GaN Vertical MOSFETs With Monolithically Integrated Freewheeling Merged pn-Schottky Diodes (MPS-MOS) for 1.2-kV Applications

We report 1.2-kV-class GaN-based vertical trench MOSFETs (T-MOS) with monolithically integrated merged pn-Schottky (MPS) diodes (MPS-MOS) by numerical simulation. The proposed MPS-MOS possesses excellent freewheeling capability, homogenized electric field distribution, as well as enhanced breakdown voltages as compared to conventional GaN vertical T-MOS with intrinsic bipolar body p-i-n diodes. With optimum design parameters by numerical simulation, the MPS-MOS exhibits a reverse turn-on voltage of
$- 0.75~{V}$
during the third-quadrant operation, a breakdown voltage of 1435 V, and a reduced reverse recovery current (
${I}_{\text {rr}}\text {)}$
and charge (
${Q}_{\text {rr}}\text {)}$
by 55% and 71%. In addition, a potential approach is provided in this work to suppress the action of the intrinsic body p-i-n diodes, and the principle of the inactivation is explored from the perspective of energy band engineering and carrier distribution modulation. These results reveal great potential of monolithically integrated GaN-based vertical MPS-MOS for high-voltage, high-power density, and high-frequency applications in modern power systems.