Formation of polycrystalline thin films of CuInS2 by a two step process

CuInS2 thin films have been prepared using a two-step process. This involved the deposition of approximately 1700 alternate layers of Cu and In onto molydenum coated glass substrates using magnetron sputtering followed by an anneal in an environment containing elemental sulphur to synthesise the compound. This process results in a Cu11In9 precursor phase free from inhomogeneous secondary phases and the synthesis of the compound using elemental sulphur. This method results in densely packed, randomly orientated polycrystalline layers with the chalcopyrite crystal structure with as-synthesised grain sizes greater than 0.75 mu m for 1 mu m thick layers. Optical data obtained for these layers indicate a direct energy band gap of 1.45 eV. This is the first time that CuInS2 layers have been produced by suphurising magnetron sputtered multiple Cu-In multilayers using elemental sulphur. (C) 1999 Elsevier Science B.V. All rights reserved.