Band alignment of wide-bandgap BeO epitaxially grown on α-Ga2O3

Abstract

The development of next-generation power electronics demands ultrawide-bandgap semiconductors that can operate under extreme conditions. While alpha-phase gallium oxide (alpha-Ga2O3) exhibits exceptional properties, its practical application is hindered by intrinsically low thermal conductivity (8.0-11.6 W/m center dot K) and limited conduction band offsets (CBOs) with conventional dielectrics. In this study, we demonstrate the successful epitaxial growth of beryllium oxide (BeO) on alpha-Ga2O3 using plasma-enhanced atomic layer deposition, which provides a large CBO and suggests potential advantages in interfacial thermal properties due to the high thermal conductivity of BeO. Structural analyses using transmission electron microscopy and X-ray diffraction verified that BeO grew as a single crystal with atomically sharp interfaces, enabled by hexagonal symmetry matching. Furthermore, the band alignment was identified as type-I, with a CBO of 2.7 eV. These results indicate that BeO is a promising dielectric for alpha-Ga2O3 devices.