Effect of Dip Time on the Structural and Optical Properties of Chemically Deposited CdSe Thin Films

Abstract

In this study, the effect of dip time on the structural and optical properties of cadmium selenide (CdSe) thin films grown by the chemical bath deposition method is reported. The films were grown with varying dip time in the range of 4 h to 12h, and the other deposition variables (substrate temperature, source to substrate distance, pH, and concentration) were kept constant. X-ray diffractometry (XRD) and optical spectroscopy were used to characterise the layers. The results show that the crystallite size and the film thickness increased with an increase in the dip time up to a "critical value" and then decreased otherwise for the latter. The increase in the crystallite size was more pronounced at the lower dip time (< 8 h), and then exhibited a marginal increase for dip time > 8 h. The energy band gap was found to be direct with an optimum value of 1.2 eV obtained for films grown at a dip time of 8 h.