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 Torr 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 αhν = B (hν − Eo)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.