Effect of Se vapor concentration on CIGS film preparation

We applied the "selenization of stack element layers" method to the preparation of Cuin_1-xGa_xSe₂ (CIGS) films. The selenium vapor concentration was precisely controlled to optimize the annealing process using a homemade bilayer tubular selenization facility, and its effect on the photoelectric characteristics of the films was studied. Auger electron spectroscopy (AES) and X-ray diffraction (XRD) were used to analyze the composition distribution in the cross-section and to obtain phase information, respectively. The output performance of the CIGS device was also measured under AM1.5 1000 W · m^-2 illumination. The results indicated that the molybdenum back contact layer was seriously degraded by the saturated selenium vapor during annealing. Annealing with a low concentration of selenium vapor led to bad performance because of segregation and defects in the film. The CIGS film was homogeneous after annealing in a selenium-free inert atmosphere and a conversion efficiency of 8.5% was obtained.