Structural and Optoelectronic Properties of Nanostructured ITO Thin Films Deposited by Chemical Spray Pyrolysis Technique

In this study, the spray pyrolysis method is used to generate an indium tin oxide （ITO） thin film on a glass substrate. In2O3 layers were deposited and doped with tin at different doping concentration ranging from 2% to 6%. ITO thin films for application in thin-film silicon solar cells with superior structure and optical properties （grain size ranging from 44 to 84 nm; transparency of〉 87%） have been investigated. This investigation elucidates the properties of ITO thin films used as antireflection front electrodes in p-n j unction Si solar cells. Microstructure, surface morphology, optoelectrical and optical properties of these films were then characterized and analyzed. Next, the effects of doping concentration of ITO film growth were discussed. The ITO thickness was optimized considering that the refractive index of Si emitter layer optimizes its optical characteristics and p-n junction solar cell spectral response. The best increasing in p-n junction solar cell conversion efficiency was 4% with an open circuit voltage （Voc） of 0.425 V, fill factor （FF） of 0.47, and short circuit current density （Jsc） of 0.91 mA/cm2.     

Effect of Enhanced Plasma Density on the Properties of Aluminium Doped Zinc Oxide Thin Films Produced by DC Magnetron Sputtering

Aluminum doped zinc oxide (AZO) thin films were prepared by DC magnetron sputtering at low substrate temperature. A coaxial solenoid coil was placed near the magnetron target to enhance the plasma density (Ji). The enhanced plasma density improved significantly the bulk resistivity (ρ) and its homogeneity in spatial distribution of AZO films. X-ray diffraction (XRD) analysis revealed that the increased Ji had inuenced the crystallinity, stress relaxation and other material properties. The AZO films deposited in low plasma density (LPD) mode showed marked variation in ρ (ranging from ～6.5×10?2 to 1.9×10-3 ·cm), whereas those deposited in high plasma density (HPD) mode showed a better homogeneity of films resistivity (ranging from ～1.3×10?3 to 3.3×10?3 ?·cm) at di?erent substrate positions. The average visible transmittance in the wavelength range of 500-800 nm was over 80%, irrespective of the deposition conditions. The atomic force microscopy (AFM) surface morphology showed that AZO films deposited in HPD mode were smoother than that in LPD mode. The high plasma density produced by the coaxial solenoid coil improved the electrical property, surface morphology and the homogeneity in spatial distribution of AZO films deposited at low substrate temperature.     

XRD and XPS Analysis of TiO2 Thin Films Annealed in Different Environments

Undoped and Nb-doped TiO2 thin films have been fabricated on glass substrate by RF magnetron sputtering. The morphologic, structural and surface composition of these films before and after annealing in different environments were investigated by atomic force microscopy （AFM） imaging, X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）. The XRD data reveal that the crystallinity is improved when the films are Nb-doped and annealed in H2 environment. The TiO2 thin films annealed in H2 environment exhibit only the anatase phase. The XPS analysis of TiO2 with Nb indicates the maximum shift in binding energy of the Ti 2p peak. A mechanism for the incorporation of Nb in the TiO2 lattice has been proposed.     

Characterization of Sol-gel-derived TiO2 and TiO2-SiO2 Films for Biomedical Applications

In order to improve the corrosion resistance and biocompatibility of NiTi surgical alloy, TiO2 and TiO2-SiO2 thin films were prepared by sol-gel method. The surface characteristics of the film, which include surface composition, microstructure and surface morphology, were studied by X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectra (XPS), respectively. A scratching test was used to assess the interface adhesive strength between the film and substrate. The corrosion resistance of NiTi alloy coated with oxide films were studied by anodic polarization curves measurement in biological solution. Additionally, a preliminary study of the in vitro bioactivity of the films was conducted. The results indicated that TiO2 and TiO2-SiO2 (Ti/Si=4:1) films have higher electrochemical corrosion resistance and can be used as protective layers on NiTi alloy. In addition, TiO2-SiO2 composite films have better bioactivity than TiO2 film.     

Microstructure Characterization of Sol-gel Prepared MoO3-TiO2 Thin Films for Oxygen Gas Sensors

Binary metal oxide MoO3-TiO2 films have been prepared using the sol-gel technique. The thin films were annealed at several temperatures including 400℃,450℃,500℃,550℃ and 600℃ for lhour. The morphology, crystalline structure and chemical composition of the films have been analysed using SEM,XRD,RBS and XPS techniques. The SEM analysis showed that the films annealed at 450℃ are mainly smooth and uniform with 20-100nm-sized grains and with few particles as large as a micrometre or more. The XRD analysis revealed that the films annealed at 400℃ were a mixture of orthorhombic and hexagonal MoO3phases. The films annealed at 450℃ increased in hexagonal phase. The preferential orientation growth along(100) plane of the hexagonal phase and (010) plane of the orthorhombic phase has been found in both samples. RBS and XPS analysis showed that the films were stoichiometric. When the annealing temperature is increased to more than 500℃, the concentration ratio of MoO3 to TiO2 decreased due to the evaporation of MoO3. For the study of the electrical and gas sensing properties, films were deposited on sapphire substrates with interdigital electrodes on the front-side and a Pt heater on the backside. The O2 gas sensing properties of MoO3-TiO2 thin films are discussed.     

Green light-emitting diodes based on hybrid perovskite films with mixed cesium and methylammonium cations

We report the formation of high-quality Cs0.4MA0.6PbBr3 thin films with nearly full surface coverage and good emission properties upon the introduction of Cs+ into perovskite crystals.The Cs0.4MA0.6PbBr3 thin films were applied as emissive layers in light-emitting diodes.A maximum external quantum efficiency of ～2.0％ was achieved for these green-emitting devices.     

Theoretical Simulation of Surface Evolution Using the Random Deposition and Surface Relaxation for Metal Oxide Film in Atomic Layer Deposition

Atomic layer deposition (ALD) has become an essential deposition method for forming nanometer scale thin films in the microelectronics industry, and its applications have been extended to multi-component thin films, as well as to single metal oxide films. In order to investigate the development of the surface structure of ultra-thin film qualitatively as well as quantitatively, ALD processes are simulated with a molecular scale. For this simulation, the film materials are deposited on a imaginary substrate that consists of small lattice. The deposition behaviors are described by using random deposition (RD) model or random deposition with surface relaxation (RDSR) model as the ALD growth mode, and the proposed model was applied to the deposition of SrO-TiO2 thin films. Through this work, growth characteristics such as surface morphology, deposited film coverage can be predicted.     

Assembly and Applications of Carbon Nanotube Thin Films

The ultimate goal of current research on carbon nanotubes （CNTs） is to make breakthroughs that advance nanotechnological applications of bulk CNT materials. Especially, there has been growing interest in CNT thin films because of their unique and usually enhanced properties and tremendous potential as components for use in nano-electronic and nano-mechanical device applications or as structural elements in various devices. If a synthetic or a post processing method can produce high yield of nanotube thin films, these structures will provide tremendous potential for fundamental research on these devices. This review will address the synthesis, the post processing and the device applications of self-assembled nanotube thin films.     

Correlation of surface morphology of polyethylene films to ink adhesion and removal

The basic phenomenon of ink adhesion and removal has been studied by looking at the surface of polyethylene films that have been subjected to a ceramic bead impact ink-removal process where printed polyethylene films, zirconium silicate beads, and water were agitated in a laboratory shaker. AFM images show that the polyethylene packaging film surfaces studied have a typical morphology of polyethylene films crystallized under mechanical stress which consists of rows, approximately 1 μm in width, of lamellar-like structures. Upon impact of the ceramic beads on the polyethylene films, the surface is roughened and the surface rows appear to be deformed. FTIR data show that the surface crystallinity of the PE film decreases with the impact ink removal process. A deinking mechanism is proposed where the beads tear the ink film, abrade the surface and deform the polyethylene substrate. Received: 18 September 2000 / Reviewed and accepted: 20 September 2000     

Effect of Applied Current Density on Morphological and Structural Properties of Electrodeposited Fe-Cu Films

A detailed study has been carried out to investigate the effect of applied current density on the composition, crystallographic structure, grain size, and surface morphology of Fe-Cu films. X-ray diffraction (XRD) results show that the films consist of a mixture of face-centered cubic (fcc) Cu and body centered cubic (bcc) α-Fe phases. The average crystalline size of both Fe and Cu particles decreases as the applied current density becomes more negative. Compositional analysis of Fe-Cu films indicates that the Fe content within the films increases with decreasing current density towards more negative values. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been used to investigate the surface morphology of Fe-Cu films. It is observed that the surface morphology of the films changes from dendritic structure to a cauliflower structure as the applied current density becomes more negative. The surface roughness and grain size of the Fe-Cu films decrease with decreasing applied current density towards more negative values.     

Preparation, characterization and optical properties ofα-Fe2O3 films by sol-spinning process

α-Fe₂O₃ films were prepared by sol-spinning process using ferric nitrate as a precursor and 2-methoxy ethanol as the solvent. The films were grown on various substrates by spin coating and were subjected to different annealing temperatures. These were characterized using X-ray and fourier transform infrared spectroscopy (FTIR). The films showed crystallinity at about 500°C. The surface morphology of these films was studied using scanning electron microscopy (SEM) which revealed cracks for films having thickness of the order of 2 μm. The band gap of these films was observed to be 2·1 eV from UV-vis spectroscopy.     

Responding Depth of Photocatalytic Activity of TiO2 Self-assembled Films

The electrostatically self-assembly method is getting strategically important to prepare multilayer thin films. With careful choice of component materials, this method should allow for the preparation of multilayer thin films with a variety of excellent technological properties. Ti02/PSS multilayer thin films with ordered structure were prepared by electrostatic self-assembly method. UV-Vis-NIR spectrophotometer, X-ray photoelectron spectroscopy (XPS), and atom force microscopy (AFM) were used to characterize the structure and performance of the multilayer films. Because electrostatically self-assembly method allows molecular-level control over the film composition and thickness, this paper studied the responding depth of photocatalytic activity of Ti02 self-assembled films in detail.     

Effect of Substrate Wettability and Surface Structure on Nucleation of Crystal

The heterogeneous nucleation behaviors of NH4Cl crystal on rough aluminum substrate surface immerged in NH4Cl-H2O solution were experimentally analyzed, and the influence mechanism of the micro/nano-scale surface structures on heterogeneous nucleation was investigated. It has been shown that wettability and nucleation are affected by substrate surface condition. The intrinsic wetting properties between nucleus and substrate surface, and the surface structure of certain geometrical scales, both impose effects on the heterogeneous nucleation properties. For a nucleus-wetting substrate surface, heterogeneous nucleation is promoted by a higher complexity of the surface morphology; but for a nucleus-nonwetting substrate surface, heterogeneous nucleation is inhibited by a higher complexity of the surface morphology.     

Comparative Study of LiMn2O4 Thin Films Heat-treated by Conventional and Rapid Thermal Annealing

Cathode material LiMn2O4 thin films were prepared by solution deposition followed by conventional thermal annealing (CTA) and rapid thermal annealing (RTA) using lithium acetate and manganese acetate as starting materials. The phase and surface morphology identification was done by X-ray diffraction and scanning electron microscopy. The electrochemical properties of the thin films were carried out by cyclic voltammetry, charge-discharge experiments, electrochemical impedance spectroscopy and potential step technique. The results show that both thin films are homogeneous and crack-free. Compared with the CTA derived thin films, the RTA derived ones with smaller grain size are more smooth and dense. The CTA and RTA derived LiMn2O4 thin films deliver the capacity of 34.5 μAh/(cm2 ·μm) and 38 μAh/(cm2 ·μm) and show the capacity loss of 0.050% and 0.037% per cycle after being cycled 100 times, respectively. The diffusion coefficient of lithium ion in the CTA derived LiMn2O4 thin-film electrode is 4.59×10-11 cm2/s, and that of lithium ion in the RTA derived one is 3.86×10-11 cm2/s.     

Tungsten Doped Indium Oxide Thin Films Deposited at Room Temperature by Radio Frequency Magnetron Sputtering

Tungsten doped indium oxide(IWO) thin films were deposited on glass substrate at room temperature by radio frequency reactive magnetron sputtering.Chemical states analysis was carried out,indicating that valence states of element W in the films were W~(4+) and W~(6+).The effects of sputtering power and film thickness on the surface morphology,optical and electrical properties of IWO thin films were investigated.The IWO thin films had high transmittance in near infrared(NIR) spectral range.The resistivity,carrier mobility and carrier concentration owned their respective optimum values as sputtering power and thickness changed.The asdeposited IWO film with the minimum resistivity of 3.23 × 10~(-4) Ω cm was obtained at a sputtering power of50 W,with carrier mobility of 27.1 cm~2 V~(-1) s~(-1),carrier concentration of 7.15 × 10~(20) cm~(-3),average transmittance about 80%in visible region and above 75%in NIR region.It may meet the application requirement of high conductivity and transparency in NIR wavelength region.     

Structural Morphological and Optical Properties of SnSb2S4 Thin Films Grown by Vacuum Evaporation Method

SnSb2S4 thin films were prepared from powder by thermal evaporation under vacuum of 1.33 × 10^-4 Pa （ 10^-6 Torr） on unheated glass substrates. The effect of thickness on the structural, morphological and optical properties of SnSb2S4 thin films was investigated. Films thickness measured by interference fringes method varied from 50 to 700 nm. X-ray diffraction analysis revealed that all the SnSb2S4 films were polycrystalline in spite without heating the substrates and the crystallinity was improved with increasing film thickness. The microstructure parameters： crystallite size, strain and dislocation density were calculated. It was observed that the crystallite size increased and the crystal defects decreased with increasing film thickness. In addition, by increasing the film thickness, an enhancement in the surface roughness root-mean-square （RMS） increased from 2.0 to 6.6 nm. The fundamental optical parameters like band gap, absorption and extinction coefficient were calculated in the strong absorption region of transmittance and reflectance spectrum. The optical absorption measurements indicated that the band （Eg） gap of the thin films decreased from 2.10 to 1.65 eV with increasing film thickness. The refractive indexes were evaluated in transparent region in terms of envelope method, which was suggested by Swanepoul. It was observed that the refractive index increased with increasing film thickness.     

NaOH处理对胶原蛋白、葡甘聚糖、壳聚糖共混膜结构和性能的影响

Collagen-konjac glucomannan-chitosan blend films were made by solution blend method. Analyses of FT infrared (FTIR),X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to determine the effects of NaOH solution on structure,surface properties and water adsorption of the blend films and the interactions between collagen, konjac glucomannan and chitosan in the films combined with X-ray photoelectron spectroscopy (XPS) and water adsorption capacity analysis at different pH values. The results have shown that there is good compatibility between collagen, konjac glucomannan and chitosan. Treatment by NaOH solution can improve the structures,surface properties and water adsorption of the blend films.     

Structure and Electrical Characteristics of Zinc Oxide Thin Films Grown on Si (111) by Metal-organic Chemical Vapor Deposition

ZnO thin films were grown on Si(111) substrates by low-pressure metal-organic chemical vapor deposition.The crystal structures and electrical properties of as-grown sample were investigated by scanning electron microscopy(SEM) and conductive atomic force microscopy(C-AFM).It can be seen that with increasing growth temperature,the surface morphology of ZnO thin films changed from flake-like to cobblestones-like structure.The current maps were simultaneously recorded with the topography,which was gained by C-AFM contact mode.Conductivity for the off-axis facet planes presented on ZnO grains enhanced.Measurement results indicate that the off-axis facet planes were more electrically active than the c-plane of ZnO flakes or particles probably due to lower Schottky barrier height of the off-axis facet planes.     

Effects of laser energy on the surface quality and properties of electrodeposited zinc-nickel-molybdenum coatings

As a substitute for toxic cadmium coatings in the aerospace industry, zinc-nickel coatings have excellent application prospects, and their properties can be improved by adding molybdenum. In this study, laser-assisted electrodeposition is used to improve the surface quality and properties of Zn–Ni–Mo coatings, with investigation of how laser energy in the range of 0–21.1 μJ affects their element content, surface morphology, crystal phase, microhardness, residual internal stress, and corrosion re...     

Effect of Injection Velocity on Structure Part Characteristic in AZ50 Die Casting Process with High Vacuum System

When diecasting large and thin Mg alloy parts,material defects occur,which include porosity,nonuniform mechanical properties,irregular surfaces,and incomplete filling.To resolve these problems,it is necessary to have uniform injection velocities and temperatures as well as control the melt.This study investigated the feasibility of producing large and thin components using a die caster by attaching a high vacuum system.In particular,the effects of injection velocity on surface quality and the mechanical properties of the products were investigated.Hence,an injection velocity scheme and a die structure capable of casting in a vacuum were proposed.As a result,it was found that the critical low injection velocity was 0.2 m/s to produce large thin Mg alloy structures having good mechanical properties.