OG-FET: An In-Situ ${O}$ xide, ${G}$ aN Interlayer-Based Vertical Trench MOSFET

In this letter, a novel device design to achieve both low ON-resistance and enhancement mode operation in a vertical GaN FET is demonstrated. In the traditional trench MOSFET structure, a dielectric is deposited on an n-p-n trenched structure and the channel forms via p-GaN inversion at the dielectric/p-GaN interface. However, this results in a relatively high ON-resistance due to poor electron mobility in the channel. By changing the structure to include a metal-organic chemical vapor deposition (MOCVD)-regrown Un-intentionally Doped (UID)-GaN interlayer followed by an in-situ dielectric (MOCVD Al
₂
O
₃
) cap on the n-p-n trenched structure, a pathway (channel) for enhanced electron mobility is created, resulting in reduced ON-resistance. Preliminary results for this device design demonstrated almost 60% reduction in the ON-resistance and similar breakdown voltage compared with a traditional trench MOSFET structure while maintaining normally off operation with a threshold voltage of 2 V.