Switching Performance Analysis of 3.5 kV Ga 2 O 3 Power FinFETs

This article presents switching performance analysis of a normally-off 3.5 kV $\beta $ -Ga2O3 power FinFET using Silvaco TCAD simulation platform. The simulated electric field and OFF-state capacitances at a drain voltage ( ${V}_{\text {D}}{)}$ of 3.5 kV were compared for FinFETs with two different structures: (i) 30-nm-thick Al2O3 in the planar regions and partially-filled (PF) inter-fin areas and (ii) 130-nm-thick Al2O3 in the planar regions and fully-filled (FF) inter-fin areas. The FF FinFET showed a smaller OFF-state ${C}_{\text {GS}}$ and ${C}_{\text {GD}}$ and the thicker Al2O3 significantly reduced peak electric field at the corner of the fin. Therefore, via TCAD device-circuit-integrated model, the impact of electron mobility in the MOS channel, bulk fin and drift region, and the substrate thickness on the device switching performances were investigated on a single-fin FF FinFET structure. The device with 100- $\mu \text{m}$ -thick substrate and ideal drift region and fin mobilities of 180 cm2/Vs showed 82.6% improvement in the total switching time and 82.2% lower switching losses compared with the device which had thicker substrate thickness ( $600~\mu \text{m}$ ) and lower electron mobilities in the drift region (130 cm2/Vs), bulk fin (30 cm2/Vs), and MOS channel (2 cm2/Vs). Moreover, the switching performance of multifin FF FinFETs with different fin width/pitch ratio was studied. At a given pitch size of 700 nm, the total power loss of the input power at a frequency of 200 kHz was reduced from 0.83% to 0.61% as pitch ratio reduced from 57.1% to 14.3%. These findings provide helpful insights for design and fabrication of Ga2O3 FinFETs with enhanced switching performance for low-waste power conversion applications.