Gate-Recessed InAlN/GaN HEMTs on SiC Substrate With Al[subscript 2]O[subscript 3] Passivation

We studied submicrometer (LG = 0.15−0.25 μm) gate-recessed InAlN/AlN/GaN high-electron mobility transistors (HEMTs) on SiC substrates with 25-nm Al2O3 passivation. The combination of a low-damage gate-recess technology and the low sheet resistance of the InAlN/AlN/GaN structure resulted in HEMTs with a maximum dc output current density of IDS,max = 1.5 A/mm and a record peak extrinsic transconductance of gm,ext = 675 mS/mm. The thin Al2O3 passivation improved the sheet resistance and the transconductance of these devices by 15% and 25%, respectively, at the same time that it effectively suppressed current collapse.