AbstractTitanium nitrides have good mechanical, tribological, electrical, biomedical, and optical properties; therefore, they are used to harden and protect cutting and sliding surfaces, as semiconductor devices, and as a nontoxic exterior for biomedical applications. The dependence of the mechanical and electrical properties of titanium nitride thin films deposited on silicon substrates by direct-current reactive magnetron sputtering technique on argon gas flow (in the range of 8 to 20 sccm) was investigated. The crystallographic structure of the films was studied by X-ray diffraction (XRD), while surface morphology was studied using atomic force microscopy (AFM). Mechanical and electrical properties of these films were investigated by nanoindentation test and a four-point probe instrument, respectively. The XRD patterns showed titanium nitride (TiN) formation with a face-centered cubic structure for all samples. It was also observed that (111) crystallographic direction was the preferred orientation for TiN thin films which became more pronounced with increasing argon gas flow. The AFM images showed a granular structure for TiN layers. The hardness, crystallite/grain size (obtained from XRD and AFM), and surface roughness increased with the flow of argon gas, while elastic modulus and dislocation density in the films decreased. The study on electrical properties showed that the dependence of voltage with current for all samples was linear, and film resistivity was increased with argon gas flow. پرونده مقاله

AbstractThis paper is an attempt to compare the influence of various annealing conditions on growth, nanostructure, surface morphology and electrical properties of copper oxide thin films. Cu thin films of 85 nm thickness were deposited on glass substrate by thermal evaporation method, and then post-annealed at different environments (air and oxygen flow), different temperatures (200–400 °C) and different times (35 and 75 min). X-ray diffraction results showed (Cu2O) cuprite phase for all annealed samples at 200 and 250 °C and (CuO) tenorite phase for all samples annealed under different conditions at 350 and 400 °C. A complex phase of CuO and Cu2O was observed for all annealed samples at 300 °C, with exception for the sample annealed with flow of oxygen for 75 min. The atomic force microscopy results showed that surface morphology of the samples was strongly affected by the changes of annealing conditions (i.e., time, temperature and environment). The size of the grains increased with annealing temperature and time, while the samples annealed with oxygen flow showed larger grains than those annealed in air. Two different behaviors with annealing temperature were distinguished for the surface roughness of the samples annealed in the air and those annealed with flow of oxygen. Resistivity and Hall effect of samples were measured by a four-point probe instrument and a Hall effect investigation system, respectively. The electrical analyses showed that the variations in annealing conditions had a remarkable effect on measured electrical parameters, namely films resistivity, carriers concentration and type, and Hall mobility. پرونده مقاله

AbstractZirconium thin films were deposited on a glass substrate using direct current magnetron sputtering technique and then post-annealed at different temperatures (100°C to 500°C in steps of 100°C) in an oxygen constant flow. The dependence of crystallographic structure, surface morphology, chemical composition, and electrical and decorative properties of the films on the annealing temperature was investigated. X-ray diffraction showed different phases of zirconium oxide at different annealing temperatures. It is observed that crystallite size and nanostrain increase with annealing temperature. Atomic force microscopy results showed granular structure in all samples, while both grain size and film surface roughness increased with the annealing temperature. Energy dispersive X-ray analysis data showed that the ratio of O/Zr was approximately 1.6, 1.7, 1.9, 2.1, and 2.2 at annealing temperatures of 100°C, 200°C, 300°C, 400°C, and 500°C, respectively. The annealed films at higher temperatures (400°C and 500°C) were transparent, while annealed films at lower temperatures (100°C to 300°C) were grey and brown, respectively. The variation of electrical resistance of samples with applied voltage was approximately constant, while it increased with annealing temperature. پرونده مقاله

AbstractThis research addresses a detailed study on the sensitivity and selectivity of ZnO thin film to volatile organic compound (VOC) vapors that can be used for the development of VOC sensors. The ZnO thin film of 100 nm thickness was prepared by post-annealing of e-beam evaporated Zn thin film. The sample was structurally, morphologically, and chemically characterized by X-ray diffraction and field emission scanning electron microscopy analyses. The sensitivity, selectivity, and detection limit of the sample were tested with respect to a wide range of common VOC vapors, including acetone, formaldehyde, acetic acid, formic acid, acetylene, toluene, benzene, ethanol, methanol, and isopropanol in the temperature range of 200–400 °C. The results show that the best sensitivity and detection limit of the sample are related to acetone vapor in the studied temperature range. The ZnO thin film-based acetone sensor also shows a good reproducibility and stability at the operating temperature of 280 °C. پرونده مقاله