Structural and optical investigations of Cd1-xZnxTe thin film

Thin films of Cd1-xZnxTe (x = 0.02, 0.04, 0.06, 0.08, 0.10) were prepared by vacuum evaporation technique in a base pressure of 10(-5) Tort on well-cleaned glass substrates. XRD and SEM were used to study the structure of as-deposited and annealed films. These studies show that there is no appreciable change in structure when films were annealed in the temperature range of 300-400 K, however, when annealed above 400 K the formation of some polycrystalline structures is seen in the amorphous phases. The transmittance and absorbance of the as-deposited films were measured in the spectral range of 400-1000 nm. The dependence of the absorption coefficient on the photon energy is well described by the relation alpha h nu = B (h nu - E-o)(2). The optical transmission of these films has been studied as a function of photon wavelength. It has been found that the optical band gap first increases with annealing temperature up to 600 K thereafter decreases continuously with increase in annealing temperature and sharply decreases near crystallization temperature. (C) 2010 Elsevier B.V. All rights reserved.