High-blocking-voltage UMOSFETs with reformed electric field distribution

A high-performance vertical GaN metal–oxide–semiconductor field-effect transistor (MOSFET) with a U-shaped gate (UMOSFET) and high blocking voltage is proposed. The main concept behind this work is to reform the electric field distribution to achieve high blocking voltage. The proposed structure includes p-regions in the drift region, which we call reformed electric field (REF) regions. Simulations using the two-dimensional SILVACO simulator reveal the optimum doping concentration, and width and height of the REF regions to achieve the maximum depletion region at the breakdown voltage in the drift region. Also, the electric field distribution in the REF-UMOSFET is reformed by producing additional peaks, which decreases the common peaks under the gate trench. We discuss herein the impact of the height, width, and doping concentration of the REF regions on the ON-resistance (R_ON) and blocking voltage. The blocking voltage, specific ON-resistance, and figure of merit \( \left( {{\text{FOM}} = \frac{{V_{{{\text{BR}}}}^{2} }}{{R_{{{\text{ON}}}} }}} \right) \) are 1140 V, 0.587 mΩ cm² (V_GS = 15 V, V_DS = 1 V), and 2.214 GW/cm², respectively. The blocking voltage and FOM are increased by about 72 % and 171 % in comparison with a conventional UMOSFET (C-UMOSFET).