Band offsets of Er2O3 films epitaxially grown on Si substrates

The experimental data on band alignments of high-k Er2O3 films epitaxially grown on Si substrates by molecular beam epitaxy are reported. By using x-ray photoelectron spectroscopy, the valence and the conduction-band offsets of Er2O3 to Si are obtained to be 3.1±0.1 and 3.5±0.3eV, respectively, showing a roughly symmetrical offset at the conduction and the valence band. The energy gap of Er2O3 is determined to be 7.6±0.3eV. From the band offset viewpoint, those obtained numbers indicate that Er2O3 could be a promising candidate for high-k gate dielectrics.