Compositional dependence of the band gap of (CuIn5S8)1–x · (FeIn2S4) x alloys

Abstract

The transmittance spectra of single-crystal CuIn5S8 and FeIn2S4 ternary compounds and (CuIn5S8)1–x · (FeIn2S4) x alloys grown by planar crystallization of the melt are studied in the region of the fundamental-absorption edge. From the experimentally recorded spectra, the band gap of the compounds and their alloys is determined, and the compositional dependence of the band gap is constructed. It is established that the band gap nonlinearly varies with the composition parameter x (with a maximum at the average content x) and can be described by a quadratic dependence.