Mahaveer Kumar Jain

Zn 1-x Cd x O thin films have been prepared by sol-gel spin coating method. Structural analysis shows that the Cd substitution into the wutrzite ZnO lattice is achieved up to about 20 mol %. The optical band gap is found to decrease with the increase in Cd content. Increase in the annealing temperature up to a certain critical temperature leads to band gap narrowing because of the proper substitution of Zn by Cd and thereafter the band gap increases due to Cd re-evaporation from the lattice sites. This critical temperature lowers down with the increase in Cd doping concentration. The resistivity decreases with the increase in Cd content and increases with the increase in annealing temperature.

Polycrystalline In x Ga 1-x N thin films were prepared by mixed source modified activated reactive evaporation (MARE) technique. The films were deposited at room temperature on glass substrates without any buffer layer. All the films crystallize in the hexagonal wurtzite structure. The indium concentration calculated from XRD peak shift using Vegard's law was found to be varying from 2% to 92%. The band gap varies from 1.72 eV to 3.2 eV for different indium compositions. The indium rich films have higher refractive indices as compared to the gallium rich films. The near infra-red absorption decreases with gallium incorporation into InN lattice which is mainly due to decrease in the free carrier concentration in the alloy system. This fact is further supported from Hall effect measurements. MARE turns out to be a promising technique to grow In x Ga 1-x N films over the entire composition range at room temperature. © 2011 Elsevier B.V. All rights reserved.

Polycrystalline MgxZn1-xO (MZO) thin films on glass substrates were prepared by sol-gel method. All the films retained the hexagonal wurtzite structure of ZnO. The band gap values determined from transmission spectra were found to be smaller than the values obtained from Vegard's law for the as-deposited MZO films. For the films with x = 0.1, 0.2 and 0.3, the band gap blue-shifted initially and then red-shifted with increase in the annealing temperature. The reason for this anomalous shift in the band gap is attributed to the proper substitution of Mg atoms into the Zn lattice sites after a certain critical annealing temperature. © Springer Science+Business Media, LLC 2009.

Highly crystalline copper nitride (Cu3N) thin films have been deposited on glass substrates at room temperature by a novel and commercially viable growth technique, known as modified activated reactive evaporation (MARE). The effects of change in radio frequency (RF) power and deposition pressure on the structural and optical properties of the films have been investigated. RF power plays a significant role for the preferential growth of these films along a particular plane whereas the deposition pressure has comparatively lesser impact on the same. However, the lattice parameter, film thickness and optical band gap are found to be strongly dependent on the deposition pressure. The MARE grown Cu3N films undergo complete decomposition into metallic Cu upon vacuum annealing at 400 °C which makes them promising candidates to be used in write once optical recording media.