Schottky source/drain Al2O3/InAlN/GaN MIS-HEMT with steep sub-threshold swing and high ON/OFF current ratio

Al₂O₃/InAlN/GaN MISHEMTs with Schottky source and drain were experimentally demonstrated with steep subthreshold swing (SS) at room temperature as well as high temperature up to 150 °C. The mechanism for the steep SS was proposed to be based on the dynamic discharging process of the interface states at the Al₂O₃/InAlN interface and the resultant positive feedback in the turn-on of the drain current. The model was validated by temperature-dependent characterization. The use of the Schottky source/drain contacts can effectively prevent the off-state leakage current, leading to high ON/OFF current ratio of ~10¹⁰ in the proposed devices. At room temperature, SS as low as 6.6 mV/dec was observed and SS lower than 60 mV/dec was obtained over a wide drain bias range of 3~10 V during the forward sweep of V_GS. The proposed device delivers a maximum drain current density of 416 mA/mm and peak extrinsic transconductance of 113 mS/mm.