Progress in α-Ga2O3 for practical device applications

Abstract Recent progress in α -phase gallium oxide ( α -Ga 2 O 3 ) grown on sapphire for low-cost and practical device applications is reviewed. This review focuses on (i) dislocations formed by heteroepitaxy, (ii) p-type conductivity (a common issue with β -Ga 2 O 3 ), and (iii) thermal instability due to the metastable phase of α -Ga 2 O 3 , and discusses efforts aimed at overcoming these issues. The results reveal guidelines for the dislocation density (<1 × 10 8 cm −2 ) so that the dislocation scattering is veiled in the electron transport, and for this purpose we mentioned buffer layers and epitaxial lateral overgrowth. Quasi-vertical Schottky barrier diodes (SBDs) show defect-insensitive behavior in current–voltage characteristics under a low current density. We also demonstrate the heterojunction pn diodes with α -phase iridium oxide ( α -Ir 2 O 3 ) or α -(Ir,Ga) 2 O 3 and the ways to improve thermal stability of α -Ga 2 O 3 . The up-to-date device characteristics, that is, low on-resistance and large current SBDs, and high reverse voltage of 1400 V of a pn junction suggest promising development in α -Ga 2 O 3 -based devices.