High-Mobility Tri-Gate $\beta$-Ga$_2$O$_3$ MESFETs with a Power Figure of Merit over 0.9 GW/cm$^2$

TL;DR

This paper demonstrates high-mobility tri-gate $eta$-Ga$_2$O$_3$ MESFETs with a record power figure of merit over 0.9 GW/cm$^2$, achieved through innovative buffer-channel design and channel engineering.

Contribution

It introduces a low-temperature undoped buffer-channel stack design that achieves record high mobilities and low ON resistance in $eta$-Ga$_2$O$_3$ MESFETs, with a focus on high power performance.

Findings

Record high power figure of merit of 0.95 GW/cm$^2$ for $eta$-Ga$_2$O$_3$ transistors.

High ON current of 187 mA/mm and low R$_{ON}$ of 20.5 $\

Very low reverse leakage until catastrophic breakdown, with breakdown voltages from 1.1 kV to 3 kV.

Abstract

In this letter, fin-shape tri-gate $\beta$-Ga$_{2}$O$_{3}$ lateral MESFETs are demonstrated with a high power figure of merit of 0.95 GW/cm$^{2}$ - a record high for any $\beta$-Ga$_{2}$O$_{3}$ transistor to date. A low-temperature undoped buffer-channel stack design is developed which demonstrates record high Hall and drift electron mobilities in doped $\beta$-Ga$_{2}$O$_{3}$ channels allowing for low ON resistances R$_{ON}$ in $\beta$-Ga$_{2}$O$_{3}$ MESFETs. Fin-widths (W$_{fin}$) were 1.2-1.5 $\mu$m and there were 25 fins (N$_{fin}$) per device with a trench depth of $\sim$1$\mu$m. A $\beta$-Ga$_2$O$_3$ MESFET with a source-drain length of 6.4 $\mu$m exhibits a high ON current (187 mA/mm), low R$_{ON}$ (20.5 $\Omega$.mm) and a high average breakdown field (4.2 MV/cm). All devices show very low reverse leakage until catastrophic breakdown for breakdown voltages scaled from 1.1kV to $\sim$3kV. This work demonstrates the potential of channel engineering in improving $\beta$-Ga$_{2}$O$_{3}$ device performance toward lower conduction losses for low-to-medium voltage applications.