Q. Raza

Bio: Q. Raza is an academic researcher. The author has contributed to research in topics: Thin film & Raman spectroscopy. The author has an hindex of 5, co-authored 13 publications receiving 140 citations.

Ellipsometric analysis of Cd1−xZnxSe thin films prepared by a thermal evaporation technique

Abstract: Cd1−xZnxSe is an important semiconducting alloy because it is possible to tune its physical properties by controlling its composition x. Thin films of Cd1−xZnxSe with different compositions (x=0.2, 0.4, 0.6 and 0.8) were deposited onto a glass substrate by the resistive thermal evaporation technique. Optical properties such as optical constants and band gap energy of these films were examined by using a spectroscopic ellipsometer. It was found that the optical constants (n and k) decrease with the addition of Zn content in the alloy. In comparison, the band gap energy was also determined by using transmission spectra and found to agree with that of the ellipsometric results. These analyses confirm that the band gap energy increases with the increase of Zn content in the alloy. The composition of the films was estimated by energy dispersive analysis of x-ray studies. The structural properties of these films were studied by using an x-ray diffractometer (XRD). The XRD patterns reveal that the two binary compounds have been completely transformed into a ternary compound with hexagonal (wurtzite) structure having preferred orientation along the c-direction with (002) planes.

One-Step Solvothermal Synthesis of Petalous Carbon-Coated Cu+-Doped CdS Nanocomposites with Enhanced Photocatalytic Hydrogen Production

Abstract: Metal ion doping and nanocoating a CdS photocatalyst have been proven to be effective strategies to inhibit photocorrosion and improve photocatalytic performance. In this study, carbon-coated Cu+-doped CdS nanocomposites (C-Cu-CdS) with a stable petalous structure and highly uniform size distribution were successfully synthesized via a facile one-step solvothermal method. Both Cu+ doping and carbon coating to the CdS photocatalyst are realized in this one-step strategy. Benefiting from the unique core–shell structure and metal ion doping, the as-prepared C-Cu-CdS catalyst exhibits significantly enhanced photostability and visible-light-driven photocatalytic efficiency. For an optimal Cu+ doping percentage of 1.0%, an average hydrogen production rate of 2796 μmol h–1 g–1 and an apparent quantum efficiency of 16.0% at a wavelength of 420 nm was observed, the latter of which is nearly 9.3 times higher than that of the carbon-coated CdS product without Cu+ doping. The origin of the improved photocatalytic act...

Electrical transport properties and Mott's parameters of chalcogenide cadmium sulphoselenide bulk glasses

Abstract: This research article was devoted to study some electrical characteristics of chalcogenide bulk Cd50S50 − xSex (30% ≤ x ≤ 50%) glassy systems. CdSSe Bulk glasses were previously prepared by the mechanical milling technique. The products of the grinding process were pressed as disc-shaped pellets of diameter 12 mm and thickness 1.5 mm by using a compressor of pressure about 6.5 MPa. Two point probe technique was used to measure the electrical resistance and dc-electrical conductivity in the temperature range 293 K–435 K. Conduction mechanism studies reveal that, the transition temperature was detected at around 370 K. Below this temperature, the conduction mechanism was via the variable range hopping conduction near Fermi level according to Mott's model. Above 370 K, the mechanism was hopping conduction via localized states by the activated thermionic emission. The activation energies of bulk CdSSe glasses were found to be decreased by adding more Se. The pre-exponential factors, Mott parameters, and the density of localized states near Fermi level, trapping state energy, the potential barrier energy, were evaluated and studied. The relation between cohesive and activation energies was discussed. All obtained data were strongly dependent upon Se-content in the bulk Cd50S50 − xSex glassy compositions.