Recessed 0.25 µm gate AlGaN/GaN HEMTs onSiC with high gate-drainbreakdown voltage using ICP-RIE

Using inductively coupled plasma reactive ion etching (ICP-RIE), recessed 0.25 µm gate-length AlGaN/GaN high electron mobility transistors (HEMTs) have been fabricated. A post-etch anneal eliminated the plasma-induced damage resulting in an improvement of the gate-drain breakdown voltage from –27 V for the as-etched to over –90 V for the annealed devices. The gate leakage current reduced from 91 to 4 µA at Vgd = –25 V, after annealing. These devices exhibited maximum drain current density of 770 mA/mm, unity gain cutoff frequency (fT) of 48 GHz, and maximum frequency of oscillation (fmax) of 108 GHz.