Heteroepitaxial ε-Ga2O3 MOSFETs on a 4-inch Sapphire Substrate with a Power Figure of Merit of 0.29 GW/cm2

We have designed and fabricated a high-voltage metal-oxide-semiconductor field effect transistor (MOSFET) based on heteroepitaxial epsilon-Ga2O3. The high-quality unintentionally-doped (UID) epsilon-Ga2O3 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) cm(-2) and mobility of 32 cm(2)/V center dot s. We proposed a dual-density channel design for the epsilon-Ga2O3 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 epsilon-Ga2O3 MOSFETs, with a gate-to-drain spacing (L-GD) of 20 mu m, exhibited a high breakdown voltage (V-br) of 2.85 kV and a specific on-resistance (R-on,R- sp) of 27.6 m ohm center dot cm(2), yielding a power figure of merit (PFOM) of 0.29 GW/cm(2). This PFOM value is the highest reported value for heteroepitaxial Ga2O3 devices and among the best in homoepitaxial beta-Ga2O3 lateral FETs.