710 v breakdown voltage in field plated Ga₂O₃ MOSFET

FJ-Gallium oxide (Ga₂O₃) is an increasingly attractive choice for next generation power electronics applications due to its high Baliga's figure of merit (BFoM) and mature bulk substrate growth technologies. Recent experiments have shown its great potential as the next generation power semiconductor. There have been reports on MOSFETs with breakdown of750 V[l], large on current densities exceeding 1.5 A/mm [2], and enhancement mode operation by interface state modulation [3]. In order to increase the breakdown voltage of Ga₂O₃ MOSFETs, the electric field needs to be reduced in the gate oxide and air near the gate-drain region; breakdown could occur in these regions before the intrinsic Ga₂O₃ breakdown in the channel. In this report, we design a composite ALD/PECVD field plate to increase the breakdown voltage of Ga₂O₃ MOSFETs achieving a maximum breakdown voltage of 710 V. The comparison between field plate and non-field plate devices suggest breakdown outside the channel and field plate oxide region, indicating the channel is still far from breakdown condition.