Heteroepitaxial $\epsilon-\text{Ga}_{2}\mathrm{O}_{3}$ MOSFETs on a 4-inch Sapphire Substrate with a Power Figure of Merit of 0.29 $\text{GW}/\text{cm}^{2}$

We have designed and fabricated a high-voltage metal-oxide-semiconductor field effect transistor (MOSFET) based on heteroepitaxial
$\varepsilon-\text{Ga}_{2}\mathrm{O}_{3}$
. The high-quality unintentionally-doped (UID)
$\varepsilon-\text{Ga}_{2}\mathrm{O}_{3}$
film was grown by metalorganic chemical vapor deposition (MOCVD) on a 4-inch sapphire substrate. Through an optimized fluorine-plasma treatment process, we achieved high-density surface doping with a carrier sheet density
$(n_{s})$
exceeding
$10^{14}\text{cm}^{-2}$
and mobility of 32
$\text{cm}^{2}/\mathrm{V}\cdot \mathrm{s}$
. We proposed a dual-density channel design for the
$\varepsilon, \text{Ga}_2\mathrm{O}_{3}$
MOSFETs, which involved high-density doping in the access region to reduce the parasitic resistance and low-density doping under the gate to ensure device pitch-off. This concept was verified using TCAD simulation before device fabrication. The fabricated
$\varepsilon-\text{Ga}_{2}\mathrm{O}_{3}$
MOSFETs, with a gate-to-drain spacing
$(L_{GD})$
of
$10 [\iota \mathrm{m}$
, exhibited a high breakdown voltage
$(V_{br})$
of
$2.85 \text{kV}$
and a specific on-resistance
$(R_{on,sp})$
of 27.6
$\mathrm{m}\Omega\cdot \text{cm}^{2}$
, yielding a power figure of merit (PFOM) of 0.29
$\text{GW}/\text{cm}^{2}$
. This PFOM value is the highest reported value for heteroepitaxial
$\text{Ga}_2\mathrm{O}_{3}$
devices and among the best in homoepitaxial
$\beta-\text{Ga}_{2}\mathrm{O}_{3}$
lateral FETs.