AlGaN/GaN HEMTs on Silicon With Hybrid Schottky-Ohmic Drain for High Breakdown Voltage and Low Leakage Current

In this letter, a hybrid Schottky-ohmic drain structure is proposed for AlGaN/GaN high-electron-mobility transistors on a Si substrate. Without additional photomasks and extra process steps, the hybrid drain design forms a Γ-shaped electrode to smooth the electric field distribution at the drain side, which improves the breakdown voltage and lowers the leakage current. In addition, the hybrid drain provides an auxiliary current path and decreases the on-resistance, in contrast to the devices with a pure Schottky drain. Compared with the conventional ohmic drain devices, the breakdown voltage could be improved up to 64.9%, and the leakage current is suppressed by one order of magnitude without degradation of the specific on-resistance.