Valence and conduction band offsets at beryllium oxide interfaces with silicon carbide and III-V nitrides

Abstract

Beryllium oxide (BeO) is a large bandgap material with extreme properties that make it an ideal gate dielectric for pairing with other wide bandgap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN). In this regard, the authors have utilized x-ray photoemission spectroscopy to determine the valence band offset (VBO) between atomic layer deposited (ALD) BeO and epilayers of the cubic form of silicon carbide (3C-SiC) grown on crystalline silicon (Si) substrates. The BeO VBO with 3C-SiC epilayers grown on both Si (111) and (001) substrates was determined to be 1.6 ± 0.1 and 1.5 ± 0.1 eV, respectively. Applying the band alignment rules of transitivity and commutativity, the authors additionally determine the VBO for BeO with GaN, aluminum nitride, and hexagonal boron nitride to be 0.9 ± 0.2, 0.7 ± 0.3, and 1.0 ± 0.2 eV, respectively. Utilizing the reported bandgap for ALD BeO (8.0 ± 0.1 eV) and literature values for SiC and the group III-nitrides (III-N), the authors find a type I band alignment with conduction band offsets >1 eV in all cases. These results indicate that BeO is a promising dielectric for wide bandgap SiC and III-N high-power, high-temperature, and high-frequency device applications.