A Comprehensive Review on Recent Developments in Ohmic and Schottky Contacts on Ga₂O₃ for Device Applications

Ultrawide bandgap β-gallium oxide (β-Ga2O3) is emerging as a viable candidate for next-generation high-power electronics, including Schottky barrier diodes (SBDs) and field-effect transistors (FETs). This is due to its excellent material properties such as ultrawide bandgap of 4.6–4.9 eV, high breakdown electric field of 8 MV/cm, very high Baliga’s figure of merit (BFOM) and mature technology for large bulk single crystals, and epitaxial techniques with controllable n-type doping. Ohmic and rectifying metal–semiconductor contacts on β-Ga2O3 have been developed over the past decade. This work comprehensively reviews the recent development of metal–semiconductor contacts on β-Ga2O3. We start with basic concepts of metal–semiconductor contacts, which is followed by summarizing the current literature on ohmic and Schottky contacts on β-Ga2O3. Finally, the status of high-power Schottky diode contact on β-Ga2O3 is presented.