Characteristics of Cu(In,Ga)Se₂Films Prepared by Atmospheric Pressure Selenization of Cu-In-Ga Precursors Using Ditert-Butylselenide as Se Source

Abstract

In this study, copper indium gallium diselenide [Cu(In,Ga)Se2; CIGS] films were prepared by selenization of Cu-In-Ga metallic precursors using ditert-butylselenide (DTBSe) under atmospheric pressure. Based on the results of θ-to-2θ X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), it was found that the films selenized at 300 or 400°C for 60 min showed the presence of Kirkendall voids along with the XRD signitures of pure copper (Cu) and certain intermediate binary selenides, copper indium diselenide (CIS) and CIGS depending on temperature while only a single CIGS structure was detected in those films selenized at 500 or 600°C for 60 min. A 5-temperature selenization process was found to enable the formation of CIGS structure with better crystalline quality and thickness uniformity. It is believed that intermediate binary and ternary selenides are formed sequentially with increasing completeness during low-temperature selenization stages of the 5-temperature selenization process. This enhances the subsequent formation of CIGS structure at high-temperature selenization stages of the 5-temperature selenization process with improved structural and morphological properties.