E-mode p-GaN Gate HEMT with p-FET Bridge for Higher VTH and Enhanced VTH Stability

a novel p-GaN gate topology is proposed to inherently increase threshold voltage (V
TH
) and enhance V
TH
stability. The gate consists of a conventional Schottky-type p-GaN gate and a normally-on p-channel FET bridge connecting source and gate. By modulating the V
TH
of the p-channel FET, a wide-range positive V
TH
from 3.6 V to 8.2 V can be achieved without subthreshold voltage degradation. Owing to the well-grounded p-GaN through the normally-on p-FET channel, a stable V
TH
is also achieved without sacrificing the low gate leakage and large gate swing enabled by the Schottky gate metal/p-GaN contact.