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

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 80K less than or equal to T less than or equal to 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. (C) 2001 Elsevier Science B.V. All rights reserved.