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

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.