Charge trap layer enabled positive tunable Vfb in β -Ga2O3 gate stacks for enhancement mode transistors

Abstract

β-Ga2O3 based enhancement mode transistor designs are critical for the realization of low loss, high efficiency next generation power devices with rudimentary driving circuits. A large positive flatband voltage (Vfb) of 10.6 V in β-Ga2O3 metal-oxide-semiconductor capacitors, with the ability to fine-tune it between 3.5 V and 10.6 V, using a polycrystalline AlN charge trap layer has been demonstrated. This can enable enhancement mode operation over a wide doping range. An excellent Vfb retention of ∼97% for 104 s at 55 °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 (Jg) for high negative gate voltages (Vg ∼−60 V) indicates the potential of this gate stack to enable superior breakdown characteristics in enhancement mode transistors.