Electrical properties and structural changes of thermally co-evaporated CuInSe films

Abstract Thermal co-evaporation technique (from two sources — Cu wire and In30Se70 ingots) was used to prepare CuInSe thin films. Controlling the evaporation rates from the sources was helpful to get films having different Cu/In content. The temperature dependence of the electrical conductivity was investigated in the temperature range 80 K ≤T≤435 K . The density of localized states at the Fermi level and the activation energy for conduction are decreased on increasing the film (Cu/In) content. The activation energy for conduction of the Cu20In20Se60 film decreases on increasing the annealing temperature. Tetragonal CuInSe2 and hexagonal Cu2Se crystalline phases resulting from heat treatment have been identified using X-ray diffractometry and transmission electron microscope.