Band offsets of $\mathrm{Er}_{2}\mathrm{O}_{3}$ films grown on Ge substrates by X-ray photoelectron spectroscopy

Abstract

The band alignments of high-k Er₂O₃ films grown on Ge substrates by molecular beam epitaxy are determined by X-ray photoelectron spectroscopy. The valence-band and the conduction-band offsets of Er₂O₃ to Ge are found to be $3.16\pm0.02$ and $2.13\pm0.02\ \mbox{eV}$, respectively. The energy gap of Er₂O₃ is $5.96\pm0.02\ \mbox{eV}$ as determined by the optical spectrophotometry. From the band offset viewpoint, the above results indicate that Er₂O₃ could be a promising candidate for high-k gate dielectrics on Ge substrate.