Structural, electrical, and optical properties of copper indium diselenide thin film prepared by thermal evaporation method

Abstract

Stoichiometric compound of copper indium diselenide (CuInSe 2) was synthesized by direct reaction of high-purity elemental copper, indium and selenium in an evacuated quartz ampoule. The phase structure and composition of the synthesized pulverized material analyzed by X-ray diffraction (XRD) and energy dispersive analysis of X-rays (EDAX) revealed the chalcopyrite structure and stoichiometry of elements. Thin films of CuInSe 2 were deposited onto organically cleaned soda lime glass substrates held at different temperatures (i.e. 300 K to 573 K) using thermal evaporation technique. CuInSe 2 thin films were then thermally annealed in a vacuum chamber at 573 K at a base pressure of 10 − 2 mbar for 1 h. The effect of substrate temperature ( T s) and thermal annealing ( T a) on structural, compositional, morphological, optical and electrical properties of films were investigated using XRD, transmission electron microscopy, EDAX, atomic force microscopy (AFM), optical transmission measurements and Hall effect techniques. XRD and EDAX studies of CuInSe 2 thin films revealed that the films deposited in the substrate temperature range of 423–573 K have preferred orientation of grains along the (112) plane and near stoichiometric composition. AFM analysis indicates that the grain size increases with increase of T s and T a. Optical and electrical characterizations of films suggest that CuInSe 2 thin films have high absorption coefficient (10 4 cm − 1 ) and resistivity value in the interval 10 − 2 –10 1 Ω cm influenced by T s and T a.