Composition and structure of CuInS2 films prepared by spray pyrolysis

CuInS2 thin films have been prepared by spray pyrolysis of an aqueous solution of CuCl2, InCl3 and thiourea onto heated glass substrates. The effect of the composition of starting solutions on the phase and chemical composition and the structure of sprayed films is studied, The Cu/In ratio in the films is higher than that in the solution. In-rich and S-rich solutions lead to the multiphase films with poor crystallinity according to X-ray diffraction. It was determined that organic phases as products of the thermal decomposition of thiourea ligand are present in the films at all used solution compositions. The formed organic secondary phases could be responsible for the formation of molten phase which together with copper sulphide act as recrystallisation agent during the growth of copper-rich films. The CuInS2 films, strongly orientated in the (112) direction with crystallites up to 300 nm in the matrix and with large crystals of some microns in agglomerated areas, are formed while the secondary phases segregated on the thin film surface. (C) 2000 Elsevier Science S.A. All rights reserved.