130 mA/mm $\beta$-Ga${}_2$O${}_3$ MESFET with Low-Temperature MOVPE-Regrown Ohmic Contacts

We report on the demonstration of metalorganic vapor phase epitaxy-regrown (MOVPE) ohmic contacts in an all MOVPE-grown $\beta$-Ga${}_2$O${}_3$ metal-semiconductor field effect transistor (MESFET). The low-temperature (600${}^{\circ }$C) heavy (n${}^{+}$) Si-doped regrown layers exhibit extremely high conductivity with sheet resistance of 73 $\mathrm{\Omega }$/$\mathrm{\square }$ and record low metal/n${}^{+}$-Ga${}_2$O${}_3$ contact resistance of 80 m$\mathrm{\Omega }$.mm and specific contact resistivity of 8.3$\times$10${}^{-7}$ $\mathrm{\Omega }$.cm${}^2$ were achieved. The fabricated MESFETs exhibit a maximum drain-to-source current of 130 mA/mm, a high I${}_{ON}$/I${}_{OFF}$ of $>$10${}^{10}$ with a high power FOM of 25 MW/cm${}^2$ were achieved without any field plates. Nanoparticle-assisted Raman thermometry, thermal modeling, and infrared thermography were performed to assess the device self-heating under the high current and power conditions. This demonstration shows the promise of MOVPE technique for the realization of high-performance lateral $\beta$-Ga${}_2$O${}_3$ devices and also highlights the need for device-level thermal management.