A Hybrid Schottky-Ohmic Drain Contact for Thermally Stressed Beta-Gallium Oxide Field-Effect Transistors

Degradation of ohmic contacts on beta-Ga2O3 under thermal stress conditions is a severe issue that hinders its high-temperature applicability. Herein, a hybrid Schottky-ohmic drain contact (HSD) is demonstrated in beta-Ga2O3 field-effect transistors (FETs). It is compared with a conventional ohmic drain contact (OD) after extended thermal annealing. Pulsed drain bias measurement is conducted to investigate the trapping process at the interface of both drain contacts with the beta-Ga2O3 channel. Even with the extended Schottky metal region, the beta-Ga2O3 FET with the HSD contact exhibits similar contact and on-resistance. Additionally, it shows field-effect mobility higher than that of the OD contact device. Enhanced off-state breakdown characteristics are achieved.