Influence of DC magnetron sputtering parameters on the properties of amorphous indium zinc oxide thin film

Amorphous or crystalline indium zinc oxide (IZO) thin films, which are highly transparent and conducting, were deposited by DC magnetron sputtering. X-Ray diffraction technique was used for analyzing microstructures of the films, and also differential thermal analysis was performed for observing their crystallization behavior. The IZO thin films prepared were crystallized at much higher temperature than ITO films were. The crystallized samples showed (222) preferred orientations. By varying process parameters, the optimum conditions for the highest electrical conductivity and optical transmittance, and the lowest surface roughness were found. The resistivity of IZO films decreased as the deposition temperature increased until 250 °C, but sharp rise occurred at or above 300 °C. The extinction coefficients diminished in the films prepared with the conditions of higher deposition temperature, sputtering gas of light mass, and heat treatment. However, excessive amount of oxygen flow during deposition brought about the increase of the extinction coefficients. The variations of extinction coefficients mainly influenced the transmittance of the samples. On the basis of X-ray photoelectron spectroscopy analysis, atomic force microscopy measurement, spectroscopic ellipsometry and spectrophotometer measurement, several characteristics of IZO thin films were discussed comparing with those of ITO thin films. Very low surface roughness of IZO thin films could satisfy the requirement for organic light-emitting diode.     

Optical and dielectric properties of CuAl2O4 films synthesized by solid-phase epitaxy

The synthesis and properties of CuAl₂O₄ thin films have been examined. The CuAl₂O₄ films were deposited via reactive direct current magnetron sputter using a CuAl₂ target. As-deposited films were amorphous. Post-deposition annealing at high temperature in oxygen yielded solid-phase epitaxy on MgO. The film orientation was cube-on-cube epitaxy on (001) MgO single-crystal substrates. The films were transparent to visible light. The band gap of crystalline CuAl₂O₄ was determined to be ∼ 4 eV using a Tauc plot from the optical transmission spectrum. The dielectric constant of the amorphous films was determined to be ∼ 20-23 at 1-100 kHz.     

In-situ electrical characterization of ultrathin TiN films grown by reactive dc magnetron sputtering on SiO2

Ultrathin TiN films were grown by reactive dc magnetron sputtering on thermally oxidized Si (100) substrates. The electrical resistance of the films was monitored in-situ during growth in order to determine the minimum thickness of a continuous film. The coalescence thickness has a minimum of 1 nm at a growth temperature of 400 °C after which it increases with growth temperature. The minimum thickness of a continuous film decreases with increasing growth temperature from 2.9 nm at room temperature to 2.2 nm at 650 °C. In-situ resistivity measurements show that films grown at 500 °C and above are resistant to oxidation indicating high density. X-ray photoelectron spectroscopy and X-ray diffraction measurements show that the TiN grain stoichiometry and grain size increases with increasing growth temperature.     

Preparation, characterization and photocatalytic activity of in situ Fe-doped TiO2 thin films

Fe-doped TiO₂ thin films were prepared in situ on stainless steel substrates by liquid phase deposition, followed by calcination at various temperatures. It was found that some Fe³⁺ ions were in situ doped into the TiO₂ thin films. At 400 °C, the film became photoactive due to the formation of anatase phase. At 500 °C, the film showed the highest photocatalytic activity due to an optimal Fe³⁺ ion concentration in the film. At 900 °C, the photocatalytic activity of the films decreased significantly due to the further increase of Fe³⁺ ion concentration, the formation of rutile phase and the sintering and growth of TiO₂ crystallites.     

Characterization and photocatalytic activity of TiO2 thin films prepared by RF magnetron sputtering

TiO₂ nano-structured thin films were prepared by RF magnetron sputtering and annealed in ambient air for 1 h at 400, 600, 800, 1000, and 1200 °C, respectively. Their phase structure, surface topography, and energy gap were characterized by X-ray diffractometer, atomic force microscope, and fluorescence spectrometer. Photocatalytic activity of the films was evaluated by light induced degradation of methyl orange (C₁₄H₁₄N₃NaO₃S) solution using a high pressure mercury lamp as lamp-house. The relation of photocatalytic activity and annealed temperature was studied in detail. It is found that the crystal phase transforms from amorphous to anatase, and rutile structure with annealing temperature increasing from room temperature to 1200 °C. Energy gap varies with annealing temperature. Photocatalytic activity is dependent on energy gap and grain size. Suitable energy gap from 2.97 to 3.07 eV is favorable for creation of electronic-hole pairs that make the films show excellent photocatalytic activity.     

Switching properties of vanadium doped TiO2 thin films prepared by magnetron sputtering

In the present work thin films of Ti-Me (where Me: V, Nb, Ta) were deposited onto glass substrates by magnetron sputtering of mosaic target in reactive oxygen plasma. The properties of the prepared thin films were studied by X-ray diffraction (XRD), electron dispersive spectroscopy, temperature-dependent electrical and optical transmission spectroscopy measurements. The structural investigations indicate that thin films were XRD-amorphous. Reversible thermoresistance effect, recorded at 52 ± 1 °C was found from electrical measurements. The prepared coatings were well transparent in the visible part of the light spectrum from ca. 350 nm.     

Structural studies of ZnS thin films grown on GaAs by RF magnetron sputtering

X-ray diffraction (XRD) studies of ZnS thin films grown on GaAs (001) substrates at different temperatures by rf magnetron sputtering have been carried out using CuKα radiation. XRD analysis reveals that deposited films below 335 °C, assumed the zinc blend structure. Samples annealed at above 335 °C showed mixed phases of the zinc blend and wurzite structures. Information about crystallite size is obtained from (001), (111) and (104) diffraction peaks. The average crystallite size of the film was determined to be ∼ 32 nm using the Scherrer formula.     

Structural and optical properties of yttrium trioxide thin films prepared by RF magnetron sputtering

Yttrium trioxide (Y₂O₃) thin films have been deposited on silicon (111) at different RF powers and the sputtering pressures by RF magnetron sputtering. The influences of the RF power and the sputtering pressures on the structural and optical properties of Y₂O₃ thin films were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscope (AFM) and spectroscopic ellipsometer (SE). The results show that chemical composition of as-deposited Y₂O₃ film is apparently close to the stoichiometric ratio and it is crystallized but crystallinity is poor. The monoclinic and cubic fluorite-like structure can coexist in as-deposited Y₂O₃ film. A four-layer-structured optical model consisting of silicon substrate, silicon dioxide (SiO₂) interlayer, Y₂O₃ layer and a surface roughness (SR) layer is built for interpreting preferably the results measured by spectroscopic ellipsometry. With the increase of RF power or decrease of sputtering pressure, the refractive index and optical bandgap of sputtered Y₂O₃ film is increased and the extinction coefficients is decreased.     

Structural and optical properties of yttrium trioxide thin films prepared by RF magnetron sputtering

Yttrium trioxide (Y₂O₃) thin films have been deposited on silicon (111) at different RF powers and the sputtering pressures by RF magnetron sputtering. The influences of the RF power and the sputtering pressures on the structural and optical properties of Y₂O₃ thin films were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscope (AFM) and spectroscopic ellipsometer (SE). The results show that chemical composition of as-deposited Y₂O₃ film is apparently close to the stoichiometric ratio and it is crystallized but crystallinity is poor. The monoclinic and cubic fluorite-like structure can coexist in as-deposited Y₂O₃ film. A four-layer-structured optical model consisting of silicon substrate, silicon dioxide (SiO₂) interlayer, Y₂O₃ layer and a surface roughness (SR) layer is built for interpreting preferably the results measured by spectroscopic ellipsometry. With the increase of RF power or decrease of sputtering pressure, the refractive index and optical bandgap of sputtered Y₂O₃ film is increased and the extinction coefficients is decreased.     

Photocatalytic properties of Au/TiO2 thin films prepared by RF magnetron co-sputtering

Au/TiO₂ thin films with various Au doping contents were deposited on quartz substrates by radio frequency (RF) magnetron co-sputtering. The as-deposited Au/TiO₂ films were characterized by energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), XRD, and UV-vis techniques. Au doping and UV treatment enhanced the photocatalytic efficiency of TiO₂ thin films. The optimal RF power of the Au target and UV treatment time were 5 W and 1 h, respectively. The enhanced photoactivity of Au(5 W)/TiO₂ thin films with UV treatment is found to result from the increased hydroxyl concentration.     

Photocatalytic activity of TiO2 thin films deposited by RF magnetron sputtering

Nano-TiO₂ thin films were deposited on silicon and glass substrates by radio-frequency (RF) magnetron sputtering using TiO₂ ceramic target and characterized by X-ray diffractometer, X-ray photoelectron spectrometer, atomic force microscope, and ultraviolet-visible spectrophotometer. Photocatalytic activity was evaluated by light induced degradation of 5 ppm methyl orange solution using a high pressure mercury lamp as lamp-house. It was found that the film as deposited is polymorph, with energy gap of 3.02 eV, and can absorb visible light. The film was repeatedly used for six times in degradation of 5 ppm methyl orange, and the degradation rates of methyl orange solution are 36.566%, 33.112%, 32.824%, 32.248%, 30.521% and 28.794%, respectively. After ultrasonic treatment in de-ionized water for ten minutes, the degradation rate of methyl orange solution resumes to 33.975%.     

Enhanced photocatalytic activity of silver nanoparticles modified TiO2 thin films prepared by RF magnetron sputtering

Ag-TiO₂ nanostructured thin films with silver volume fraction of 0–40% were prepared by RF magnetron sputtering. The microstructure, surface topography, and optical properties of the films were characterized by X-ray diffractometer, transmission electron microscope, and ultraviolet–visible spectrophotometer. Photocatalytic activity of the films was evaluated by light-induced degradation of methyl orange (C₁₄H₁₄N₃NaO₃S) solution using a high pressure mercury lamp as lamp-house. The relation of photocatalytic activity and silver content was studied in detail. It is found that silver content influences microstructure of TiO₂ thin films, and silver in the films is metallic Ag (Ag⁰). Photocatalytic activity of the films increases with increasing silver content up to 5 vol.% Ag and then decreases to values significantly still bigger than that of pure TiO₂ thin films. Silver nanoparticles significantly enhance the photocatalytic activity of TiO₂ films. The better separation between electrons and holes on silver modified TiO₂ thin films surface allowed more efficiency for the oxidation and reduction reactions. The enhanced photocatalytic activity was mainly attributed to the decrease of energy gap of the films and the increase of oxygen anion radicals O₂⁻ and reactive center of surface Ti³⁺ on silver modified TiO₂ thin films surface.     

Hydrophilic properties of nano-TiO2 thin films deposited by RF magnetron sputtering

Microstructure and hydrophilicity of nano-titanium dioxide (TiO₂) thin films, deposited by radio frequency magnetron sputtering, annealed at different temperatures, were studied by field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and water contact angle methods. It is found that the crystal phase transforms from amorphous to rutile structure with increase of annealing temperature from room temperature to 800 °C. It is also indicated that the organic contaminants on the surface of the films can be removed and the oxygen vacancies can be reduced by the annealing treatment. Annealed at the temperature below 300 °C, amorphous TiO₂ thin films show rather poor hydrophilicity, and annealed at the temperature range from 400 to 650 °C, the super hydrophilicity anatase of TiO₂ thin films can be observed. However, when the annealing temperature reaches 800 °C, the hydrophilicity of the films declines mainly derived from the appearance of rutile.     

Conductivity of nanometer TiO2 thin films by magnetron sputtering

The conductivity of nanometer TiO₂ thin films was presented in this paper. The dependence of the conductivity of TiO₂ thin films on the thickness of the film and the substrate material were educed. The TiO₂ films were deposited by reactive magnetron sputtering of a Ti targets in an Ar+O₂ mixture in a conventional sputtering reactor. The thickness of the films deposited on Ti varied in the range from 15 to 225 nm. The resistivity of the films was measured at room temperature in the air. It was found that the conductivity of TiO₂ thin films varies in the range from conductor, semiconductor to nonconductor. This was attributed to electrons transfer at the interface between the TiO₂ and substrates, and the depth of electrons transfer was determined by the difference of work function.     

射频磁控溅射制备Mn掺杂ZnO薄膜的结构与光学性能

采用反应射频磁控溅射方法制备Zn1-xMnxO薄膜(0≤x≤0.25),并在不同温度下进行退火处理.通过原子力显微镜、薄膜X射线衍射、透射电子显微镜和透射光谱对薄膜的成分、表面形貌、微结构和光学性质进行了研究.结果表明,薄膜结晶质量明显地依赖于掺杂Mn元素的浓度,所有薄膜都表现了沿(002)晶面方向择优取向生长,当Mn...     

Photocatalytic activity studies of TiO2 thin films prepared by r.f. magnetron reactive sputtering

A series of transparent titanium dioxide thin films have been obtained on microscope glass slides by means of r.f. magnetron reactive sputtering using Ar and O₂ mixed gases. The photocatalytic activity of the TiO₂ thin films was evaluated by the degradation of rhodamine B dye wastewater. The influences of substrate temperatures and total sputtering pressures on the photocatalytic activity of the TiO₂ films were investigated. It was observed that substrate temperature had little influences on the photocatalytic activity, but the photocatalytic activity of the TiO₂ thin films was improved by decreasing the total sputtering pressure.     

Photocatalytic Zn-doped TiO2 films prepared by DC reactive magnetron sputtering

Zn-doped TiO₂ films were prepared by means of pulsed DC reactive magnetron sputtering method using Ti and Zn mixed target. The deposition condition was optimized to produce uniform and transparent TiO₂ films. Titanium was in the Ti⁴⁺ oxidation state in all Zn-doped TiO₂ films. The zinc oxide deposited on the substrate was in the fully oxidized state of ZnO. Increase of zinc concentration inhibited the crystal growth in the TiO₂ films. The surface morphology gradually changed from crystalline to amorphous along with the increase of doped zinc concentration. The optical transmittances of these films decreased only slightly with increasing zinc concentration due to very similar band edges of ZnO and anatase TiO₂. The doped ZnO had weak influence on light absorption of the TiO₂ films. When zinc concentration was very low (<1 at%), the photocatalytic activities of the doped films had nearly no difference from that of pure TiO₂ film. Photocatalytic activities decreased obviously in the films containing high amount of zinc oxide.     

Comparison of hydrophilic properties of TiO2 thin films prepared by sol-gel method and reactive magnetron sputtering system

This article reports on preparation, characterization and comparison of TiO₂ films prepared by sol-gel method using the titanium isopropoxide sol (TiO₂ coating sol 3%) as solvent precursor and reactive magnetron sputtering from substoichiometric TiO_2 − x targets of 50 mm in diameter. Dual magnetron supplied by dc bipolar pulsed power source was used for reactive magnetron sputtering. Depositions were performed on unheated glass substrates. Comparison of photocatalytic properties was based on measurements of hydrophilicity, i.e. evaluation of water contact angle on the film surface after UV irradiation. It is shown, that TiO₂ films prepared by the sol-gel method exhibited higher hydrophilicity in the as-deposited state but has significant deterioration of hydrophilicity during aging, compared to TiO₂ films prepared by magnetron sputtering. To explain this effect AFM, SEM and high resolution XPS measurements were performed. It is shown that the deterioration of hydrophilicity of sol-gel TiO₂ films can be suppressed if as-deposited films are exposed to the plasma of microwave oxygen discharge.     

Structural, optical and electrical characterization of spray-deposited TiO2 thin films

Titanium oxide (TiO₂) thin films were deposited onto glass substrates by means of spray pyrolysis method using methanolic titanyl acetyl acetonate as precursor solution. The thin films were deposited at three different temperatures namely 350, 400 and 450 °C. As-deposited thin films were amorphous having 100–300 nm thickness. The thin films were subsequently annealed at 500 °C in air for 2 h. Structural, optical and electrical properties of TiO₂ thin films have been studied. Polycrystalline thin films with rutile crystal structure, as evidenced from X-ray diffraction pattern, were obtained with major reflexion along (1 1 0). Surface morphology and growth stages based on atomic force microscopy measurements are discussed. Electrical properties have been studied by means of electrical resistivity and thermoelectric power measurements. Optical study shows that TiO₂ possesses direct optical transition with band gap of 3.4 eV.     

Characterization of inhomogeneity in TiO2 thin films prepared by pulsed dc reactive magnetron sputtering

This article discusses an analytical method for characterizations of TiO₂ thin films and determinations of the degree of their inhomogeneity. The TiO₂ films were prepared by a pulsed dc magnetron sputtering with an operating pressure as a main experimental parameter. The obtained films were primarily characterized for film crystallinity, microstructures and optical properties by spectroscopic ellipsometry. The measured ellipsometric data were analyzed by the single-, the double, and the triple-layer models in order to match with the inhomogeneous film structure proposed in the Thornton structure zone model. The results were then compared with those obtained from grazing-incidence X-ray diffraction, field-emission scanning electron microscopy and high-resolution transmission electron microscopy. The study revealed that the pulsed dc sputtered TiO₂ films could be best described by the inhomogeneous triple-layer physical model. Although the films deposited at lower operating pressure had a dense structure with a mirror-like surface topography, the films deposited at higher operating pressure had the porous structure with the rough surface and the void.