Energy band offsets of BeO dielectrics grown via atomic-layer deposition on β-Ga2O3 substrates

Abstract

We report the energy-band alignment of atomic layer-deposited (ALD) beryllium oxide (BeO) films and β-Ga2O3 substrates. BeO is a unique oxide with a high dielectric constant and bandgap energy that can be used as a gate dielectric; however, it also has an extremely high thermal conductivity. It has great potential to improve the heat dissipation of β-Ga2O3 power devices. In this study, the conduction band offset between the BeO film and β-Ga2O3 substrate was found to be 3.4 eV, which was larger than those of conventional high-k gate dielectrics. In addition, the bandgap energies (8.6 eV and 4.7 eV for BeO and β-Ga2O3, respectively) were determined using reflection electron energy loss spectroscopy. The valence band offset (0.5 eV) was calculated using Kraut's method with the core level and valence band maximum energies of the BeO film and β-Ga2O3 substrate. The high conduction band offset provided by the ALD BeO dielectric on the β-Ga2O3 substrate lowered the gate leakage current density of a β-Ga2O3 power device.