Analytical Model for the Threshold Voltage of p -(Al)GaN High-Electron-Mobility Transistors.

An analytical model for the calculation of the threshold voltage for enhancement-mode (E-mode) p -(Al)GaN high-electron-mobility transistors (HEMTs) is presented. The ON-state behavior (at low output voltages) of both p -GaN HEMTs and p -AlGaN HEMTs—including the gate injection transistor—are discussed in detail, and closed expressions for the threshold voltage VT of both devices are deduced. It is found that the threshold voltage values for both devices are close to one another, and that there is an ideal upper limit when the p -type doping in the AlGaN gate is perfectly tailored, yielding more positive threshold voltages. This ideal case might be difficult to realize technologically, but can serve as a benchmark for the VT of p -(Al)GaN HEMTs. [ABSTRACT FROM PUBLISHER]