Structural and electrical properties of a La₂O₃ thin film as a gate dielectric

La₂O₃ thin films with thicknesses of about 12 nm were directly deposited on Si substrates by using metalorganic chemical-vapor deposition (MOCVD) with La(tmhd)₃ as a source precursor. The structural and the electrical properties of the as-deposited and annealed films were investigated as functions of annealing temperature and the results were compared with those for La₂O₃ films with thicknesses of 42 nm. The 12-nm-thick film did not crystallize when annealed at temperatures up to 900 °C while the 42-nm-thick film did crystallize. The dielectric constant of the as-deposited 12-nm-thick film was 21, and the capacitance equivalent-oxide thickness was 2.2 nm. The leakage current density of the film was about 10^-2 A/cm² at +1 V. As the annealing temperature was increase, the dielectric constant and the leakage current density of the film decreased. Although the dielectric constants of the films with thicknesses of 12 nm were small and the leakage current densities were high compared with the films with thicknesses of 42 nm, the dielectric constant was high enough for applications as a future gate dielectric.