Investigations on Wide-Gap Al0.21Ga0.79N Channel MOS-HFETs With In0.12Al0.76Ga0.12N Barrier/Buffer and Drain Field-Plate

This work investigates, for the first time, wide-gap Al0.21Ga0.79N channel metal-oxide-semiconductor heterostructure field-effect transistors (MOS-HFETs) with In0.12Al0.76Ga0.12N barrier/buffer and drain field-plate (DFP) designs. High-k and wide-gap Al2O3 was grown as the gate oxide and surface passivation by using non-vacuum ultrasonic spray pyrolysis deposition (USPD) technique. A control device having the same epitaxial layers, except with In0.12Al0.88N barrier/buffer was studied in comparison. Enhanced spontaneous polarization effect, improved interfacial quality, and enhanced carrier confinement have been achieved by using the In0.12Al0.76Ga0.12N barrier/buffer design, which has successfully resulted in improved carrier transport, increased electron concentration, and high current densities. The present In0.12Al0.76Ga0.12N/AlN/Al0.21Ga0.79N MOS-HFET design with (without) DFP design has demonstrated superior maximum drain-source current density
$(I_{DS, max})$
of >1 (>1) A/mm at
$V_{DS}\,\,=$
20 V, high saturated drain-source current density at
$V_{GS}\,\,=$
0 V
$(I_{DSS0})$
of 791.1 (755) mA/mm, and low specific on-resistance
$(R_{on, sp})$
of 2.83 (2.81)
$\text{m}\Omega $
/cm 2. High device figure-of-merit (FOM) on
$BV_{DS}^{2}/R_{on, sp}$
of 93.7 (75.4) MW/cm 2 was also obtained with the three-terminal on-state drain-source breakdown voltage
$(BV_{DS})$
of 515 (460) V. The present design is promisingly advantageous to high-current and high-voltage power-switching circuit applications.