AlGaN/GaN HEMTs With Low Leakage Current and High On/Off Current Ratio

In this letter, we propose using an oxide-filled isolation structure followed by N2/H2postgate annealing to reduce the leakage current in AlGaN/GaN HEMTs. An off-state drain leakage current that is smaller than 10-9A/mm (minimum 5.1 × 10-10A/mm) can be achieved, and a gate leakage current in the range of 7.8 ×10-10to 9.2 × 10-11A/mm (VGSfrom -10 to 0 V andVDS= 10 V) is obtained. The substantially reduced leakage current results in an excellent on/off current ratio that is up to 1.5 × 108. An improved flicker noise characteristic is also observed in the oxide-filled devices compared with that in the traditional mesa-isolated GaN HEMTs.