Charge trap layer enabled positive tunable V$_{fb}$ in $\beta$-Ga$_{2}$O$_{3}$ gate stacks for enhancement mode transistors

Abstract

$\beta$-Ga$_{2}$O$_{3}$ based enhancement mode transistor designs are critical for the realization of low loss, high efficiency next generation power devices with rudimentary driving circuits. A novel approach towards attaining a high positive flat band voltage (V$_{fb}$) of 10.6 V in $\beta$-Ga$_{2}$O$_{3}$ metal-oxide-semiconductor capacitors (MOSCAPs), with the ability to fine tune it between 3.5 V to 10.6 V, using a polycrystalline AlN charge trap layer has been demonstrated. This can enable enhancement mode operation over a wide doping range. Excellent V$_{fb}$ retention of ${\sim}$97% for 10$^{4}$ s at 55 $^{\circ}$C was exhibited by the gate stacks after charge trapping, hence reducing the requirement of frequent charge injection cycles. In addition, low gate leakage current density (J$_{g}$) for high negative gate voltages (V$_{g}$${\sim}$-60 V) indicates the potential of this gate stack to enable superior breakdown characteristics in enhancement mode transistors.