MIS structures Al-Sm2O3-Si were formed by vacuum evaporation of the rare earth element on silicon wafer and by thermal oxidation of the rare earth metal layer in the air at a temperature of 500-550 degrees C. The current-voltage characteristics and temperature dependence of current were measured using direct current. The surface with silicon was determined using the method of high-frequency capacitance-voltage characteristics. The barrier energies on the interfaces Al-Sm2O3 (2.88-2.92 eV) Ni-Sm2O3 (3.28-3.32 eV), Si-Sm2O3, (2.69-2.72 eV) were evaluated from the spectral characteristics of photocurrent by the threshold to internal electron emission and from the dependence of photocurrent on the bias applied to the structure. The main characteristics of photo-injection current and charge trapping in MIS structures with samarium oxide film are described.