High Breakdown Voltage (−201) $\beta $ -Ga2O3 Schottky Rectifiers

β-Ga
₂
O
₃
Schottky barrier diodes were fabricated in a vertical geometry structure consisting of Ni/Au rectifying contacts without edge termination on Si-doped epitaxial layers (10 μm, n~4×10
¹⁵
cm
^-3
) on Sn-doped bulk Ga
₂
O
₃
substrates with full-area Ti/Au back Ohmic contacts. The reverse breakdown voltage, VBR, was a function of rectifying contact area, ranging from 1600 Vat 3.1×10
^-6
cm
²
(20-μm diameter) to ~250 Vat 2.2×10
^-3
cm
^-2
(0.53-mm diameter). The current density near breakdown was not strongly dependent on contact circumference but did scale with contact area, indicating that the bulk current contribution was dominant. The lowest ON-state resistance, Ron, was 1.6 mQ· cm
²
for the largest diode and 25 mQ·cm
²
for the 1600-V rectifier, leading to a Baliga figure-of-merit (V2BR/Ron) for the latter of approximately 102.4 MW·cm
^-2
. The ON-OFF ratio was measured at a forward voltage of 1.3 V and ranged from 3×10
⁷
to 2.5×10
⁶
for reverse biases from -5 to -40 V and showed only a small dependence on temperature in the range from 25 °C to 100 °C.