Trapping characteristics of lanthanum oxide gate dielectric film explored from temperature dependent current–voltage and capacitance–voltage measurements

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 °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 °C are greatly improved as a consequence of O-vacancy removal and formation of interfacial silicon oxide layer.