La2O3 films are grown on Si (100) substrates by the radio-frequency magnetron sputtering technique.The band alignment of the La2O3/Si heterojunction is analyzed by the x-ray photoelectron spectroscopy.The valenceband and the conduction-band offsets of La2O3 films to Si substrates are found to be 2.40±0.1 and 1.66±0.3eV,respectively.Based on O 1s energy loss spectrum analysis,it can be noted that the energy gap of La2O3 films is 5.18±0.2eV,which is confirmed by the ultra-violet visible spectrum.According to the suitable band offset and large band gap,it can be concluded that La2 O3 could be a promising candidate to act as high-k gate dielectrics.