DC and RF characteristics of AlGaN/GaN HEMTs on SiC with gate recessed by using ICP etching of BCl3/Cl2

Abstract

We fabricated a 0.17-μm gate-length AlGaN/GaN high electron mobility transistor (HEMT) on SiC recessed by using ICP gate etching with a gas mixture of BCl3/Cl2. The ICP gate recess process exhibited an etch rate of 20 nm/min for the AlGaN layer and the clean surface characteristics at the etched AlGaN/gate metal interface for the AlGaN/GaN HEMT devices. The recessed 0.17 μm × 200 μm AlGaN/GaN HEMT devices showed good DC characteristics, having a high gateto-drain breakdown voltage of -177 V, a good Schottky diode ideality factor of 1.32, an extrinsic transconductance (g m ) of 245 mS/mm, and a threshold voltage (V th ) of -2.6 V. The recessed 0.17 μm × 200 μm AlGaN/GaN HEMT devices also exhibited high RF performance, having a cut-off frequency (f T ) of 46 GHz and a maximum oscillation frequency (f max ) of 150 GHz.