High Performance β-Ga2O3 vertical Schottky Barrier Diodes

Gallium oxide (Ga
₂
O
₃
) has received much attention in recent years, for its ultra-wide bandgap (4.5-4.8 eV), high theoretical breakdown field (8 MV/cm), low cost and large-size native substrate. Benefiting from the high current handling capability, Ga
₂
O
₃
vertical Schottky barrier diodes (SBDs) are much more desirable for power switching applications. However, there is a high-density interface state at the dielectric/Ga
₂
O
₃
interface in the vertical β-Ga
₂
O
₃
SBDs, resulting in high reverse leakage current and poor breakdown characteristics. To overcome the aforementioned problem, a high-performance vertical β-Ga
₂
O
₃
Schottky Barrier Diode (SBD) with a novel homologous air bridge field plate (HABFP) is reported. An air space is constructed at the foot of the anode, using a double dielectric layer with 20 nm SiO
₂
and 300 nm SiN
_x
by self-aligned wet etching. The HABFP structure effectively suppresses the high peak electric field at anode foot, since the anode metal is separated from the dielectric/Ga
₂
O
₃
interface. Compared with devices with a conventional field plate (CFP) using single SiN
_x
or SiO
₂
, the fabricated HABFP β-Ga
₂
O
₃
SBD demonstrates a much higher breakdown voltage (V
_br
) of 1100 V, while maintaining a relatively low specific on-resistance (Ron,sp) of 1.83 mΩ·cm
²
. Besides, the mechanism of the novel HABFP structure on the performance of β-Ga
₂
O
₃
SBD is also analyzed, indicating that HABFP structure is a simple and effective termination technique.