Band offsets of high K gate oxides on III-V semiconductors

TLDR

III‑V semiconductors, prized for high mobility, require gate dielectrics with band offsets exceeding 1 eV to suppress leakage in field‑effect transistors. Band offsets for HfO₂, Al₂O₃, Gd₂O₃, Si₃N₄, and SiO₂ on GaAs, InAs, GaSb, and GaN were computed via charge‑neutrality‑level calculations. The calculations show that most dielectrics exhibit conduction band offsets above 1 eV and sizable valence offsets, except SrTiO₃ and a few GaN interfaces, and these results largely agree with experimental data, though the GaAs:SrTiO₃ case is anomalous.

Abstract

III-V semiconductors have high mobility and will be used in field effect transistors with the appropriate gate dielectric. The dielectrics must have band offsets over 1eV to inhibit leakage. The band offsets of various gate dielectrics including HfO2, Al2O3, Gd2O3, Si3N4, and SiO2 on III-V semiconductors such as GaAs, InAs, GaSb, and GaN have been calculated using the method of charge neutrality levels. Generally, the conduction band offsets are found to be over 1eV, so they should inhibit leakage for these dielectrics. On the other hand, SrTiO3 has minimal conduction band offset. The valence band offsets are also reasonably large, except for Si nitride on GaN and Sc2O3 on GaN which are 0.6–0.8eV. There is reasonable agreement with experiment where it exists, although the GaAs:SrTiO3 case is even worse in experiment.