Enhancement-Mode Ga2O3 Vertical Transistors With Breakdown Voltage >1 kV

High-voltage vertical Ga
₂
O
₃
MISFETs are developed employing halide vapor phase epitaxial (HVPE) layers on bulk Ga
₂
O
₃
(001) substrates. The low charge concentration of ~10
¹⁶
cm
^-3
in the n-drift region allows three terminal breakdown voltages to reach up to 1057 V without field plates. The devices operate in the enhancement mode (E-mode) with a threshold voltage of ~1.2-2.2 V, a current ON/OFF ratio of ~10
⁸
, an ON resistance of ~13-18 mΩ·cm
²
, and an output current of >300 A/cm
²
. This is the first report of high-voltage vertical Ga
₂
O
₃
transistors with E-mode operation, a significant milestone toward realizing Ga
₂
O
₃
based power electronics.