A non-selenization technology by co-sputtering deposition for solar cell applications

This work presents a novel method to form polycrystalline Cu(In _1-xGa_x)Se₂ (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 175 cm^-1, while no signal at 258 cm^-1 indicated the exclusion of Cu_2-xSe phase. Hall effect measurements confirmed the polycrystalline Cu(In; Ga)Se₂ thin film to be of p type semiconductor with a film resistivity and mobility of 2.19 × 102 O cm and 88 cm²/V s, respectively.