I. Introduction
Beta-gallium oxide (β-Ga2O3) has emerged as a promising candidate material for high-efficiency power switching applications under harsh operating conditions, including high voltage, high temperature and radiation, owing to its ultra-wide bandgap (~4.8 eV), high critical breakdown field (8 MV/cm), large Baliga’s figure-of-merit and high thermal stability[1]-[3]. In addition, high-quality and large-sized Ga2O3 single crystal substrates can be obtained by melt growth methods, which provides a guarantee for the large-scale production and commercialization of power devices based on Ga2O3 in the future.