Properties of CuInSe2 polycrystalline thin films prepared by selenization of Co-sputtered Cu-In alloys

A method of synthesizing of CuInSe2 thin films by selenization of co-sputtered Cu-In alloy precursors in a partially closed graphite system using a two-step profile is reported. CuInSe films of a wide range of composition (0.52 < Cu/In ratio < 1.29) were produced. The structural, composition, film morphology, resistivity and low-temperature photoluminescence measurements were used to characterize all of the thin films. The precursors exhibit a uniform and dense crystal structure, whilst the structure and morphology of selenised films show some dependence on the Cu/In ratio. Single phase CuInSe2 films of chalcopyrite structure with preferential orientation in the (112) direction were obtained. The room temperature resistivity of p-CuInSe2 films Varied from 10(-2) to 10(3) Omega .cm depending on the Cu/In ratio of the alloy precursors. By means of the temperature and excitation intensity dependent photoluminescence measurements, the observed luminescence peaks can be ascribed to various intrinsic defects.