Gallium oxide (Ga<inf>2</inf>O<inf>3</inf>) is promising next-generation semiconductor material for high power and low loss devices. Its wide band gap of 4.5-4.9 eV results in a high breakdown field of <tex>$\sim 8\ \mathrm{MV}/\mathrm{cm}$</tex> and Baliga's FOM of <tex>$\sim 3400$</tex>. Among several polytypes of Ga<inf>2</inf>O<inf>3</inf>, β-Ga<inf>2</inf>O<inf>3</inf> is the most viable option that can provide cost-effective and high-quality wafers with an edge-defined film-fed growth (EFG) method [1]. Several groups have reported excellent electric characteristics of vertical-type power devices using the β-Ga<inf>2</inf>O<inf>3</inf> wafers [2]–[4]. We also demonstrated Schottky barrier diodes (SBDs) [5], trench metal-oxide-semiconductor SBDs (MOSSBDs) [6], junction barrier Schottky diodes [7], and trench metal-oxide-semiconductor field-effect transistors (MOSFETs) [8].