Comparative Study on Various Thicknesses of Thermal Vacuum-Evaporated ZnTe Thin Films and Their Band Gap Properties

Abstract

This study presents a detailed investigation into how film thickness influences the structural, optical, and electronic properties of zinc telluride (ZnTe) thin films prepared by the thermal vacuum evaporation technique. ZnTe thin films with thicknesses of 50 nm, 100 nm, 200 nm, and 300 nm were successfully deposited onto clean glass substrates under controlled vacuum conditions to ensure uniformity and reproducibility. The optical characteristics of the films were examined using UV–Visible spectroscopy, with particular emphasis on evaluating the optical band gap as a function of thickness. The absorption spectra revealed a systematic shift in the absorption edge with increasing film thickness. Analysis using Tauc plots indicated that the optical band gap decreases as the thickness increases, which can be attributed to reduced quantum confinement effects in thicker films and improvements in crystallite size and microstructural ordering. Thinner films exhibited higher band gap values due to stronger confinement of charge carriers, while thicker films showed band gap values approaching that of bulk ZnTe. These thickness-dependent variations significantly affect the electronic behavior of the material. The results demonstrate that controlling film thickness is a crucial parameter for tailoring the optoelectronic properties of ZnTe thin films. Consequently, the study provides valuable insights for optimizing ZnTe-based materials for applications in optoelectronic devices such as solar cells, photodetectors, and light-emitting devices.