Fabrication and Characterization of ZnTe Based Thin Films by Closed Space Sublimation (CSS) Technique

Abstract

In the present work, a coating unit for depositing thin films has been developed which works on the technique ―Closed Space Sublimation‖ where powdered material is deposited under vacuum. Zinc Telluride thin films have been deposited on a glass substrate. Structural, morphological, compositional, optical, and electrical properties of the samples have been determined before and after doping. The main goal is to enhance p-type conductivity of ZnTe thin films using Bismuth as dopant. The optical properties of the films are also very important from the application point of view so that improvement in conductivity and reduction in resistivity clearly achieved. The structure of the films was studied by XRD, SEM and composition of the films was measured by EDX. A Swanpoel model is used for the calculation of optical parameters (optical band gap, refractive index, and films thickness) from the optical transmission spectra recorded by spectrophotometer. To reduce the resistivity of the thin films, Bismuth was doped. Bismuth was doped using Closed Space Sublimation unit and doped film were vacuum annealed at different temperatures in order to diffuse it in as-deposited samples of ZnTe .XRD results confirmed the diffusion and formation of Bismuth with in ZnTe.