Characteristics of CIGS thin films prepared by RF sputtering employing CIGS single target

摘要

CuIn_(1-x)Ga_xSe_2 (CIGS) films were prepared by a RF sputtering system using a CIGS single target having a composition of CuIn_(0.75)Ga_(0.25)xSe_2. X-ray diffraction measurements confirmed that CIGS films grown on Mo-coated soda-lime glass at 350℃ exhibited only (112) diffraction, while CIGS films annealed at 550℃ and for 30 min in rapid thermal annealing (RTA) chamber showed (112), (220), (312), and other diffraction peaks of the chalcopyrite structure. The CIGS films annealed showed much higher intensity of (112) diffraction than that of the films grown at 350℃, demonstrating improvement of crystal-quality of the films. However, no peaks originated from other phase were observed. The average composition of the CIGS films determined by energy dispersive x-ray spectrometer (EDX) was in good agreement with that of the target. Furthermore, secondary ion mass spectrometry (SIMS) analysis revealed that RTA treatment for Mo layer prior to CIGS film deposition suppresses the inter-diffusion of In, Ga, and Mo at the interface. These results demonstrate that RF sputtering of CIGS single target can be a promising method to fabricate high-quality CIGS films and heat treatment of Mo layer is indispensible to control the interface of CIGS/Mo.