GaN-on-Si Quasi-Vertical Power MOSFETs

We demonstrate the first GaN vertical transistor on silicon, based on a 6.7-
$\mu \text{m}$
-thick n-p-n heterostructure grown on 6-inch silicon substrate by metal organic chemical-vapor deposition. The devices consist of trench-gate quasi-vertical metal–oxide–semiconductor field-effect transistors with a 4-
$\mu \text{m}$
-thick drift layer, exhibiting enhancement-mode operation with a threshold voltage of 6.3V and an ON/OFF ratio of over 10
⁸
. A high OFF-state breakdown voltage of 645 V along with a specific ON-resistance of
$6.8~\textsf {m}\Omega \cdot \textsf {cm}^{{\textsf {2}}}$
were achieved thanks to the high-quality 4-
$\mu \text{m}$
-thick GaN drift layer, presenting a relatively low defect density and very high electron mobility (720 cm
$^{{\textsf {2}}}/\textsf {V}\cdot \textsf {s}$
). This excellent performance represents a major step toward the realization of high-performance GaN vertical power transistors on low-cost silicon substrates.