­Influence of Cold Plasma Exposure Time on Structural and Optical Properties of Chemically Deposited CdSe Thin Films

Abstract

The influence of cold plasma at various intervals on the optical and structural characteristics of cadmium selenide (CdSe) films, produced via chemical bath deposition, was evaluated using X-ray diffraction (XRD) and UV-visible spectroscopy methods. The observed decrease in optical energy gap along with the increase in Urbach energy and extinction coefficient suggests that cold plasma irradiation introduced additional localized states and structural defects within the CdSe films. These defect states broaden the Urbach tail and enhance photon absorption, leading to reduced optical transmittance. The results indicate that plasma treatment significantly modifies the electronic and crystalline structure of the films. The reduction in crystal stress after cold plasma irradiation can be attributed to partial relaxation of the crystal structure and improved atomic rearrangement, which contributes to grain growth and reduces internal distortions within the CdSe films. These results indicate that cold plasma significantly affects the structural and crystalline properties of the films.