Real-time study of phase transformations in Cu–In chalcogenide thin films using in situ Raman spectroscopy and XRD Original Research Article

The growth of polycrystalline CuInSe2 and CuInS2 thin films from metallic precursor layers is investigated using two complementary in situ methods which give bulk sensitive (XRD) and surface sensitive (Raman) information. From the time evolution of the XRD and Raman peak intensities the phase transformation sequences and the reaction kinetics can be derived. In both cases the chalcogenization of the Cu–In precursors proceeds at the top surface. Thus, the process is at least limited by cation diffusion through the metallic precursor. However, the growth kinetics of CuInSe2 and CuInS2 films differ. While the CuInSe2 growth is limited by the reaction of binary phases, CuInS2 growth is controlled by fast diffusion which is solely restricted to the period of raising temperature during the process.