Effect of Zinc (Zn) Doping on Characteristics of Cadmium Telluride (CdTe) Thin Film

Cadmium Telluride (CdTe) thin film having 500 nm thickness is deposited on glass substrate using thermal vacuum evaporation technique by evaporating CdTe powder and Zinc (Zn) doping is performed by stacked layer method which is further characterized by X-ray diffractometer (XRD) and UV-VIS-NIR spectrophotometer. XRD patterns revealed Zn doped CdTe thin film as a polycrystalline material with cubic structure and has miller indices of (111) at maximum X-ray intensity. Substrate temperature is fixed at 250°C and annealed for 15 minutes at 300°C and we got maximum XRD intensity decreases as the percentage of Zn doping increases. Optical properties like transmittance, dielectric constant, energy bandgap and reflectance are also extracted and found promising results. Transmittance in near-infrared region for all the four types of films are greater than 76 %, variable reflectance of (6-43) %, energy bandgap from 1.43 eV to 1.51 eV and fluctuation in dielectric constant. This optical bandgap is maximum for undoped CdTe and gets lower as the percentage of Zn doping increases.