High-Voltage Polarization-Superjunction GaN HEMT With Built-In SBD for Low Reverse Conduction Loss

A GaN Reverse-Conducting HEMT (RC-HEMT) is proposed and fabricated on the GaN/AlGaN/GaN platform. It features an integrated Schottky barrier diode (SBD) to realize reverse conduction and the double-heterojunction to enhance breakdown voltage (BV). Compared with the inherent reverse conduction capability of the conventional HEMT (Con. HEMT), the built-in SBD exhibits a low reverse turn-on voltage (
$V_{\text{RT}}$
) and its
$V_{\text{RT}}$
is independent of the threshold voltage and gate bias. At the off-state, the fixed positive and negative polarization charges form the polarization superjunction (PSJ). Therefore, the depletion region is extended and more uniform E-field distribution is obtained. Experimental results show that the RC-PSJ-HEMT achieves a low
$V_{\text{RT}}$
of 0.68 V, which decreases 69.1% compared with that of the Con. HEMT. The BV of the RC-PSJ-HEMT (with
$7.5 \mu \text{m}$

$V_{\text{GD}}$
) is increased to 723 V from 202 V of the Con. HEMT.