Synthesis of homogeneous pentenary chalcopyrite alloys with a classical two-step growth process Original Research Article

Homogeneous single-phase Cu(In0.75Ga0.25)(Se1−ySy)2 chalcopyrite alloys were prepared by a novel two-step growth process. CuIn0.75Ga0.25 precursors were deposited by DC magnetron sputtering and the subsequent reaction processes in a reactive H2Se/Ar/H2S atmosphere was optimized to prevent the formation and separation of stable ternary phases. X-ray diffraction (XRD) analysis of these films revealed characteristic chalcopyrite peaks with a high degree of symmetry, indicative of homogeneous rather than compositionally graded material. The lattice parameters of the single-phase Cu(In0.75Ga0.25)(Se1−ySy)2 pentenary alloys decreased linearly with an increase in the S/(S+Se) ratio in accordance with Vegardʹs law. X-ray photoelectron spectroscopy (XPS) depth profiling confirmed the in-depth compositional uniformity of the pentenary alloys, prepared under optimized selenization/sulfurization conditions.