Multi-kV class $\beta$-Ga$_2$O$_3$ MESFETs with a Lateral Figure of Merit up to 355 MW/cm$^2$

TL;DR

This paper reports the development of high-voltage, high-performance $eta$-Ga$_2$O$_3$ lateral MESFETs with a record figure of merit, achieved through advanced epitaxy, passivation, and device design techniques.

Contribution

The study introduces a novel fabrication process and device design that significantly enhances the breakdown voltage and lateral figure of merit of $eta$-Ga$_2$O$_3$ MESFETs.

Findings

Achieved over 3 kV breakdown voltage in $eta$-Ga$_2$O$_3$ MESFETs.

Realized a lateral figure of merit up to 355 MW/cm$^2$.

Demonstrated improved device performance with a low contact resistance of 1.4 Ω·mm.

Abstract

We demonstrate over 3 kV gate-pad-connected field plated (GPFP) $\beta$-Ga$_2$O$_3$ lateral MESFETs with high lateral figure of merit (LFOM) using metalorganic vapor phase epitaxy (MOVPE) grown channel layers and regrown ohmic contact layers. Using an improved low-temperature MOVPE selective area epitaxy process, we show that a total contact resistance to the channel as low as 1.4 $\Omega$.mm can be achieved.The GPFP design adopted here using PECVD (plasma-enhanced chemical vapor deposition) deposited SiN$_x$ dielectric and SiN$_x$/SiO$_2$ wrap-around passivation exhibits up to ~14% improved R$_{ON}$, up to ~70% improved breakdown voltage (V$_{BR}$ = V$_{DS}$ - V$_{GS}$) resulting in up to $\sim$3$\times$ higher LFOM compared to non-FP $\beta$-Ga$_2$O$_3$ lateral MESFETs. The V$_{BR}$ (~2.5 kV) and LFOM (355 MW/cm$^2$) measured simultaneously in our GPFP $\beta$-Ga$_2$O$_3$ lateral MESFET (with L$_{GD}$ = 10 $\mu$m) is the highest value achieved in any depletion-mode $\beta$-Ga$_2$O$_3$ lateral device.