Electrical properties and structural changes of thermally co-evaporated CuInSe ®lms

Thermal co-evaporation technique (from two sources Ð Cu wire and In30Se70 ingots) was used to prepare CuInSe thin ®lms. Controlling the evaporation rates from the sources was helpful to get ®lms having different Cu/In content. The temperature dependence of the electrical conductivity was investigated in the temperature range 80K T 435 K. The density of localized states at the Fermi level and the activation energy for conduction are decreased on increasing the ®lm (Cu/ In) content. The activation energy for conduction of the Cu20In20Se60 ®lm decreases on increasing the annealing temperature. Tetragonal CuInSe2 and hexagonal Cu2Se crystalline phases resulting from heat treatment have been identi®ed using X-ray diffractometry and transmission electron microscope. # 2001 Elsevier Science B.V. All rights reserved