Impact of channel thickness on the performance of an E-mode p-channel MOSHFET in GaN

Abstract

Introduction of positive polarization charge by utilising an AlGaN cap layer between the gate oxide and the channel is one of the promising techniques to deplete a two-dimensional hole gas (2DHG) to achieve an E-mode p-channel GaN MOSHFET. The results from TCAD simulations indicate that the off-state leakage increases by orders of magnitude for channel layers thicker than 20 nm in this structure. Biasing the two-dimensional electron gas beneath the 2DHG helps alleviate this limitation at the cost of reducing on-current. Scaling the access regions and combining the two techniques allow maximum benefit in terms of on-state current, negative threshold voltage, and the on/off current ratio.