Switching Performance Analysis of 3.5 kV Ga2O3 Power FinFETs

This article presents switching performance analysis of a normally-off 3.5 kV
$\beta $
-Ga
₂
O
₃
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 Al
₂
O
₃
in the planar regions and partially-filled (PF) inter-fin areas and (ii) 130-nm-thick Al
₂
O
₃
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 Al
₂
O
₃
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 cm
²
/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 cm
²
/Vs), bulk fin (30 cm
²
/Vs), and MOS channel (2 cm
²
/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 Ga
₂
O
₃
FinFETs with enhanced switching performance for low-waste power conversion applications.