Silicon nanocomposites (nc-Si) with rare earth metals (REM) were synthesized by electron-beam evaporation. The structure of nanocomposites was studied by atomic-force microscopy. The size of nanocrystallites was about 10–40 nm. Also chemical composition of obtained material was examined. The distribution of rare earth elements (REE) was uniform in film thickness, but it was characterized by a presence of maximum peak at the interface film-substrate. In the work the electrical and optical properties of nanocomposites Si:REE were investigated. Silicon nanocomposites with Eu or Y were characterized by high sensitivity to visible radiation. The ratio of dark to light resistance was achieved to 2 orders of magnitude, making this material very promising to use in thin-film photosensors. After deposition of nanocomposites Si:REE on silicon substrate, the heterojunction was formed at the interface film-substrate, for which the sensitivity to visible radiation was observed too (1–2 mA/lmV). Also, the presence of photovoltaic effect in such structures was shown, so they can be the basis of cheap thin-film solar cells, using the relevant design solutions.