Thin transparent W-doped indium-zinc oxide (WIZO) layer on glass

Annealing effect on structural and electrical properties of W-doped IZO (WIZO) films for thin film transistors (TFT) was studied under different process conditions. Thin WIZO films were deposited on glass substrates by RF magnetron co-sputtering technique using indium zinc oxide (10 wt.% ZnO-doped In2O3) and WO3 targets in room temperature. The post annealing temperature was executed from 200 degrees C to 500 degrees C under various O2/Ar ratios. We could not find any big difference from the surface observation of as grown films while it was found that the carrier density and sheet resistance of WIZO films were controlled by O2/Ar ratio and post annealing temperature. Furthermore, the crystallinity of WIZO film was changed as annealing temperature increased, resulting in amorphous structure at the annealing temperature of 200 degrees C, while clear In2O3 peak was observed for the annealed over 300 degrees C. The transmittance of as-grown films over 89% in visible range was obtained. As an active channel layer for TFT, it was found that the variation of resistivity, carrier density and mobility concentration of WIZO film decreased by annealing process.     

The effects of substrate and annealing on structural and electrochemical properties in LiCoO2 thin films prepared by DC magnetron sputtering

LiCoO2 thin films were fabricated by direct current magnetron sputtering method on STS304 and Ti substrates. The effects of substrate and annealing on their structural and electrochemical properties of LiCoO2 thin film cathode were studied. Crystal structures and surface morphologies of the deposited films were investigated by X-ray diffraction and field emission scanning electron microscopy. The as-deposited films on both substrates have amorphous structure. The (104) oriented perfect crystallization was obtained by annealing over 600 degrees C in STS304 substrate. The LiCoO2 thin film deposited on Ti substrate shows the (003) texture after annealing at 700 degrees C. The electrochemical properties were investigated by the cyclic voltammetry and charge-discharge measurement. The 600 degrees C-annealed LiCoO2 film deposited on STS304 substrate exhibits the inithial discharge capacity of 22 uAh/cm2 and the 96% capacity retention rate at 50th cycles. The electrochemical measurement on annealed films over 600 degrees C was impossible due to the formed TiO2 insulator layer using Ti substrate. As a result, it was found that the STS304 substrate seems to be more suitable material than the Ti substrate in fabricating LiCoO2 thin film cathode.     

Amorphous tungstate precursor route to nanostructured tungsten oxide film with electrochromic property

Electrochromic tungsten oxide (WO3) films on ITO glass were fabricated by spin-coating with a tungsten peroxy acid solution, which was prepared by adding an equivolume mixture of hydrogen peroxide and glacial acetic acid to tungsten metal powder. The structural evolution of the tungstate precursor upon heat treatment was studied by X-ray diffraction (XRD) and X-ray absorption near edge structure (XANES) analyses, which indicated that the as-synthesized tungstate transformed into nanocrystalline WO3 upon heating. It is, therefore, quite clear that as-synthesized tungstate can be a good precursor for electrochromic WO3 films. A series of WO3 thin films were prepared on ITO glass by spin-coating with different concentrations of tungsten peroxy acid solution and then post-annealing at various temperatures. Depending on the concentration of the tungstate coating solution (200-500 mg mL(-1)) and the annealing temperature (100-300 degrees C), the thickness and WO3 content as well as the electrochromic properties of WO3 films can be controlled. As a result, the optimum fabrication conditions were determined to be a tungstate solution concentration of 300-400 mg mL(-1) and a post-annealing temperature of 200 degrees C. Finally, an inorganic-inorganic hybrid electrochromic device (ECD) composed of optimized WO3 and Prussian Blue (PB) with desirable coloration efficiency was successfully developed.     

Effects of temperature on columnar microstructure and recrystallization of TiO2 film produced by ion-assisted deposition

Titanium oxide thin films were deposited by electron-beam evaporation with ion-beam-assisted deposition. The effect of the substrate temperature and annealing temperature on the columnar microstructure and recrystallization of titanium oxide was studied. The values of the refractive index varied from 2.26 to 2.4, indicating that the different substrate temperatures affected the film density. X-ray diffraction revealed that all films were amorphous as deposited. At annealing temperatures from 100 degrees C to 300 degrees C, only the anatase phase was formed. As the substrate temperature increased from 150 degrees C to 200 degrees C to 250 degrees C, the recrystallization temperature fell from 300 degrees C through 250 degrees C to 200 degrees C. Changing the substrate temperature resulted in the formation of various types of columnar microstructure, as determined by scanning-electron microscopy. Different columnar structures resulted in different surface morphologies, as measured by atomic-force microscopy.     

Diffusion barrier properties of ionized metal plasma deposited tantalum nitride thin films between copper and silicon dioxide

Tantalum nitride thin films with different thickness are sputtered deposited on silicon dioxide in the Cu/TaN/SiO₂/Si multiplayer structure. Using resistivity analyses, X-ray diffraction, scanning electron microscopy and Rutherford backscattering spectroscopy, this work examines the impact of varying layer thickness on the crystal structure, resistivity, intermixing and reactions at the interfaces before and after annealing. The thinner the film thickness of TaN, the severe the reactions at the interface of Cu/TaN and consumed more conductive Cu. All the structures shown similar degradation process, and were found to be stable up to 500°C for 35 min. Accelerated grain growth and agglomeration were also observed after annealing temperature higher than 550°C at all Cu surfaces of the samples.     

Visible-light active photocatalytic WO3 films loaded with Pt nanoparticles deposited by sputtering

Visible-Light active photocatalytic tungsten trioxide (WO3) films were deposited at a substrate temperature of 800 degrees C by dc reactive magnetron sputtering using a W metal target. In addition, Platinum (Pt) was deposited on the WO3 film surfaces at room temperature, also by sputtering. In the early stages of Pt growth, formation of Pt nanoparticles could be expected because of the island structure observed in Volmer-Weber-type growth mode. The surface coverage of Pt on the WO3 films was estimated quantitatively by X-ray photoelectron spectroscopy and was found to be approximately 60% after 7 s deposition. High resolution electron microscopy (HREM) demonstrated that Pt nanoparticles with a diameter of about 2.5 nm were generated and dispersed uniformly on the entire surface area of the columnar polycrystalline WO3 films. These Pt-loaded films exhibited high photocatalytic activity in the decomposition of acetaldehyde (CH3CHO) under visible light irradiation.     

Characterization of iron oxide thin films prepared by sol-gel processing

Iron oxide thin films were prepared by spin-coating a gel solution of iron(III) nitrate dissolved in 2-methoxyethanol and acetylacetone on glass and quartz substrates. The film thickness was adjusted by changing the spinning rate of the spin coater. Annealing was carried out between 300 degrees C to 600 degrees C to investigate the phases present in the films. Viscosity of the main solution was found as 0.0035 Pa.s by viscosity measurement. TGA/DTA analyses showed that heat treatment should be done between 330 degrees C and 440 degrees C in order to produce maghemite thin films. SEM studies showed that single layer thickness of the films were between 65 and 80 nm. The structural characteristics were evaluated by changing the experimental parameters which are annealing temperature, annealing time and thickness of the films. From the X-ray diffraction analysis, maghemite formation was observed with decreasing annealing temperature, annealing time and film thickness. TEM results verified the presence of the maghemite phase by electron diffraction and selected area electron diffraction (SAED) methods. According to UV-Vis results transmittance of the films decreases with increasing annealing temperature.     

溅射工艺对BST薄膜取向行为的影响

采用射频磁控溅射法在Si(100)衬底上沉积了Ba0.65Sr0.35TiO3薄膜.借助XRD、AFM和SEM研究了衬底温度、退火温度、溅射气压等不同的溅射参数对Ba0.65Sr0.35TiO3薄膜的晶化行为和显微结构的影响.在室温下沉积并未经退火处理的Ba0.65Sr0.35TiO3 薄膜是无定形态,在较高温度下沉积的薄膜晶化相对较好;随着在氧气气氛中退火温度的升高,X射线衍射峰的半峰宽变窄,衍射峰强度增强;在0.37～1.2Pa气压下沉积的Ba0.65Sr0.35TiO3薄膜有(110)和(200)主衍射峰,且其强度随溅射气压的增加而增强;当溅射气压继续升到3.9Pa,(110)和(200)衍射峰明显增强,说明Ba0.65Sr0.35TiO3 薄膜具有(110) (200)择优取向.AFM和SEM结果显示薄膜晶粒细小均匀、结构致密、表面平整,且无裂纹、无孔洞.分析结果显示优化工艺参数制备的Ba0.65Sr0.35TiO3 薄膜是用以制备非致冷红外探测器的优质材料.     

Effect of substrate temperature on properties of Cu(In,Ga, Al)Se<Subscript>2</Subscript> films grown by magnetron sputtering

Cu(In, Ga, Al)Se₂ (CIGAS) thin films were deposited by magnetron sputtering on Si(100) and soda-lime glass substrates at different substrate temperatures, followed by post-deposition annealing at 350 or 520 °C for 5 h in vacuum. Electron probe micro-analysis and secondary ion mass spectroscopy were used to determine the composition of the films and the distribution of Al across the film thickness, respectively. X-ray diffraction analysis showed that the (112) peak of CIGAS films shifts to higher 2θ values with increasing substrate temperature but remains unchanged when the films were annealed at 520 °C for 5 h. Scanning electron microscopy and atomic force microscopy images revealed dense and well-defined grains for both as-deposited and annealed films. However, notable increase in grain size and roughness was observed for films deposited at 500 °C. The bandgap of CIGAS films was determined from the optical transmittance and reflectance spectra and was found to increase as the substrate temperature was increased.     

Y0.9 Er0.1 Al3(BO3)4 thin films prepared by the polymeric precursor method for integrated optics

This work reports on the optimization of Yo.9 Er0.1 Al3(BO3)4 thin films for integrated optics. The films were deposited on silica and silicon substrates using the spin-coating technique involving solutions previously prepared by the polymeric precursor method. These deposits, 400-800 nm thick, were prepared by a 5-10 multi-layer process and heat treatments at different temperatures from glass transition to crystallization temperature, using heating rates of 2 or 5 degrees C/min. The structural characterizations were performed using grazing incidence X-ray diffraction and Fourier transform infrared spectroscopy (FT-IR). Water and/or hydroxyl contents were also evaluated from FT-IR spectra. Microstructural evolution in term of annealing temperatures was analyzed by high resolution scanning electronic microscopy and atomic force microscopy. Optical transmission spectra were used to determine the refractive index and thickness through the envelope method of the films. Finally, the film guiding and optical properties were studied by m-line spectroscopy. The best film showed a good waveguiding with high light-coupling efficiency close to the theoretical limit.     

Preparation of aluminum doped zinc oxide films and the study of their microstructure, electrical and optical properties

Aluminum doped zinc oxide (AZO) polycrystalline thin films were prepared by sol-gel dip-coating process on optical glass substrates. Zinc acetate solutions of 0.5 M in isopropanol stabilized by diethanolamine and doped with a concentrated solution of aluminum nitrate in ethanol were used. The content of aluminum in the sol was varied from 1 to 3 at.%. Crystalline ZnO thin films were obtained following an annealing process at temperatures between 300 °C and 500 °C for 1 h. The coatings have been characterized by X-ray diffraction, UV-Visible spectrophotometry, scanning electron microscopy, and electrical resistance measurement. The ZnO:Al thin films are transparent (∼ 90%) in near ultraviolet and visible regions. With the annealing temperature increasing from 300 °C to 500 °C, the film was oriented more preferentially along the (0 0 2) direction, the grain size of the film increased, the transmittance also became higher and the electrical resistivity decreased. The X-ray diffraction analysis revealed single-phase ZnO hexagonal wurtzite structure. The best conductors were obtained for the AZO films containing 1 at.% of Al, annealed at 500 °C, 780 nm film thickness.     

Optical characterization of ZnO thin films deposited by Sol-gel method

In this paper, ZnO thin film is deposited on Pt/TiO₂/SiO₂/Si substrate using the sol-gel method and the effect of annealing temperature on the structural morphology and optical properties of ZnO thin films is investigated. The ZnO thin films are crystallized by the heat treatment at over 400°C. The ZnO thin film annealed at 600°C exhibits the greatest c-axis orientation and the Full-Width-Half-Maximum (FWHM) of X-ray peak is 0.4360°. A dense ZnO thin film is deposited by the growth of uniform grains with the increase of annealing temperature but when the annealing temperature increases to 700°C, the surface morphology of ZnO thin film becomes worse by the aggregation of ZnO particles. In the results of surface morphology of ZnO thin film using atomic force microscope (AFM), the surface roughness of ZnO thin film annealed at 600°C is smallest, that is, approximately 1.048 nm. For the PL characteristics of ZnO thin film, it is observed that ZnO thin film annealed at 600°C exhibits the greatest UV (ultraviolet) exciton emission at approximately 378 nm, and the smallest visible emission at approximately 510 nm among ZnO thin films annealed at various temperatures. It is deduced that ZnO thin film annealed at 600°C is formed most stoichiometrically, since the visible emission at approximately 510 nm comes from either oxygen vacancies or impurities.     

Al掺杂ZnO薄膜的制备及其电学性能研究

采用溶胶-凝胶法在玻璃基底上制备掺杂铝的氧化锌薄膜.研究了不同的铝掺杂浓度、薄膜厚度以及退火温度对电阻率的影响,结果表明掺杂铝摩尔分数为2%、退火温度在550℃时电阻率最低,电阻率随着薄膜厚度的增加而减小.通过XRD和SEM对薄膜的组织结构和形貌进行了表征,结果表明样品表面相对平整、致密,AZO薄膜保持着ZnO六角纤锌矿结构,说明了Al原子对Zn原子的有效替位.     

NH3 sensing characteristics of nano-WO3 thin films deposited on porous silicon

The NH3 sensing characteristics of nano-tungsten trioxide (WO3) thin films deposited on porous silicon (PS) were investigated in the present study. Porous silicon layer was first prepared by electrochemical etching in an HF-based solution on a p(+)-type silicon substrate. Then, WO3 nano-films were deposited on the porous silicon layer by DC magnetron sputtering. Pt electrodes were deposited on the top surface of the WO3 films to obtain the WO3/PS gas sensor. The WO3 films deposited on PS were characterized by SEM, XRD and XPS. The NH3 sensing characteristics for WO3/PS gas sensor were tested at room temperature and 50 degrees C. The results showed that the NH3 sensing characteristics of WO3/PS were superior to WO3/Al2O3 at room temperature. The sensing mechanism of the nano-WO3 thin films based on PS was also discussed.     

双氧水和退火温度对WO_3薄膜光电化学性质的影响

以WO3粉体合成的W络合离子作为前驱液,超声喷雾热裂解法（USP）制备出WO_3薄膜,研究前驱液中H_2O_2添加量、薄膜沉积温度和薄膜退火温度对WO_3薄膜光电化学性能的影响,利用XRD、UV-vis和光电流光谱（IPCE）等对薄膜进行表征,实验结果表明,USP制备的WO_3薄膜为单斜相且沿（200）晶面优势生长;前驱液中双氧水量的增加导致WO_3薄膜禁带宽度（E_g）增加;薄膜的平带电位（Vfb）在-0.27~-0.05V之间（vs.SCE,pH=7）,且掺杂浓度随退火温度升高而降低;在0.1M的Na_2SO_3溶液中,薄膜的IPCE随退火温度升高而降低,随H_2O_2量的减小IPCE增高。     

Surface and in depth chemistry of polycrystalline WO/sub 3/ thin films studied by X-ray and soft X-ray photoemission spectroscopies

The chemical composition of surface and underneath layers of WO/sub 3/ thin films, deposited by thermal evaporation and annealed in air at different temperatures, has been studied by means of soft X-ray and X-ray photoemission spectroscopies. Both the W 4f and valence band spectra have been analyzed. The analysis has been performed on samples as inserted and after an annealing process in an ultra high vacuum. The results have shown that the surface always presents a nonstoichiometric WO/sub 3/ compound, whose spectral components do not depend on the sample preparation. Instead, the study of the underneath layers has shown that the WO/sub 3/ films annealed in air at 500/spl deg/C are highly stoichiometric and stable, while the samples heated in air at 300/spl deg/C are much more sensitive to the vacuum thermal treatment showing the presence of reduced WO/sub x/ phases, whose intensity and chemical states change after the in vacuum annealing procedure.     

Nano-polycrystalline vanadium oxide thin films prepared by pulsed laser deposition

Nano-polycrystalline vanadium oxide thin films have been successfully produced by pulsed laser deposition on Si(100) substrates using a pure vanadium target in an oxygen atmosphere. The vanadium oxide thin film is amorphous when deposited at relatively low substrate temperature (500 degrees C) and enhancing substrate temperature (600-800 degrees C) appears to be efficient in crystallizing VOx thin films. Nano-polycrystalline V3O7 thin film has been achieved when deposited at oxygen pressure of 8 Pa and substrate temperature of 600 degrees C. Nano-polycrystalline VO2 thin films with a preferred (011) orientation have been obtained when deposited at oxygen pressure of 0.8 Pa and substrate temperatures of 600-800 degrees C. The vanadium oxide thin films deposited at high oxygen pressure (8 Pa) reveal a mix-valence of V5+ and V4+, while the VOx thin films deposited at low oxygen pressure (0.8 Pa) display a valence of V4+. The nano-polycrystalline vanadium oxide thin films prepared by pulsed laser deposition have smooth surface with high qualities of mean crystallite size ranging from 30 to 230 nm and Ra ranging from 1.5 to 22.2 nm. Relative low substrate temperature and oxygen pressure are benifit to aquire nano-polycrystalline VOx thin films with small grain size and low surface roughness.     

The effect of sputtering gas pressure on structure and photocatalytic properties of nanostructured titanium oxide self-cleaning thin film

Titanium oxide thin films were deposited by DC reactive magnetron sputtering on ZnO (80 nm thickness)/soda-lime glass and SiO₂ substrates at different gas pressures. The post annealing on the deposited films was performed at 400 °C in air atmosphere. The results of X-ray diffraction (XRD) showed that the films had anatase phase after annealing at 400 °C. The structure and morphology of deposited layers were evaluated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface grain size and roughness of TiO₂ thin films after annealing were around 10-15 nm and 2-8 nm, respectively. The optical transmittance of the films was measured using ultraviolet-visible light (UV-vis) spectrophotometer and photocatalytic activities of the samples were evaluated by the degradation of Methylene Blue (MB) dye. Using ZnO thin film as buffer layer, the photocatalytic properties of TiO₂ films were improved.     

Synthesis,characterization and gas sensing performance of SnO<Subscript>2</Subscript> thin films prepared by spray pyrolysis

In this work, SnO₂ thin films were deposited onto alumina substrates at 350°C by spray pyrolysis technique. The films were studied after annealing in air at temperatures 550°C, 750°C and 950°C for 30 min. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption spectroscopy technique. The grain size was observed to increase with the increase in annealing temperature. Absorbance spectra were taken to examine the optical properties and bandgap energy was observed to decrease with the increase in annealing temperature. These films were tested in various gases at different operating temperatures ranging from 50–450°C. The film showed maximum sensitivity to H ₂S gas. The H₂S sensing properties of the SnO₂ films were investigated with different annealing temperatures and H ₂S gas concentrations. It was found that the annealing temperature significantly affects the sensitivity of the SnO₂ to the H ₂S. The sensitivity was found to be maximum for the film annealed at temperature 950°C at an operating temperature of 100°C. The quick response and fast recovery are the main features of this film. The effect of annealing temperature on the optical, structural, morphological and gas sensing properties of the films were studied and discussed.     

Fabrication of LiCoO2 thin film cathodes by DC magnetron sputtering method

LiCoO₂ thin films were fabricated on Al substrate by direct current magnetron sputtering method. The effects of Ar/O₂ gas rates and annealing temperatures were investigated. Crystal structures and surface morphologies of the deposited films were investigated by X-ray diffraction, Raman scattering spectroscopy and field emission scanning electron microscopy. The as-deposited LiCoO₂ thin films exhibited amorphous structure. The crystallization starts at the annealing temperature over 400 °C. However, the annealed films have the partially disordered structure without completely ordered crystalline structure even at 600 °C annealing. The electrochemical properties of the LiCoO₂ films were investigated by the charge–discharge and cycle measurements. The 500 °C annealing film has the highest capacity retention rate of 78.2% at 100th cycles.