Recessed-gate enhancement-mode GaN HEMT with high threshold voltage

摘要

Fabrication of enhancement-mode high electron mobility transistors (E-HEMTs) on GaN/AlGaN heterostructures grown on SiC substrates is reported. Enhancement-mode operation was achieved with high threshold voltage (V/sub T/) through the combination of low-damage and controllable dry gate-recessing and the annealing of the Ni/Au gates. As-recessed E-HEMTs with 1.0 /spl mu/m gates exhibited a threshold voltage (V/sub T/) of 0.35 V, maximum drain current (I/sub D,max/) of 505 mA/mm, and maximum transconductance (g/sub m,max/) of 345 mS/mm; the corresponding post-gate anneal characteristics were 0.47 V, 455 mA/mm and 310 mS/mm, respectively. The RF performance is unaffected by the post-gate anneal process with a unity current gain cutoff frequency (f/sub T/) of 10 GHz.