High-Speed, Enhancement-Mode GaN Power Switch With Regrown ${\rm n}+$ GaN Ohmic Contacts and Staircase Field Plates

We report a novel GaN heterojunction field-effect transistor device that incorporates vertically scaled epilayers, a nanoscale gate with integrated staircase-shaped field plates, and regrown ohmic contacts. This device technology has an unprecedented combination of high breakdown (176 V), low ON-resistance (1.2 Ωmm), enhancement-mode operation (V
_TH
=+0.35 V), and excellent high-frequency performance (f
_T
/f
_max
=50/120 GHz), which enables new applications as a high-frequency power switch or a microwave power amplifier. The gate design manages the electric field at the drain edge of the gate, which mitigates dynamic ON-resistance degradation.