Structure and optical properties of CdTe thin films obtained via discrete vacuum thermal evaporation

Abstract

CdTe films were obtained via discrete vacuum thermal evaporation (DVTE) with CdCl₂ treatment and annealing in an air atmosphere. The CdTe samples were investigated using several techniques: energy-dispersive X-ray spectroscopy, scanning electron microscopy, atomic-force microscopy, grazing incidence X-ray diffraction, and Raman analysis. It has been observed that the samples of CdTe films have a cubic structure with predominant orientation (111), a smooth surface without pores or cracks, and the stoichiometric Cd/Te ratio approaches 1. The band gap width is 1.51 eV, and the Urbach energy is in the range of 13–25 meV, increasing for CdTe thin films synthesized with CdCl₂. It has been shown that films based on CdTe fabricated via DVTE with CdCl₂ treatment and annealing in an air atmosphere at 400 °C predominantly crystallize in the cubic structure of CdTe, have good structural and topographic parameters, are low defectless, have an optimal band gap value, and can be applied as a perspective material for high-efficiency solar cell creation.