Vertical Ga2O3 Schottky barrier diodes on single-crystal β-Ga2O3 (−201) substrates

Owing to the large bandgap, breakdown electric field (E
_b
) and high carrier mobility, wide-bandgap semiconductor (e.g. SiC and GaN) based power devices have been extensively studied for next-generation power-switching applications [1-2]. Recently, a new wide-bandgap oxide semiconductor, gallium oxide (β-Ga
₂
O
₃
), has attracted attention for power-switching applications because it has an extremely large bandgap of 4.5~4.9 eV enabling a high breakdown voltage (V
_br
) and a high Baliga's figure of merit [3]. Furthermore, large-area and high-quality bulk substrates of Ga
₂
O
₃
can be grown by low-cost methods, which remains a significant challenge for both SiC and GaN. Schottky barrier diodes (SBDs), with a low turn-on voltage and a fast switching speed due to majority carrier conduction, are ideal candidates for high-power and high-speed rectifiers. Recently, Higashiwaki et al. have demonstrated excellent device results, which includes SBDs with V
_br
~115 V on (010) Ga
₂
O
₃
substrates (with a net doping concentration N
_D
-N
_A
~ 5×10
¹⁶
cm
^-3
) [4] and SBDs with epitaxial Si-doped n-Ga
₂
O
₃
drift layers (N
_D
-N
_A
~ 1.4×10
¹⁶
cm
^-3
) grown by HVPE on (001) Ga
₂
O
₃
substrates with V
_br
~ 500 V [5]. Oishi et al reported Ni-based SBDs on (-201) Ga
₂
O
₃
with a Nd-Na ~ 1×10
¹⁷
cm
^-3
and V
_br
~ 40 V [6]. However, no high voltage (V
_br
> 100 V) devices have been reported yet on (-201) Ga
₂
O
₃
, the crystal orientation readily available in up to 4 inch diameter wafer. In this work, we report Pt-based SBDs fabricated on unintentionally-doped (UID) (-201) n-type Ga
₂
O
₃
substrates with V
_br
> 100 V.