Physico-chemical characterization of spray-deposited CuInS2 thin films

CuInS2 thin films have been deposited by spray pyrolysis. X-Ray diffraction spectra show that a substrate temperature T-s greater than or equal to 590 K with a ratio of the concentration in the pulverized solution of [Cu]/[In ] = 1.1 permits well crystallized thin films with a preferential orientatio n along the (112) direction to be obtained. Scanning electron micrographs o f the cross-sectional and top views of the surface show evidence of the goo d homogeneity of the films. Microprobe analysis as well as X-ray photoelect ron spectroscopy show that an almost stoichiometric composition is obtained . In the best films only 3-8 at.% of oxygen is present, which is very promi sing for such a simple growth technique. Moreover, the oxygen present in th e films segregates at the grain boundaries since there is not any significa nt variation of the interplanar spacing and the optical band gap with the p resence of oxygen. The optical band gap values (1.45 eV) increases slightly with the crystalline state. (C) 2001 Elsevier Science B.V. All rights rese rved.