to 450 degree(s)C. The films were characterized by x-ray diffractometry (XRD), scanning electron microscopy (SEM) UV- visible spectroscopy and cyclic voltammetry (CV). XRD showed that they had a polycrystalline WO3 structure for heat treatment temperatures at above 350 degree(s)C. The SEM examinations showed that the surface texture was very uniform and homogeneous. In situ electrochemical reduction of WO3/ITO (2M HCl) produced a blue color in less than a second. Coloration efficiency (CE) was found to be 21 cm2/mC. In situ spectroscopic investigations showed that these films could be used as a working electrode in electrochromic devices.

  8. In situ Oxidation of Ultrathin Silver Films on Ni(111)

    SciTech Connect

    A Meyer; I Flege; S Senanayake; B Kaemena; R Rettew; F Alamgir; J Falta

    2011-12-31

    Oxidation of silver films of one- and two-monolayer thicknesses on the Ni(111) surface was investigated by low-energy electron microscopy at temperatures of 500 and 600 K. Additionally, intensity-voltage curves were measured in situ during oxidation to reveal the local film structure on a nanometer scale. At both temperatures, we find that exposure to molecular oxygen leads to the destabilization of the Ag film with subsequent relocation of the silver atoms to small few-layer-thick silver patches and concurrent evolution of NiO(111) regions. Subsequent exposure of the oxidized surface to ethylene initiates the transformation of bilayer islands back into monolayer islands, demonstrating at least partial reversibility of the silver relocation process at 600 K.

  9. Electrochemical formation of a composite polymer-aluminum oxide film

    NASA Astrophysics Data System (ADS)

    Runge-Marchese, Jude Mary

    1997-10-01

    The formation of polymer films through electrochemical techniques utilizing electrolytes which include conductive polymer is of great interest to the coatings and electronics industries as a means for creating electrically conductive and corrosion resistant finishes. One of these polymers, polyamino-benzene (polyaniline), has been studied for this purpose for over ten years. This material undergoes an insulator-to-metal transition upon doping with protonic acids in an acid/base type reaction. Review of prior studies dealing with polyaniline and working knowledge of aluminum anodization has led to the development of a unique process whereby composite polymer-aluminum oxide films are formed. The basis for the process is a modification of the anodizing electrolyte which results in the codeposition of polyaniline during aluminum anodization. A second process, which incorporates electrochemical sealing of the anodic layer with polyaniline was also developed. The formation of these composite films is documented through experimental processing, and characterized by way of scientific analysis and engineering tests. Analysis results revealed the formation of unique dual phase anodic films with fine microstructures which exhibited full intrusion of the columnar aluminum oxide structure with polyaniline, indicating the polymer was deposited as the metal oxidation proceeded. An aromatic amine derivative of polyaniline with aluminum sulfate was determined to be the reaction product within the aluminum oxide phase of the codeposited films. Scientific characterization determined the codeposition process yields completely chemically and metallurgically bound composite films. Engineering studies determined the films, obtained through a single step, exhibited superior wear and corrosion resistance to conventionally anodized and sealed films processed through two steps, demonstrating the increased manufacturing process efficiency that can be realized with the modification of the

  10. Electrochromic behavior in CVD grown tungsten oxide films

    NASA Astrophysics Data System (ADS)

    Gogova, D.; Iossifova, A.; Ivanova, T.; Dimitrova, Zl; Gesheva, K.

    1999-03-01

    Solid state electrochemical devices (ECDs) for smart windows, large area displays and automobile rearview mirrors are of considerable technological and commercial interest. In this paper, we studied the electrochromic properties of amorphous and polycrystalline CVD carbonyl tungsten oxide films and the possibility for sol-gel thin TiO 2 film to play the role of passive electrode in an electrochromic window with solid polymer electrolyte.

  11. Review of solution-processed oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Si Joon; Yoon, Seokhyun; Kim, Hyun Jae

    2014-02-01

    In this review, we summarize solution-processed oxide thin-film transistors (TFTs) researches based on our fulfillments. We describe the fundamental studies of precursor composition effects at the beginning in order to figure out the role of each component in oxide semiconductors, and then present low temperature process for the adoption of flexible devices. Moreover, channel engineering for high performance and reliability of solution-processed oxide TFTs and various coating methods: spin-coating, inkjet printing, and gravure printing are also presented. The last topic of this review is an overview of multi-functional solution-processed oxide TFTs for various applications such as photodetector, biosensor, and memory.

  12. Room Temperature Oxide Deposition Approach to Fully Transparent, All-Oxide Thin-Film Transistors.

    PubMed

    Rembert, Thomas; Battaglia, Corsin; Anders, André; Javey, Ali

    2015-10-28

    A room temperature cathodic arc deposition technique is used to produce high-mobility ZnO thin films for low voltage thin-film transistors (TFTs) and digital logic inverters. All-oxide, fully transparent devices are fabricated on alkali-free glass and flexible polyimide foil, exhibiting high performance. This provides a practical materials platform for the low-temperature fabrication of all-oxide TFTs on virtually any substrate. PMID:26455916

  13. Mechanisms of polarization switching in graphene oxides and poly(vinylidene fluoride)-graphene oxide films

    NASA Astrophysics Data System (ADS)

    Jiang, Zhiyuan; Zheng, Guangping; Zhan, Ke; Han, Zhuo; Wang, Hao

    2016-04-01

    Polarization switching in graphene oxides (GOs) and poly(vinylidene fluoride) (PVDF)-GO nanocomposite is investigated by piezoelectric force microscopy (PFM). The dynamical switching results reveal that GO films exhibit ferroelectric and piezoelectric properties with two-dimensional characteristics. Abnormal polarization switching is observed in PVDF-GO films, which is promising for electronic applications.

  14. Surface and sub-surface thermal oxidation of thin ruthenium films

    SciTech Connect

    Coloma Ribera, R.; Kruijs, R. W. E. van de; Yakshin, A. E.; Bijkerk, F.; Kokke, S.; Zoethout, E.

    2014-09-29

    A mixed 2D (film) and 3D (nano-column) growth of ruthenium oxide has been experimentally observed for thermally oxidized polycrystalline ruthenium thin films. Furthermore, in situ x-ray reflectivity upon annealing allowed the detection of 2D film growth as two separate layers consisting of low density and high density oxides. Nano-columns grow at the surface of the low density oxide layer, with the growth rate being limited by diffusion of ruthenium through the formed oxide film. Simultaneously, with the growth of the columns, sub-surface high density oxide continues to grow limited by diffusion of oxygen or ruthenium through the oxide film.

  15. Investigation of solution-processed bismuth-niobium-oxide films

    SciTech Connect

    Inoue, Satoshi; Ariga, Tomoki; Matsumoto, Shin; Onoue, Masatoshi; Miyasako, Takaaki; Tokumitsu, Eisuke; Shimoda, Tatsuya; Chinone, Norimichi; Cho, Yasuo

    2014-10-21

    The characteristics of bismuth-niobium-oxide (BNO) films prepared using a solution process were investigated. The BNO film annealed at 550°C involving three phases: an amorphous phase, Bi₃NbO₇ fluorite microcrystals, and Nb-rich cubic pyrochlore microcrystals. The cubic pyrochlore structure, which was the main phase in this film, has not previously been reported in BNO films. The relative dielectric constant of the BNO film was approximately 140, which is much higher than that of a corresponding film prepared using a conventional vacuum sputtering process. Notably, the cubic pyrochlore microcrystals disappeared with increasing annealing temperature and were replaced with triclinic β-BiNbO₄ crystals at 590°C. The relative dielectric constant also decreased with increasing annealing temperature. Therefore, the high relative dielectric constant of the BNO film annealed at 550°C is thought to result from the BNO cubic pyrochlore structure. In addition, the BNO films annealed at 500°C contained approximately 6.5 atm.% carbon, which was lost at approximately 550°C. This result suggests that the carbon in the BNO film played an important role in the formation of the cubic pyrochlore structure.

  16. Large and pristine films of reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Ahn, Sung Il; Kim, Kukjoo; Jung, Jura; Choi, Kyung Cheol

    2015-12-01

    A new self-assembly concept is introduced to form large and pristine films (15 cm in diameter) of reduced graphene oxide (RGO). The resulting film has different degrees of polarity on its two different sides due to the characteristic nature of the self-assembly process. The RGO film can be easily transferred from a glass substrate onto water and a polymer substrate after injection of water molecules between the RGO film and glass substrate using an electric steamer. The RGO film can also be easily patterned into various shapes with a resolution of around ±10 μm by a simple taping method, which is suitable for mass production of printed electronics at low cost.

  17. Enhanced optical constants of nanocrystalline yttrium oxide thin films

    SciTech Connect

    Ramana, C. V.; Mudavakkat, V. H.; Bharathi, K. Kamala; Atuchin, V. V.; Pokrovsky, L. D.; Kruchinin, V. N.

    2011-01-17

    Yttrium oxide (Y{sub 2}O{sub 3}) films with an average crystallite-size (L) ranging from 5 to 40 nm were grown by sputter-deposition onto Si(100) substrates. The optical properties of grown Y{sub 2}O{sub 3} films were evaluated using spectroscopic ellipsometry measurements. The size-effects were significant on the optical constants and their dispersion profiles of Y{sub 2}O{sub 3} films. A significant enhancement in the index of refraction (n) is observed in well-defined Y{sub 2}O{sub 3} nanocrystalline films compared to that of amorphous Y{sub 2}O{sub 3}. A direct, linear L-n relationship found for Y{sub 2}O{sub 3} films suggests that tuning optical properties for desired applications can be achieved by controlling the size at the nanoscale dimensions.

  18. Large and pristine films of reduced graphene oxide

    PubMed Central

    Ahn, Sung Il; Kim, Kukjoo; Jung, Jura; Choi, Kyung Cheol

    2015-01-01

    A new self-assembly concept is introduced to form large and pristine films (15 cm in diameter) of reduced graphene oxide (RGO). The resulting film has different degrees of polarity on its two different sides due to the characteristic nature of the self-assembly process. The RGO film can be easily transferred from a glass substrate onto water and a polymer substrate after injection of water molecules between the RGO film and glass substrate using an electric steamer. The RGO film can also be easily patterned into various shapes with a resolution of around ±10 μm by a simple taping method, which is suitable for mass production of printed electronics at low cost. PMID:26689267

  19. Comparison of topotactic fluorination methods for complex oxide films

    SciTech Connect

    Moon, E. J. Choquette, A. K.; Huon, A.; Kulesa, S. Z.; May, S. J.; Barbash, D.

    2015-06-01

    We have investigated the synthesis of SrFeO{sub 3−α}F{sub γ} (α and γ ≤ 1) perovskite films using topotactic fluorination reactions utilizing poly(vinylidene fluoride) as a fluorine source. Two different fluorination methods, a spin-coating and a vapor transport approach, were performed on as-grown SrFeO{sub 2.5} films. We highlight differences in the structural, compositional, and optical properties of the oxyfluoride films obtained via the two methods, providing insight into how fluorination reactions can be used to modify electronic and optical behavior in complex oxide heterostructures.

  20. Combinatorial measurements of Hall effect and resistivity in oxide films.

    PubMed

    Clayhold, J A; Kerns, B M; Schroer, M D; Rench, D W; Logvenov, G; Bollinger, A T; Bozovic, I

    2008-03-01

    A system for the simultaneous measurement of the Hall effect in 31 different locations as well as the measurement of the resistivity in 30 different locations on a single oxide thin film grown with a composition gradient is described. Considerations for designing and operating a high-throughput system for characterizing highly conductive oxides with Hall coefficients as small as 10(-10) m3/C are discussed. Results from measurements on films grown using combinatorial molecular beam epitaxy show the usefulness of characterizing combinatorial libraries via both the resistivity and the Hall effect. PMID:18377026

  1. Oxidized film structure and method of making epitaxial metal oxide structure

    DOEpatents

    Gan, Shupan [Richland, WA; Liang, Yong [Richland, WA

    2003-02-25

    A stable oxidized structure and an improved method of making such a structure, including an improved method of making an interfacial template for growing a crystalline metal oxide structure, are disclosed. The improved method comprises the steps of providing a substrate with a clean surface and depositing a metal on the surface at a high temperature under a vacuum to form a metal-substrate compound layer on the surface with a thickness of less than one monolayer. The compound layer is then oxidized by exposing the compound layer to essentially oxygen at a low partial pressure and low temperature. The method may further comprise the step of annealing the surface while under a vacuum to further stabilize the oxidized film structure. A crystalline metal oxide structure may be subsequently epitaxially grown by using the oxidized film structure as an interfacial template and depositing on the interfacial template at least one layer of a crystalline metal oxide.

  2. Characterization of reliability of printed indium tin oxide thin films.

    PubMed

    Hong, Sung-Jei; Kim, Jong-Woong; Jung, Seung-Boo

    2013-11-01

    Recently, decreasing the amount of indium (In) element in the indium tin oxide (ITO) used for transparent conductive oxide (TCO) thin film has become necessary for cost reduction. One possible approach to this problem is using printed ITO thin film instead of sputtered. Previous studies showed potential for printed ITO thin films as the TCO layer. However, nothing has been reported on the reliability of printed ITO thin films. Therefore, in this study, the reliability of printed ITO thin films was characterized. ITO nanoparticle ink was fabricated and printed onto a glass substrate followed by heating at 400 degrees C. After measurement of the initial values of sheet resistance and optical transmittance of the printed ITO thin films, their reliabilities were characterized with an isothermal-isohumidity test for 500 hours at 85 degrees C and 85% RH, a thermal shock test for 1,000 cycles between 125 degrees C and -40 degrees C, and a high temperature storage test for 500 hours at 125 degrees C. The same properties were investigated after the tests. Printed ITO thin films showed stable properties despite extremely thermal and humid conditions. Sheet resistances of the printed ITO thin films changed slightly from 435 omega/square to 735 omega/square 507 omega/square and 442 omega/square after the tests, respectively. Optical transmittances of the printed ITO thin films were slightly changed from 84.74% to 81.86%, 88.03% and 88.26% after the tests, respectively. These test results suggest the stability of printed ITO thin film despite extreme environments. PMID:24245331

  3. Magnetron sputtered nanostructured cadmium oxide films for ammonia sensing

    SciTech Connect

    Dhivya, P.; Prasad, A.K.; Sridharan, M.

    2014-06-01

    Nanostructured cadmium oxide (CdO) films were deposited on to glass substrates by reactive dc magnetron sputtering technique. The depositions were carried out for different deposition times in order to obtain films with varying thicknesses. The CdO films were polycrystalline in nature with cubic structure showing preferred orientation in (1 1 1) direction as observed by X-ray diffraction (XRD). Field-emission scanning electron microscope (FE-SEM) micrographs showed uniform distribution of grains of 30–35 nm size and change in morphology from spherical to elliptical structures upon increasing the film thickness. The optical band gap value of the CdO films decreased from 2.67 to 2.36 eV with increase in the thickness. CdO films were deposited on to interdigitated electrodes to be employed as ammonia (NH{sub 3}) gas sensor. The fabricated CdO sensor with thickness of 294 nm has a capacity to detect NH{sub 3} as low as 50 ppm at a relatively low operating temperature of 150 °C with quick response and recovery time. - Highlights: • Nanostructured CdO films were deposited on to glass substrates using magnetron sputtering. • Deposition time was varied in order to obtain films with different thicknesses. • The CdO films were polycrystalline in nature with preferred orientation along (1 1 1) direction. • The optical bandgap values of the films decreased on increasing the thickness of the films. • CdO films with different thickness such as 122, 204, 294 nm was capable to detect NH{sub 3} down to 50 ppm at operating temperature of 150 °C.

  4. Tungsten oxide proton conducting films for low-voltage transparent oxide-based thin-film transistors

    SciTech Connect

    Zhang, Hongliang; Wan, Qing; Wan, Changjin; Wu, Guodong; Zhu, Liqiang

    2013-02-04

    Tungsten oxide (WO{sub x}) electrolyte films deposited by reactive magnetron sputtering showed a high room temperature proton conductivity of 1.38 Multiplication-Sign 10{sup -4} S/cm with a relative humidity of 60%. Low-voltage transparent W-doped indium-zinc-oxide thin-film transistors gated by WO{sub x}-based electrolytes were self-assembled on glass substrates by one mask diffraction method. Enhancement mode operation with a large current on/off ratio of 4.7 Multiplication-Sign 10{sup 6}, a low subthreshold swing of 108 mV/decade, and a high field-effect mobility 42.6 cm{sup 2}/V s was realized. Our results demonstrated that WO{sub x}-based proton conducting films were promising gate dielectric candidates for portable low-voltage oxide-based devices.

  5. Tungsten oxide proton conducting films for low-voltage transparent oxide-based thin-film transistors

    NASA Astrophysics Data System (ADS)

    Zhang, Hongliang; Wan, Qing; Wan, Changjin; Wu, Guodong; Zhu, Liqiang

    2013-02-01

    Tungsten oxide (WOx) electrolyte films deposited by reactive magnetron sputtering showed a high room temperature proton conductivity of 1.38 × 10-4 S/cm with a relative humidity of 60%. Low-voltage transparent W-doped indium-zinc-oxide thin-film transistors gated by WOx-based electrolytes were self-assembled on glass substrates by one mask diffraction method. Enhancement mode operation with a large current on/off ratio of 4.7 × 106, a low subthreshold swing of 108 mV/decade, and a high field-effect mobility 42.6 cm2/V s was realized. Our results demonstrated that WOx-based proton conducting films were promising gate dielectric candidates for portable low-voltage oxide-based devices.

  6. Plasma enhanced chemical vapor deposition (PECVD) method of forming vanadium oxide films and vanadium oxide thin-films prepared thereby

    DOEpatents

    Zhang, Ji-Guang; Tracy, C. Edwin; Benson, David K.; Turner, John A.; Liu, Ping

    2000-01-01

    A method is disclosed of forming a vanadium oxide film on a substrate utilizing plasma enhanced chemical vapor deposition. The method includes positioning a substrate within a plasma reaction chamber and then forming a precursor gas comprised of a vanadium-containing chloride gas in an inert carrier gas. This precursor gas is then mixed with selected amounts of hydrogen and oxygen and directed into the reaction chamber. The amounts of precursor gas, oxygen and hydrogen are selected to optimize the final properties of the vanadium oxide film An rf plasma is generated within the reaction chamber to chemically react the precursor gas with the hydrogen and the oxygen to cause deposition of a vanadium oxide film on the substrate while the chamber deposition pressure is maintained at about one torr or less. Finally, the byproduct gases are removed from the plasma reaction chamber.

  7. Manganese oxide nanowires, films, and membranes and methods of making

    SciTech Connect

    Suib, Steven Lawrence; Yuan, Jikang

    2011-02-15

    Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves and methods of making the same are disclosed. A method for forming nanowires includes hydrothermally treating a chemical precursor composition in a hydrothermal treating solvent to form the nanowires, wherein the chemical precursor composition comprises a source of manganese cations and a source of counter cations, and wherein the nanowires comprise ordered porous manganese oxide-based octahedral molecular sieves.

  8. Tungsten oxide nanowire synthesis from amorphous-like tungsten films.

    PubMed

    Seelaboyina, Raghunandan

    2016-03-18

    A synthesis technique which can lead to direct integration of tungsten oxide nanowires onto silicon chips is essential for preparing various devices. The conversion of amorphous tungsten films deposited on silicon chips by pulsed layer deposition to nanowires by annealing is an apt method in that direction. This perspective discusses the ingenious features of the technique reported by Dellasega et al on the various aspects of tungsten oxide nanowire synthesis. PMID:26871521

  9. Ambient-Temperature Sputtering Of Composite Oxide Films

    NASA Technical Reports Server (NTRS)

    Thakoor, Sarita

    1992-01-01

    Technique for deposition of homogeneous films of multicomponent oxides on substrates at ambient temperature based on sequential sputter deposition of individual metal components, as alternating ultra-thin layers, from multiple targets. Substrates rotated over sputtering targets of lead, zirconium, and titanium. Dc-magnetron sputtering of constituent metals in reactive ambient of argon and oxygen leads to formation of the respective metal oxides intermixed on extremely fine scale in desired composition. Compatible with low-temperature microelectronic processing.

  10. Tungsten oxide nanowire synthesis from amorphous-like tungsten films

    NASA Astrophysics Data System (ADS)

    Seelaboyina, Raghunandan

    2016-03-01

    A synthesis technique which can lead to direct integration of tungsten oxide nanowires onto silicon chips is essential for preparing various devices. The conversion of amorphous tungsten films deposited on silicon chips by pulsed layer deposition to nanowires by annealing is an apt method in that direction. This perspective discusses the ingenious features of the technique reported by Dellasega et al on the various aspects of tungsten oxide nanowire synthesis.

  11. Effects of the polarizability and packing density of transparent oxide films on water vapor permeation.

    PubMed

    Koo, Won Hoe; Jeong, Soon Moon; Choi, Sang Hun; Kim, Woo Jin; Baik, Hong Koo; Lee, Sung Man; Lee, Se Jong

    2005-06-01

    The tin oxide and silicon oxide films have been deposited on polycarbonate substrates as gas barrier films, using a thermal evaporation and ion beam assisted deposition process. The oxide films deposited by ion beam assisted deposition show a much lower water vapor transmission rate than those by thermal evaporation. The tin oxide films show a similar water vapor transmission rate to the silicon oxide films in thermal evaporation but a lower water vapor transmission rate in IBAD. These results are related to the fact that the permeation of water vapor with a large dipole moment is affected by the chemistry of oxides and the packing density of the oxide films. The permeation mechanism of water vapor through the oxide films is discussed in terms of the chemical interaction with water vapor and the microstructure of the oxide films. The chemical interaction of water vapor with oxide films has been investigated by the refractive index from ellipsometry and the OH group peak from X-ray photoelectron spectroscopy, and the microstructure of the composite oxide films was characterized using atomic force microscopy and a transmission electron microscope. The activation energy for water vapor permeation through the oxide films has also been measured in relation to the permeation mechanism of water vapor. The diffusivity of water vapor for the tin oxide films has been calculated from the time lag plot, and its implications are discussed. PMID:16852387

  12. New fabrication of zinc oxide nanostructure thin film gas sensors

    NASA Astrophysics Data System (ADS)

    Hendi, A. A.; Alorainy, R. H.

    2014-02-01

    The copper doped zinc oxide thin films have been prepared by sol-gel spin coating method. The structural and morphology properties of the Cu doped films were characterized by X-ray diffraction and atomic force microscope. XRD studies confirm the chemical structure of the ZnO films. The optical spectra method were used to determined optical constants and dispersion energy parameters of Cu doped Zno thin films. The optical band gap of undoped ZnO was found to be 3.16 eV. The Eg values of the films were changed with Cu doping. The refractive index dispersion of Cu doped ZnO films obeys the single oscillator model. The dispersion energy and oscillator energy values of the ZnO films were changed with Cu doping. The Cu doped ZnO nanofiber-based NH3 gas sensors were fabricated. The sensor response of the sensors was from 464.98 to 484.61 when the concentration of NH3 is changed 6600-13,300 ppm. The obtained results indicate that the response of the ZnO film based ammonia gas sensors can be controlled by copper content.

  13. Correlation between density and oxidation temperature for pyrolytic-gas passivated ultrathin silicon oxide films

    NASA Astrophysics Data System (ADS)

    Yamada, Hiroshi

    2004-01-01

    Pyrolytic-gas passivation (PGP) with a small amount nitrogen gas enhances the breakdown reliability of silicon oxide gate films. To clarify the reliability retention of the PGP-grown films oxidized at low temperature, densities (ρox's) of the 3.5-6.5-nm-thick PGP-grown films on Si(100) oxidized at 700-900 °C were investigated. Since ρox's correlate well with the reliability and are useful as an index of the intrinsic structural characteristics of the films. Moreover, changes in ρox and nitrogen content corresponding to oxidation temperature are similar to those in breakdown reliability and interface state density (Dit), respectively. In addition, ρox's of the 700 °C-grown PGP films do not deteriorate as much when compared with those of the films grown by normal ultradry oxidation at 800 °C and their Dit's are less than about 6×1010/eV cm2. This suggests that PGP probably improves the reliability by generating the higher-ρox microscopic structure with few Si dangling bonds and effective passivation. .

  14. 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.

  15. Investigation of the Carbon Monoxide Gas Sensing Characteristics of Tin Oxide Mixed Cerium Oxide Thin Films

    PubMed Central

    Durrani, Sardar M. A.; Al-Kuhaili, Mohammad F.; Bakhtiari, Imran A.; Haider, Muhammad B.

    2012-01-01

    Thin films of tin oxide mixed cerium oxide were grown on unheated substrates by physical vapor deposition. The films were annealed in air at 500 °C for two hours, and were characterized using X-ray photoelectron spectroscopy, atomic force microscopy and optical spectrophotometry. X-ray photoelectron spectroscopy and atomic force microscopy results reveal that the films were highly porous and porosity of our films was found to be in the range of 11.6–21.7%. The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive. We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm. Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively. PMID:22736967

  16. Growth of ultrathin vanadium oxide films on Ag(100)

    NASA Astrophysics Data System (ADS)

    Nakamura, Takuya; Sugizaki, Yuichi; Ishida, Shuhei; Edamoto, Kazuyuki; Ozawa, Kenichi

    2016-07-01

    Vanadium oxide films were grown on Ag(100) by vanadium deposition in O2 and subsequent annealing at 450 °C. It was found that at least three types of ordered V oxide films, which showed (1 × 1), hexagonal, and (4 × 1) LEED patterns, were formed on Ag(100) depending on the O2 pressure during deposition and conditions during postannealing. The films with the hexagonal and (1 × 1) periodicities were characterized by photoelectron spectroscopy (PES) and near-edge X-ray absorption fine structure (NEXAFS) analysis. The film with the (1 × 1) periodicity was ascribed to a VO(100) film. On the other hand, the film with the hexagonal periodicity was found to be composed of V2O3, and the analysis of the LEED pattern revealed that the lattice parameter of the hexagonal lattice is 0.50 nm, which is very close to that of corundum V2O3(0001) (0.495 nm).

  17. Nanostructured zinc oxide thin film by simple vapor transport deposition

    NASA Astrophysics Data System (ADS)

    Athma, P. V.; Martinez, Arturo I.; Johns, N.; Safeera, T. A.; Reshmi, R.; Anila, E. I.

    2015-09-01

    Zinc oxide (ZnO) nanostructures find applications in optoelectronic devices, photo voltaic displays and sensors. In this work zinc oxide nanostructures in different forms like nanorods, tripods and tetrapods have been synthesized by thermal evaporation of zinc metal and subsequent deposition on a glass substrate by vapor transport in the presence of oxygen. It is a comparatively simpler and environment friendly technique for the preparation of thin films. The structure, morphology and optical properties of the synthesized nanostructured thin film were characterized in detail by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and photoluminescence (PL). The film exhibited bluish white emission with Commission International d'Eclairage (CIE) coordinates x = 0.22, y = 0.31.

  18. Magnetic Transparent Conducting Oxide Film And Method Of Making

    DOEpatents

    Windisch, Jr., Charles F.; Exarhos, Gregory J.; Sharma, Shiv K.

    2006-03-14

    Cobalt-nickel oxide films of nominal 100 nm thickness, and resistivity as low as 0.06 O·cm have been deposited by spin-casting from both aqueous and organic precursor solutions followed by annealing at 450° C. in air. An increase in film resistivity was found upon substitution of other cations (e.g., Zn2+, Al3+) for Ni in the spinel structure. However, some improvement in the mechanical properties of the films resulted. On the other hand, addition of small amounts of Li decreased the resistivity. A combination of XRD, XPS, UV/Vis and Raman spectroscopy indicated that NiCo2O4 is the primary conducting component and that the conductivity reaches a maximum at this stoichiometry. When x<0.67, NiO forms leading to an increase in resistivity; when x>0.67, the oxide was all spinel but the increased Co content lowered the conductivity.

  19. 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.

  20. Perovskite Oxide Thin Film Growth, Characterization, and Stability

    NASA Astrophysics Data System (ADS)

    Izumi, Andrew

    Studies into a class of materials known as complex oxides have evoked a great deal of interest due to their unique magnetic, ferroelectric, and superconducting properties. In particular, materials with the ABO3 perovskite structure have highly tunable properties because of the high stability of the structure, which allows for large scale doping and strain. This also allows for a large selection of A and B cations and valences, which can further modify the material's electronic structure. Additionally, deposition of these materials as thin films and superlattices through techniques such as pulsed laser deposition (PLD) results in novel properties due to the reduced dimensionality of the material. The novel properties of perovskite oxide heterostructures can be traced to a several sources, including chemical intermixing, strain and defect formation, and electronic reconstruction. The correlations between microstructure and physical properties must be investigated by examining the physical and electronic structure of perovskites in order to understand this class of materials. Some perovskites can undergo phase changes due to temperature, electrical fields, and magnetic fields. In this work we investigated Nd0.5Sr 0.5MnO3 (NSMO), which undergoes a first order magnetic and electronic transition at T=158K in bulk form. Above this temperature NSMO is a ferromagnetic metal, but transitions into an antiferromagnetic insulator as the temperature is decreased. This rapid transition has interesting potential in memory devices. However, when NSMO is deposited on (001)-oriented SrTiO 3 (STO) or (001)-oriented (LaAlO3)0.3-(Sr 2AlTaO6)0.7 (LSAT) substrates, this transition is lost. It has been reported in the literature that depositing NSMO on (110)-oriented STO allows for the transition to reemerge due to the partial epitaxial growth, where the NSMO film is strained along the [001] surface axis and partially relaxed along the [11¯0] surface axis. This allows the NSMO film enough

  1. Optical properties of thin In-Sn oxide films

    NASA Astrophysics Data System (ADS)

    Christian, K. D. J.; Shatynski, S. R.

    Indium-tin oxide (ITO) films were produced by evaporating an alloy of In-5wt%Sn in vacuum (1 × 10 -7 Torr) or in an oxygen partial pressure of 1 × 10 -4 Torr on soda-lime glass. After evaporation, these films were annealed in air at 95°C for 22 h. The films were examined using a ratio recording spectrophotometer to determine the transmission of both the visible and infra-red radiation. Further analysis of the samples was performed using SEM and EDAX analysis. Excellent optical properties were obtained for ITO films on soda-lime glass by evaporating 250 Å of In-5wt%Sn in an oxygen environment of 1 × 10 -4 Torr on a substrate held at 50°C and annealing at 95°C for 22 h.

  2. Indium oxide inverse opal films synthesized by structure replication method

    NASA Astrophysics Data System (ADS)

    Amrehn, Sabrina; Berghoff, Daniel; Nikitin, Andreas; Reichelt, Matthias; Wu, Xia; Meier, Torsten; Wagner, Thorsten

    2016-04-01

    We present the synthesis of indium oxide (In2O3) inverse opal films with photonic stop bands in the visible range by a structure replication method. Artificial opal films made of poly(methyl methacrylate) (PMMA) spheres are utilized as template. The opal films are deposited via sedimentation facilitated by ultrasonication, and then impregnated by indium nitrate solution, which is thermally converted to In2O3 after drying. The quality of the resulting inverse opal film depends on many parameters; in this study the water content of the indium nitrate/PMMA composite after drying is investigated. Comparison of the reflectance spectra recorded by vis-spectroscopy with simulated data shows a good agreement between the peak position and calculated stop band positions for the inverse opals. This synthesis is less complex and highly efficient compared to most other techniques and is suitable for use in many applications.

  3. Structural transformation of nickel hydroxide films during anodic oxidation

    SciTech Connect

    Crocker, R.W.; Muller, R.H.

    1992-05-01

    The transformation of anodically formed nickel hydroxide/oxy-hydroxide electrodes has been investigated. A mechanism is proposed for the anodic oxidation reaction, in which the reaction interface between the reduced and oxidized phases of the electrode evolves in a nodular topography that leads to inefficient utilization of the active electrode material. In the proposed nodular transformation model for the anodic oxidation reaction, nickel hydroxide is oxidized to nickel oxy-hydroxide in the region near the metal substrate. Since the nickel oxy-hydroxide is considerably more conductive than the surrounding nickel hydroxide, as further oxidation occurs, nodular features grow rapidly to the film/electrolyte interface. Upon emerging at the electrolyte interface, the reaction boundary between the nickel hydroxide and oxy-hydroxide phases spreads laterally across the film/electrolyte interface, creating an overlayer of nickel oxy-hydroxide and trapping uncharged regions of nickel hydroxide within the film. The nickel oxy-hydroxide overlayer surface facilitates the oxygen evolution side reaction. Scanning tunneling microscopy of the electrode in its charged state revealed evidence of 80 {endash} 100 Angstrom nickel oxy-hydroxide nodules in the nickel hydroxide film. In situ spectroscopic ellipsometer measurements of films held at various constant potentials agree quantitatively with optical models appropriate to the nodular growth and subsequent overgrowth of the nickel oxy-hydroxide phase. A two-dimensional, numerical finite difference model was developed to simulate the current distribution along the phase boundary between the charged and uncharged material. The model was used to explore the effects of the physical parameters that govern the electrode behavior. The ratio of the conductivities of the nickel hydroxide and oxy-hydroxide phases was found to be the dominant parameter in the system.

  4. Performance of supercapacitor with electrodeposited ruthenium oxide film electrodes—effect of film thickness

    NASA Astrophysics Data System (ADS)

    Park, Bong-Ok; Lokhande, C. D.; Park, Hyung-Sang; Jung, Kwang-Deog; Joo, Oh-Shim

    Thin-film ruthenium oxide electrodes are prepared by cathodic electrodeposition on a titanium substrate. Different deposition periods are used to obtain different film thicknesses. The electrodes are used to form a supercapacitor with a 0.5 M H 2SO 4 electrolyte. The specific capacitance and charge-discharge periods are found to be dependent on the electrode thickness. A maximum specific capacitance of 788 F g -1 is achieved with an electrode thickness of 0.0014 g cm -2. These results are explained by considering the morphological changes that take place with increasing film thickness.

  5. Epitaxial Zinc Oxide Semiconductor Film deposited on Gallium Nitride Substrate

    NASA Astrophysics Data System (ADS)

    McMaster, Michael; Oder, Tom

    2011-04-01

    Zinc oxide (ZnO) is a wide bandgap semiconductor which is very promising for making efficient electronic and optical devices. The goal of this research was to produce high quality ZnO film on gallium nitride (GaN) substrate by optimizing the substrate temperature. The GaN substrates were chemically cleaned and mounted on a ceramic heater and loaded into a vacuum deposition chamber that was pumped down to a base pressure of 3 x 10-7 Torr. The film deposition was preceded by a 30 minute thermal desorption carried in vacuum at 500 ^oC. The ZnO thin film was then sputter-deposited using an O2/Ar gas mixture onto GaN substrates heated at temperatures varying from 20 ^oC to 500 ^oC. Post-deposition annealing was done in a rapid thermal processor at 900 ^oC for 5 min in an ultrapure N2 ambient to improve the crystal quality of the films. The films were then optically characterized using photoluminescence (PL) measurement with a UV laser excitation. Our measurements reveal that ZnO films deposited on GaN substrate held at 200 ^oC gave the best film with the highest luminous intensity, with a peak energy of 3.28 eV and a full width half maximum of 87.4 nm. Results from low temperature (10 K) PL measurements and from x-ray diffraction will also be presented.

  6. Lateral solid-phase epitaxy of oxide thin films on glass substrate seeded with oxide nanosheets.

    PubMed

    Taira, Kenji; Hirose, Yasushi; Nakao, Shoichiro; Yamada, Naoomi; Kogure, Toshihiro; Shibata, Tatsuo; Sasaki, Takayoshi; Hasegawa, Tetsuya

    2014-06-24

    We developed a technique to fabricate oxide thin films with uniaxially controlled crystallographic orientation and lateral size of more than micrometers on amorphous substrates. This technique is lateral solid-phase epitaxy, where epitaxial crystallization of amorphous precursor is seeded with ultrathin oxide nanosheets sparsely (≈10% coverage) deposited on the substrate. Transparent conducting Nb-doped anatase TiO2 thin films were fabricated on glass substrates by this technique. Perfect (001) orientation and large grains with lateral sizes up to 10 μm were confirmed by X-ray diffraction, atomic force microscopy, and electron beam backscattering diffraction measurements. As a consequence of these features, the obtained film exhibited excellent electrical transport properties comparable to those of epitaxial thin films on single-crystalline substrates. This technique is a versatile method for fabricating high-quality oxide thin films other than anatase TiO2 and would increase the possible applications of oxide-based thin film devices. PMID:24867286

  7. Study of the doping of thermally evaporated zinc oxide thin films with indium and indium oxide

    NASA Astrophysics Data System (ADS)

    Palimar, Sowmya; Bangera, Kasturi V.; Shivakumar, G. K.

    2013-12-01

    The present paper reports observations made on investigations carried out to study structural, optical and electrical properties of thermally evaporated ZnO thin films and their modulations on doping with metallic indium and indium oxide separately. ZnO thin film in the undoped state is found to have a very good conductivity of 90 Ω-1 cm-1 with an excellent transmittance of up to 90 % in the visible region. After doping with metallic indium, the conductivity of the film is found to be 580 Ω-1 cm-1, whereas the conductivity of indium oxide-doped films is increased up to 3.5 × 103 Ω-1 cm-1. Further, the optical band gap of the ZnO thin film is widened from 3.26 to 3.3 eV when doped with indium oxide and with metallic indium it decreases to 3.2 eV. There is no considerable change in the transmittance of the films after doping. All undoped and doped films were amorphous in nature with smooth and flat surface without significant modifications due to doping.

  8. Texture Control in Cerium Oxide Films (Poster)

    SciTech Connect

    van Hest, M. F. A. M.; Leenheer, A. J.; Perkins, J. D.; Teplin, C. W.; Ginley, D. S.

    2006-05-01

    The conclusions are: (1) Texture control is possible in cerium oxide by epitaxial growth or adjusting the substrate angle; (2) Biaxial (111) texture emerges with inclined angle depositions on glass; and (3) Biaxial (200) texture emerges by epitaxial growth on YSZ.

  9. Development of metal oxide impregnated stilbite thick film ethanol sensor

    NASA Astrophysics Data System (ADS)

    Mahabole, M. P.; Lakhane, M. A.; Choudhari, A. L.; Khairnar, R. S.

    2016-05-01

    This paper presents the study of the sensing efficiency of Titanium oxide/ Stilbite and Copper oxide /Stilbite composites towards detection of hazardous pollutants like ethanol. Stilbite based composites are prepared by physically mixing zeolite with metal oxides namely TiO2 and CuO with weight ratios of 25:75, 50:50 and 75:25. The resulting sensor materials are characterized by X-ray diffraction and Fourier Transform Infrared Spectroscopy techniques. Composite sensors are fabricated in the form of thick film by using screen printing technique. The effect of metal oxide concentration on various ethanol sensing parameters such as operating temperature, maximum uptake capacity and response/recovery time are investigated. The results indicate that metal oxide impregnated stilbite composites have great potential as low temperature ethanol sensor.

  10. Zinc oxide doped graphene oxide films for gas sensing applications

    NASA Astrophysics Data System (ADS)

    Chetna, Kumar, Shani; Garg, A.; Chowdhuri, A.; Dhingra, V.; Chaudhary, S.; Kapoor, A.

    2016-05-01

    Graphene Oxide (GO) is analogous to graphene, but presence of many functional groups makes its physical and chemical properties essentially different from those of graphene. GO is found to be a promising material for low cost fabrication of highly versatile and environment friendly gas sensors. Selectivity, reversibility and sensitivity of GO based gas sensor have been improved by hybridization with Zinc Oxide nanoparticles. The device is fabricated by spin coating of deionized water dispersed GO flakes (synthesized using traditional hummer's method) doped with Zinc Oxide on standard glass substrate. Since GO is an insulator and functional groups on GO nanosheets play vital role in adsorbing gas molecules, it is being used as an adsorber. Additionally, on being exposed to certain gases the electric and optical characteristics of GO material exhibit an alteration in behavior. For the conductivity, we use Zinc Oxide, as it displays a high sensitivity towards conduction. The effects of the compositions, structural defects and morphologies of graphene based sensing layers and the configurations of sensing devices on the performances of gas sensors were investigated by Raman Spectroscopy, X-ray diffraction(XRD) and Keithley Sourcemeter.

  11. Changes in the Young Modulus of hafnium oxide thin films

    NASA Astrophysics Data System (ADS)

    Vargas, André Luís Marin; de Araújo Ribeiro, Fabiana; Hübler, Roberto

    2015-12-01

    Hafnium-oxide (HfO2)-based materials have been extensively researched due to their excellent optical and electrical properties. However, the literature data on the mechanical properties of these materials and its preparation for heavy machinery application is very limited. The aim of this work is to deposit hafnium oxide thin films by DC reactive magnetron sputtering with different Young's Modulus from the Ar/O2 concentration variation in the deposition chamber. The thin films were deposited by DC reactive magnetron sputtering with different Ar/O2 gas concentrations in plasma. After deposition, HfOx thin films were characterized through XRD, AFM, RBS and XRF. In this regard, it was observed that the as-deposited HfO2 films were mostly amorphous in the lower Ar/O2 gas ratio and transformed to polycrystalline with monoclinic structure as the Ar/O2 gas ratios grows. RBS technique shows good compromise between the experimental data and the simulated ones. It was possible to tailored the Young Modulus of the films by alter the Ar/O2 content on the deposition chamber without thermal treatment.

  12. Photoassisted oxidation of oil films on water

    SciTech Connect

    Heller, A.; Brock, J.R.

    1991-08-01

    The objective of the project is to develop TiO{sub 2}-based photocatalysts for the solar assisted oxidative dissolution of oil slicks. In a TiO{sub 2} crystal, absorption of a photon generates an electron-hole pair. The electron reacts with surface-adsorbed oxygen, reducing it to hydrogen peroxide; the hole directly oxidizes adsorbed organic compounds, usually via an intermediate OH radical. Since the density of TiO{sub 2} (3.8g/cc for anatase, 4.3 g/cc for rutile) is greater than that of either oil or seawater, TiO{sub 2} crystals are attached to inexpensive, engineered hollow glass microspheres to ensure flotation on the oil slick surface. Portions of the microsphere surface not covered by TiO{sub 2} are made oleophilic so that the microbeads will be preferentially attracted to the oil-air interface.

  13. Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

    DOEpatents

    Bates, John B.

    2003-04-29

    Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

  14. Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

    DOEpatents

    Bates, John B.

    2003-05-13

    Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

  15. Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

    DOEpatents

    Bates, John B.

    2002-01-01

    Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

  16. Investigation and characterization of oxidized cellulose and cellulose nanofiber films

    NASA Astrophysics Data System (ADS)

    Yang, Han

    Over the last two decades, a large amount of research has focused on natural cellulose fibers, since they are "green" and renewable raw materials. Recently, nanomaterials science has attracted wide attention due to the large surface area and unique properties of nanoparticles. Cellulose certainly is becoming an important material in nanomaterials science, with the increasing demand of environmentally friendly materials. In this work, a novel method of preparing cellulose nanofibers (CNF) is being presented. This method contains up to three oxidation steps: periodate, chlorite and TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxyl) oxidation. The first two oxidation steps are investigated in the first part of this work. Cellulose pulp was oxidized to various extents by a two step-oxidation with sodium periodate, followed by sodium chlorite. The oxidized products can be separated into three different fractions. The mass ratio and charge content of each fraction were determined. The morphology, size distribution and crystallinity index of each fraction were measured by AFM, DLS and XRD, respectively. In the second part of this work, CNF were prepared and modified under various conditions, including (1) the introduction of various amounts of aldehyde groups onto CNF by periodate oxidation; (2) the carboxyl groups in sodium form on CNF were converted to acid form by treated with an acid type ion-exchange resin; (3) CNF were cross-linked in two different ways by employing adipic dihydrazide (ADH) as cross-linker and water-soluble 1-ethyl-3-[3-(dimethylaminopropyl)] carbodiimide (EDC) as carboxyl-activating agent. Films were fabricated with these modified CNF suspensions by vacuum filtration. The optical, mechanical and thermo-stability properties of these films were investigated by UV-visible spectrometry, tensile test and thermogravimetric analysis (TGA). Water vapor transmission rates (WVTR) and water contact angle (WCA) of these films were also studied.

  17. Facile fabrication of superhydrophobic octadecylamine-functionalized graphite oxide film.

    PubMed

    Lin, Ziyin; Liu, Yan; Wong, Ching-ping

    2010-10-19

    We demonstrated a facile strategy of producing superhydrophobic octadecylamine (ODA)-functionalized graphite oxide (GO) films. ODA was chemically grafted on GO sheets by the nucleophilic substitution reaction of amine groups with epoxy groups. The long hydrocarbon chain in ODA reduces the surface energy of the GO sheet. The fabricated ODA-functionalized GO film exhibited a high contact angle (163.2°) and low hysteresis (3.1°). This method is promising in terms of low-cost and large-scale superhydrophobic coatings and has potential applications for surface modification of GO paper or other GO-based composite materials. PMID:20857962

  18. Vapor-gel processing and applications in oxide film depositions

    SciTech Connect

    Chour, K.W.; Xu, R.; Takada, T.

    1995-12-31

    The Vapor-gel processing of oxide films is discussed for the prototypic system of LiTa(OBut{sup n}){sub 6}-LiTaO{sub 3}. It is found that the hydrolysis-polycondensation reaction scheme, commonly used in Sol-gel processing, can be used in a vapor deposition environment. High quality films can be deposited at low temperatures. We present some initial results regarding this deposition method and discuss its advantages and disadvantages as compared with Sol-gel processing and typical MOCVD.

  19. Synthesis of tin oxide nanoparticle film by cathodic electrodeposition.

    PubMed

    Kim, Seok; Lee, Hochun; Park, Chang Min; Jung, Yongju

    2012-02-01

    Three-dimensional SnO2 nanoparticle films were deposited onto a copper substrate by cathodic electrodeposition in a nitric acid solution. A new formation mechanism for SnO2 films is proposed based on the oxidation of Sn2+ ion to Sn4+ ion by NO+ ion and the hydrolysis of Sn4+. The particle size of SnO2 was controlled by deposition potential. The SnO2 showed excellent charge capacity (729 mAh/g) at a 0.2 C rate and high rate capability (460 mAh/g) at a 5 C rate. PMID:22630013

  20. 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.

  1. Formation of zinc oxide films using submicron zinc particle dispersions

    SciTech Connect

    Rajachidambaram, Meena Suhanya; Varga, Tamas; Kovarik, Libor; Sanghavi, Rahul P.; Shutthanandan, V.; Thevuthasan, Suntharampillai; Han, Seungyeol; Chang, Chih-hung; Herman, Gregory S.

    2012-07-27

    The thermal oxidation of submicron metallic Zn particles was studied as a method to form nanostructured ZnO films. The particles used for this work were characterized by electron microscopy, x-ray diffraction and thermal analysis to evaluate the Zn-ZnO core shell structure, surface morphology, and oxidation characteristics. Significant nanostructural changes were observed for films annealed to 400 °C or higher, where nanoflakes, nanoribbons, nanoneedles and nanorods were formed as a result of stress induced fractures arising in the ZnO outer shell due to differential thermal expansion between the metallic Zn core and the ZnO shell. Mass transport occurs through these defects due to the high vapor pressure for metallic Zn at temperatures above 230 °C, whereupon the Zn vapor rapidly oxidizes in air to form the ZnO nanostructures. The Zn particles were also incorporated into zinc indium oxide precursor solutions to form thin film transistor test structures to evaluate the potential of forming nanostructured field effect sensors using simple solution processing.

  2. rf plasma oxidation of Ni thin films sputter deposited to generate thin nickel oxide layers

    NASA Astrophysics Data System (ADS)

    Hoey, Megan L.; Carlson, J. B.; Osgood, R. M.; Kimball, B.; Buchwald, W.

    2010-10-01

    Nickel oxide (NiO) layers were formed on silicon (Si) substrates by plasma oxidation of nickel (Ni) film lines. This ultrathin NiO layer acted as a barrier layer to conduction, and was an integral part of a metal-insulator-metal (MIM) diode, completed by depositing gold (Au) on top of the oxide. The electrical and structural properties of the NiO thin film were examined using resistivity calculations, current-voltage (I-V) measurements and cross-sectional transmission electron microscopy (XTEM) imaging. The flow rate of the oxygen gas, chamber pressure, power, and exposure time and their influence on the characteristics of the NiO thin film were studied.

  3. A comparative analysis of graphene oxide films as proton conductors

    NASA Astrophysics Data System (ADS)

    Smirnov, V. A.; Denisov, N. N.; Dremova, N. N.; Vol'fkovich, Y. M.; Rychagov, A. Y.; Sosenkin, V. E.; Belay, K. G.; Gutsev, G. L.; Shulga, N. Yu.; Shulga, Y. M.

    2014-12-01

    The electrical conductivity of graphene oxide (GO) films in vapors of water and acid solutions is found to be close to the conductivity of a film formed after drying the solution of phenol-2,4-disulfonic acid in polyvinyl alcohol, which is known to be a proton conductor. We found that the conductivity of a GO film in vapors of the H2O-H2SO4 electrolyte possesses a sharp maximum at ~1 % by weight of sulfuric acid. The highest conductivity of GO films can be expected when placing the films over acid vapors where the acid concentration is essentially lower than in the acid solutions at their maximum conductivity. Since the conductivity of the H2O-H2SO4 electrolyte itself has a maximum at ~30 % by weight of sulfuric acid, the use of intermediate concentrations of H2SO4 is recommended in practical applications. The GO films permeated with water or acid solution in water are expected to possess the proton-exchange properties similar to those of other proton-exchanging membranes.

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

    NASA Astrophysics Data System (ADS)

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

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

  5. Transition of oxide film configuration and the critical stress inferred by scanning probe microscopy at nanoscale

    NASA Astrophysics Data System (ADS)

    Fang, Xufei; Li, Yan; Zhang, Changxing; Dong, Xuelin; Feng, Xue

    2016-09-01

    Scanning probe microscopy (SPM) equipped in high temperature nanoindentation instrument is adopted to in situ characterize the oxide film growth on Ni-base single crystal at nanoscale. SPM images reveal a transition of oxide film configuration that the originally flat surface roughens during oxidation. Based on the stress-diffusion coupling effect during oxidation, the stress evolution in the oxide film and the evolution of surface configuration are analyzed. A new method to infer the critical stress in the oxide film at the transition point is proposed by measuring the undulated surface wavelength based on the surface morphology obtained by SPM.

  6. Photoassisted oxidation of oil films on water

    SciTech Connect

    Heller, A.; Brock, J.R.

    1990-10-01

    The objective of the project is to develop a method for the solar assisted oxidation of oil slicks. A semiconducting photocatalyst, titanium dioxide, is used. Upon absorbing a photon, an electron-hole pair is generated in the TiO{sub 2} microcrystal. The electron reacts with surface-adsorbed oxygen, reducing it to hydrogen peroxide; the hole directly oxidizes adsorbed organic compounds. Titanium dioxide is denser than either oil or seawater; the density of its anatase phase is 3.8 and that of its rutile phase is 4.3. In order to keep the titanium dioxide at the air/oil interface, it is attached to a low density, floating material. The particles of the latter are sufficiently small to make the system economical. Specifically, the photocatalyst particles are attached to inexpensive hollow glass microbeads of about 100{mu}m diameter. Those areas of the microbeads that are not covered by photocatalyst are made oleophilic, so that the microbeads will follow the oil slick and not migrate to either the air/water or the water/oil interface.

  7. Vanadium oxide thin film with improved sheet resistance uniformity

    NASA Astrophysics Data System (ADS)

    Généreux, Francis; Provençal, Francis; Tremblay, Bruno; Boucher, Marc-André; Julien, Christian; Alain, Christine

    2014-06-01

    This paper reports on the deposition of vanadium oxide thin films with sheet resistance uniformity better than 2.5% over a 150 mm wafer. The resistance uniformity within the array is estimated to be less than 1%, which is comparable with the value reported for amorphous silicon-based microbolometer arrays. In addition, this paper also shows that the resistivity of vanadium oxide, like amorphous silicon, can be modeled by Arrhenius' equation. This result is expected to significantly ease the computation of the correction table required for TEC-less operation of VOx-based microbolometer arrays.

  8. Preparation and Evaluation of Nitrogen Doped Tungsten Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Nakagawa, Koichi; Miura, Noboru; Matsumoto, Setsuko; Nakano, Ryotaro; Matsumoto, Hironaga

    Nitrogen doped tungsten oxide thin films were prepared by RF reactive sputtering in a gas mixture of argon, oxygen and nitrogen at room temperature. As a result of X-ray photoelectron spectroscopy, it was thought that the doped nitrogen in the films is bonding to tungsten of WO3 bonding states as anion and exits in substitution sites in WO3. The optical absorption edge was shifted to lower energy region with nitrogen doping. The nitrogen doped thin films exhibit a coloration to black from transparent yellow by electrochromism. Additionally, a new peak at 2.3 eV related to nitrogen doping is observed in the spectra of color center at bleaching process.

  9. Reversible superconductivity in electrochromic indium-tin oxide films

    NASA Astrophysics Data System (ADS)

    Aliev, Ali E.; Xiong, Ka; Cho, Kyeongjae; Salamon, M. B.

    2012-12-01

    Transparent conductive indium tin oxide (ITO) thin films, electrochemically intercalated with sodium or other cations, show tunable superconducting transitions with a maximum Tc at 5 K. The transition temperature and the density of states, D(EF) (extracted from the measured Pauli susceptibility χp) exhibit the same dome shaped behavior as a function of electron density. Optimally intercalated samples have an upper critical field ≈ 4 T and Δ/kBTc ≈ 2.0. Accompanying the development of superconductivity, the films show a reversible electrochromic change from transparent to colored and are partially transparent (orange) at the peak of the superconducting dome. This reversible intercalation of alkali and alkali earth ions into thin ITO films opens diverse opportunities for tunable, optically transparent superconductors.

  10. Infrared spectroscopic study of sputtered tungsten oxide films

    SciTech Connect

    Paul, J.L.; Lassegues, J.C. )

    1993-10-01

    Recent infrared and Raman spectroscopic studies of various tungsten oxide films concluded either the formation of W=O terminal bonds or the transformation of such bonds into W-OH groups upon proton insertion. The infrared transmission and reflection spectra of bleached and colored sputtered films were reinvestigated in order to resolve the previous contradictory interpretations and for better insight into the mechanism of electrochromism at the molecular level. The new results confirm the first interpretation and allow us to show that H[sup +] or Li[sup +] insertion creates shorter ([approximately]1.7[angstrom]) and longer ([approximately]2 [angstrom]) W-O bonds around the W[sup 5+] centers. These results are in agreement with the concepts of small polaron and of intervalence charge transfer mechanism. They illustrate the local lattice distortion around a W[sup 5+] site. Aging of the initial films has also been followed and characterized by H/D in situ isotopic exchange.

  11. Enhanced electrochromism in cerium doped molybdenum oxide thin films

    SciTech Connect

    Dhanasankar, M.; Purushothaman, K.K.; Muralidharan, G.

    2010-12-15

    Cerium (5-15% by weight) doped molybdenum oxide thin films have been prepared on FTO coated glass substrate at 250 {sup o}C using sol-gel dip coating method. The structural and morphological changes were observed with the help of XRD, SEM and EDS analysis. The amorphous structure of the Ce doped samples, favours easy intercalation and deintercalation processes. Mo oxide films with 10 wt.% of Ce exhibit maximum anodic diffusion coefficient of 24.99 x 10{sup -11} cm{sup 2}/s and the change in optical transmittance of ({Delta}T at 550 nm) of 79.28% between coloured and bleached state with the optical density of ({Delta}OD) 1.15.

  12. Manganese oxide nanowires, films, and membranes and methods of making

    DOEpatents

    Suib, Steven Lawrence; Yuan, Jikang

    2008-10-21

    Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves, and methods of making, are disclosed. A single crystal ultra-long nanowire includes an ordered porous manganese oxide-based octahedral molecular sieve, and has an average length greater than about 10 micrometers and an average diameter of about 5 nanometers to about 100 nanometers. A film comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is stacked on a surface of a substrate, wherein the nanowires of each layer are substantially axially aligned. A free standing membrane comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is aggregately stacked, and wherein the nanowires of each layer are substantially axially aligned.

  13. Combinatorial study of zinc tin oxide thin-film transistors

    SciTech Connect

    McDowell, M. G.; Sanderson, R. J.; Hill, I. G.

    2008-01-07

    Groups of thin-film transistors using a zinc tin oxide semiconductor layer have been fabricated via a combinatorial rf sputtering technique. The ZnO:SnO{sub 2} ratio of the film varies as a function of position on the sample, from pure ZnO to SnO{sub 2}, allowing for a study of zinc tin oxide transistor performance as a function of channel stoichiometry. The devices were found to have mobilities ranging from 2 to 12 cm{sup 2}/V s, with two peaks in mobility in devices at ZnO fractions of 0.80{+-}0.03 and 0.25{+-}0.05, and on/off ratios as high as 10{sup 7}. Transistors composed predominantly of SnO{sub 2} were found to exhibit light sensitivity which affected both the on/off ratios and threshold voltages of these devices.

  14. Investigation of tungsten doped tin oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Yang, Jianwen; Meng, Ting; Yang, Zhao; Cui, Can; Zhang, Qun

    2015-11-01

    Tungsten doped tin oxide thin film transistors (TWO-TFTs) were fabricated by radio frequency magnetron sputtering. With TWO thin films as the channel layers, the TFTs show lower off-current and positive shift turn-on voltage than the intrinsic tin oxide TFTs, which can be explained by the reason that W doping is conducive to suppress the carrier concentration of the TWO channel layer. It is important to elect an appropriate channel thickness for improving the TFT performance. The optimum TFT performance in enhancement mode is achieved at W doping content of 2.7 at% and channel thickness of 12 nm, with the saturation mobility, turn-on voltage, subthreshold swing value and on-off current ratio of 5 cm2 V-1 s-1, 0.4 V, 0.4 V/decade and 2.4  ×  106, respectively.

  15. Tungsten oxide nanowires grown on amorphous-like tungsten films.

    PubMed

    Dellasega, D; Pietralunga, S M; Pezzoli, A; Russo, V; Nasi, L; Conti, C; Vahid, M J; Tagliaferri, A; Passoni, M

    2015-09-11

    Tungsten oxide nanowires have been synthesized by vacuum annealing in the range 500-710 °C from amorphous-like tungsten films, deposited on a Si(100) substrate by pulsed laser deposition (PLD) in the presence of a He background pressure. The oxygen required for the nanowires formation is already adsorbed in the W matrix before annealing, its amount depending on deposition parameters. Nanowire crystalline phase and stoichiometry depend on annealing temperature, ranging from W18O49-Magneli phase to monoclinic WO3. Sufficiently long annealing induces the formation of micrometer-long nanowires, up to 3.6 μm with an aspect ratio up to 90. Oxide nanowire growth appears to be triggered by the crystallization of the underlying amorphous W film, promoting their synthesis at low temperatures. PMID:26292084

  16. Photocatalytic oxide films in the built environment

    NASA Astrophysics Data System (ADS)

    Österlund, Lars; Topalian, Zareh

    2014-11-01

    The possibility to increase human comfort in buildings is a powerful driving force for the introduction of new technology. Among other things our sense of comfort depends on air quality, temperature, lighting level, and the possibility of having visual contact between indoors and outdoors. Indeed there is an intimate connection between energy, comfort, and health issues in the built environment, leading to a need for intelligent building materials and green architecture. Photocatalytic materials can be applied as coatings, filters, and be embedded in building materials to provide self-cleaning, antibacterial, air cleaning, deodorizing, and water cleaning functions utilizing either solar light or artificial illumination sources - either already present in buildings, or by purposefully designed luminaries. Huge improvements in indoor comfort can thus be made, and also alleviate negative health effects associated with buildings, such as the sick-house syndrome. At the same time huge cost savings can be made by reducing maintenance costs. Photocatalytic oxides can be chemically modified by changing their acid-base surface properties, which can be used to overcome deactivation problems commonly encountered for TiO2 in air cleaning applications. In addition, the wetting properties of oxides can be tailored by surface chemical modifications and thus be made e.g. oleophobic and water repellent. Here we show results of surface acid modified TiO2 coatings on various substrates by means of photo-fixation of surface sulfate species by a method invented in our group. In particular, we show that such surface treatments of photocatalytic concrete made by mixing TiO2 nanoparticles in reactive concrete powders result in concrete surfaces with beneficial self-cleaning properties. We propose that such approaches are feasible for a number of applications in the built environment, including glass, tiles, sheet metals, plastics, etc.

  17. Oxidative stability of LARC (tm)-TPI films

    NASA Technical Reports Server (NTRS)

    Hinkley, Jeffrey A.

    1992-01-01

    The oxidative aging of 50-micron-thick films of LARC-TPI was studied using conventional thermogravimetric techniques and measurements of plane-stress fracture toughness. It was shown that at high temperature, most of the toughness loss occurred very early relative to the weight loss. The difficulties of interpreting TGA results in this regime and the problems of extrapolations to long times are discussed.

  18. Oxidation Effects in Rare Earth Doped Topological Insulator Thin Films.

    PubMed

    Figueroa, A I; van der Laan, G; Harrison, S E; Cibin, G; Hesjedal, T

    2016-01-01

    The breaking of time-reversal symmetry (TRS) in topological insulators is a prerequisite for unlocking their exotic properties and for observing the quantum anomalous Hall effect (QAHE). The incorporation of dopants which exhibit magnetic long-range order is the most promising approach for TRS-breaking. REBiTe3, wherein 50% of the Bi is substitutionally replaced by a RE atom (RE = Gd, Dy, and Ho), is a predicted QAHE system. Despite the low solubility of REs in bulk crystals of a few %, highly doped thin films have been demonstrated, which are free of secondary phases and of high crystalline quality. Here we study the effects of exposure to atmosphere of rare earth-doped Bi2(Se, Te)3 thin films using x-ray absorption spectroscopy. We demonstrate that these RE dopants are all trivalent and effectively substitute for Bi(3+) in the Bi2(Se, Te)3 matrix. We find an unexpected high degree of sample oxidation for the most highly doped samples, which is not restricted to the surface of the films. In the low-doping limit, the RE-doped films mostly show surface oxidation, which can be prevented by surface passivation, encapsulation, or in-situ cleaving to recover the topological surface state. PMID:26956771

  19. Laser micromachining of oxygen reduced graphene-oxide films

    NASA Astrophysics Data System (ADS)

    Sinar, Dogan; Knopf, George K.; Nikumb, Suwas; Andrushchenko, Anatoly

    2014-03-01

    Non-conductive graphene-oxide (GO) inks can be synthesized from inexpensive graphite powders and deposited on functionalized flexible substrates using inkjet printing technology. Once deposited, the electrical conductivity of the GO film can be restored through laser assisted thermal reduction. Unfortunately, the inkjet nozzle diameter (~40μm) places a limit on the printed feature size. In contrast, a tightly focused femtosecond pulsed laser can create precise micro features with dimensions in the order of 2 to 3 μm. The smallest feature size produced by laser microfabrication is a function of the laser beam diameter, power level, feed rate, material characteristics and spatial resolution of the micropositioning system. Laser micromachining can also remove excess GO film material adjacent to the electrode traces and passive electronic components. Excess material removal is essential for creating stable oxygen-reduced graphene-oxide (rGO) printed circuits because electron buildup along the feature edges will alter the conductivity of the non-functional film. A study on the impact of laser ablation on the GO film and the substrate are performed using a 775nm, 120fs pulsed laser. The average laser power was 25mW at a spot size of ~ 5μm, and the feed rate was 1000-1500mm/min. Several simple microtraces were fabricated and characterized in terms of electrical resistance and surface topology.

  20. Oxidation Effects in Rare Earth Doped Topological Insulator Thin Films

    NASA Astrophysics Data System (ADS)

    Figueroa, A. I.; van der Laan, G.; Harrison, S. E.; Cibin, G.; Hesjedal, T.

    2016-03-01

    The breaking of time-reversal symmetry (TRS) in topological insulators is a prerequisite for unlocking their exotic properties and for observing the quantum anomalous Hall effect (QAHE). The incorporation of dopants which exhibit magnetic long-range order is the most promising approach for TRS-breaking. REBiTe3, wherein 50% of the Bi is substitutionally replaced by a RE atom (RE = Gd, Dy, and Ho), is a predicted QAHE system. Despite the low solubility of REs in bulk crystals of a few %, highly doped thin films have been demonstrated, which are free of secondary phases and of high crystalline quality. Here we study the effects of exposure to atmosphere of rare earth-doped Bi2(Se, Te)3 thin films using x-ray absorption spectroscopy. We demonstrate that these RE dopants are all trivalent and effectively substitute for Bi3+ in the Bi2(Se, Te)3 matrix. We find an unexpected high degree of sample oxidation for the most highly doped samples, which is not restricted to the surface of the films. In the low-doping limit, the RE-doped films mostly show surface oxidation, which can be prevented by surface passivation, encapsulation, or in-situ cleaving to recover the topological surface state.

  1. Ellipsometric study of oxide films formed on LDEF metal samples

    NASA Technical Reports Server (NTRS)

    Franzen, W.; Brodkin, J. S.; Sengupta, L. C.; Sagalyn, P. L.

    1992-01-01

    The optical constants of samples of six different metals (Al, Cu, Ni, Ta, W, and Zr) exposed to space on the Long Duration Exposure Facility (LDEF) were studied by variable angle spectroscopic ellipsometry. Measurements were also carried out on portions of each sample which were shielded from direct exposure by a metal bar. A least-squares fit of the data using an effective medium approximation was then carried out, with thickness and composition of surface films formed on the metal substrates as variable parameters. The analysis revealed that exposed portions of the Cu, Ni, Ta, and Zr samples are covered with porous oxide films ranging in thickness from 500 to 1000 A. The 410 A thick film of Al2O3 on the exposed Al sample is practically free of voids. Except for Cu, the shielded portions of these metals are covered by thin non-porous oxide films characteristic of exposure to air. The shielded part of the Cu sample has a much thicker porous coating of Cu2O. The tungsten data could not be analyzed.

  2. Oxidation Effects in Rare Earth Doped Topological Insulator Thin Films

    PubMed Central

    Figueroa, A. I.; van der Laan, G.; Harrison, S. E.; Cibin, G.; Hesjedal, T.

    2016-01-01

    The breaking of time-reversal symmetry (TRS) in topological insulators is a prerequisite for unlocking their exotic properties and for observing the quantum anomalous Hall effect (QAHE). The incorporation of dopants which exhibit magnetic long-range order is the most promising approach for TRS-breaking. REBiTe3, wherein 50% of the Bi is substitutionally replaced by a RE atom (RE = Gd, Dy, and Ho), is a predicted QAHE system. Despite the low solubility of REs in bulk crystals of a few %, highly doped thin films have been demonstrated, which are free of secondary phases and of high crystalline quality. Here we study the effects of exposure to atmosphere of rare earth-doped Bi2(Se, Te)3 thin films using x-ray absorption spectroscopy. We demonstrate that these RE dopants are all trivalent and effectively substitute for Bi3+ in the Bi2(Se, Te)3 matrix. We find an unexpected high degree of sample oxidation for the most highly doped samples, which is not restricted to the surface of the films. In the low-doping limit, the RE-doped films mostly show surface oxidation, which can be prevented by surface passivation, encapsulation, or in-situ cleaving to recover the topological surface state. PMID:26956771

  3. Mixed metal oxide films as pH sensing materials

    NASA Astrophysics Data System (ADS)

    Arshak, Khalil; Gill, Edric; Korostynska, Olga; Arshak, Arousian

    2007-05-01

    Due to the demand for accurate, reliable and highly sensitive pH sensors, research is being pursued to find novel materials to achieve this goal. Semiconducting metal oxides, such as TiO, SnO and SnO II and insulating oxides such as Nb IIO 5 and Bi IIO 3, and their mixtures in different proportions are being investigated for this purpose. The films of these materials mixtures are used in conjunction with an interdigitated electrode pattern to produce a conductimetric/capacitive pH sensor. The advantages of this approach include straightforward manufacturing, versatility and cost-effectiveness. It was noted that upon contact with a solution, the electrical parameters of the films, such as resistance etc., change. The correlation of these changes with pH values is the basis for the proposed system development. The ultimate goal is to find materials composition, which would have the highest sensitivity towards the pH level of the solutions. It was found that the materials that produced the highest sensitivity either had a long response time or were unstable over a wide pH range. Those exhibiting lower sensitivities were found to be more stable over a wide pH range. All oxide films tested demonstrated a change in electrical parameters upon contact with buffers of known pH value.

  4. Oxidation of electrodeposited black chrome selective solar absorber films

    SciTech Connect

    Holloway, P.H.; Shanker, K.; Pettit, R.B.; Sowell, R.R.

    1980-01-01

    X-ray photoelectron and Auger electron spectroscopies have been used to study the composition and oxidation of electrodeposited black chrome films. The outer layer of the film is Cr/sub 2/O/sub 3/ with the inner layer being a continuously changing mixture of Cr + Cr/sub 2/O/sub 3/. Initially, approximately 40% by volume of the film is combined as Cr/sub 2/O/sub 3/, and the volume percentage of Cr/sub 2/O/sub 3/ increases to greater than 60% after only 136 hours at 250/sup 0/C. After approximately 3600 hours at 400/sup 0/C, the volume percentage of Cr/sub 2/O/sub 3/ increased to as high as 80%. The thermal emittance decreased approximately linearly with increasing oxide content, while the solar absorptance remained constant until the percentage of Cr/sub 2/O/sub 3/ exceeded approximately 70%. Oxidation was slower when the Cr/sup +3/ concentration in the plating bath was reduced from 16 g/l to 8 g/l, and when black chrome was deposited on stainless steel rather than sulfamate nickel.

  5. Hafnium carbide formation in oxygen deficient hafnium oxide thin films

    NASA Astrophysics Data System (ADS)

    Rodenbücher, C.; Hildebrandt, E.; Szot, K.; Sharath, S. U.; Kurian, J.; Komissinskiy, P.; Breuer, U.; Waser, R.; Alff, L.

    2016-06-01

    On highly oxygen deficient thin films of hafnium oxide (hafnia, HfO2-x) contaminated with adsorbates of carbon oxides, the formation of hafnium carbide (HfCx) at the surface during vacuum annealing at temperatures as low as 600 °C is reported. Using X-ray photoelectron spectroscopy the evolution of the HfCx surface layer related to a transformation from insulating into metallic state is monitored in situ. In contrast, for fully stoichiometric HfO2 thin films prepared and measured under identical conditions, the formation of HfCx was not detectable suggesting that the enhanced adsorption of carbon oxides on oxygen deficient films provides a carbon source for the carbide formation. This shows that a high concentration of oxygen vacancies in carbon contaminated hafnia lowers considerably the formation energy of hafnium carbide. Thus, the presence of a sufficient amount of residual carbon in resistive random access memory devices might lead to a similar carbide formation within the conducting filaments due to Joule heating.

  6. Oxidation stress evolution and relaxation of oxide film/metal substrate system

    NASA Astrophysics Data System (ADS)

    Dong, Xuelin; Feng, Xue; Hwang, Keh-Chih

    2012-07-01

    Stresses in the oxide film/metal substrate system are crucial to the reliability of the system at high temperature. Two models for predicting the stress evolution during isothermal oxidation are proposed. The deformation of the system is depicted by the curvature for single surface oxidation. The creep strain of the oxide and metal, and the lateral growth strain of the oxide are considered. The proposed models are compared with the experimental results in literature, which demonstrates that the elastic model only considering for elastic strain gives an overestimated stress in magnitude, but the creep model is consistent with the experimental data and captures the stress relaxation phenomenon during oxidation. The effects of the parameter for the lateral growth strain rate are also analyzed.

  7. Electrical characterization of hydrogenated amorphous silicon oxide films

    NASA Astrophysics Data System (ADS)

    Itoh, Takashi; Katayama, Ryuichi; Yamakawa, Koki; Matsui, Kento; Saito, Masaru; Sugiyama, Shuhichiroh; Sichanugrist, Porponth; Nonomura, Shuichi; Konagai, Makoto

    2015-08-01

    The electrical characterization of hydrogenated amorphous silicon oxide (a-SiOx:H) films was performed by electron spin resonance (ESR) and electrical conductivity measurements. In the ESR spectra of the a-SiOx:H films, two ESR peaks with g-values of 2.005 and 2.013 were observed. The ESR peak with the g-value of 2.013 was not observed in the ESR spectra of a-Si:H films. The photoconductivity of the a-SiOx:H films decreased with increasing spin density estimated from the ESR peak with the g-value of 2.005. On the other hand, photoconductivity was independent of spin density estimated from the ESR peak with the g-value of 2.013. The optical absorption coefficient spectra of the a-SiOx:H films were also measured. The spin density estimated from the ESR peak with the g-value of 2.005 increased proportionally with increasing optical absorption owing to the gap-state defect.

  8. Electrical properties of vanadium tungsten oxide thin films

    SciTech Connect

    Nam, Sung-Pill; Noh, Hyun-Ji; Lee, Sung-Gap; Lee, Young-Hie

    2010-03-15

    The vanadium tungsten oxide thin films deposited on Pt/Ti/SiO{sub 2}/Si substrates by RF sputtering exhibited good TCR and dielectric properties. The dependence of crystallization and electrical properties are related to the grain size of V{sub 1.85}W{sub 0.15}O{sub 5} thin films with different annealing temperatures. It was found that the dielectric properties and TCR properties of V{sub 1.85}W{sub 0.15}O{sub 5} thin films were strongly dependent upon the annealing temperature. The dielectric constants of the V{sub 1.85}W{sub 0.15}O{sub 5} thin films annealed at 400 {sup o}C were 44, with a dielectric loss of 0.83%. The TCR values of the V{sub 1.85}W{sub 0.15}O{sub 5} thin films annealed at 400 {sup o}C were about -3.45%/K.

  9. Investigation of optical loss mechanisms in oxide thin films

    SciTech Connect

    Chow, A.F.; Kingon, A.I.; Auciello, O.; Poker, D.B.

    1995-05-01

    KNbO{sub 3}, K(Ta,Nb)O{sub 3}, KTaO{sub 3}, and Ta{sub 2}O{sub 5} thin films have been grown by ion-beam sputter deposition. KNbO{sub 3} has excellent nonlinear properties for second harmonic generation; however, high optical losses are still characteristic of these films. Several loss mechanisms, such as, high angle grain boundaries, twin domains, interface and surface scattering, and oxygen vacancies can all contribute to the high losses. In order to isolate the various mechanisms, amorphous Ta{sub 2}O{sub 5} films, epitaxial cubic KTaO{sub 3} and tetragonal K(Ta,Nb)O{sub 3} films were grown on MgO and Al{sub 2}O{sub 3} substrates subjected to post-deposition annealing treatments and various oxygen pressure conditions. The optical losses and refractive indices were observed to differ depending on the substrate surface and annealing treatments. Resonant scattering experiments were performed to analyze the oxygen composition. The optical properties of these oxide thin film systems are reported and the breakdown of the loss mechanisms is addressed.

  10. Highly Conducting Transparent Indium-Doped Zinc Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Singh, Budhi; Ghosh, Subhasis

    2014-09-01

    Highly conducting transparent indium-doped zinc oxide (IZO) thin films have been achieved by controlling different growth parameters using radio frequency magnetron sputtering. The structural, electrical, and optical properties of the IZO thin films have been investigated for varied indium content and growth temperature ( T G) in order to find out the optimum level of doping to achieve the highest conducting transparent IZO thin films. The highest mobility and carrier concentration of 11.5 cm2/V-s and 3.26 × 1020 cm-3, respectively, have been achieved in IZO doped with 2% indium. It has been shown that as T G of the 2% IZO thin films increase, more and more indium atoms are substituted into Zn sites leading to shift in (002) peaks towards higher angles which correspond to releasing the stress within the IZO thin film. The minimum resistivity of 5.3 × 10-4 Ω-cm has been achieved in 2% indium-doped IZO grown at 700°C.

  11. Synthesis and tribology of doped carbon films and oxide multilayers

    NASA Astrophysics Data System (ADS)

    Freyman, Christina A.

    The focus of this research is to synthesize thin films coatings by reactive magnetron sputtering with properties that will result in energy savings. Tailoring of hydrogenated carbon film properties to minimize environment effects on friction is accomplished by sulfur doping. Synthesis results in smooth surfaces and mid-range hardness. The stabilization of ultra-low friction in humid air can be attributed to the reduction of water adsorption on the surface, which is verified by results of quartz crystal microbalance and temperature-programmed desorption experiments. Even at 90% relative humidity, sulfur-doped films have less than one monolayer of water adsorbed on the surface. This reduction in water coverage is due to the decrease in residence time of water on the surface, which is related to the strength of the bonding between water molecules and the sulfur-doped surface. These results indicate that sulfur doping results in weaker bonding between water and the film surface due to a reduction in the polar nature of the surface. Metal nitrides, carbides, and borides are widely used as protective coatings due to their high hardness, but are not stable above 600°C due to coating oxidation. Hardness enhancement techniques have been applied to thermally stable oxide multilayers for use at high temperatures. Amorphous Al2 O3 and crystalline TiO2 nanoscale layers have been deposited using reactive d.c. magnetron sputtering at different partial pressures of oxygen. Hardness enhancement of twice the rule of mixtures has been observed in oxide multilayers for the first time due to clear interfaces and large difference in modulus between amorphous Al2O3 and crystalline TiO2 layers. Multilayer films with majority bilayer component of Al2O3 showed greater resistance to wear due to increased elastic recovery and H/E ratio over monolithic films and TiO2 majority phase multilayers. Multilayer films retain their high hardness up to ˜800°C in air; some hardness enhancement in the

  12. Aqueous sol-gel routes to conducting films of indium oxide and indium-tin-oxide

    NASA Astrophysics Data System (ADS)

    Perry, Carole C.; McGiveron, J. K.; Harrison, Philip G.

    2000-05-01

    Thin films of indium tin oxide (ITO) are of interest because of their high transparency and low electrical resistivity. Applications include use as electrodes for liquid crystal display and as heat mirrors for solar energy devices. We have developed totally aqueous routes to indium oxide (IO) and ITO materials because, (1) the particulate sols afford a longer shelf life than for alkoxyide derived materials, (2) organics do not have to be removed from the films by baking, and (3) the starting materials are cheaper than the corresponding alkoxides. Indium and mixed indium/tin sols have been prepared form inorganic solutions and treated with alkali to produce white thixotropic sols ca. 0.64 in Mz+ ions. This films were prepared by spinning on low iron or pure silica slides previously cleaned with DECON and washed with distilled water. Films were subsequently heated at 773K in air, or 1173K in air or nitrogen. The film with the lowest resistivity contained ca. 5 percent Sn and had an average optical transmittance between 400 and 600nm of 95 percent. The film was non-porous, smooth in texture, approximately 300nm thick and had a band gap energy of 3.22eV.

  13. Synthesis of nanoporous activated iridium oxide films by anodized aluminum oxide templated atomic layer deposition.

    SciTech Connect

    Comstock, D. J.; Christensen, S. T.; Elam, J. W.; Pellin, M. J.; Hersam, M. C.

    2010-08-01

    Iridium oxide (IrOx) has been widely studied due to its applications in electrochromic devices, pH sensing, and neural stimulation. Previous work has demonstrated that both Ir and IrOx films with porous morphologies prepared by sputtering exhibit significantly enhanced charge storage capacities. However, sputtering provides only limited control over film porosity. In this work, we demonstrate an alternative scheme for synthesizing nanoporous Ir and activated IrOx films (AIROFs). This scheme utilizes atomic layer deposition to deposit a thin conformal Ir film within a nanoporous anodized aluminum oxide template. The Ir film is then activated by potential cycling in 0.1 M H{sub 2}SO{sub 4} to form a nanoporous AIROF. The morphologies and electrochemical properties of the films are characterized by scanning electron microscopy and cyclic voltammetry, respectively. The resulting nanoporous AIROFs exhibit a nanoporous morphology and enhanced cathodal charge storage capacities as large as 311 mC/cm{sup 2}.

  14. Oxide Film and Porosity Defects in Magnesium Alloy AZ91

    SciTech Connect

    Wang, Liang; Rhee, Hongjoo; Felicelli, Sergio D.; Sabau, Adrian S; Berry, John T.

    2009-01-01

    Porosity is a major concern in the production of light metal parts. This work aims to identify some of the mechanisms of microporosity formation in magnesium alloy AZ91. Microstructure analysis was performed on several samples obtained from gravity-poured ingots in graphite plate molds. Temperature data during cooling was acquired with type K thermocouples at 60 Hz at three locations of each casting. The microstructure of samples extracted from the regions of measured temperature was then characterized with optical metallography. Tensile tests and conventional four point bend tests were also conducted on specimens cut from the cast plates. Scanning electron microscopy was then used to observe the microstructure on the fracture surface of the specimens. The results of this study revealed the existence of abundant oxide film defects, similar to those observed in aluminum alloys. Remnants of oxide films were detected on some pore surfaces, and folded oxides were observed in fracture surfaces indicating the presence of double oxides entrained during pouring.

  15. Electrochemical deposition of conducting ruthenium oxide films from solution

    SciTech Connect

    Anderson, D.P.; Warren, L.F.

    1984-02-01

    In the last decade, ruthenium oxide, RuO /sub x/ (x less than or equal to 2), has been used extensively as the active anode electrocatalyst constituent for Cl/sub 2/ and O/sub 2/ evolution reactions, in chlorate production, and in metal electrowinning from mixed chloride-sulfate solutions. More recently, this material has been incorporated in several light-induced water electrolysis schemes and apparently possesses the ability to inhibit CdS photocorrosion by acting as a hole scavenger. The numerous applications for this catalyst material certainly warrant further studies of its electrochemical properties on a variety of substrates, e.g., semiconductors. The lack of a simple technique for controlled deposition of ruthenium oxide onto conducting substrates prompted us to investigate an electrochemical approach to this problem. We describe here a new way to electrochemically deposit conducting films of hydrated ruthenium oxide from an aqueous solution of the benzeneruthenium (II)aqua complex. The films slowly dissolve in aqueous electrolytes upon potential cycling, yet appear to be catalytic with regards to water oxidation.

  16. Self-formed copper oxide contact interlayer for high-performance oxide thin film transistors

    SciTech Connect

    Gao, Xu E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Aikawa, Shinya; Mitoma, Nobuhiko; Lin, Meng-Fang; Kizu, Takio; Tsukagoshi, Kazuhito E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Nabatame, Toshihide

    2014-07-14

    Oxide thin film transistor employing copper source/drain electrodes shows a small turn on voltage and reduced hysteresis. Cross-sectional high-resolution transmission electron microscopy image confirmed the formation of ∼4 nm CuO{sub x} related interlayer. The lower bond-dissociation energy of Cu-O compared to Si-O and In-O suggests that the interlayer was formed by adsorbing oxygen molecules from surrounding environment instead of getting oxygen atoms from the semiconductor film. The formation of CuO{sub x} interlayer acting as an acceptor could suppress the carrier concentration in the transistor channel, which would be utilized to control the turn on voltage shifts in oxide thin film transistors.

  17. Thin copper oxide films prepared by ion beam sputtering with subsequent thermal oxidation: Application in chemiresistors

    NASA Astrophysics Data System (ADS)

    Horak, P.; Bejsovec, V.; Vacik, J.; Lavrentiev, V.; Vrnata, M.; Kormunda, M.; Danis, S.

    2016-12-01

    Copper oxide films were prepared by thermal oxidation of thin Cu films deposited on substrates by ion beam sputtering. The subsequent oxidation was achieved in the temperature range of 200 °C-600 °C with time of treatment from 1 to 7 h (with a 1-h step) in a furnace open to air. At temperatures 250 °C-600 °C, the dominant phase formed was CuO, while at 200 °C mainly the Cu2O phase was identified. However, the oxidation at 200 °C led to a more complicated composition - in the depth Cu2O phase was observed, though in the near-surface layer the CuO dominant phase was found with a significant presence of Cu(OH)2. A limited amount of Cu2O was also found in samples annealed at 600 °C. The sheet resistance RS of the as-deposited Cu sample was 2.22 Ω/□, after gradual annealing RS was measured in the range 2.64 MΩ/□-2.45 GΩ/□. The highest RS values were obtained after annealing at 300 °C and 350 °C, respectively. Oxygen depth distribution was studied using the 16O(α,α) nuclear reaction with the resonance at energy 3032 keV. It was confirmed that the higher oxidation degree of copper is located in the near-surface region. Preliminary tests of the copper oxide films as an active layer of a chemiresistor were also performed. Hydrogen and methanol vapours, with a concentration of 1000 ppm, were detected by the sensor at an operating temperature of 300 °C and 350 °C, respectively. The response of the sensors, pointed at the p-type conductivity, was improved by the addition of thin Pd or Au catalytic films to the oxidic film surface. Pd-covered films showed an increased response to hydrogen at 300 °C, while Au-covered films were more sensitive to methanol vapours at 350 °C.

  18. Magnetic transparent conducting oxide film and method of making

    DOEpatents

    Windisch, Jr., Charles F.; Exarhos, Gregory J.; Sharma, Shiv K.

    2004-07-13

    Cobalt-nickel oxide films of nominal 100 nm thickness, and resistivity as low as 0.06 .OMEGA..multidot.cm have been deposited by spin-casting from both aqueous and organic precursor solutions followed by annealing at 450.degree. C. in air. Films deposited on sapphire substrates exhibit a refractive index of about 1.7 and are relatively transparent in the wavelength region from 0.6 to 10.0 .mu.m. They are also magnetic. The electrical and spectroscopic properties of the oxides have been studied as a function of x=Co/(Co+Ni) ratio. An increase in film resistivity was found upon substitution of other cations (e.g., Zn.sup.2+, Al.sup.3+) for Ni in the spinel structure. However, some improvement in the mechanical properties of the films resulted. On the other hand, addition of small amounts of Li decreased the resistivity. A combination of XRD, XPS, UV/Vis and Raman spectroscopy indicated that NiCo.sub.2 O.sub.4 is the primary conducting component and that the conductivity reaches a maximum at this stoichiometry. When x<0.67, NiO forms leading to an increase in resistivity; when x>0.67, the oxide was all spinel but the increased Co content lowered the conductivity. The influence of cation charge state and site occupancy in the spinel structure markedly affects calculated electron band structures and contributes to a reduction of p-type conductivity, the formation of polarons, and the reduction in population of mobile charge carriers that tend to limit transmission in the infrared.

  19. Electrical and Optical Properties of Copper Oxide Thin Films by Sol-Gel Technique

    NASA Astrophysics Data System (ADS)

    Hashim, H.; Shariffudin, S. S.; Saad, P. S. M.; Ridah, H. A. M.

    2015-11-01

    Copper oxide were prepared by sol-gel technique and deposited onto quartz substrates as thin films using spin coating method. The aim of this research was to study the effects of different spin coating speeds of copper oxide thin films on the electrical and optical properties of the thin films. Five samples of copper oxide thin films with different spin coating speeds of 1000, 1500, 2000, 2500 and 3000 rpm were annealed at 600°C for 30 minutes. UV-Vis spectrophotometer and two-point probe technique were used to characterize the optical and electrical properties of the deposited films. Based on the results obtained, it revealed that the electrical conductivity of the copper oxide thin films reduce as the spin coating speeds increase. The calculated optical band gap and the resistivity of the copper oxide thin films also decrease when the spin coating speeds are increased.

  20. CSA doped polypyrrole-zinc oxide thin film sensor

    NASA Astrophysics Data System (ADS)

    Chougule, M. A.; Jundale, D. M.; Raut, B. T.; Sen, Shashwati; Patil, V. B.

    2013-02-01

    The polypyrrole-zinc oxide (PPy-ZnO) hybrid sensor doped with different weight ratios of camphor sulphonic acid (CSA) were prepared by spin coating technique. These CSA doped PPy-ZnO hybrids were characterized by field emission scanning electron microscope (FESEM) and fourier transform infrared (FTIR) which proved the formation of polypyrrole, PPy-ZnO and the interaction between polypyrrole - ZnO (PPy-ZnO) hybrid with CSA doping. The gas sensing properties of the PPy-ZnO hybrid films doped with CSA have been studied for oxidizing (NO2) as well as reducing (H2S, NH3, CH4OH and CH3OH) gases at room temperature. We demonstrate that CSA doped PPy-ZnO hybrid films are highly selective to NO2 along with high-sensitivity at low concentration (80% to 100 ppm) and better stability, which suggested that the CSA doped PPy-ZnO hybrid films are potential candidate for NO2 detection at room temperature.

  1. Solution-Processed Indium Oxide Based Thin-Film Transistors

    NASA Astrophysics Data System (ADS)

    Xu, Wangying

    Oxide thin-film transistors (TFTs) have attracted considerable attention over the past decade due to their high carrier mobility and excellent uniformity. However, most of these oxide TFTs are usually fabricated using costly vacuum-based techniques. Recently, the solution processes have been developed due to the possibility of low-cost and large-area fabrication. In this thesis, we have carried out a detailed and systematic study of solution-processed oxide thin films and TFTs. At first, we demonstrated a passivation method to overcome the water susceptibility of solution-processed InZnO TFTs by utilizing octadecylphosphonic acid (ODPA) self-assembled monolayers (SAMs). The unpassivated InZnO TFTs exhibited large hysteresis in their electrical characteristics due to the adsorbed water at the semiconductor surface. Formation of a SAM of ODPA on the top of InZnO removed water molecules weakly absorbed at the back channel and prevented water diffusion from the surroundings. Therefore the passivated devices exhibited significantly reduced hysteretic characteristics. Secondly, we developed a simple spin-coating approach for high- k dielectrics (Al2O3, ZrO2, Y 2O3 and TiO2). These materials were used as gate dielectrics for solution-processed In2O3 or InZnO TFTs. Among the high-k dielectrics, the Al2O3-based devices showed the best performance, which is attributed to the smooth dielectric/semiconductor interface and the low interface trap density besides its good insulating property. Thirdly, the formation and properties of Al2O3 thin films under various annealing temperatures were intensively studied, revealing that the sol-gel-derived Al2O3 thin film undergoes the decomposition of organic residuals and nitrate groups, as well as conversion of aluminum hydroxides to form aluminum oxide. Besides, the Al2O 3 film was used as gate dielectric for solution-processed oxide TFTs, resulting in high mobility and low operating voltage. Finally, we proposed a green route for

  2. Surfactant-assisted ultrasonic spray pyrolysis of nickel oxide and lithium-doped nickel oxide thin films, toward electrochromic applications

    NASA Astrophysics Data System (ADS)

    Denayer, Jessica; Bister, Geoffroy; Simonis, Priscilla; Colson, Pierre; Maho, Anthony; Aubry, Philippe; Vertruyen, Bénédicte; Henrist, Catherine; Lardot, Véronique; Cambier, Francis; Cloots, Rudi

    2014-12-01

    Lithium-doped nickel oxide and undoped nickel oxide thin films have been deposited on FTO/glass substrates by a surfactant-assisted ultrasonic spray pyrolysis. The addition of polyethylene glycol in the sprayed solution has led to improved uniformity and reduced light scattering compared to films made without surfactant. Furthermore, the presence of lithium ions in NiO films has resulted in improved electrochromic performances (coloration contrast and efficiency), but with a slight decrease of the electrochromic switching kinetics.

  3. Highly conductive grain boundaries in copper oxide thin films

    NASA Astrophysics Data System (ADS)

    Deuermeier, Jonas; Wardenga, Hans F.; Morasch, Jan; Siol, Sebastian; Nandy, Suman; Calmeiro, Tomás; Martins, Rodrigo; Klein, Andreas; Fortunato, Elvira

    2016-06-01

    High conductivity in the off-state and low field-effect mobility compared to bulk properties is widely observed in the p-type thin-film transistors of Cu2O, especially when processed at moderate temperature. This work presents results from in situ conductance measurements at thicknesses from sub-nm to around 250 nm with parallel X-ray photoelectron spectroscopy. An enhanced conductivity at low thickness is explained by the occurrence of Cu(II), which is segregated in the grain boundary and locally causes a conductivity similar to CuO, although the surface of the thick film has Cu2O stoichiometry. Since grains grow with an increasing film thickness, the effect of an apparent oxygen excess is most pronounced in vicinity to the substrate interface. Electrical properties of Cu2O grains are at least partially short-circuited by this effect. The study focuses on properties inherent to copper oxide, although interface effects cannot be ruled out. This non-destructive, bottom-up analysis reveals phenomena which are commonly not observable after device fabrication, but clearly dominate electrical properties of polycrystalline thin films.

  4. Rapid thermal chemical vapor deposition of thin silicon oxide films using silane and nitrous oxide

    NASA Astrophysics Data System (ADS)

    Xu, X. L.; Kuehn, R. T.; Wortman, J. J.; Öztürk, M. C.

    1992-06-01

    Thin (80-200 Å) silicon dioxide (SiO2) films have been deposited by low pressure rapid thermal chemical vapor deposition (RTCVD), using silane (SiH4) and nitrous oxide (N2O) as the reactive gases for the first time. A deposition rate of 55 Å/min has been achieved at 800 °C with a SiH4/N2O flow rate ratio of 2%. Auger electron spectroscopy (AES) and Rutherford back scattering spectroscopy (RBS) have shown a uniform and stoichiometric composition throughout the deposited oxide films. Electrical characterization of the films have shown an average catastrophic breakdown field of 13 MV/cm and a midgap interface trap density (Dit) of equal to or less than 5×1010 eV-1 cm-2. The results suggest that the deposited RTCVD SiO2 films using SiH4-N2O gas system may have the potential to be used as the gate dielectric in future low-temperature metal oxide semiconductor (MOS) device processes for ultralarge scale integration (ULSI).

  5. Oxide Film Aging on Alloy 22 in Halide Containing Solutions

    SciTech Connect

    Rodriguez, Martin A.; Carranza, Ricardo M.; Rebak, Raul B.

    2007-07-01

    Passive and corrosion behaviors of Alloy 22 in chloride and fluoride containing solutions, changing the heat treatment of the alloy, the halide concentration and the pH of the solutions at 90 deg. C, was investigated. The study was implemented using electrochemical techniques, which included open circuit potential monitoring over time, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements carried out at open circuit and at passivity potentials. Corrosion rates obtained by EIS measurements after 24 h immersion in naturally aerated solutions were below 0.5 {mu}m/year. The corrosion rates were practically independent of solution pH, alloy heat treatment and halide ion nature and concentration. EIS low frequency resistance values increased with applied potential in the passive domain and with polarization time in pH 6 - 1 M NaCl at 90 deg. C. This effect was attributed to an increase in the oxide film thickness and oxide film aging. High frequency capacitance measurements indicated that passive oxide on Alloy 22 presented a double n-type/p-type semiconductor behavior in the passive potential range. (authors)

  6. Studies on nickel-tungsten oxide thin films

    SciTech Connect

    Usha, K. S.; Sivakumar, R.; Sanjeeviraja, C.

    2014-10-15

    Nickel-Tungsten oxide (95:5) thin films were prepared by rf sputtering at 200W rf power with various substrate temperatures. X-ray diffraction study reveals the amorphous nature of films. The substrate temperature induced decrease in energy band gap with a maximum transmittance of 71%1 was observed. The Micro-Raman study shows broad peaks at 560 cm{sup −1} and 1100 cm{sup −1} correspond to Ni-O vibration and the peak at 860 cm{sup −1} can be assigned to the vibration of W-O-W bond. Photoluminescence spectra show two peaks centered on 420 nm and 485 nm corresponding to the band edge emission and vacancies created due to the addition of tungsten, respectively.

  7. Studies on nickel-tungsten oxide thin films

    NASA Astrophysics Data System (ADS)

    Usha, K. S.; Sivakumar, R.; Sanjeeviraja, C.

    2014-10-01

    Nickel-Tungsten oxide (95:5) thin films were prepared by rf sputtering at 200W rf power with various substrate temperatures. X-ray diffraction study reveals the amorphous nature of films. The substrate temperature induced decrease in energy band gap with a maximum transmittance of 71%1 was observed. The Micro-Raman study shows broad peaks at 560 cm-1 and 1100 cm-1 correspond to Ni-O vibration and the peak at 860 cm-1 can be assigned to the vibration of W-O-W bond. Photoluminescence spectra show two peaks centered on 420 nm and 485 nm corresponding to the band edge emission and vacancies created due to the addition of tungsten, respectively.

  8. High angular sensitivity thin film tin oxide sensor

    NASA Astrophysics Data System (ADS)

    Kaur, Davinder; Madaan, Divya; Sharma, V. K.; Kapoor, A.

    2016-05-01

    We present theoretical anlaysis of a thin film SnO2 (Tin Oxide) sensor for the measurement of variation in the refractive index of the bulk media. It is based on lossy mode resonance between the absorbing thin film lossy modes and the evanescent wave. Also the addition of low index dielectric matching layer between the prism and the lossy waveguiding layer future increase the angular sensitivity and produce an efficient refractive index sensor. The angular interrogation is done and obtained sensitivity is 110 degree/RIU. Theoretical analysis of the proposed sensor based on Fresnel reflection coefficients is presented. This enhanced sensitivity will further improve the monitoring of biomolecular interactions and the higher sensitivity of the proposed configurations makes it to be a much better option to be employed for biosensing applications.

  9. Oxide nucleation on thin films of copper during in situ oxidation in an electron microscope

    NASA Technical Reports Server (NTRS)

    Heinemann, K.; Rao, D. B.; Douglass, D. L.

    1975-01-01

    Single-crystal copper thin films were oxidized at an isothermal temperature of 425 C and at an oxygen partial pressure of 0.005 torr. Specimens were prepared by epitaxial vapor deposition onto polished faces of rocksalt and were mounted in a hot stage inside the ultrahigh-vacuum chamber of a high-resolution electron microscope. An induction period of roughly 30 min was established which was independent of the film thickness but depended strongly on the oxygen partial pressure and to exposure to oxygen prior to oxidation. Neither stacking faults nor dislocations were found to be associated with the Cu2O nucleation sites. The experimental data, including results from oxygen dissolution experiments and from repetitive oxidation-reduction-oxidation sequences, fit well into the framework of an oxidation process involving the formation of a surface charge layer, oxygen saturation of the metal with formation of a supersaturated zone near the surface, and nucleation followed by surface diffusion of oxygen and bulk diffusion of copper for lateral and vertical oxide growth, respectively.

  10. Stress generation in thermally grown oxide films. [oxide scale spalling from superalloy substrates

    NASA Technical Reports Server (NTRS)

    Kumnick, A. J.; Ebert, L. J.

    1981-01-01

    A three dimensional finite element analysis was conducted, using the ANSYS computer program, of the stress state in a thin oxide film thermally formed on a rectangular piece of NiCrAl alloy. The analytical results indicate a very high compressive stress in the lateral directions of the film (approximately 6200 MPa), and tensile stresses in the metal substrate that ranged from essentially zero to about 55 MPa. It was found further that the intensity of the analytically determined average stresses could be approximated reasonably well by the modification of an equation developed previously by Oxx for stresses induced into bodies by thermal gradients.

  11. Electrochemical glucose oxidation on dendritic cuprous oxide film fabricated by PSS-assisted electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Yang, Ming; Jin, Xiaoqi; Huang, Qiao

    2011-02-01

    Cuprous oxides (Cu 2O) with different morphologies were deposited on F-doped tin oxide (FTO) covered glass substrates by potentiostatic deposition. The as-deposited samples were characterized by XRD, BET surface area and SEM. The effects of Poly(styrene sulfonic acid) sodium salt (PSS) on the crystal morphologies of Cu 2O were studied. Different crystal morphologies of Cu 2O can be obtained by varying the concentrations of PSS in the electrolytes. The formation of dendritic microstructure in Cu 2O film depends on the concentration of PSS in the electrolyte. Dendritic Cu 2O crystals formed gradually with the increase of the concentration of PSS in the electrolyte from 0 to 4 g L -1. More symmetrical Cu 2O crystals appear when the concentration of PSS is changed from 4 to 8 g L -1. However, the Cu 2O nanoparticles formed instead of dendritic Cu 2O crystals if the concentration of PSS reaches to 12 g L -1, which is due to the slower diffusion rate of reactive species in high concentration of PSS. The as-deposited Cu 2O thin films with different morphologies all exhibit the electrochemical glucose oxidation properties. The improved performance of glucose oxidation is achieved on the dendritic Cu 2O film electrode. The result indicates that the dendritic microstructure is beneficial for decreasing the resistance and improving transportation and diffusion of reactants and products.

  12. Vibrational spectra of CO adsorbed on oxide thin films: A tool to probe the surface defects and phase changes of oxide thin films

    SciTech Connect

    Savara, Aditya

    2014-03-15

    Thin films of iron oxide were grown on Pt(111) single crystals using cycles of physical vapor deposition of iron followed by oxidative annealing in an ultrahigh vacuum apparatus. Two procedures were utilized for film growth of ∼15–30 ML thick films, where both procedures involved sequential deposition+oxidation cycles. In procedure 1, the iron oxide film was fully grown via sequential deposition+oxidation cycles, and then the fully grown film was exposed to a CO flux equivalent to 8 × 10{sup −7} millibars, and a vibrational spectrum of adsorbed CO was obtained using infrared reflection-absorption spectroscopy. The vibrational spectra of adsorbed CO from multiple preparations using procedure 1 show changes in the film termination structure and/or chemical nature of the surface defects—some of which are correlated with another phase that forms (“phase B”), even before enough of phase B has formed to be easily detected using low energy electron diffraction (LEED). During procedure 2, CO vibrational spectra were obtained between deposition+oxidation cycles, and these spectra show that the film termination structure and/or chemical nature of the surface defects changed as a function of sequential deposition+oxidation cycles. The authors conclude that measurement of vibrational spectra of adsorbed CO on oxide thin films provides a sensitive tool to probe chemical changes of defects on the surface and can thus complement LEED techniques by probing changes not visible by LEED. Increased use of vibrational spectra of adsorbed CO on thin films would enable better comparisons between films grown with different procedures and by different groups.

  13. Deposition of transparent, conductive tin oxide films on glass using a radio-frequency induction heater.

    PubMed

    Solano, I; Schwoebel, P R

    2009-12-01

    Tin oxide films are often used as transparent, conductive coatings on glass in the scientific research setting. The standard approach of depositing these films in an oven leads to poor visibility of the substrate and thus inhibits the ready formation of uniform, low resistivity films. In this note we describe a simple tin oxide film deposition technique using a radio-frequency induction heater that allows for in situ visualization of the deposition process and resulting film. Uniform films having resistivities as low as 2 mohm cm with transmittances of approximately 85% in the visible light spectrum were readily deposited. PMID:20059179

  14. Anodic Oxidation in Aluminum Electrode by Using Hydrated Amorphous Aluminum Oxide Film as Solid Electrolyte under High Electric Field.

    PubMed

    Yao, Manwen; Chen, Jianwen; Su, Zhen; Peng, Yong; Zou, Pei; Yao, Xi

    2016-05-01

    Dense and nonporous amorphous aluminum oxide (AmAO) film was deposited onto platinized silicon substrate by sol-gel and spin coating technology. The evaporated aluminum film was deposited onto the AmAO film as top electrode. The hydrated AmAO film was utilized as a solid electrolyte for anodic oxidation of the aluminum electrode (Al) film under high electric field. The hydrated AmAO film was a high efficiency electrolyte, where a 45 nm thick Al film was anodized completely on a 210 nm thick hydrated AmAO film. The current-voltage (I-V) characteristics and breakdown phenomena of a dry and hydrated 210 nm thick AmAO film with a 150 nm thick Al electrode pad were studied in this work. Breakdown voltage of the dry and hydrated 210 nm thick AmAO film were 85 ± 3 V (405 ± 14 MV m(-1)) and 160 ± 5 V (762 ± 24 MV m(-1)), respectively. The breakdown voltage of the hydrated AmAO film increased about twice, owing to the self-healing behavior (anodic oxidation reaction). As an intuitive phenomenon of the self-healing behavior, priority anodic oxidation phenomena was observed in a 210 nm thick hydrated AmAO film with a 65 nm thick Al electrode pad. The results suggested that self-healing behavior (anodic oxidation reaction) was occurring nearby the defect regions of the films during I-V test. It was an effective electrical self-healing method, which would be able to extend to many other simple and complex oxide dielectrics and various composite structures. PMID:27070754

  15. High temperature nitrogen oxides sensing enabled by indium oxide thin films

    NASA Astrophysics Data System (ADS)

    Kannan, Srinivasan

    Generation of power using fossil fuel combustion invariably results in formation of undesirable gas species (NOx, SOx, CO, CO2, etc.) at high-temperatures which are harmful to the environment. Thus, there is a continual need to develop sensitive, responsive, stable, selective, robust and low-cost sensor systems and sensor materials for combustion monitoring. This work investigates the viability of microfabricated NO x sensors based on sputtered indium oxide (In2O3) utilizing microhotplate structures. The material becomes resistive when exposed to oxidizing gases like NOx, with its conductivity dependent upon the temperature, partial pressure of the test gas and morphological structure. We believe this device would help increase efficiency and decrease emissions through improved combustion process control, leading to a comparably economic and responsive sensor. In this work, more than 600 sensors were fabricated and tested, including RF and pulsed-DC sputtered films. About 50 unique sensor conditions were characterized and related to the gas sensor response. The sensor conditions included deposition parameters (power, pressure, time, etc.) and postdeposition processes (anneals, promoter layers, etc.). In2O3 thin films were RF sputter deposited on microhotplate structures with different thickness (40 to 300 nm) in pure Ar. Additionally, a combination of reactive and RF sputtering of In2O3 material was-deposited in Ar and O2 (10% and 25%) mixture. In2O3 films without promoter layers and with gold or TiOx promoter layers (~ 3 nm) were investigated for NOx sensing. Selectivity, stability and repeatability of indium oxide (In2O3) thin film sensor to detect NOx (25 ppm) in presence of other exhaust gas pollutants including H2, NH3 and CO2 at high operating temperatures (greater than 350 °C) was investigated in N2 carrier gas. In2O 3 films (150nm thick) deposited in Ar and O2 (25% O 2) presented the highest response (S ~ 50) to 25 ppm NOx at 500 °C when compared to films

  16. Rate of organic film formation and oxidation on aqueous drops

    NASA Astrophysics Data System (ADS)

    Aumann, E.; Tabazadeh, A.

    2008-12-01

    Previous studies suggest that saturated fatty acids or other lipids, which are known to be strong film-forming agents, form condensed films on aqueous drops. Specifically, stearic acid (SA) has been used in laboratory and modeling studies to mimic the surface composition of some particles in the atmosphere. In this study, laboratory measurements were used to determine the rate of SA spreading from a solid on aqueous surfaces,ranging in composition from ammonium sulfate to highly acidic sulfuric acid. Maximum spreading rates were measured on neutral electrolyte solutions, while spreading was not observed on aqueous sulfuric and hydrochloric acids (pH < 0). Also, the spreading rates on water and electrolyte surfaces declined sharply as the solution pH was lowered from 7 to 3. Spreading rates are reported with a dependence on the length of solid-aqueous-air boundary (triple interface perimeter). Spreading rates measured on bulk solutions were modeled on atmospheric particles to determine the time constant of organic film formation on aqueous drops. The time required for a saturated fatty acid to spread and coat a submicron salt particle or a cloud drop is on the order of seconds to minutes or minutes to hours, respectively. In conclusion, lipid coatings can form quickly on neutral or slightly acidic salt drops if a sufficient amount of lipid is present in the drop and the lipid is in direct contact with the aqueous solution surface. Rapid film formation and fast heterogeneous oxidation can provide an efficient way of converting water-insoluble organic films into more water-soluble components in aerosols or cloud drops.

  17. Absorption of ac fields in amorphous indium-oxide films

    NASA Astrophysics Data System (ADS)

    Ovadyahu, Z.

    2014-08-01

    Absorption data from applied ac fields in Anderson-localized amorphous indium-oxide (InxO) films are shown to be frequency and disorder dependent. The absorption shows a roll-off at a frequency which is much lower than the electron-electron scattering rate of the material when it is in the diffusive regime. This is interpreted as evidence for discreteness of the energy spectrum of the deeply localized regime. This is consistent with recent many-body localization scenarios. As the metal-insulator transition is approached, the absorption shifts to higher frequencies. Comparing with the previously obtained results on the crystalline version of indium-oxide (In2O3-x) implies a considerably higher inelastic electron-phonon scattering rate in the amorphous material. The range over which the absorption versus frequency decreases may indicate that a wide distribution of localization length is a common feature in these systems.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

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

    PubMed

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

    2016-12-01

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

  20. Defect Mediated Ferromagnetism in Zinc Oxide Thin Film Heterostructures

    NASA Astrophysics Data System (ADS)

    Mal, Siddhartha

    Recent developments in the field of spintronics (spin based electronics) have led to an extensive search for materials in which semiconducting properties can be integrated with magnetic properties to realize the objective of successful fabrication of spin-based devices. Since zinc oxide (ZnO) posits a promising player, it is important to elucidate the critical issues regarding the origin and nature of magnetism in ZnO thin film heterostructures. Another critical issue in the development of practical devices based on metal oxides is the integration of high quality epitaxial thin films on the existing technology based on Si (100) substrates, which requires appropriate substrate templates. The present research work is focused on the study of room temperature ferromagnetism (RTFM) caused by intrinsic defects and precise control of RTFM using thermal treatments and laser and ion irradiation. We performed a systematic study of the structural, chemical, electrical, optical and magnetic properties of undoped ZnO films grown under different conditions as well as the films that were annealed in various environments. Oxygen annealed films displayed a sequential transition from ferromagnetism to diamagnetism as a function of the annealing temperature. An increase in the green band intensity has been observed in oxygen annealed ZnO films. Reversible switching of room-temperature ferromagnetism and n-type conductivity have been demonstrated by oxygen and vacuum annealing. Detailed electron energy loss spectroscopy and secondary ion mass spectroscopy studies have been presented to rule out the possibility of external source of magnetism. Electron-Paramagnetic Resonance (EPR) measurements indicate the presence of a broad peak at g=2.01. This would be most consistent with the magnetic moment arising from the oxygen vacancies (g=1.996), although the possible contribution from Zn vacancies (g=2.013) cannot be entirely ruled out. The magnetic moment in these films may arise from the

  1. Properties of mixed molybdenum oxide iridium oxide thin films synthesized by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Patil, P. S.; Kawar, R. K.; Sadale, S. B.; Inamdar, A. I.; Deshmukh, H. P.

    2006-09-01

    Molybdenum-doped iridium oxide thin films have been deposited onto corning glass- and fluorine-doped tin oxide coated corning glass substrates at 350 °C by using a pneumatic spray pyrolysis technique. An aqueous solution of 0.01 M ammonium molybdate was mixed with 0.01 M iridium trichloride solution in different volume proportions and the resultant solution was used as a precursor solution for spraying. The as-deposited samples were annealed at 600 °C in air medium for 1 h. The structural, electrical and optical properties of as-deposited and annealed Mo-doped iridium oxide were studied and values of room temperature electrical resistivity, and thermoelectric power were estimated. The as-deposited samples with 2% Mo doping exhibit more pronounced electrochromism than other samples, including pristine Ir oxide.

  2. Nanoscale reduction of graphene oxide thin films and its characterization

    NASA Astrophysics Data System (ADS)

    Lorenzoni, M.; Giugni, A.; Di Fabrizio, E.; Pérez-Murano, Francesc; Mescola, A.; Torre, B.

    2015-07-01

    In this paper, we report on a method to reduce thin films of graphene oxide (GO) to a spatial resolution better than 100 nm over several tens of micrometers by means of an electrochemical scanning probe based lithography. In situ tip-current measurements show that an edged drop in electrical resistance characterizes the reduced areas, and that the reduction process is, to a good approximation, proportional to the applied bias between the onset voltage and the saturation thresholds. An atomic force microscope (AFM) quantifies the drop of the surface height for the reduced profile due to the loss of oxygen. Complementarily, lateral force microscopy reveals a homogeneous friction coefficient of the reduced regions that is remarkably lower than that of native graphene oxide, confirming a chemical change in the patterned region. Micro Raman spectroscopy, which provides access to insights into the chemical process, allows one to quantify the restoration and de-oxidation of the graphitic network driven by the electrochemical reduction and to determine characteristic length scales. It also confirms the homogeneity of the process over wide areas. The results shown were obtained from accurate analysis of the shift, intensity and width of Raman peaks for the main vibrational bands of GO and reduced graphene oxide (rGO) mapped over large areas. Concerning multilayered GO thin films obtained by drop-casting we have demonstrated an unprecedented lateral resolution in ambient conditions as well as an improved control, characterization and understanding of the reduction process occurring in GO randomly folded multilayers, useful for large-scale processing of graphene-based material.

  3. Transient laser annealing of zinc oxide nanoparticle inks to fabricate zinc oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Willemann, Michael

    Display technology, which relies exclusively on amorphous silicon as the active material for driver electronics, has reached multiple impasses that limit future progress. In order to deliver higher resolutions, higher refresh rates, new display technologies, and innovative form factors, driver electronics must transition to higher performance materials like amorphous oxide semiconductors (AOSs). Transient laser annealing offers an attractive means to maximize performance while minimizing thermal budget, making it compatible with flexible back plane materials and roll-to-roll processing. This research investigates the deposition and annealing of zinc oxide nanoparticle inks to form fully densified crystalline and amorphous zinc oxide films. Processing routes for nanoparticle annealing, including ligand removal, calcining, and excimer pulse laser sintering on the nanosecond time scale, will be introduced that minimize defect formation and suppress the anomalous n-conductivity which is a major challenge to zinc oxide processing. Resistivities as high as 6 x 107 O-cm have been demonstrated. Laser processing on longer millisecond time scales can control defect formation to produce ZnO films without extrinsic doping which have low resistivity for intrinsic oxides, in the range of 10-1 - 10-2 O-cm. Finally, a viable process for the production of backgated ZnO transistors with promising characteristics is presented and the future implications for AOSs and transient thermal processing will be discussed.

  4. Thermally evaporated mechanically hard tin oxide thin films for opto-electronic apllications

    NASA Astrophysics Data System (ADS)

    Tripathy, Sumanta K.; Rajeswari, V. P.

    2014-01-01

    Tungsten doped tin oxide (WTO) and Molybdenum doped tin oxide (MoTO) thin film were deposited on corn glass by thermal evaporation method. The films were annealed at 350°C for one hour. Structural analysis using Xray diffraction data shows both the films are polycrystalline in nature with monoclinic structure of tin oxide, Sn3O4, corresponding to JCPDS card number 01-078-6064. SEM photograph showed that both the films have spherical grains with size in the range of 20-30 nm. Compositional analysis was carried out using EDS which reveals the presence of Sn, O and the dopant Mo/W only thereby indicating the absence of any secondary phase in the films. The films are found to contain nearly 6 wt% of Mo, 8 wt% of W as dopants respectively. The transmission pattern for both the films in the spectral range 200 - 2000 nm shows that W doping gives a transparency of nearly 80% from 380 nm onwards while Mo doping has less transparency of 39% at 380nm. Film hardness measurement using Triboscope shows a film hardness of about 9-10 GPa for both the films. It indicates that W or M doping in tin oxide provides the films the added advantage of withstanding the mechanical wear and tear due to environmental fluctuations By optimizing the optical and electrical properties, W/Mo doped tin oxide films may be explored as window layers in opto-electronic applications such as solar cells.

  5. Formation of Flexible and Transparent Indium Gallium Zinc Oxide/Ag/Indium Gallium Zinc Oxide Multilayer Film

    NASA Astrophysics Data System (ADS)

    Kim, Jun Ho; Kim, Da-Som; Kim, Sun-Kyung; Yoo, Young-Zo; Lee, Jeong Hwan; Kim, Sang-Woo; Seong, Tae-Yeon

    2016-08-01

    In this study, the electrical, optical, and bending characteristics of amorphous indium gallium zinc oxide (IGZO)/Ag/IGZO (39 nm/19 nm/39 nm) multilayer films deposited on polyethylene terephthalate (PET) substrate at room temperature were investigated and compared with those of Sn-doped indium oxide (ITO) (100 nm thick) films. At 500 nm the ITO film transmitted 91.3% and the IGZO/Ag/IGZO multilayer film transmitted 88.8%. The calculated transmittance spectrum of the multilayer film was similar to the experimental result. The ITO film and IGZO/Ag/IGZO multilayer film, respectively, showed carrier concentrations of 1.79 × 1020 and 7.68 × 1021 cm-3 and mobilities of 27.18 cm2/V s and 18.17 cm2/V s. The ITO film had a sheet resistance of 134.9 Ω/sq and the IGZO/Ag/IGZO multilayer film one of 5.09 Ω/sq. Haacke's figure of merit (FOM) was calculated to be 1.94 × 10-3 for the ITO film and 45.02 × 10-3 Ω-1 for the IGZO/Ag/IGZO multilayer film. The resistance change of 100 nm-thick ITO film was unstable even after five cycles, while that of the IGZO/Ag/IGZO film was constant up to 1000 cycles.

  6. Formation of Flexible and Transparent Indium Gallium Zinc Oxide/Ag/Indium Gallium Zinc Oxide Multilayer Film

    NASA Astrophysics Data System (ADS)

    Kim, Jun Ho; Kim, Da-Som; Kim, Sun-Kyung; Yoo, Young-Zo; Lee, Jeong Hwan; Kim, Sang-Woo; Seong, Tae-Yeon

    2016-05-01

    In this study, the electrical, optical, and bending characteristics of amorphous indium gallium zinc oxide (IGZO)/Ag/IGZO (39 nm/19 nm/39 nm) multilayer films deposited on polyethylene terephthalate (PET) substrate at room temperature were investigated and compared with those of Sn-doped indium oxide (ITO) (100 nm thick) films. At 500 nm the ITO film transmitted 91.3% and the IGZO/Ag/IGZO multilayer film transmitted 88.8%. The calculated transmittance spectrum of the multilayer film was similar to the experimental result. The ITO film and IGZO/Ag/IGZO multilayer film, respectively, showed carrier concentrations of 1.79 × 1020 and 7.68 × 1021 cm-3 and mobilities of 27.18 cm2/V s and 18.17 cm2/V s. The ITO film had a sheet resistance of 134.9 Ω/sq and the IGZO/Ag/IGZO multilayer film one of 5.09 Ω/sq. Haacke's figure of merit (FOM) was calculated to be 1.94 × 10-3 for the ITO film and 45.02 × 10-3 Ω-1 for the IGZO/Ag/IGZO multilayer film. The resistance change of 100 nm-thick ITO film was unstable even after five cycles, while that of the IGZO/Ag/IGZO film was constant up to 1000 cycles.

  7. Amorphous semiconducting and conducting transparent metal oxide thin films and production thereof

    SciTech Connect

    Perkins, John; Van Hest, Marinus Franciscus Antonius Maria; Ginley, David; Taylor, Matthew; Neuman, George A.; Luten, Henry A.; Forgette, Jeffrey A.; Anderson, John S.

    2010-07-13

    Metal oxide thin films and production thereof are disclosed. An exemplary method of producing a metal oxide thin film may comprise introducing at least two metallic elements and oxygen into a process chamber to form a metal oxide. The method may also comprise depositing the metal oxide on a substrate in the process chamber. The method may also comprise simultaneously controlling a ratio of the at least two metallic elements and a stoichiometry of the oxygen during deposition. Exemplary amorphous metal oxide thin films produced according to the methods herein may exhibit highly transparent properties, highly conductive properties, and/or other opto-electronic properties.

  8. Energy dissipation of highly charged ions on Al oxide films.

    PubMed

    Lake, R E; Pomeroy, J M; Sosolik, C E

    2010-03-01

    Slow highly charged ions (HCIs) carry a large amount of potential energy that can be dissipated within femtoseconds upon interaction with a surface. HCI-insulator collisions result in high sputter yields and surface nanofeature creation due to strong coupling between the solid's electronic system and lattice. For HCIs interacting with Al oxide, combined experiments and theory indicate that defect mediated desorption can explain reasonably well preferential O atom removal and an observed threshold for sputtering due to potential energy. These studies have relied on measuring mass loss on the target substrate or probing craters left after desorption. Our approach is to extract highly charged ions onto the Al oxide barriers of metal-insulator-metal tunnel junctions and measure the increased conductance in a finished device after the irradiated interface is buried under the top metal layer. Such transport measurements constrain dynamic surface processes and provide large sets of statistics concerning the way individual HCI projectiles dissipate their potential energy. Results for Xe(q +) for q = 32, 40, 44 extracted onto Al oxide films are discussed in terms of postirradiation electrical device characteristics. Future work will elucidate the relationship between potential energy dissipation and tunneling phenomena through HCI modified oxides. PMID:21389384

  9. Growth of Ordered Ultrathin Tungsten Oxide Films on Pt(111)

    SciTech Connect

    Li, Zhenjun; Zhang, Zhenrong; Kim, Yu Kwon; Smith, R. Scott; Netzer, Falko; Kay, Bruce D.; Rousseau, Roger J.; Dohnalek, Zdenek

    2011-04-07

    Ordered tungsten oxide ultra-thin films were prepared on a Pt(111) substrate at 700 K via direct sublimation of monodispersed cyclic (WO3)3 trimers. The surface composition, structure and morphology were determined using a combination of atomically resolved imaging, ensemble-averaged surface-sensitive spectroscopies, and density functional theory (DFT). We find that half of the (WO3)3 tungsten atoms get partially reduced to the (5+) oxidation state in the first layer at the Pt(111) interface. The opening of the (WO3)3 ring leads to the formation of a tungsten oxide layer with a zig-zag chain structure with a c(4×2) periodicity. In the second layer, the (WO3)3 clusters remain intact and form an ordered (3×3) array of molecularly-bound (WO3)3. DFT calculations provide a detailed understanding of the structure, oxidation states, and the vibrational frequencies for both the c(4×2) and (3×3) overlayers.

  10. Oxidation Effect in Octahedral Hafnium Disulfide Thin Film.

    PubMed

    Chae, Sang Hoon; Jin, Youngjo; Kim, Tae Soo; Chung, Dong Seob; Na, Hyunyeong; Nam, Honggi; Kim, Hyun; Perello, David J; Jeong, Hye Yun; Ly, Thuc Hue; Lee, Young Hee

    2016-01-26

    Atomically smooth van der Waals materials are structurally stable in a monolayer and a few layers but are susceptible to oxygen-rich environments. In particular, recently emerging materials such as black phosphorus and perovskite have revealed stronger environmental sensitivity than other two-dimensional layered materials, often obscuring the interesting intrinsic electronic and optical properties. Unleashing the true potential of these materials requires oxidation-free sample preparation that protects thin flakes from air exposure. Here, we fabricated few-layer hafnium disulfide (HfS2) field effect transistors (FETs) using an integrated vacuum cluster system and study their electronic properties and stability under ambient conditions. By performing all the device fabrication and characterization procedure under an oxygen- and moisture-free environment, we found that few-layer AA-stacking HfS2-FETs display excellent field effect responses (Ion/Ioff ≈ 10(7)) with reduced hysteresis compared to the FETs prepared under ambient conditions. Oxidation of HfS2 occurs uniformly over the entire area, increasing the film thickness by 250% at a prolonged oxidation time of >120 h, while defects on the surface are the preferential initial oxidation sites. We further demonstrated that the stability of the device in air is significantly improved by passivating FETs with BN in a vacuum cluster. PMID:26735305

  11. Energy dissipation of highly charged ions on Al oxide films

    NASA Astrophysics Data System (ADS)

    Lake, R. E.; Pomeroy, J. M.; Sosolik, C. E.

    2010-03-01

    Slow highly charged ions (HCIs) carry a large amount of potential energy that can be dissipated within femtoseconds upon interaction with a surface. HCI-insulator collisions result in high sputter yields and surface nanofeature creation due to strong coupling between the solid's electronic system and lattice. For HCIs interacting with Al oxide, combined experiments and theory indicate that defect mediated desorption can explain reasonably well preferential O atom removal and an observed threshold for sputtering due to potential energy. These studies have relied on measuring mass loss on the target substrate or probing craters left after desorption. Our approach is to extract highly charged ions onto the Al oxide barriers of metal-insulator-metal tunnel junctions and measure the increased conductance in a finished device after the irradiated interface is buried under the top metal layer. Such transport measurements constrain dynamic surface processes and provide large sets of statistics concerning the way individual HCI projectiles dissipate their potential energy. Results for Xeq + for q = 32, 40, 44 extracted onto Al oxide films are discussed in terms of postirradiation electrical device characteristics. Future work will elucidate the relationship between potential energy dissipation and tunneling phenomena through HCI modified oxides.

  12. Biopolymer-modified graphite oxide nanocomposite films based on benzalkonium chloride-heparin intercalated in graphite oxide

    NASA Astrophysics Data System (ADS)

    Meng, Na; Zhang, Shuang-Quan; Zhou, Ning-Lin; Shen, Jian

    2010-05-01

    Heparin is a potent anticoagulant agent that interacts strongly with antithrombin III to prevent the formation of fibrin clots. In the present work, poly(dimethylsiloxane)(PDMS)/graphite oxide-benzalkonium chloride-heparin (PDMS/modified graphite oxide) nanocomposite films were obtained by the solution intercalation technique as a possible drug delivery system. The heparin-benzalkonium chloride (BAC-HEP) was intercalated into graphite oxide (GO) layers to form GO-BAC-HEP (modified graphite oxide). Nanocomposite films were characterized by XRD, SEM, TEM, ATR-FTIR and TGA. The modified graphite oxide was observed to be homogeneously dispersed throughout the PDMS matrix. The effect of modified graphite oxide on the mechanical properties of the nanocomposite film was investigated. When the modified graphite oxide content was lower than 0.2 wt%, the nanocomposites showed excellent mechanical properties. Furthermore, nanocomposite films become delivery systems that release heparin slowly to make the nanocomposite films blood compatible. The in vitro studies included hemocompatibility testing for effects on platelet adhesion, platelet activation, plasma recalcification profiles, and hemolysis. Results from these studies showed that the anticoagulation properties of PDMS/GO-BCA-HEP nanocomposite films were greatly superior to those for no treated PDMS. Cell culture assay indicated that PDMS/GO-BCA-HEP nanocomposite films showed enhanced cell adhesion.

  13. Amperometric detection and electrochemical oxidation of aliphatic amines and ammonia on silver-lead oxide thin-film electrodes

    SciTech Connect

    Ge, Jisheng

    1996-01-08

    This thesis comprises three parts: Electrocatalysis of anodic oxygen-transfer reactions: aliphatic amines at mixed Ag-Pb oxide thin-film electrodes; oxidation of ammonia at anodized Ag-Pb eutectic alloy electrodes; and temperature effects on oxidation of ethylamine, alanine, and aquated ammonia.

  14. Formation of hybrid hafnium oxide by applying sacrifacial silicon film

    NASA Astrophysics Data System (ADS)

    Lin, Chiung-Wei; Zheng, Bo-Shen; Huang, Jing-Wei

    2016-01-01

    In the fabrication of hafnium oxide (HfO2)-based metal-insulator-semiconductor (MIS) devices, a sacrificial amorphous silicon (a-Si) film was used as silicon source for facilitating the formation of hafnium silicate (Hf-silicate; HfSiO) between HfO2 and crystallized Si (c-Si). HfSiO can assist in changing the phase of the HfO2 film into the tetragonal phase and achieve high dielectric constant. The combination of HfSiO and HfO2 was named as “Hybrid HfO2”. When this Hybrid HfO2 insulator was applied to MIS devices, it can form a good insulator/semiconductor interface with c-Si. Hybrid HfO2 cannot only suppress the leakage current but also show high dielectric strength. The Hybrid HfO2 film in this work exhibited a high dielectric constant of 25.5 and a high dielectric strength of 17.9 MV/cm.

  15. Pulsed laser deposition of nanostructured indium-tin-oxide film

    NASA Astrophysics Data System (ADS)

    Yong, Thian Kok; Nee, Chen Hon; Yap, Seong Shan; Siew, Wee Ong; Sáfran, György; Yap, Yoke Kin; Tou, Teck Yong

    2010-08-01

    Effects of O2, N2, Ar and He on the formation of micro- and nanostructured indium tin oxide (ITO) thin films were investigated in pulsed Nd:YAG laser deposition on glass substrate. For O2 and Ar, ITO resistivity of <= 4 × 10-4 Ωcm and optical transmittance of > 90% were obtained with substrate temperature of 250 °C. For N2 and He, low ITO resisitivity could be obtained but with poor optical transmittance. SEM images show nano-structured ITO thin films for all gases, where dense, larger and highly oriented, microcrystalline structures were obtained for deposition in O2 and He, as revealed from the XRD lines. EDX results indicated the inclusion of Ar and N2 at the expense of reduced tin (Sn) content. When the ITO films were applied for fabrication of organic light emitting devices (OLED), only those deposited in Ar and O2 produced comparable performance to single-layer OLED fabricated on the commercial ITO.

  16. Electrochromic properties of electrodeposited tungsten oxide (WO3) thin film

    NASA Astrophysics Data System (ADS)

    Dalavi, D. S.; Kalagi, S. S.; Mali, S. S.; More, A. J.; Patil, R. S.; Patil, P. S.

    2012-06-01

    In this work, we report on a potentiostatic electrochemical procedure employing an ethanolic solution of peroxotungstic acid yielded tungsten oxide (WO3) films specifically for transmissive electrochromic devices (ECDs) such as "smart windows". WO3 film was confirmed from the binding energy determination by X-ray photoelectron spectroscopic studies. The diffusion coefficient during intercalation and deintercalation was found to be 2.59×10-10 and 2.40×10-10 cm2/C. Electrodeposited WO3 produce high color/bleach transmittance difference up to 74% at 630 nm. On reduction of WO3, the CIELAB 1931 2% color space coordinates show the transition from colorless to the deep blue state (L=95.18, a=2.12, b=0.3138, and L=57.78, a=-21.79, b=0.244) with steady decrease in relative luminance. The highest coloration efficiency (CE) of 92 cm2/C and good response time of 10.28 for coloration (reduction) and 3.2 s for bleaching (oxidation) was observed with an excellent reversibility of 89%.

  17. Surface plasmon resonance biochip based on ZnO thin film for nitric oxide sensing.

    PubMed

    Feng, Wei-Yi; Chiu, Nan-Fu; Lu, Hui-Hsin; Shih, Hsueh-Ching; Yang, Dongfang; Lin, Chii-Wann

    2008-01-01

    In this study, the design of a novel optical sensor that comprises surface plasmon resonance sensing chip and zinc oxide nano-film was proposed for the detection of nitric oxide gas. The electrical and optical properties of zinc oxide film vary in the presence of nitric oxide. This effect was utilized to prepare biochemical sensors with transduction based on surface plasmon resonance. Due to the refractive index of the transparent zinc oxide film that was deposited on the gold film, however, changes will be observed in the surface plasmon resonance spectra. For this reason, the thickness of zinc oxide film will be investigated and determined in this study. The interaction of nitric oxide with a 20 nm zinc oxide layer on gold leads to the shift of the resonance angle. The analysis on the reflectance intensity of light demonstrates that such effect is caused by the variation of conductivity and permittivity of zinc oxide film. Finally, a shift in surface plasmon resonance angle was measured in 25 ppm nitric oxide at 180 C and a calibration curve of nitride oxide concentration versus response intensity was successfully obtained in the range of 250 to 1000 ppm nitric oxide at lower temperature of 150 C. Moreover, these effects are quasi-reversible. PMID:19164025

  18. Indium doped zinc oxide nanowire thin films for antireflection and solar absorber coating applications

    SciTech Connect

    Shaik, Ummar Pasha; Krishna, M. Ghanashyam

    2014-04-24

    Indium doped ZnO nanowire thin films were prepared by thermal oxidation of Zn-In metal bilayer films at 500°C. The ZnO:In nanowires are 20-100 nm in diameter and several tens of microns long. X-ray diffraction patterns confirm the formation of oxide and indicate that the films are polycrystalline, both in the as deposited and annealed states. The transmission which is <2% for the as deposited Zn-In films increases to >90% for the ZnO:In nanowire films. Significantly, the reflectance for the as deposited films is < 10% in the region between 200 to 1500 nm and < 2% for the nanowire films. Thus, the as deposited films can be used solar absorber coatings while the nanowire films are useful for antireflection applications. The growth of nanowires by this technique is attractive since it does not involve very high temperatures and the use of catalysts.

  19. Optical and structural characterization of iron oxide and cobalt oxide thin films at 800 nm

    NASA Astrophysics Data System (ADS)

    Garcia, Hans A.; de Melo, Ronaldo P.; Azevedo, Antonio; de Araújo, Cid B.

    2013-05-01

    We report on optical and structural properties of α-Fe2O3 and Co3O4 thin films, grown by direct oxidation of pure metal films deposited on soda-lime glass. Structural characteristics and morphology of the films were investigated by X-ray diffraction, atomic force microscopy, and scanning electron microscopy. Linear optical absorption, and linear refraction as well as nonlinear optical properties were investigated. The third-order optical susceptibilities were measured applying the Thermally managed Z- scan technique using a Ti: sapphire laser (150 fs; 800 nm). The results obtained for the Co3O4 film were {Re} χ^{( 3 )} = -(5.7 ± 2.4) ×10-9 esu and {Im} χ^{(3)} = -(1.8 ± 0.2) ×10-8 esu while for the α-Fe2O3 film we determined {Re} χ^{(3)} = +(6.6 ± 2.4) ×10-10 esu and {Im} χ^{(3)} = +(2.2 ± 0.4) ×10-10 esu.

  20. Thin Films and Josephson Junctions of Yttrium Barium Copper Oxide

    NASA Astrophysics Data System (ADS)

    Rosenthal, Peter Andrew

    We have studied the growth of superconducting films of rm Y_1Ba_2Cu_3O _{7-delta} using reactive electron beam coevaporation. Emphasis was placed on determining the most important growth parameters, and optimizing the instrumentation for controlling the growth environment. We have experimented with atomic absorption based deposition rate control, quartz lamp based substrate heating, and various forms of activated oxygen. Methods for generating and delivering molecular oxygen, oxygen ion beams, ozone and atomic oxygen were investigated and their effects on film quality were characterized. We found that the specific method of oxidation was not critical to the film quality but that optimal films were produced at lower pressures (~10^{-4} T) for more chemically reactive allotropes of oxygen. Composition was found to be quite important in determining the film properties. These results are discussed in the context of growth kinetics and equilibrium thermodynamics. We have studied the transport properties of artificial grain boundary Josephson junctions of rm Y_1Ba_2Cu_3O_{7-delta }. Measurements and modeling of the magnetic interference patterns of the critical currents revealed the presence of extensive disorder within the junctions. The temperature dependence of the critical currents revealed behavior consistent with the resistively shunted junction (RSJ) model. Modeling the inhomogeneous junctions as parallel arrays of RSJ-like junctions explained the clean RSJ-like current-voltage characteristics even in junctions showing extremely complicated magnetic interference patterns. The observed modulation period of the single junction interference patterns showed an unusual w^{-2} width dependence that could be quantitatively explained by a model of flux focusing based on the London theory. A model of the diffraction patterns for junctions fabricated from extremely thin films shows unexpected deviations from the usual behavior. These peculiarities are understood in terms of

  1. Strong, self-standing oxygen barrier films from nanocelluloses modified with regioselective oxidative treatments.

    PubMed

    Sirviö, Juho Antti; Kolehmainen, Aleksi; Visanko, Miikka; Liimatainen, Henrikki; Niinimäki, Jouko; Hormi, Osmo E O

    2014-08-27

    In this work, three self-standing nanocellulose films were produced from birch pulp using regioselective oxidation and further derivatization treatments. The modified celluloses were synthesized using periodate oxidation, followed by chlorite oxidation, bisulfite addition, or reductive amination with amino acid taurine, which resulted in dicarboxylic acid cellulose (DCC), α-hydroxy sulfonic acid cellulose (HSAC), and taurine-modified cellulose (TC), respectively. The nanocelluloses were fabricated by mechanical disintegration using high-pressure homogenization. Mechanical and barrier properties of the nanocellulose films were characterized. Two (2,2,6,6-tetramethyl-piperidin-1-yl)oxyl (TEMPO) oxidation-based nanocellulose films were also produced, and their properties were compared to the periodate-based nanocellulose films. All of the periodate-based nanocellulose films showed high tensile strength (130-163 MPa) and modulus (19-22 GPa). Oxygen barrier properties of the films were superior to many synthetic and composite materials; in particular, the nanofibrillated DCC films had oxygen permeability as low as 0.12 cm(3) μm/(m(2) d kPa) at 50% relative humidity. Compared to films of TEMPO-oxidized nanocelluloses, all of the periodate-based nanocellulose films had similar or even better mechanical and barrier properties, demonstrating versatility of periodate oxidation to obtain nanocellulose films with adjustable properties. Also, for the first time, amino-acid-based cellulose modification was used in the production of nanocellulose. PMID:25089516

  2. Flexible Electronics Powered by Mixed Metal Oxide Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Marrs, Michael

    A low temperature amorphous oxide thin film transistor (TFT) and amorphous silicon PIN diode backplane technology for large area flexible digital x-ray detectors has been developed to create 7.9-in. diagonal backplanes. The critical steps in the evolution of the backplane process include the qualification and optimization of the low temperature (200 °C) metal oxide TFT and a-Si PIN photodiode process, the stability of the devices under forward and reverse bias stress, the transfer of the process to flexible plastic substrates, and the fabrication and assembly of the flexible detectors. Mixed oxide semiconductor TFTs on flexible plastic substrates suffer from performance and stability issues related to the maximum processing temperature limitation of the polymer. A novel device architecture based upon a dual active layer improves both the performance and stability. Devices are directly fabricated below 200 ºC on a polyethylene naphthalate (PEN) substrate using mixed metal oxides of either zinc indium oxide (ZIO) or indium gallium zinc oxide (IGZO) as the active semiconductor. The dual active layer architecture allows for adjustment to the saturation mobility and threshold voltage stability without the requirement of high temperature annealing, which is not compatible with flexible plastic substrates like PEN. The device performance and stability is strongly dependent upon the composition of the mixed metal oxide; this dependency provides a simple route to improving the threshold voltage stability and drive performance. By switching from a single to a dual active layer, the saturation mobility increases from 1.2 cm2/V-s to 18.0 cm2/V-s, while the rate of the threshold voltage shift decreases by an order of magnitude. This approach could assist in enabling the production of devices on flexible substrates using amorphous oxide semiconductors. Low temperature (200°C) processed amorphous silicon photodiodes were developed successfully by balancing the tradeoffs

  3. Epitaxial growth of intermetallic MnPt films on oxides and large exchange bias

    DOE PAGESBeta

    Liu, Zhiqi; Biegalski, Michael D.; Hsu, Shang-Lin; Shang, Shunli; Marker, Cassie; Liu, Jian; Li, Li; Fan, Lisha S.; Meyer, Tricia L.; Wong, Anthony T.; et al

    2015-11-05

    High-quality epitaxial growth of intermetallic MnPt films on oxides is achieved, with potential for multiferroic heterostructure applications. Antisite-stabilized spin-flipping induces ferromagnetism in MnPt films, although it is robustly antiferromagnetic in bulk. Thus, highly ordered antiferromagnetic MnPt films exhibit superiorly large exchange coupling with a ferromagnetic layer.

  4. Epitaxial Growth of Intermetallic MnPt Films on Oxides and Large Exchange Bias.

    PubMed

    Liu, Zhiqi; Biegalski, Michael D; Hsu, Shang-Lin; Shang, Shunli; Marker, Cassie; Liu, Jian; Li, Li; Fan, Lisha; Meyer, Tricia L; Wong, Anthony T; Nichols, John A; Chen, Deyang; You, Long; Chen, Zuhuang; Wang, Kai; Wang, Kevin; Ward, Thomas Z; Gai, Zheng; Lee, Ho Nyung; Sefat, Athena S; Lauter, Valeria; Liu, Zi-Kui; Christen, Hans M

    2016-01-01

    High-quality epitaxial growth of inter-metallic MnPt films on oxides is achieved, with potential for multiferroic heterostructure applications. Antisite-stabilized spin-flipping induces ferromagnetism in MnPt films, although it is robustly antiferromagnetic in bulk. Moreover, highly ordered antiferromagnetic MnPt films exhibit superiorly large exchange coupling with a ferromagnetic layer. PMID:26539758

  5. Wettability of oxide thin films prepared by pulsed laser deposition: New insights

    NASA Astrophysics Data System (ADS)

    Prakash, Saurav

    The objective of the thesis is to investigate the wettability of good quality oxide thin films prepared by pulsed laser deposition (PLD). In this work, many shortfalls in the water contact angle measurement of thin films of oxides, responsible for the wide scatter in the values reported in literature, have been addressed. (Abstract shortened by UMI.).

  6. Doped, porous iron oxide films and their optical functions and anodic photocurrents for solar water splitting

    SciTech Connect

    Kronawitter, Coleman X.; Mao, Samuel S.; Antoun, Bonnie R.

    2011-02-28

    The fabrication and morphological, optical, and photoelectrochemical characterization of doped iron oxide films is presented. The complex index of refraction and absorption coefficient of polycrystalline films are determined through measurement and modeling of spectral transmission and reflection data using appropriate dispersion relations. Photoelectrochemical characterization for water photo-oxidation reveals that the conversion efficiencies of electrodes are strongly influenced by substrate temperature during their oblique-angle physical vapor deposition. These results are discussed in terms of the films' morphological features and the known optoelectronic limitations of iron oxide films for application in solar water splitting devices.

  7. Structural and physical properties of tin oxide thin films for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Lin, Su-Shia; Tsai, Yung-Shiang; Bai, Kai-Ren

    2016-09-01

    Tin oxide films were deposited on glass substrates by RF magnetron sputtering. At a lower sputtering pressure, the tin oxide film comprised nanocrystalline orthorhombic SnO with a (110) orientation, greater p-type conductivity and better hydrophobicity. Increasing substrate temperature resulted in the coexistence of nanocrystalline orthorhombic SnO and tetragonal SnO2 in the deposited film, favoring hydrophilicity, changing the p-type conductivity to n-type conductivity, and reducing resistivity. As the sputtering pressure or substrate temperature increased, the tin oxide film exhibited a lower surface roughness, a larger optical energy gap, and higher optical transmission.

  8. Anisotropy and micromagnetics in complex oxide thin films

    NASA Astrophysics Data System (ADS)

    Wynn, Thomas Andrew

    Complex oxide perovskites are a class of material with a remarkably wide range of functional properties including magnetism, superconductivity, metal-to-insulator transitions, colossal magnetoresistance, and in some cases high magnetocrystalline anisotropy. Reduction in length scales through thin film deposition and nanopatterning results in altered properties from their bulk constituents. In this work, thin films of La0.7Sr0.3CoO3 (LSCO) and LSCO/La 0.7Sr0.3MnO3 (LSMO) bilayers of varying thicknesses were deposited onto (LaAlO3)0.3(Sr2TaAlO 6)0.7 (LSAT) substrates, and their anisotropic magnetic properties were measured along the in- plane [100] and [110] directions using superconducting quantum interference device (SQUID) magnetometry and soft x-ray magnetic spectroscopy. The LSCO showed thickness dependent magnetism, and films were non-magnetic below a critical thickness of 4 nm. Magnetic LSCO films showed unique anisotropic effects on the saturation magnetization (Ms), with a lower M s in the [110] direction than the [100] direction. This potentially indicates the existence of a hard component in the [110] direction that is not being switched at fields in the SQUID magnetometer (7 T). Normalized hysteresis loops indicate the LSCO films display little magnetocrystalline anisotropy within the plane of the film. LSCO/LSMO bilayers with a fixed LSMO layer of 6 nm in thickness showed cobalt magnetism at thicknesses where single layers were non-magnetic, suggesting that the substrate/film interface is not the cause of the non-magnetic layer in the LSCO thin films. Magnetic coupling occurs in bilayers with LSCO layer thicknesses of below 4 nm, and both LSCO and LSMO layers showed a [110] easy axis. When the layer thickness of LSCO was increased above 8 nm, the LSCO layer developed a soft component at the LSCO/LSMO interface. This soft LSCO component remained coupled with the LSMO, though the easy axis changed to the [100] direction, and the harder, non-interface LSCO

  9. Growth and Dissolution of Iron and Manganese Oxide Films

    SciTech Connect

    Scot T. Martin

    2008-12-22

    Growth and dissolution of Fe and Mn oxide films are key regulators of the fate and transport of heavy metals in the environment, especially during changing seasonal conditions of pH and dissolved oxygen. The Fe and Mn are present at much higher concentrations than the heavy metals, and, when Fe and Mn precipitate as oxide films, heavy metals surface adsorb or co-precipitate and are thus essentially immobilized. Conversely, when the Fe and Mn oxide films dissolve, the heavy metals are released to aqueous solution and are thus mobilized for transport. Therefore, understanding the dynamics and properties of Fe and Mn oxide films and thus on the uptake and release of heavy metals is critically important to any attempt to develop mechanistic, quantitative models of the fate, transport, and bioavailablity of heavy metals. A primary capability developed in our earlier work was the ability to grow manganese oxide (MnO{sub x}) films on rhodochrosite (MnCO{sub 3}) substrate in presence of dissolved oxygen under mild alkaline conditions. The morphology of the films was characterized using contact-mode atomic force microscopy. The initial growth began by heteroepitaxial nucleation. The resulting films had maximum heights of 1.5 to 2 nm as a result of thermodynamic constraints. Over the three past years, we have investigated the effects of MnO{sub x} growth on the interactions of MnCO{sub 3} with charged ions and microorganisms, as regulated by the surface electrical properties of the mineral. In 2006, we demonstrated that MnO{sub x} growth could induce interfacial repulsion and surface adhesion on the otherwise neutral MnCO{sub 3} substrate under environmental conditions. Using force-volume microscopy (FVM), we measured the interfacial and adhesive forces on a MnO{sub x}/MnCO{sub 3} surface with a negatively charged silicon nitride tip in a 10-mM NaNO3 solution at pH 7.4. The interfacial force and surface adhesion of MnOx were approximately 40 pN and 600 pN, respectively

  10. The effect of lithiation on the electrochromism of sol-gel derived niobium oxide films

    SciTech Connect

    Macek, M.; Orel, B.; Krasovec, U.O.

    1997-09-01

    Niobium oxide films are promising cathodic electrochromic materials that in certain aspects can compete with the more frequently studied WO{sub 3} films. The films reported here were prepared using the sol-gel route from a NbCl{sub 5} precursor. The electrochromic properties were pronounced for crystalline films heat-treated at 500 C exhibiting transmittance changes between the colored and bleached states of 60% in the ultraviolet (UV) and 80% in the visible and near-infrared spectral regions. The reversibility of electrochromic changes of thick niobium oxide films (d > 250 nm) was enhanced by lithiation.

  11. Transparent conductive reduced graphene oxide thin films produced by spray coating

    NASA Astrophysics Data System (ADS)

    Shi, HongFei; Wang, Can; Sun, ZhiPei; Zhou, YueLiang; Jin, KuiJuan; Yang, GuoZhen

    2015-01-01

    Reduced graphene oxide thin films were fabricated on quartz by spray coating method using a stable dispersion of reduced graphene oxide in N,N-Dimethylformamide. The dispersion was produced by chemical reduction of graphene oxide, and the film thickness was controlled with the amount of spray volume. AFM measurements revealed that the thin films have near-atomically flat surface. The chemical and structural parameters of the samples were analyzed by Raman and XPS studies. It was found that the thin films show electrical conductivity with good optical transparency in the visible to near infrared region. The sheet resistance of the films can be significantly reduced by annealing in vacuum and reach 58 kΩ with a light transmittance of 68.69% at 550 nm. The conductive transparent properties of the reduced graphene oxide thin films would be useful to develop flexible electronics.

  12. Reversible transformations of silver oxide and metallic silver nanoparticles inside SiO{sub 2} films

    SciTech Connect

    Pal, Sudipto; De, Goutam

    2009-02-04

    Reversible transformation of silver oxide and metallic nanoparticles inside a relatively porous silica film has been established. Annealing of Ag-doped films in oxidizing (air) atmosphere at 450 deg. C yielded colorless films containing AgO{sub x}. These films were turned yellow when heated in H{sub 2}-N{sub 2} (reducing atmosphere) due to the formation of Ag nanoparticles. This yellow coloration (due to nano Ag{sup 0}) and bleaching (conversion of Ag{sup 0} {yields} Ag{sup +}) are reversible. Optical and photoluminescence spectra are well consistent with this coloration and bleaching. The soaking test of the air-annealed film in Na{sub 2}S{sub 2}O{sub 3} solution supports the presence of Ag{sup +}. Grazing incidence X-ray diffraction and transmission electron microscopy studies reveal the formation of Ag-oxides and Ag nanoparticles in the oxidized and reduced films, respectively.

  13. Carboxylate Precursor Effects on MOD Derived Metal Oxide (Nickel/Nickel Oxide ) Thin Films

    NASA Astrophysics Data System (ADS)

    Gao, Xiang

    Thin films in the (Ni/NiO) system have been widely studied because of their significant potential for use in batteries, fuel cells, solar cells, supercapacitors, magnetic devices and various sensor applications. Such films typically are deposited onto suitable substrates by electrochemical or vapor deposition methods, followed by heat treatment to develop the oxide structure. In this study, by contrast, the Ni/NiO thin films were prepared by metallo-organic decomposition (MOD) technique in order to facilitate the development of nano structure feature as well as molecular scale mixing and excellent composition control. Critical parameters that must be controlled during this deposition process to achieve high quality films include: carboxylate precursor chemistry, solution chemistry, film structure chemistry, film deposition characteristics, film structure development and pyrolysis characteristics. These crucial control parameters are, for the most areas, poorly understood for this system especially for the carboxylate precursor chemistry effects on properties of Ni/NiO thin films. The goal of this work, therefore, is to understand and design those parameters in term of precursor species, viscosity, solute concentration and solvent composition as well as film deposition and heat treatment conditions that can lead to the controlled fabrication of nano-sized, high surface area, low resistive Ni/NiO thin films on Si and metallic substrates such as stainless steels and silver. The solvent system used consisted of a unique mixture of propionic acid and amylamine, in molar ratio of 0.5--2.0, with Ni acetate as the solute precursor in the concentration range of 0.2--2 mol/l. The films were prepared by spin deposition at 3000 rpm from carboxylate solution precursors with viscosity range of 10--640 cP. Good quality nano-sized Ni/NiO thin films, in the range of 0.2--2 microm thickness, on Si or stainless steel substrates were obtained by a mixed AA/PPA solvent system in the

  14. Determination of an oxide film on the surface of perlite steel

    SciTech Connect

    Krutikov, P.G.; Bykova, E.M.; Nemirov, N.V.; Papurin, N.M.

    1986-04-01

    When studying the formation of oxide films on the surface of circuits and systems in atomic and thermal power stations made of perlite steels, the need arises for the determination of the specific amount and thickness of oxide films. In order to reduce the error and the time required for such a determination, the authors have developed a new procedure, based on the selective dissolution of iron oxides with a proposed composition in the weak etching of themetal base. In this approach, the sample of perlite steel with the film is weighed before and after immersion in a solution of hydrochloric acid in acetone. The proposed procedure can be applied to dissolve dense oxide films. The total duration of a determination of the specific amount of oxide film on the surface of perlite steel by the proposed procedure is 20-25 minutes by using six samples at a time.

  15. Measurements of the optical properties of thin films of silver and silver oxide

    NASA Technical Reports Server (NTRS)

    Peters, Palmer N.; Sisk, Robert C.; Brown, Yolanda; Gregory, John C.; Nag, Pallob K.; Christl, Ligia

    1995-01-01

    The optical properties of silver films and their oxides are measured to better characterize such films for use as sensors for atomic oxygen. Good agreement between properties of measured pure silver films and reported optical constants is observed. Similar comparisons for silver oxide have not been possible because of a lack of reported constants, but self-consistencies and discrepancies in our measured results are described.

  16. Electrochemical oxide film formation at noble metals as a surface-chemical process

    NASA Astrophysics Data System (ADS)

    Conway, B. E.

    1995-08-01

    The mechanisms of electrochemical oxide film formation at noble metals are described and exemplified by the cases of Pt and Au, especially in the light of recent experimentation by means of cyclic voltammetry, ellipsometry and vacuum surface-science studies using LEED and AES. Unlike the mechanisms of base-metal oxidation, e.g., in corrosion processes, anodic oxide film formation at noble metals proceeds by surface chemical processes involving, initially, sub-monolayer, through monolayer, formation of 2-dimensional {OH}/{O} arrays. During such 2-d processes, place-exchange between electrosorbed OH or O species on the surface, and Pt or Au atoms within the surface lattice, takes place leading to a quasi-2-d compact film which then grows ultimately to a multilayer hydrous oxide film, probably by continuing injection of ions of the substrate metal and their migration through the growing film under the influence of the field. The initial, sub-monolayer stage of electrosorption of OH involves competitive chemisorption by anions, e.g. HSO 4-, ClO 4-, Cl -, which inhibits onset of the first stage of surface oxidation. These processes are demonstrable in experiments on single-crystal surfaces. The combination of such anion effects with place-exchange during the extension of the film, leads to a general mechanism of noble metal oxide film formation. The formation of the oxide films can be examined in detail by recording the distinguishable stages in the film's electrochemical reduction in linear-sweep voltammetry which is sensitive down to {OH}/{O} fractional coverages as low as 0.5% and over time-scales down to 50μs in experiments on time-evolution and transformation of the states of the oxide films. By means of LEED, AES and STM or AFM experiments, the reconstructions and perturbations (e.g. generation of stepped terraces) which oxide films cause on singlecrystal surfaces can be followed.

  17. Metal oxide semiconductor thin-film transistors for flexible electronics

    NASA Astrophysics Data System (ADS)

    Petti, Luisa; Münzenrieder, Niko; Vogt, Christian; Faber, Hendrik; Büthe, Lars; Cantarella, Giuseppe; Bottacchi, Francesca; Anthopoulos, Thomas D.; Tröster, Gerhard

    2016-06-01

    The field of flexible electronics has rapidly expanded over the last decades, pioneering novel applications, such as wearable and textile integrated devices, seamless and embedded patch-like systems, soft electronic skins, as well as imperceptible and transient implants. The possibility to revolutionize our daily life with such disruptive appliances has fueled the quest for electronic devices which yield good electrical and mechanical performance and are at the same time light-weight, transparent, conformable, stretchable, and even biodegradable. Flexible metal oxide semiconductor thin-film transistors (TFTs) can fulfill all these requirements and are therefore considered the most promising technology for tomorrow's electronics. This review reflects the establishment of flexible metal oxide semiconductor TFTs, from the development of single devices, large-area circuits, up to entirely integrated systems. First, an introduction on metal oxide semiconductor TFTs is given, where the history of the field is revisited, the TFT configurations and operating principles are presented, and the main issues and technological challenges faced in the area are analyzed. Then, the recent advances achieved for flexible n-type metal oxide semiconductor TFTs manufactured by physical vapor deposition methods and solution-processing techniques are summarized. In particular, the ability of flexible metal oxide semiconductor TFTs to combine low temperature fabrication, high carrier mobility, large frequency operation, extreme mechanical bendability, together with transparency, conformability, stretchability, and water dissolubility is shown. Afterward, a detailed analysis of the most promising metal oxide semiconducting materials developed to realize the state-of-the-art flexible p-type TFTs is given. Next, the recent progresses obtained for flexible metal oxide semiconductor-based electronic circuits, realized with both unipolar and complementary technology, are reported. In particular

  18. Electronic properties of epitaxial cerium oxide films during controlled reduction and oxidation studied by resonant inelastic X-ray scattering.

    PubMed

    Gasperi, Gabriele; Amidani, Lucia; Benedetti, Francesco; Boscherini, Federico; Glatzel, Pieter; Valeri, Sergio; Luches, Paola

    2016-07-27

    We investigated the evolution of the electronic structure of cerium oxide ultrathin epitaxial films during reduction and oxidation processes using resonant inelastic X-ray scattering at the Ce L3 absorption edge, a technique sensitive to the electronic configurations at the 4f levels and in the 5d band thanks to its high energy resolution. We used thermal treatments in high vacuum and in oxygen partial pressure to induce a controlled and reversible degree of reduction in cerium oxide ultrathin epitaxial films of different thicknesses. Two dominant spectral components contribute to the measured spectra at the different degrees of oxidation/reduction. In ultrathin films a modification of the electronic properties associated with platinum substrate proximity and with dimensionality is identified. The different electronic properties induce a higher reducibility in ultrathin films, ascribed to a decrease of the surface oxygen vacancy formation energy. PMID:27405957

  19. Ultrastrong, Chemically Resistant Reduced Graphene Oxide-based Multilayer Thin Films with Damage Detection Capability.

    PubMed

    Guin, Tyler; Stevens, Bart; Krecker, Michelle; D'Angelo, John; Humood, Mohammad; Song, Yixuan; Smith, Ryan; Polycarpou, Andreas; Grunlan, Jaime C

    2016-03-01

    Multilayer thin films of graphene oxide (GO) and poly(vinylamine) (PVAm) were deposited via layer-by-layer assembly. Poly(vinylamine) pH was used to tailor film thickness and GO layer spacing. Graphene oxide concentration in the films was controlled through simple pH adjustment. Thermal reduction of the PVAm/GO multilayer thin films rendered them electrically conductive, which could be further tailored with PVAm pH. These reduced films also exhibited exceptionally high elastic modulus of 30 GPa and hardness of 1.8 GPa, which are among the highest of any graphene-filled polymer composite values ever reported. Cross-linking of these films with glutaraldehyde improved their chemical resistance, allowing them to survive strongly acidic or salty solutions. Additionally, scratches in the films can be instantaneously detected by a simple electrical resistance measurement. These films are promising for a variety of packaging and electronic applications. PMID:26885558

  20. The application of the barrier-type anodic oxidation method to thickness testing of aluminum films.

    PubMed

    Chen, Jianwen; Yao, Manwen; Xiao, Ruihua; Yang, Pengfei; Hu, Baofu; Yao, Xi

    2014-09-01

    The thickness of the active metal oxide film formed from a barrier-type anodizing process is directly proportional to its formation voltage. The thickness of the consumed portion of the metal film is also corresponding to the formation voltage. This principle can be applied to the thickness test of the metal films. If the metal film is growing on a dielectric substrate, when the metal film is exhausted in an anodizing process, because of the high electrical resistance of the formed oxide film, a sudden increase of the recorded voltage during the anodizing process would occur. Then, the thickness of the metal film can be determined from this voltage. As an example, aluminum films are tested and discussed in this work. This method is quite simple and is easy to perform with high precision. PMID:25273741

  1. The application of the barrier-type anodic oxidation method to thickness testing of aluminum films

    NASA Astrophysics Data System (ADS)

    Chen, Jianwen; Yao, Manwen; Xiao, Ruihua; Yang, Pengfei; Hu, Baofu; Yao, Xi

    2014-09-01

    The thickness of the active metal oxide film formed from a barrier-type anodizing process is directly proportional to its formation voltage. The thickness of the consumed portion of the metal film is also corresponding to the formation voltage. This principle can be applied to the thickness test of the metal films. If the metal film is growing on a dielectric substrate, when the metal film is exhausted in an anodizing process, because of the high electrical resistance of the formed oxide film, a sudden increase of the recorded voltage during the anodizing process would occur. Then, the thickness of the metal film can be determined from this voltage. As an example, aluminum films are tested and discussed in this work. This method is quite simple and is easy to perform with high precision.

  2. Aqueous phase deposition of dense tin oxide films with nano-structured surfaces

    SciTech Connect

    Masuda, Yoshitake Ohji, Tatsuki; Kato, Kazumi

    2014-06-01

    Dense tin oxide films were successfully fabricated in an aqueous solution. The pH of the solutions was controlled to pH 1.3 by addition of HCl. Precise control of solution condition and crystal growth allowed us to obtain dense tin oxide films. Concave–convex surface of fluorine-doped tin oxide (FTO) substrates was entirely-covered with the continuous films. The films were about 65 nm in thickness and had nano-structured surfaces. Morphology of the films was strikingly different from our previous reported nano-sheet assembled structures. The films were not removed from the substrates by strong water flow or air blow to show strong adhesion strength. The aqueous solution process can be applied to surface coating of various materials such as nano/micro-structured surfaces, particles, fibers, polymers, metals or biomaterials. - Graphical abstract: Dense tin oxide films of 65 nm were successfully fabricated in an aqueous solution. They had nano-structured surfaces. Concave-convex substrates were entirely-covered with the continuous films. - Highlights: • Dense tin oxide films of 65 nm were successfully fabricated in an aqueous solution. • They had nano-structured surfaces. • Concave–convex substrates were entirely-covered with the continuous films.

  3. Growth and characterization of single phase Cu2O by thermal oxidation of thin copper films

    NASA Astrophysics Data System (ADS)

    Choudhary, Sumita; Sarma, J. V. N.; Gangopadhyay, Subhashis

    2016-04-01

    We report a simple and efficient technique to form high quality single phase cuprous oxide films on glass substrate using thermal evaporation of thin copper films followed by controlled thermal oxidation in air ambient. Crystallographic analysis and oxide phase determination, as well as grain size distribution have been studied using X-ray diffraction (XRD) method, while scanning electron microscopy (SEM) has been utilized to investigate the surface morphology of the as grown oxide films. The formation of various copper oxide phases is found to be highly sensitive to the oxidation temperature and a crystalline, single phase cuprous oxide film can be achieved for oxidation temperatures between 250°C to 320°C. Cu2O film surface appeared in a faceted morphology in SEM imaging and a direct band gap of about 2.1 eV has been observed in UV-visible spectroscopy. X-ray photoelectron spectroscopy (XPS) confirmed a single oxide phase formation. Finally, a growth mechanism of the oxide film has also been discussed.

  4. Thermally-driven structural changes of graphene oxide multilayer films deposited on glass substrate

    NASA Astrophysics Data System (ADS)

    Lazauskas, A.; Baltrusaitis, J.; Grigaliūnas, V.; Guobienė, A.; Prosyčevas, I.; Narmontas, P.; Abakevičienė, B.; Tamulevičius, S.

    2014-11-01

    Graphene oxide (GO) has been recognized as an important intermediate compound for a potential low-cost large-scale graphene-like film fabrication. In this work, graphene oxide multilayer films deposited on glass substrate were reduced using different thermal reduction methods, including low-temperature annealing, flame-induced and laser reduction, and the corresponding surface morphology and structural properties were investigated. These graphene oxide thermal reduction methods strongly affected surface morphology and differently facilitated structural and chemical transformations of graphene oxide. As evidenced by Raman measurements, thermal annealing and laser reduction of graphene oxide produced more ordered graphene-like structure multilayer films. However, surface morphological differences were observed and attributed to the different de-oxidation mechanisms of GO. This Letter provides an important systematic comparison between the GO reduction methods and thermally-driven structural changes they provide to the reduced GO multilayer films obtained.

  5. Deformation behavior of the oxide film on the surface of cold sprayed powder particle

    NASA Astrophysics Data System (ADS)

    Yin, Shuo; Wang, Xiaofang; Li, Wenya; Liao, Hanlin; Jie, Hongen

    2012-10-01

    In cold spraying, oxide-free interface is an important factor for metal-to-metal contact between powder particles and substrate, which determines the bonding strength and final coating quality. In this study, a systematic finite element analysis (FEA) is performed to examine the deformation behavior of the oxide film on an Al 6061-T6 particle surface after deposition. The simulation results show that the oxide film can be disrupted during the high velocity impact. Part of the cracked oxides remains at the interface and mainly accumulates at the central region after particle deposition. Substrate hardness, particle velocity and spray angle are found to influence the deformation behavior and final state of the oxide film. Besides, interparticle interaction is also investigated in the present work to clarify the deformation behavior of the oxide film inside the coating.

  6. ZnO Films with Very High Haze Value for Use as Front Transparent Conductive Oxide Films in Thin-Film Silicon Solar Cells

    NASA Astrophysics Data System (ADS)

    Hongsingthong, Aswin; Krajangsang, Taweewat; Afdi Yunaz, Ihsanul; Miyajima, Shinsuke; Konagai, Makoto

    2010-05-01

    We successfully increased the haze value of zinc oxide (ZnO) films fabricated using metal-organic chemical vapor deposition (MOCVD) by conducting glass-substrate etching before film deposition. It was found that with increasing the glass treatment time, the surface morphology of ZnO films changed from conventional pyramid-like single texture to greater cauliflower-like multi texture. Further, the rms roughness and the haze value of the films increased remarkably. Using ZnO films with a high haze value as front transparent conductive oxide (TCO) films in hydrogenated microcrystalline silicon (µc-Si:H) solar cells, we improved the quantum efficiency of these cells particularly in the long-wavelength region.

  7. Continuously controlled optical band gap in oxide semiconductor thin films

    DOE PAGESBeta

    Herklotz, Andreas; Rus, Stefania Florina; Ward, Thomas Zac

    2016-02-02

    The optical band gap of the prototypical semiconducting oxide SnO2 is shown to be continuously controlled through single axis lattice expansion of nanometric films induced by low-energy helium implantation. While traditional epitaxy-induced strain results in Poisson driven multidirectional lattice changes shown to only allow discrete increases in bandgap, we find that a downward shift in the band gap can be linearly dictated as a function of out-of-plane lattice expansion. Our experimental observations closely match density functional theory that demonstrates that uniaxial strain provides a fundamentally different effect on the band structure than traditional epitaxy-induced multiaxes strain effects. In conclusion, chargemore » density calculations further support these findings and provide evidence that uniaxial strain can be used to drive orbital hybridization inaccessible with traditional strain engineering techniques.« less

  8. Continuously Controlled Optical Band Gap in Oxide Semiconductor Thin Films.

    PubMed

    Herklotz, Andreas; Rus, Stefania Florina; Ward, Thomas Zac

    2016-03-01

    The optical band gap of the prototypical semiconducting oxide SnO2 is shown to be continuously controlled through single axis lattice expansion of nanometric films induced by low-energy helium implantation. While traditional epitaxy-induced strain results in Poisson driven multidirectional lattice changes shown to only allow discrete increases in bandgap, we find that a downward shift in the band gap can be linearly dictated as a function of out-of-plane lattice expansion. Our experimental observations closely match density functional theory that demonstrates that uniaxial strain provides a fundamentally different effect on the band structure than traditional epitaxy-induced multiaxes strain effects. Charge density calculations further support these findings and provide evidence that uniaxial strain can be used to drive orbital hybridization inaccessible with traditional strain engineering techniques. PMID:26836282

  9. Decomposition of Organometal Halide Perovskite Films on Zinc Oxide Nanoparticles.

    PubMed

    Cheng, Yuanhang; Yang, Qing-Dan; Xiao, Jingyang; Xue, Qifan; Li, Ho-Wa; Guan, Zhiqiang; Yip, Hin-Lap; Tsang, Sai-Wing

    2015-09-16

    Solution processed zinc oxide (ZnO) nanoparticles (NPs) with excellent electron transport properties and a low-temperature process is a viable candidate to replace titanium dioxide (TiO2) as electron transport layer to develop high-efficiency perovskite solar cells on flexible substrates. However, the number of reported high-performance perovskite solar cells using ZnO-NPs is still limited. Here we report a detailed investigation on the chemistry and crystal growth of CH3NH3PbI3 perovskite on ZnO-NP thin films. We find that the perovskite films would severely decompose into PbI2 upon thermal annealing on the bare ZnO-NP surface. X-ray photoelectron spectroscopy (XPS) results show that the hydroxide groups on the ZnO-NP surface accelerate the decomposition of the perovskite films. To reduce the decomposition, we introduce a buffer layer in between the ZnO-NPs and perovskite layers. We find that a commonly used buffer layer with small molecule [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) can slow down but cannot completely avoid the decomposition. On the other hand, a polymeric buffer layer using poly(ethylenimine) (PEI) can effectively separate the ZnO-NPs and perovskite, which allows larger crystal formation with thermal annealing. The power conversion efficiencies of perovskite photovoltaic cells are significantly increased from 6.4% to 10.2% by replacing PC61BM with PEI as the buffer layer. PMID:26280249

  10. Nickel oxide and molybdenum oxide thin films for infrared imaging prepared by biased target ion-beam deposition

    NASA Astrophysics Data System (ADS)

    Jin, Yao; Saint John, David; Jackson, Tom N.; Horn, Mark W.

    2014-06-01

    Vanadium oxide (VOx) thin films have been intensively used as sensing materials for microbolometers. VOx thin films have good bolometric properties such as low resistivity, high negative temperature coefficient of resistivity (TCR) and low 1/f noise. However, the processing controllability of VOx fabrication is difficult due to the multiple valence states of vanadium. In this study, metal oxides such as nickel oxide (NiOx) and molybdenum oxide (MoOx) thin films have been investigated as possible new microbolometer sensing materials with improved process controllability. Nickel oxide and molybdenum oxide thin films were prepared by reactive sputtering of nickel and molybdenum metal targets in a biased target ion beam deposition tool. In this deposition system, the Ar+ ion energy (typically lower than 25 eV) and the target bias voltage can be independently controlled since ions are remotely generated. A residual gas analyzer (RGA) is used to precisely control the oxygen partial pressure. A real-time spectroscopic ellipsometry is used to monitor the evolution of microstructure and properties of deposited oxides during growth and post-deposition. The properties of deposited oxide thin films depend on processing parameters. The resistivity of the NiOx thin films is in the range of 0.5 to approximately 100 ohm-cm with a TCR from -2%/K to -3.3%/K, where the resistivity of MoOx is between 3 and 2000 ohm-cm with TCR from -2.1%/K to -3.2%/K. We also report on the thermal stability of these deposited oxide thin films.