Effects of nitrogen radical irradiation on device characteristics of vertical β-Ga2O3(010) FinFETs

We investigated effects of nitrogen radical irradiation on device characteristics of vertical β-Ga2O3(010) fin field-effect transistors (FinFETs). A positive shift in threshold voltage with improved in-plane distribution uniformity occurred for nitridated FinFETs due to fixed negative charges formed in nitridated layers on fin sidewalls, indicating that the nitridation treatment can effectively re-establish the post-etched sidewall surface conditions. The breakdown voltage (Vbr) was also uniformly distributed for the nitridated FinFETs, while the specific on-resistance (Ron) was reduced by adopting multi-fin structure and increasing fin width. The nitridated Ga2O3(010) multi-FinFET with a fin width of 300 nm achieved normally off operation with superior device characteristics of a subthreshold swing of 73 mV/decade, an Ion/Ioff ratio of >1010, an Ron of 9.5 mΩ cm2, a Vbr of 1213 V, and a power figure of merit of 1.55 × 108 W/cm2.