70-nm-gated InAlN/GaN HEMTs grown on SiC substrate with fT/fmax > 160 GHz**Project supported by the National Natural Science Foundation of China (No. 61306113).

Abstract

InAlN/GaN high-electron-mobility transistors (HEMTs) on SiC substrate were fabricated and characterized. Several techniques, consisting of high electron density, 70 nm T-shaped gate, low ohmic contacts and a short drain–source distance, are integrated to gain high device performance. The fabricated InAlN/GaN HEMTs exhibit a maximum drain saturation current density of 1.65 A/mm at Vgs = 1 V and a maximum peak transconductance of 382 mS/mm. In addition, a unity current gain cut-off frequency (fT) of 162 GHz and a maximum oscillation frequency (fmax/ of 176 GHz are achieved on the devices with the 70 nm gate length.