SiO₂ Passivation Effects on the Leakage Current in AlGaN/GaN High-Electron-Mobility Transistors Employing Additional Schottky Gate

Abstract

The leakage current of AlGaN/GaN high-electron-mobility transistors employing the additional Schottky gate before and after SiO2 passivation is investigated. The SiO2 passivation successfully decreases the drain leakage current from 1.70 µA to 88.05 nA due to the suppressed conduction of surface trap states. The leakage current injection from additional-gate to main-gate is observed in the unpassivated device while no leakage current injection at additional-gate is observed in the passivated device. The measured leakage current at additional-gate in the unpassivated device and passivated one are 15.58 µA and 7.10 pA respectively. The measured leakage current at main-gate in those devices are -50.72 µA and -91.10 nA respectively. The SiO2 passivation for AlGaN/GaN HEMT employing additional Schottky gate successfully decreases the leakage current through surface trap states as well as the undesirable leakage current between Schottky contacts.