High-Voltage-Design and Ultrafast-Switching Issues of an UWBG Vertical Ga₂O₃MOSFET

The availability of large substrates, excellent doping control and ability to grow drift layers with low background impurities are key technological advantages of Ga2O3 besides its large breakdown field strengths and good electron mobility. While low thermal conductivity is a challenge, the low positive temperature co-efficient of resistance combined with advanced packaging solutions offer potential pathway for thermal management. This paper focuses on the design issues of world's first high-voltage (10-20 kV) β-Ga2 O3 based vertical insulated gate MOSFET including its structural, epitaxial, and thermal issues. Although 10 kV lateral MOSFETs have been demonstrated, vertical MOSFETs offer advantages in terms of minimizing surface related effects as the high fields are buried in the drift layers. Moreover, vertical devices offer compact layout as the breakdown can be increased without increasing the lateral dimensions. Additionally, this manuscript discusses the ultrafast switching challenges and potential solutions for such a HV ultra-wide-bandgap device at extremely high current and voltage slew rates of 100 A/ns and 250 V/ns.