Recessed gate GaN MODFETs

Abstract

MODFETs, with and without gate recess, were fabricated on a GaNAl0.27Ga0.73N heterostructure. The gate recess etch was performed with an ECR etch. The gate recess etch improved the maximum transconductance from 23 to 45 mS/mm, ft from 11.4 to 14 GHz, and fmax from 21.2 to 42.5 GHz. The physical gate length of 0.25 μm before recess etch increased to 0.4 μm due to the etching of the resist. Through gate recess, the decrease of the distance between the gate and 2DEG increased the maximum transconductance and the decrease of the effective gate length increased ft and fmax.