Microstructure and Raman scattering of Cu$_{2}$ZnSnSe$_{4}$ thin films deposited onto flexible metal substrates

Cu$_{2}$ZnSnSe$_{4}$ thin films are produced by selenizing electrochemically layer-by-layer deposited and preliminarily annealed Cu–Zn–Sn precursors. For flexible metal substrates, Mo and Ta foils are used. The morphology, elemental and phase compositions, and crystal structure of Cu$_{2}$ZnSnSe$_{4}$ films are studied by scanning electron microscopy, X-ray spectral microanalysis, X-ray phase analysis, and Raman spectroscopy.