Effect of working pressure on growth of Cu(In,Ga)Se2 thin film deposited by sputtering from a single quaternary target

Abstract

CIGS thin films were deposited on soda lime glass substrates by RF magnetron sputtering process from a single target at different working pressure. All CIGS thin films were deposited on heated substrates without post-selenization process. Energy dispersive X-ray results show CIGS thin films are Cu-poor state. The Cu content in the films decrease as the working pressure increased. The results of X-ray diffraction and Raman spectra analysis indicate that all CIGS thin films are the chalcopyrite-type structure and pure phase. It has better crystalline quality of CIGS thin film deposited at lower working pressure. However, the rms roughness of the CIGS thin films decreases with the increasing of the working pressures which is related to the grain size of different thin films. The grain size of thin films deposited at lower working pressure is larger. Further transmission spectra demonstrate the optical band gaps of all CIGS thin films.