Vapour Growth of CuGaS2 and Its Optical Properties

Abstract

Single crystals of CuGaS2 are prepared by the iodine vapour transport method using either solution grown crystals or two constituent binary compounds, Cu2S and Ga2S3 as the starting materials. In both cases, a slight difference in the growth condition leads to different colouration of the crystals yielded; yellow, red and black varieties. Polarization measurements of transmission, reflection and photoconduction on these different coloured crystals also show different characteristics of these crystals. From the results of both growth experiments and optical measurements, the differences in colouration and optical properties among these crystals are expected to be due to a slightly off-stoichiometric unbalance between Cu2S and Ga2S3, and the yellow crystal is considered to be the most stoichiometric one.