4.4 kV β-Ga2O3 Power MESFETs with Lateral Figure of Merit exceeding 100 MW/cm2
Abstract
Field-plated (FP) depletion-mode MOVPE-grown β-Ga2O3 lateral MESFETs are realized with superior reverse breakdown voltages and ON currents. A sandwiched SiNx dielectric field plate design was utilized that prevents etching-related damage in the active region and a deep mesa-etching was used to reduce reverse leakage. The device with LGD = 34.5 μm exhibits an ON current (IDMAX) of 56 mA/mm, a high ION/IOFF ratio > 108 and a very low reverse leakage until catastrophic breakdown at 4.4kV. The highest measurable VBR recorded was 4.57 kV (LGD = 44.5 μm). An LFOM of 132 MW/cm2 was calculated for a VBR of 4.4 kV. The reported results are the first > 4kV-class Ga2O3 transistors to surpass the theoretical FOM of Silicon. These are also the highest IDMAX and lowest RON values achieved simultaneously for any β-Ga2O3 device with VBR > 4kV to date. This work highlights that high breakdown voltages (VBR), high lateral figure of merit (LFOM) and high ON currents can be achieved simultaneously in β-Ga2O3 lateral transistors.