Oxidized Metal Schottky Contacts on (010) $\beta$ -Ga2O3

Oxidized Ir, Pd, Pt, Ag and Au Schottky contacts (SCs) were fabricated on (010) β-Ga
₂
O
₃
single crystal substrates via reactive RF sputtering using an O
₂
: Ar plasma. The use of in situ oxidizing conditions resulted in SCs with very high rectifying barriers in excess of 2.0 eV for all the metals investigated, representing an increase of 0.4-0.9 eV compared with the corresponding plain metal versions. Both the plain and oxidized metal SCs showed evidence of Fermi level pinning with their laterally homogeneous barrier heights lying in narrow ranges of ~1.3-1.5 eV and ~2.2-2.4 eV, respectively, with little correlation with metal work function. This was attributed to the influence of metal-induced oxygen vacancies and gap states at the SC interface, respectively. The very high barriers of the oxidized SCs resulted in excellent high-temperature performance with ~10 orders of magnitude of rectification at 180 °C, indicating the potential of this technique for the fabrication of high-temperature unipolar devices.