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Deposition Temperature (deposition + temperature)
Selected AbstractsDeposition and Characterization of Dielectric Thin Films from Allyltrimethylsilane Glow DischargesPLASMA PROCESSES AND POLYMERS, Issue 4 2007Antonella Milella Abstract Thin films with a dielectric constant in the range of 1.9,4.5 have been deposited under different experimental conditions from allyltrimethylsilane (ATMS) and oxygen fed glow discharges. The thermal stability of the coatings is evaluated from thickness loss during the annealing process at 400 and 450,°C. Extremely low values of dielectric constant can be obtained at low input power and oxygen flow rate. However, control over the annealing temperature must be gained in order to avoid excessive film matrix collapse with subsequent deterioration of dielectric properties. For the lowest dielectric constant of 1.9, thickness shrinkage of 11% has been detected. Deposition temperature is also found to strongly affect film dielectric constant and chemical composition while input power modulation does not improve the dielectric properties of the films. [source] Influence of substrate temperature on the properties of electron beam evaporated ZnSe filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2010M. G. Syed Basheer Ahamed Abstract ZnSe films were deposited on glass substrates keeping the substrate temperatures, at room temperature (RT), 75, 150 and 250 °C. The films have exhibited cubic structure oriented along the (111) direction. Both the crystallinity and the grain size increased with increasing deposition temperature. A very high value of absorption co-efficient (104 cm -1) is observed. The band gap values decrease from a value of 2.94 eV to 2.69 eV with increasing substrate temperature. The average refractive index value is in the range of 2.39 , 2.41 for the films deposited at different substrate temperatures. The conductivity values increases continuously with temperature. Laser Raman spectra showed peaks at 140.8 cm -1, 246.7 cm -1and 204.5 cm -1which are attributable to 2TA LO phonon and TO phonon respectively. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Physical properties of Dy and La doped SnO2 thin films prepared by a cost effective vapour deposition techniqueCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2006J. Joseph Abstract Stannous oxide (SnO2) thin film is one of the most widely used n-type transparent semi-conductor films in electronics, electro-optics and solar energy conversion. By achieving controlled non-stoichiometry, we can get good transparency and high electrical conductivity simultaneously in SnO2 thin films. Dy and La doped SnO2 thin films have been prepared by a cost effective vapour deposition technique. The structural, photo-electronic, optical and electrical properties of the doped and undoped films were studied. The results of X-ray Diffraction studies reveals the polycrystalline nature of the films with preferential orientation along the (101), (211) and (301) planes and their average grain size variation for different deposition temperature. Photoconductivity and Photovoltaic studies of the films were also performed. The optical properties of these films were studied by measuring their optical transmission as a function of wavelength. The optical transmission is found to be increased on Dy doping and decreased on La doping. The band gap, refractive index and thickness of the films were calculated from U-V transmittance and Absorption graphs. The optical band gap of undoped film is found to be 4.08 eV, but on doping it shifts to lower energies and then increases on increasing the concentration of both dopants. Its electrical parameters such as sheet resistance, resistivity, mobility, Hall coefficient, and carrier concentration were determined by Four Probe, Van der Pauw and Hall Probe method. On doping with Dy, carrier conversion takes place from n-type to p-type and p-conductivity dominates. On La doping no carrier conversion takes place but resistivity decreases. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of deposition temperature on the properties of thin polymer films deposited by plasma-enhanced CVD using cyclo-hexa-hydrocarbons as monomersELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 4 2010Kazunori Moriki Abstract Plasma CVD is a candidate technology for the fabrication of optical polymer waveguides. It can deposit a film on any surface geometry and any substrate material at a temperature under 200 °C in a vacuum process. It also provides good thickness controllability and uniformity of the deposition film. In the present study, the effects of the deposition temperature on film properties, specifically the refractive index, deposition rate, and molecular structure, are discussed. The refractive index decreases as the deposition temperature rises. The logarithm of the deposition rate increases with the reciprocal of the temperature and the gradient of the deposition rate depends on the relative abundance of double bonds in the monomer source. The gradient does not change when CF4 is used instead of Ar as the gas mixed into the plasma, although the deposition rate increases by a factor of about five. We speculate that the deposition rate increases due to the increase in the abundance precursors produced by the presence of CF4 in the plasma and due to an increased abundance of dangling bonds on the surface of the deposition film caused by F radicals. We further speculate that the precursors incorporated into the polymer are selected on the substrate by the density of adsorption sites and the adsorption energy. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(4): 27,35, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10171 [source] Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-DopantADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Kyoung Soo Yook Abstract Cesium azide (CsN3) is employed as a novel n-dopant because of its air stability and low deposition temperature. CsN3 is easily co-deposited with the electron transporting materials in an organic molecular beam deposition chamber so that it works well as an n-dopant in the electron transport layer because its evaporation temperature is similar to that of common organic materials. The driving voltage of the p-i-n device with the CsN3 -doped n-type layer and a MoO3 -doped p-type layer is greatly reduced, and this device exhibits a very high power efficiency (57,lm W,1). Additionally, an n-doping mechanism study reveals that CsN3 was decomposed into Cs and N2 during the evaporation. The charge injection mechanism was investigated using transient electroluminescence and capacitance,voltage measurements. A very highly efficient tandem organic light-emitting diodes (OLED; 84,cd A,1) is also created using an n,p junction that is composed of the CsN3 -doped n-type organic layer/MoO3 p-type inorganic layer as the interconnecting unit. This work demonstrates that an air-stable and low-temperature-evaporable inorganic n-dopant can very effectively enhance the device performance in p-i-n and tandem OLEDs, as well as simplify the material handling for the vacuum deposition process. [source] Optimized La0.6Sr0.4CoO3,, Thin-Film Electrodes with Extremely Fast Oxygen-Reduction KineticsADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Judith Januschewsky Abstract La0.6Sr0.4CoO3,, (LSC) thin-film electrodes are prepared on yttria-stabilized zirconia (YSZ) substrates by pulsed laser deposition at different deposition temperatures. The decrease of the film crystallinity, occurring when the deposition temperature is lowered, is accompanied by a strong increase of the electrochemical oxygen exchange rate of LSC. For more or less X-ray diffraction (XRD)-amorphous electrodes deposited between ca. 340 and 510,°C polarization resistances as low as 0.1,, cm2 can be obtained at 600,°C. Such films also exhibit the best stability of the polarization resistance while electrodes deposited at higher temperatures show a strong and fast degradation of the electrochemical kinetics (thermal deactivation). Possible reasons for this behavior and consequences with respect to the preparation of high-performance solid oxide fuel cell (SOFC) cathodes are discussed. [source] Gate Dielectric Microstructural Control of Pentacene Film Growth Mode and Field-Effect Transistor Performance,ADVANCED MATERIALS, Issue 18 2007C. Kim Organic semiconductor/dielectric interfacial characteristics play a critical role in influencing organic thin-film transistor (OTFT) performance characteristics (see figure). Clear correlations between pentacene film deposition temperature, estimated polymer dielectric surface microstructural mobility, and the corresponding film growth mode, semiconductor phase composition, and carrier mobilities are established. [source] Microscale Inhomogeneities in Aluminum Solution-Doping of Silica-Based Optical FibersJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2007Feng Z. Tang The microstructure of aluminum (Al) solution-doped soot layers in modified chemical vapor deposition fabrication of silica-based optical fibers has been studied. It is shown that such Al doping is predominantly determined by deposition temperature. Radial and longitudinal Al doping distributions have been investigated in soot layers, in fully sintered glass layers, and in collapsed preforms. Formation mechanisms are discussed. [source] Processing Dependence of Texture, and Critical Properties of YBa2Cu3O7,, Films on RABiTS Substrates by a Non-Fluorine MOD MethodJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2006Y. Xu YBa2Cu3O7,, (YBCO or Y123) films on rolling-assisted biaxially textured substrates (RABiTS) were prepared via a fluorine-free metallorganic deposition (MOD) through spin coating, burnout, and high temperature anneal. The effects of substrate texture and surface energy of the CeO2 cap layer were investigated. Except for the commonly accepted key factors, such as the textures of substrate and buffer layers, we found some other factors, for example, the deposition temperature of the cap layer, are also critical to the epitaxial growth of Y123 phase. With the CeO2 cap layer deposited at relative high temperature of 700°C, a critical current density, Jc, over 1 MA/cm2 has been demonstrated for the first time on Ni-RABiTS by a fluorine-free MOD method. Whereas for samples with CeO2 cap layers deposited at a lower temperature of 600°C, even though XRD data showed a better texture on these buffer layers, texture degradations of YBCO grains under the optimized processing conditions were observed and a lower oxygen partial pressure around 40 ppm was necessary for the epitaxial growth of Y123 phase. As a result, Jc fell to 0.45 MA/cm2 at 77 K. The observed phenomena points to the change of surface energy and reactivity of the CeO2 cap layer with respect to the CeO2 deposition temperature. In this paper, the YBCO phase diagram was also summarized. [source] Aluminum Silicate Films Obtained by Low-Pressure Metal-Organic Chemical Vapor DepositionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2003Dong-Hau Kuo Amorphous alumina-silica films with film thickness of 0.41,2.69 ,m were prepared on glass and silicon substrates by metal-organic chemical vapor deposition using a mixture of aluminum tri-sec-butoxide (ATSB), hexamethyldisilazane (HMDSN), and argon. By controlling the inputs of ATSB and HMDSN, alumina-silica thin films could contain varied compositions and adjustable properties. Basically, the codeposition of alumina and silica to form alumina-silica using ATSB and HMDSN had a faster growth rate than their individual components. The internal stress could be adjusted by deposition temperature and reactant inputs. Adhesion could be improved by having a silicon-rich thin film, whereas an aluminum-rich film could have slightly higher hardness. Optical properties, e.g., refractive index and optical transmittance, were also measured. [source] Enhancing nanocrystalline diamond surface conductivity by deposition temperature and chemical post-processingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2009H. Kozak Abstract The surface conductivity of nanocrystalline diamond (NCD) films as a function of deposition temperature and chemical post-processing was characterized by current,voltage measurements using co-planar Au electrodes. Raman spectroscopy was applied to investigate the bulk quality of NCD films and characterize the relative amount of sp3 diamond phase in the volume. The surface material properties and morphology were studied using atomic force microscopy (AFM) in tapping and phase detection regimes. The results indicate that the chemical post-processing of as-grown NCD films by boiling in acid and re-hydrogenation leads to a significant increase in the surface conductivity by three orders of magnitude, in the order of 10,7 (,/,),1. As a function of the deposition temperature (with re-hydrogenation temperature kept constant) the surface conductivity of nanocrystalline diamond films shows optimum around 600 °C. This enhancement is attributed to the lowest amount of sp2 phase on the surface. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Helicon-wave-excited plasma sputtering deposition of Ga-doped ZnO transparent conducting filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2006Mutsumi Sugiyama Abstract Sputtering deposition of Ga-doped ZnO (ZnO:Ga) thin films was carried out using the helicon-wave-excited plasma sputtering (HWPS) method. The films sputtered above 150 °C had a preferential {0001} orientation. According to the surface-damage-free nature, the films having featureless surface morphology exhibited an optical transmittance greater than 80% in the visible spectral wavelengths. However, because the deposition temperature was limited to 250 °C, the electron mobility was limited to as low as 2,3 cm2/V s due to the small grain size (,25 nm). The results indicate that ZnO:Ga films deposited by HWPS can be used in the transparent conducting oxide layer, provided that higher electron mobility is achieved. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A novel calixarene-containing hyperbranched aliphatic polyester incorporated with pendant europium complexesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2009Jichang Feng Abstract A novel calixarene-containing hyperbranched aliphatic polyester incorporated with pendant europium complexes (H20-Cal-Eu) was synthesized and characterized by FTIR, UV, and element analysis. The polymer H20-Cal-Eu shows a glass-transition temperature (Tg) of 127°C, and a deposition temperature in the range of 280,600°C, as revealed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The investigation on its photoluminescence (PL) properties revealed that the polymer emitted a remarkably strong red luminescence. Furthermore, its half spectral bandwidth of the polymer film is only about 10,nm as determined from luminescence spectra, suggesting that the light is nearly monochromatic. It is proposed that the hyperbranched polymer (HBP) containing rare earth element exhibits great potential as a red light emitting material. Copyright © 2009 John Wiley & Sons, Ltd. [source] Atomic layer deposition of Zn1,xMgxO buffer layers for Cu(In,Ga)Se2 solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 3 2007T. Törndahl Abstract Fabrication of Zn1,xMgxO films by atomic layer deposition (ALD) has been studied for use as buffer layers in Cu(In,Ga)Se2 (CIGS)-based solar cell devices. The Zn1,xMgxO films were grown using diethyl zinc, bis-cyclopentadienyl magnesium and water as precursors in the temperature range from 105 to 180°C. Single-phase ZnO-like films were obtained for x,<,0·2, followed by a two phase region of ZnO- and MgO-like structures for higher Mg concentrations. Increasing optical band gaps of up to above 3·8,eV were obtained for Zn1,xMgxO with increasing x. It was found that the composition of the Zn1,xMgxO films varied as an effect of deposition temperature as well as by increasing the relative amount of magnesium precursor pulses during film growth. Completely Cd-free CIGS-based solar cells devices with ALD-Zn1,xMgxO buffer layers were fabricated and showed efficiencies of up to 14·1%, which was higher than that of the CdS references. Copyright © 2006 John Wiley & Sons, Ltd. [source] High-efficiency copper indium gallium diselenide (CIGS) solar cells with indium sulfide buffer layers deposited by atomic layer chemical vapor deposition (ALCVD)PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2003N. Naghavi Abstract This paper presents optimization studies on the formation of indium sulfide buffer layers for high-efficiency copper indium gallium diselenide (CIGS) thin-film solar cells with atomic layer chemical vapour deposition (ALCVD) from separate pulses of indium acetylacetonate and hydrogen sulfide. A parametric study of the effect of deposition temperature between 160° and 260°C and thickness (15,30,nm) shows an optimal value at about 220°C for a layer thickness of 30,nm, leading to an efficiency of 16·4%. Analysis of the device shows that indium sulfide layers are characterised by an improvement of the blue response of the cells compared with a standard CdS-processed cell, due to a high apparent band gap (2·7,2·8,eV), higher open-circuit voltages (up to 665,mV) and fill factor (78%). This denotes high interface quality. Atomic diffusion processes of sodium and copper in the buffer layer are demonstrated. Copyright © 2003 John Wiley & Sons, Ltd. [source] High-rate deposition of epitaxial layers for efficient low-temperature thin film epitaxial silicon solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2001Lars Oberbeck Low,temperature deposition of Si for thin-film solar cells has previously been hampered by low deposition rates and low material quality, usually reflected by a low open-circuit voltage of these solar cells. In contrast, ion-assisted deposition produces Si films with a minority-carrier diffusion length of 40,,m, obtained at a record deposition rate of 0.8,,m/min and a deposition temperature of 650°C with a prebake at 810°C. A thin-film Si solar cell with a 20-,m-thick epitaxial layer achieves an open-circuit voltage of 622,mV and a conversion efficiency of 12.7% without any light trapping structures and without high-temperature solar cell process steps. Copyright © 2001 John Wiley & Sons, Ltd. [source] Cracking study of pentakis(dimethylamino)tantalum vapors by Knudsen cell mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2010Perrine Violet Organometallic molecules are commonly used as gaseous precursors in Atomic Layer Deposition/Chemical Vapor Deposition (ALD/CVD) processes. However, the use of these molecules, which are generally thermally unstable at temperatures close to the deposition temperature, requires an understanding of their gas-phase chemical behavior. The thermal cracking of the gaseous precursor, pentakis(dimethylamino) tantalum (PDMAT), generally adopted in the ALD/CVD TaN deposition processes, has been studied in the temperature range from 343 to 723K using a specific reactor coupled with a high-temperature mass spectrometer. This reactor , built as tandem Knudsen cells , consists of two superimposed cells. The first stage reactor , an evaporation cell , provides an input saturated vapor flow operating from room temperature to 333K. The second stage cell, named the cracking cell, operated from 333 to 723K in the present study. Experiments showed the appearance of many gaseous species when the cracking temperature increased and, in particular, dimethylamine, corresponding to the saturated organic branches of PDMAT. Decomposition products of the HNC2H6 branch were observed at relatively high temperature, namely above 633K. This gas-phase study , as for the preceding saturated one , shows the presence of oxygen-containing molecules in PDMAT cracked vapor. Thus, it explains the systematic presence of oxygen contamination in the deposited TaN films observed in ALD/CVD industrial processes. Copyright © 2010 John Wiley & Sons, Ltd. [source] Effects of Processing Parameters in the MOCVD Growth of Nanostructured Lanthanum Trifluoride and Oxyfluoride Thin Films,CHEMICAL VAPOR DEPOSITION, Issue 12 2006G. Malandrino Abstract Using metal,organic (MO)CVD, lanthanum trifluoride (LaF3) and oxyfluoride (LaOF) films are deposited on Si(100), glass, and quartz from a La(hfa)3diglyme single-source precursor. The films are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). They are found to be crystalline with a high degree of fiber texture even when deposited on glass or quartz substrates. The SEM indicates very homogeneous surfaces with grain dimensions decreasing upon increasing the deposition temperature and the oxygen flow. The AFM data indicate a very smooth surface with a root mean square (rms) roughness of 0.96,nm for films deposited at high temperature/high oxygen flow. [source] Atmospheric Pressure CVD of Molybdenum Diselenide Films on Glass,CHEMICAL VAPOR DEPOSITION, Issue 11 2006D. Boscher Abstract Atmospheric pressure (AP)CVD of molybdenum diselenide films on glass substrates was achieved by reaction of diethyl selenide or di- tert -butylselenide with MoCl5 at 500,650,°C. X-ray diffraction (XRD) showed that the MoSe2 films were crystalline with a mixed 2Hb/3R polytype stacking and typical cell constants of a,=,3.28, c,=,6.48,Å (c -axis is,×,2 for the 2Hb form and,×,3 for the 3R form). Energy dispersive X-ray analysis (EDAX) gave a Mo/Se ratio close to 1:2 for films formed at 600,650,°C, those formed at lower temperatures contained some chlorine. The films were brown in appearance, were adhesive, passed the Scotch tape, test but could be scratched with a steel scalpel. Scanning electron microscopy (SEM) showed that the films were composed of needlelike agglomerates which became longer and thinner with increasing deposition temperature. The films showed high absorbance in the visible spectrum but were more transparent in the near-infrared. [source] Iridium Metal Thin Films and Patterned IrO2 Nanowires Deposited Using Iridium(I) Carbonyl PrecursorsCHEMICAL VAPOR DEPOSITION, Issue 7 2006Y.-L. Chen Abstract Highly volatile iridium(I) carbonyl complexes (1,5) with three anionic fluorinated chelates, namely ketoiminate, aminoalkoxide, or iminoalkoxide, have been synthesized and their physical properties relevant to CVD are evaluated. A single-crystal X-ray diffraction (XRD) study on Ir(CO)2(amakNMe2) (3) confirms a square-planar geometry with two cis-orientated carbonyl ligands. Metallic iridium, polycrystalline IrO2 thin films, or even patterned IrO2 nanowires are deposited using Ir(CO)2(hfdaNnPr) (5) as the CVD precursor. A systematic investigation of the deposition of IrO2 nanowires is conducted, showing a close correlation of observed crystallite morphology with applied system pressure, underlying growth surface, and deposition temperature. Of particular importance, tilted and vertically aligned IrO2 nanowires are obtained on LiTaO3(012) and LiNbO3(100) surfaces under a pressure of 30,Torr of oxygen at 425,°C. The morphology and structural composition of the IrO2 are confirmed by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and XRD analyses. [source] Deposition of Antimony and Antimony Oxides by MOCVD,CHEMICAL VAPOR DEPOSITION, Issue 1 2004C.P. Myers Abstract Thin films of antimony and antimony oxides have been deposited by metal,organic (MO) CVD from a variety of metal,organic precursors at temperatures in the range 150,650,°C under both atmospheric and reduced pressure. Below 400,°C, uniform films of pure senarmontite (Sb2O3) with a microstructure and crystal texture that was strongly dependent on the deposition temperature, were deposited. Above 400,°C, mixed phase material was produced, with isolated crystallites of pure antimony becoming the dominant phase as the temperature was increased. The maximum temperature at which pure senarmontite could be formed was higher for larger precursor ligands. Addition of oxygen to the precursor flow led to the production of higher antimony oxidation states. [source] Pt Thin Film Collectors Prepared by Liquid-Delivery Metal,Organic CVD Using Pt(C2H5C5H4)(CH3)3 for LiCoO2 Thin Film Cathodes,CHEMICAL VAPOR DEPOSITION, Issue 6 2003W.-G. Choi Abstract Platinum thin film collectors were deposited onto p-type Si(100) planar and trench substrates by liquid-delivery metal,organic (LD-MO) CVD using Pt(EtCp)Me3, Pt(C2H5C5H4)(CH3)3, for microbatteries. The resistivity and root-mean-square (rms) roughness of Pt thin films with (111) preferred orientation increased with the increase of both deposition temperature and system pressure. The deposition of Pt thin films was controlled by a gas-phase mass-transfer mechanism and Pt thin films deposited at 350,°C showed the lowest resistivity, rms roughness, and the highest step coverage, 57,%, in trench structure. The LiCoO2 cathode films (step coverage,=,51,%) deposited on the trench Pt collector showed an increase in discharge capacity of approximately two and half times that of the planar Pt collector. Platinum thin films deposited by LD-MOCVD have a possible application as collector materials for LiCoO2 thin film cathodes. [source] A Study on the Metal Organic CVD of Pure Copper Films from Low Cost Copper(II) Dialkylamino-2-propoxides: Tuning the Thermal Properties of the Precursor by Small Variations of the Ligand,CHEMICAL VAPOR DEPOSITION, Issue 3 2003R. Becker Abstract Pure copper metal thin films were grown on SiO2/Si(100) substrates by metal,organic (MO) CVD in a horizontal cold-wall reactor employing the two metal,organic compounds, Cu(OCHMeCH2NR2)2, where R,=,Et (1) and R,=,Me (2) as precursors. Thermogravimetric analyses proved them to be convenient compounds for the deposition of copper without a reducing agent. Depositions were carried out at various substrate temperatures in the range 230,350,°C. X-ray diffraction (XRD) indicated that the resulting films were highly crystalline and showed a strong (111) preferred orientation, which increased with increasing deposition temperature. Photoelectron spectroscopy (XPS) revealed that copper films deposited at 230,°C and 260,°C consisted solely of metallic copper with no detectable carbon, nitrogen, or oxygen contamination. Copper films obtained from 1 at 260,°C had a resistivity of 2.16,,,,cm. [source] Preparation of Pt,Ru Alloyed Thin Films Using a Single-Source CVD Precursor,CHEMICAL VAPOR DEPOSITION, Issue 3 2003S.-F. Huang Abstract Treatment of (dimethylaminomethyl)ruthenocene with cis -Pt(DMSO)2Cl2 led to the formation of a ruthenocenyl platinum complex [CpRu(,5 -C5H3CH2NMe2)Pt(DMSO)Cl] (1); subsequent treatment of 1 with [Na(hfac)] afforded an air-stable Pt,Ru complex [CpRu(,5 -C5H3CH2NMe2)Pt(hfac)] (2). Its volatility and other physical data relevant to CVD experiments were assessed by thermogravimetric analysis (TGA). The Pt,Ru thin films were then deposited at two deposition temperatures, 300,°C and 400,°C, using O2 as the reactive carrier gas. The as-deposited thin films were characterized using energy dispersive X-ray (EDX), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Results indicated the formation of a homogeneous Pt,Ru solid solution at the lower deposition temperature. However, upon raising the temperature to 400,°C, phase separation between Pt and Ru occurred, which then induced the growth of RuO2 grains at the substrate surface and caused depletion of the alloy in ruthenium. The electrocatalytic activities of the films, in respect of methanol oxidation, were investigated, in half-cell experiments, by cyclic voltammetry. [source] Optimized La0.6Sr0.4CoO3,, Thin-Film Electrodes with Extremely Fast Oxygen-Reduction KineticsADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Judith Januschewsky Abstract La0.6Sr0.4CoO3,, (LSC) thin-film electrodes are prepared on yttria-stabilized zirconia (YSZ) substrates by pulsed laser deposition at different deposition temperatures. The decrease of the film crystallinity, occurring when the deposition temperature is lowered, is accompanied by a strong increase of the electrochemical oxygen exchange rate of LSC. For more or less X-ray diffraction (XRD)-amorphous electrodes deposited between ca. 340 and 510,°C polarization resistances as low as 0.1,, cm2 can be obtained at 600,°C. Such films also exhibit the best stability of the polarization resistance while electrodes deposited at higher temperatures show a strong and fast degradation of the electrochemical kinetics (thermal deactivation). Possible reasons for this behavior and consequences with respect to the preparation of high-performance solid oxide fuel cell (SOFC) cathodes are discussed. [source] TEM/STEM Observation of ZrC Coating Layer for Advanced High-Temperature Gas-Cooled Reactor Fuel, Part IIJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2009Jun Aihara The Japan Atomic Energy Agency (JAEA) has started to study and develop zirconium carbide (ZrC)-coated fuel particles for advanced high-temperature gas-cooled reactors. The ZrC coating layer has been fabricated at JAEA by chemical vapor deposition using a pyrolytic reaction of zirconium bromide. The microstructures of the ZrC layers, whose nominal deposition temperatures could be measured and controlled during the deposition process, were characterized by means of TEM and STEM. In the present study, three batches were prepared and compared with each other as well as the previous batches. The crystallographic orientation of ZrC with regard to the growth direction in the ZrC layers deposited at a constant temperature of 1630 K was different from that deposited at varying temperatures in the 1493,1823 K range. A thin layer of turbostratic carbon was observed at the boundary between pyrolytic carbon and ZrC in particles deposited at the highest temperature among those used in this study (the nominal temperature was 1769 K); no such structure was found in a batch deposited at a lower temperature (the nominal temperature was 1632 K). Therefore, precise control of temperature is shown to be critical to the formation of good ZrC coatings. [source] Ferromagnetism in epitaxial Zn0.95Co0.05O films grown on ZnO and Al2O3PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 14 2006K. Nielsen Abstract In this article, the possible mechanisms resulting in strong ferromagnetic coupling in transition metal(TM)-doped ZnO and other diluted magnetic semiconductors (DMS) are reviewed and the prerequisites for the observation of room temperature ferromagnetism in TM-doped ZnO are defined. In order to study the ferromagnetic behavior we have grown epitaxial Zn0.95Co0.05O films simultaneously on (0001) ZnO and Al2O3 substrates by laser molecular beam epitaxy at different deposition temperatures. A systematic study of the structural and magnetic properties has been performed to reveal their interdependence. Room temperature ferromagnetism has been found in Zn0.95Co0.05O films grown on ZnO, whereas for films deposited on sapphire only weak ferromagnetic signals have been detected which could not unambiguously be separated from those of the substrate. The different behavior is explained by different structural properties and defect densities in both films. Our experimental findings are in good agreement with a spin split impurity band model, where strong ferromagnetic exchange in ZnO:Co2+ is obtained by a strong hybridization between the magnetic Co2+ ion states and the donor states due to a large density of native defects. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Atomic Layer Deposition of HfO2 and ZrO2 using Advanced Metallocene Precursors and H2O as the Oxygen Source,CHEMICAL VAPOR DEPOSITION, Issue 11-12 2008Charles L. Dezelah IV Abstract The atomic layer deposition (ALD) of HfO2 and ZrO2 thin films is investigated using (MeCp)2HfMe2, (MeCp)2Hf(OMe)(Me), (MeCp)2ZrMe2, and (MeCp)2Zr(OMe)(Me) as the precursors at deposition temperatures between 300 and 500,°C, with water vapor as the oxygen source. A self-limiting growth mechanism is confirmed at 350,°C for all the metal precursors examined. The processes provide nearly stoichiometric HfO2 and ZrO2 films with carbon and hydrogen concentrations below 0.5 and 1.0 at.-%, respectively, for representative samples. All films are polycrystalline as deposited, and possess a thin interfacial SiO2 layer. The capacitance-voltage (C - V) and current density-voltage (I - V) behavior is reported and discussed for capacitor structures containing films from this study. [source] Influence of Growth Temperature and Carrier Flux on the Structure and Transport Properties of Highly Oriented CrO2 on Al2O3 (0001),CHEMICAL VAPOR DEPOSITION, Issue 10 2007M. Sousa Abstract In this work we report on the structure and magnetic and electrical transport properties of CrO2 films deposited onto (0001) sapphire by atmospheric pressure (AP)CVD from a CrO3 precursor. Films are grown within a broad range of deposition temperatures, from 320 to 410,°C, and oxygen carrier gas flow rates of 50,500,sccm, showing that it is viable to grow highly oriented a -axis CrO2 films at temperatures as low as 330,°C i.e., 60,70,°C lower than is reported in published data for the same chemical system. Depending on the experimental conditions, growth kinetic regimes dominated either by surface reaction or by mass-transport mechanisms are identified. The growth of a Cr2O3 interfacial layer as an intrinsic feature of the deposition process is studied and discussed. Films synthesized at 330,°C keep the same high quality magnetic and transport properties as those deposited at higher temperatures. [source] Thin Films of ZrO2 for High- k Applications Employing Engineered Alkoxide- and Amide-Based MOCVD Precursors,CHEMICAL VAPOR DEPOSITION, Issue 2-3 2007R. Thomas Abstract Ultrathin ZrO2 films were deposited on SiOx/Si in a multiwafer planetary metal-organic (MO)CVD reactor combined with a liquid delivery system. Two different alkoxide-based precursors, [Zr(OiPr)2(tbaoac)2] and [Zr(OtBu)2(tbaoac)2] are compared with two amide-based precursors, [Zr(NEt2)2(dbml)2] and [Zr(NEtMe)2(guanid)2]. Growth rate, surface roughness, density, and crystallization behavior are compared over a wide range of deposition temperatures (400,700,°C). In addition, the influence of the solvents, n -butylacetate, toluene, and hexane, is discussed. The best growth results in terms of low temperature deposition rate, surface roughness, film density, and carbon content were obtained for the new [Zr(NEtMe)2(guanid)2] precursor. The electrical properties were investigated with metal,insulator,semiconductor (MIS) capacitors. The relative dielectric permittivity was in the range 17,24, depending on the precursor. Compared to standard SiO2 capacitors of similar equivalent oxide thickness, low leakage currents were obtained. [source] | ||||||||||||||||