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

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.