GaN-on-Si Quasi-Vertical Power MOSFETs

Abstract

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 108. 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.