Sputter deposition of high transparent TiO2−xNx/TiO2/ZnO layers on glass for development of photocatalytic self-cleaning application

In this study, TiO_2−xN_x/TiO₂ double layers thin film was deposited on ZnO (80 nm thickness)/soda-lime glass substrate by a dc reactive magnetron sputtering. The TiO₂ film was deposited under different total gas pressures of 1 Pa, 2 Pa, and 4 Pa with constant oxygen flow rate of 0.8 sccm. Then, the deposition was continued with various nitrogen flow rates of 0.4, 0.8, and 1.2 sccm in constant total gas pressure of 4 Pa. Post annealing was performed on as-deposited films at various annealing temperatures of 400, 500, and 600 °C in air atmosphere to achieve films crystallinity. The structure and morphology of deposited films were evaluated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). The chemical composition of top layer doped by nitrogen was evaluated by X-ray photoelectron spectroscopy (XPS). Photocatalytic activity of samples was measured by degradation of Methylene Blue (MB) dye. The optical transmittance of the multilayer film was also measured using ultraviolet-visible light (UV-vis) spectrophotometer. The results showed that by nitrogen doping of a fraction (∼1/5) of TiO₂ film thickness, the optical transmittance of TiO_2−xN_x/TiO₂ film was compared with TiO₂ thin film. Deposited films showed also good photocatalytic and hydrophilicity activity at visible light.     

Study of microstructure and nanomechanical properties of Zr films prepared by pulsed magnetron sputtering

The present work studies the effect of substrate temperature on the growth characteristics of zirconium films prepared by pulsed magnetron sputtering. Formation of α-phase of zirconium was observed in the temperature range 300-873 K. X-ray diffraction of Zr films revealed predominantly [0 0 1] texture. It is noticed that crystallite size increases with increasing substrate temperature. Hexagonal shaped crystallites seem to grow along the surface normal of the substrate for the films deposited at 773 K. Nanoindentation measurements showed that the hardness of the films is in the range 6-10 GPa. The scratch test indicated that the films deposited at higher substrate temperatures had excellent bonding with the substrate and no significant critical failure was noticed up to an applied load of 20 N.     

Crystal orientation control of polycrystalline TiN thin films using ZnO under layers deposited by magnetron sputtering

The effect of ZnO under layers on crystal growth of TiN thin films was investigated. TiN single layers and double-layered ZnO/TiN thin films were deposited on soda-lime-silicate glass substrates by magnetron sputtering. XRD analysis indicated that TiN single layers exhibited {1 1 1} preferred orientation on glass substrates; on the other hand, the TiN thin films with {1 0 0} preferred orientation were obtained using ZnO under layers and crystallized better than the TiN single layers. This crystal orientation change of TiN thin films should come from heteroepitaxial-like growth because the TiN{1 0 0} and ZnO{0 0 1} crystal lattice planes have similar atomic arrangements. Besides, the possible mismatch between TiN and ZnO atomic arrangements was estimated to be 7.8%. Furthermore, the resistivity and optical absorbance of TiN thin films decreased when they were deposited on ZnO under layers. It can be considered that electrical and optical properties should be improved due to the well-crystallization of TiN thin films using ZnO under layers.     

Realization of p-ZnO thin films by GaP codoping

An attempt has been made to realize p-ZnO by directly doping (codoping) GaP into ZnO thin films. GaP codoped ZnO thin films of different concentrations (1, 2 and 4 mol%) have been grown by RF magnetron sputtering. The grown films on sapphire substrate have been characterized by X-ray diffraction (XRD), Hall measurement, Photoluminescence (PL) and Energy dispersive spectroscopy (EDS) to validate the p-type conduction. XRD result shows that all the films have been preferentially oriented along (0 0 2) orientation. The decrease of full-width at half maximum (FWHM) with increase in GaP doping depicts the decrease in native donor defects. Hall measurement shows that among the three films, 2 and 4 mol% GaP doped ZnO shows p-conductivity due to the sufficient amount of phosphorous incorporation. It has been found that low resistivity (2.17 Ωcm) and high hole concentration (1.8×10¹⁸ cm⁻³) for 2% GaP codoped ZnO films due to best codoping. The red shift in near-band-edge (NBE) emission and donar-acceptor-pair (DAP) and neutral acceptor bound recombination (A°X) observed by room temperature and low temperature (10 K) PL, respectively, well acknowledged the formation of p-ZnO. The incorporated phosphorous in the film has been also confirmed by EDS analysis.     

Annealing of defect clusters in irradiated tungsten

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in tungsten irradiated at reactor ambient tempeaature, ～ 70°C. Annealing, consisting of the growth and eventual elimination of the clusters, is observed to occur in two stages, one at temperatures below 435°C and one at temperatures above 740°C, which are interpreted as being due to interstitial and vacancy migration, respectively. The changes in defect cluster size and density are paralleled by similar changes in the measured strength of the material, and can be quantitatively correlated with the shear stress on the basis of a model of dislocation movement through a random array of obstacles.     

Accommodation coefficients for low-energy ions on metal surfaces

The interaction of low-energy ions (E = 3 to 100 eV) with the surface of a solid cannot be treated in terms of gas dynamics. The scattering of particles at an energy of E _o > 20 eV may be explained in terms of binary collisions with the atoms of the target. The validity of the single collision model with free surface atoms for medium energies from 10 to 100 eV and even down to 1 eV was confirmed on the basis of both experimental and computational data. This paper describes experimental studies of the secondary ion emission from the (100) and (110) faces of a Mo single crystal and both experimental and theoretical studies of alkaline ion accommodation coefficient on polycrystalline Mo within the energy range E = 3 to 50 eV with a varying direction of the primary ion beam from normal to the glancing angle of incidence (ρ = 0 to 75°). On the basis of the retarding potential method using a spherical condenser whose central electrode was the target, we measured the energy distribution of secondary ions. Calculations have been performed for the energy of scattered ions and the high energy portion of accommodation coefficient on the basis of single and double binary collisions using the Born-Mayer potential and taking into consideration the influence of adsorption forces at the surface of the target.     

Comments on “role of impurities on the primary process for f-coloring in alkali halides”

Growth of the V₄ centers during and after pulsed electron irradiation of KBr was measured between 77K and 200K. It is found that the growth during pulsed irradiation is clearly different from that due to the thermal motion of the H centers. Critical discussions on the mechanism of the interstitial interaction in the primary step of the Frenkel-pair creation were made.     

Features of sputtering of nitrides and their components

The sputtering behaviour of hexagonal or wurtzite polycrystal nitrides of boron, aluminium, and gallium was explored employing methods of molecular dynamics. The sputtering yield Y of nitrides and the average energy ē ₁ of emitted particles were studied as dependent on the mass m ₁ of bombarding He, Li, B, N, Ne, Al, Ar, Ni, Ga, Kr, and Xe ions with the initial energy E ₀ between 200 and 10,000 eV. Y(m ₁) and ē ₁(m ₁) were researched upon for preferential sputtering of nitride components at low E ₀. It was revealed that the ratio between the sputtering yield of the light component and that of the heavy one depends on ion energy and mass. At E ₀=200 eV and m ₁=40, the ratio for BN, AlN, and GaN amounts to 1.2, 2.2, and 2.4, respectively. For nitride components, an anomalous dependence of sputtering on ion mass was found, its maximum occurring at a certain ratio m ₂/m ₁, where m ₂ is the averagè mass of two nitride components.     

Anisotropic angular distribution of sputtered atoms

The sputtering yield angular distributions have been calculated on the basis of the ion energy dependence of total sputtering yields for Ni and Mo targets bombarded by low-energy Hg⁺ ions. The calculated curves show excellent agreement with the corresponding Wehner's experimental results of sputtering yield angular distributions. This fact clearly demonstrates the intrinsic relation between the ion energy dependence of total sputtering yields and the sputtering yield angular distribution. This intrinsic relation had been ignored in Yamamura's papers [Yamamura, Y. (1982). Theory of sputtering and comparison to experimental data, Nucl. Instr. and Meth., 194, 515–522; Yamamura, Y. (1981). Contribution of anisotropic velocity distribution of recoil atoms to sputtering yields and angular distributions of sputtered atoms, Rad. Eff., 55, 49–55.] due to some obvious mistakes.     

Vanadium oxide thin films produced by magnetron sputtering from a V2O5 target at room temperature

Vanadium oxide thin films were grown by RF magnetron sputtering from a V₂O₅ target at room temperature, an alternative route of production of vanadium oxide thin films for infrared detector applications. The films were deposited on glass substrates, in an argon–oxygen atmosphere with an oxygen partial pressure from nominal 0% to 20% of the total pressure.X-ray diffraction (XRD) and X-ray photon spectroscopy (XPS) analyses showed that the films were a mixture of several vanadium oxides (V₂O₅, VO₂, V₅O₉ and V₂O₃), which resulted in different colors, from yellow to black, depending on composition. The electrical resistivity varied from 1 mΩ cm to more than 500 Ω cm and the thermal coefficient of resistance (TCR), varied from −0.02 to −2.51% K⁻¹.Computational thermodynamics was used to simulate the phase diagram of the vanadium–oxygen system. Even if plasma processes are far from equilibrium, this diagram provides the range of oxygen pressures that lead to the growth of different vanadium oxide phases. These conditions were used in the present work.