By measuring the current-voltage and capacitance-voltage characteristics of thin La2O3 film at several different temperatures ranging from 100 to 400 K and after constant-voltage stressing at different durations, we reveal the existence of a shallow electron trap with energy of about 0. 19 eV below the conduction band edge of La2O3. This kind of trap is involved in the thermal-assisted Poole-Frenkel tunneling through the dielectric layer. Significant charge trapping and detrapping are found in samples annealed in nitrogen at 400 degrees C. The charge trapping-detrapping events are attributed to the oxygen vacancies with activation energy of 0.332 eV, which is assigned to the relaxation between the charging states of the O-vacancies. The trapping characteristics of samples annealed at 600 degrees C are greatly improved as a consequence of O-vacancy removal and formation of interfacial silicon oxide layer. (C) 2007 Elsevier Ltd. All rights reserved.