Sulfurization in Gas Mixture of H₂S and O₂ for Growth of CuInS₂ Thin Films

Abstract

We propose a new sulfurization process for the preparation of homogeneous CuInS 2 films. The process was carried out in a gas mixture of H 2 S and O 2 with varying O 2 /H 2 S ratios, using an InS/Cu/Na 2 O 2 /In stacked layer as the precursor. In this method, the decomposition of H 2 S is induced at low temperatures by O 2 incorporation, thereby promoting the sulfurization of the precursor. Consequently, the serious problem of In metal segregation, which deteriorates the uniformity of CuInS 2 films, is prevented. This method has realized the highest efficiency of Cu-poor CuInS 2 -based solar cells known to date.