Surface topology using laser backscattering and photoluminescence on Cu- and In-rich CuInSe2 thin films

Abstract

An easy-to-arrange imaging system was fabricated and used to probe surface topology of polycrystalline CuInSe2 thin films used for solar cell fabrication. Surface images developed using laser backscattering and photoluminescence (PL) showed correlation with AFM images. Imaging by laser backscattering was faster compared to PL imaging. The backscattered image was a profile of the air–film interface, which represented more closely the topology obtained using atomic force microscopy (AFM) analysis. Surface roughness calculated using laser backscattering was found to be agreeable with the value obtained using a stylus probe. PL topology was of lower resolution probably because of the infrared emission wavelength used for the imaging. Cu-rich films possessed hills and valleys on their surfaces while In-rich films were smoother with rounded features. The spatial distribution of PL intensity was correlated with the spatial defect distribution.