Delta Doped $\beta$ -Ga2O3 Field Effect Transistors With Regrown Ohmic Contacts

We report silicon delta-doped β-Ga₂O₃ metal semiconductor field effect transistors (MESFETs) with source-drain ohmic contacts formed by patterned regrowth of n-type Ga₂O₃. We show that regrown n-type contacts can enable a lateral low-resistance contact to the two-dimensional electron gas channel, with contact resistance lower than 1.5 Ω-mm. The fabricated MESFET has a peak drain current (I_D,MAX) of 140 mA/mm, transconductance (g_m) of 34 mS/mm, and 3-terminal off-state breakdown voltage of 170 V. The proposed device structure could provide a promising path towards vertically scaled β-Ga₂O₃ field effect transistors.