Characterization of CuIn0.7Ga0.3Se2 Thin Films Deposited by Single Stage Thermal Evaporation Process

Abstract

Single phase CuIn0.7Ga0.3Se2 (CIGS) thin films are successfully deposited on glass substrates via a single stage thermal evaporation from a stoichiometric powder of CIGS. X‐ray photoelectron spectroscopy measurements reveal the existence of Cu‐ and Ga‐rich surface of the as‐grown CIGS thin films. The post‐growth annealing process lead to migration of the metallic atoms from the surface region into the bulk during the crystallization process, which subsequently causes a significant reduction in the reflection and a change in the mechanism of conduction. From the photoconductivity measurements it was deduced that the deposited CIGS films demonstrated a drastic decrease in resistivity under different illumination intensities. The post‐growth annealing effect on the morphology and structure of CIGS thin films is investigated by means of the atomic force microscopy and X‐ray diffraction measurements, respectively. Results show that there is a significant change in surface roughness as well as in degree of crystallinity of the films following the annealing process at different temperatures.