Gate mesa terminal with drain-field-plated β-Ga2O3 MOSFET with ultra-high power figure of merit

Abstract

In this article, a novel gate mesa terminal (GMT) device structure incorporating a drain field plate is proposed. This design features mesa terminals with varying bevel angles positioned atop the gate. The objective is to enhance the breakdown voltage (V_br) and reduce the on-resistance (R_on) of the lateral β-Ga₂O₃ metal-oxide-semiconductor field-effect transistor (MOSFET). Through the implementation of the GMT structure, the peak electric field within the β-Ga₂O₃ MOSFET is redirected towards the passivation layer. This effectively mitigates the electric field in the epitaxial layer, thereby increasing V_br. The optimal values for V_br, specific on-resistance (R_on,sp) and maximum transconductance (g_m) across various GMT structures are 4827 V, 9.9 mΩ·cm² and 15.32 mS/mm, respectively. These metrics represent a 2.63-fold, 0.88-fold, and 1.25-fold improvement compared to the non-GMT structure. Additionally, when the doping concentration of epitaxial layer is 1 × 10¹⁶ cm⁻³, the GMT achieves an enhanced threshold voltage of +0.26 V. By simulating different bevel angles, field plate parameters, epitaxial layer doping concentrations, and mesa thicknesses, an optimal power figure of merit (PFOM) of 1.914 GW cm⁻² is attained. This innovative design introduces a fresh concept for the development of the next generation of high voltage and high-power devices rated above 4 KV.