Enhancement-mode Ga₂O₃ MOSFETs with Si-ion-implanted source and drain

Enhancement-mode β-Ga₂O₃ metal-oxide-semiconductor field-effect transistors with low series resistance were achieved by Si-ion implantation doping of the source/drain contacts and access regions. An unintentionally doped Ga₂O₃ channel with low background carrier concentration that was fully depleted at a gate bias of 0 V gave rise to a positive threshold voltage without additional constraints on the channel dimensions or device architecture. Transistors with a channel length of 4 μm delivered a maximum drain current density (I_DS) of 1.4 mA/mm and an IDS on/off ratio near 10⁶. Nonidealities associated with the Al₂O₃ gate dielectric as well as their impact on enhancement-mode device performance are discussed.