Single and multi-fin normally-off Ga2O3 vertical transistors with a breakdown voltage over 2.6 kV

We demonstrate record-high performance in normally-off single and multi-fin b-Ga
₂
O
₃
vertical power transistors. The effective channel mobility is significantly improved up to ~130 cm
²
/V·s with a post-deposition annealing process. With a fin-channel width of 0.15 μm, true normally-off operation is achieved with a threshold voltage of >1.5 V; a record-high breakdown voltage of 2.66 kV (at V
_gs
=0 V) and a specific on-resistance of 25.2 mW·cm
²
are obtained in multi-fin devices, corresponding to a Baliga's figure-of-merit of 280 MW/cm
²
, which is the highest among all Ga
₂
O
₃
transistors. Devices with (100)-like fin-channel sidewalls exhibit the lowest interface trapped charge density and a significantly higher current than other fin orientations. These findings offer important insights on the development of Ga
₂
O
₃
MOSFETs and show great promise of Ga
₂
O
₃
vertical power devices.