Scaled β-Ga2O3 thin channel MOSFET with 5.4 MV/cm average breakdown field and near 50 GHz fMAX.

This Letter reports a high performance β -Ga₂O₃ thin channel MOSFET with T gate and degenerately doped (n++) source/drain contacts regrown by metal organic chemical vapor deposition. Highly scaled T-gate with a gate length of 160–200 nm was fabricated to achieve enhanced RF performance and passivated with 200 nm silicon nitride. Peak drain current (I_D,MAX) of 285 mA/mm and peak transconductance (g_m) of 52 mS/mm were measured at 10 V drain bias with 23.5 Ω mm on resistance (R_ON). Metal/n++ contact resistance of 0.078 Ω mm was extracted from transfer length measurements. R_ON is possibly dominated by interface resistance between channel and highly doped n++ regrown layer. A gate-to-drain breakdown voltage of 192 V is measured for L_GD = 355 nm resulting in average breakdown field (E_AVG) of 5.4 MV/cm. This E_AVG is the highest reported among all sub-micron gate length lateral FETs. Current gain cut off frequency (f_T) of 11 GHz and record power gain cut off frequency (f_MAX) of approximately 48 GHz were extracted from small signal measurements. f_T is limited by DC-RF dispersion due to interface traps which needs further investigation. The f_T·V_BR product is 2.112 THz V for 192 V breakdown voltage. Device surpasses the switching figure of merit of Silicon and competitive with mature wide bandgap devices. [ABSTRACT FROM AUTHOR]