Analytical compact model for mobile charge density in III-nitride multiple-channel field-effect transistors

An analytical compact model is developed for the mobile charge density of multiple-channel field-effect transistors based on the III-nitride material system. Two-dimensional electron and hole gases can be potentially induced by spontaneous and piezoelectric polarization in polar heterostructures. Focusing on the active region of devices that employ a multiple quantum-well layout, the total electron and hole populations are estimated from fundamental electrostatic and quantum mechanical principles. Hole gas depletion techniques, revolving around intentional donor doping, are modeled and evaluated, culminating in a generalized closed-form equation for the mobile carrier density across the doping schemes examined. The utility of this model is illustrated by exploring AlGaN/GaN, AlInN/GaN, and AlScN/GaN heterostructures. The compact framework provided herein considerably elucidates and enhances the efficiency of multi-layered transistor design.