[en] In the article Cu-In-Se thin films obtained by dosed deposition of Cu onto indium selenide starting layer with the further annealing of the two-layered composition in Se atmosphere were investigated by transmission electron microscopy (TEM) and by energy-dispersive X-ray spectroscopy (EDS). The samples with various Cu content, Cu/In<1 and Cu/In>1, were prepared. It was revealed that all films after selenization had a modulated structure, which was formed due to Cu diffusion into the indium selenide film. Such modulated structures have been formed by both equilibrium phases of the Cu₂Se-In₂Se₃ pseudo-binary section of the Cu-In-Se ternary system and by metastable ones