Quasi-Vertical GaN-Based Trench Gate MOSFETs Treated with Fluorine-Plasma

In this paper, a quasi-vertical GaN-based trench gate MOSFETs treated with F-plasma is proposed. The F-plasma-treated devices exhibit a breakdown voltage (Vbr) increased from 170 V to 275 V compared to the untreated devices. TCAD simulations reveal that F-plasma treatment significantly reduces the peak electric field of the device, lowering the peak electric field from 18.7 MV/cm to 4.08 MV/cm (at a drain voltage of 900 V). For the F-plasma-treated device with a 4 μm gate trench dimension, the maximum saturation current is 2258.2 A/cm2, and the specific on-resistance (Ron,sp) is 7.2 mΩ·cm2. Stress testing results show that both the treated and untreated devices have their threshold voltage affected by interface charges and traps, with no additional impact of the F-plasma treatment on the threshold voltage stability of the device.