6.5 V High Threshold Voltage AlGaN/GaN Power Metal-Insulator-Semiconductor High Electron Mobility Transistor Using Multilayer Fluorinated Gate Stack

In this letter, the approach of partial AlGaN recess and multiple layers of fluorinated Al₂O₃ gate dielectric is utilized to achieve highest reported positive gate threshold voltage (V_TH) without severe reduction on 2-D electron gas carrier mobility in AlGaN/GaN HEMTs. Guided by the design and verification through analytical model, proper fluorine ions incorporation is made through fabrication. The approach resulted in a high V_TH of +6.5 V and competitive drain saturation current (I_DMAX) of 340 mA/mm. Furthermore, low gate leakage current and high breakdown voltage of 1140 V were also demonstrated.