Effect of CdCl2/annealing on the crystalline transformation of CdTe thin films grown by evaporation at a low substrate temperature

Abstract

The structural and optical properties of CdTe thin films prepared at a low substrate temperature were investigated before and after the Cd$CI _2$ /annealing. The crystal structure of CdTe film was cubic with a strong (111) preferential orientation. Annealing at 400 ◦C without Cd$CI _2$ treatment results in a decrease in the (111) peak intensity while the intensities of the (220), (311) and (331) peaks appeared, indicating that the texture is significantly changed. However, after the Cd$CI _2$ /annealing, the film exhibited a hexagonal phase as a dominant structure. The scanning electron microscopy patterns showed that the as-deposited and annealed samples had almost the same grain size. However, the grain size of the sample annealed after the Cd$CI _2$ treatment increased significantly. The optical band gap values for the as grown and Cd$CI _2$ /annealed films were determined to be ∼1.48 eV and ∼1.49 eV, respectively.