Breakdown Characteristics of $\beta$ -(Al0.22Ga0.78)2O3/Ga2O3 Field-Plated Modulation-Doped Field-Effect Transistors

We investigate voltage breakdown of a β-(Al
_0.22
Ga
_0.78
)
₂
O
₃
/Ga
₂
O
₃
modulation-doped field-effect transistor with a gate-connected field-plate and silicon nitride (SiN
_x
) as the passivation layer. Breakdown characteristics were found to be limited by the Schottky gate. We demonstrate a high breakdown voltage of 1.37 kV for a gate-to-drain separation (LGD) of 16 μm with a specific ON-resistance of 120.1 mQ · cm
²
. A high average electric field of 3.9 MV/cm is extracted for LGD = 320 nm. The reported results suggest SiN
_x
as a potential passivation dielectric for Ga
₂
O
₃
.