Normally-off recessed gate β-Ga₂O₃ MOSHFETs with a modulation-doped heterostructure back-barrier

This study demonstrates enhancement-mode recessed-gate β -Ga 2 O 3 metal–oxide–semiconductor heterojunction field-effect transistors (MOSHFETs) with a combination of the MOS channel and a modulation-doped heterostructure to improve maximum drain current and on-resistance (R ON ). In this proposed device concept, modulation doping in the heterostructure back-barrier inserted into the MOS channel increases the electron density in the MOS channel while maintaining a normally-off operation. First, 2D simulations of enhancement-mode recessed-gate β -Ga 2 O 3 metal–oxide–semiconductor field-effect transistors (MOSFETs) were performed in a Silvaco ATLAS TCAD environment to calibrate the transfer characteristics with the measured data of the investigated device reported previously. Second, using calibrated physical models and parameters, the transfer and transconductance characteristics, and output and off-state characteristics of the enhancement-mode recessed-gate β -Ga 2 O 3 MOSHFETs were comprehensively investigated. The maximum drain current at V GS = 8 V and V DS = 10 V could be increased up to 32.6 mA mm −1 from 9.1 mA mm −1 with the MOSHFET in comparison with that of the recessed-gate MOSFET. The breakdown voltage increased considerably from 186 V to 226 V for the recessed-gate MOSHFET. The proposed device also showed a lower R ON , which decreased from 354 Ω.mm to 214 Ω.mm owing to greater electron accumulation in the channel owing to the introduction of the modulation-doped heterostructure.