Polycrystalline Cu(In, Ga)Se₂ thin films and PV devices sputtered from a binary target without additional selenization

This work presents a novel method to form polycrystalline CuIn _1-xGa_xSe₂ (CIGS) thin film by co-sputtering of In-Se and Cu- Ga alloy targets without an additional selenization process. An attempt was also made to thoroughly elucidate the surface morphology, crystalline phases, physical properties, and chemical properties of the CIGS films by using material analysis methods. Experimental results indicate that CIGS thin films featured densely packed grains and chalcopyrite phase peaks of (112), (220), (204), (312), and (116). Raman spectroscopy analysis revealed chalcopyrite CIGS phase with Raman shift at 175cm^-1, while no signal at 258cm^-1 indicated the exclusion of Cu^2-xSe phase. Devices built with these films exhibit efficiencies as high as 8.6%.