Gate leakage suppression and contact engineering in nitride heterostructures

Abstract

We present a self-consistent approach to examine current flow in a general metal–polar heterostructure junction. The approach is applied to examine properties of three classes of junctions that are important in devices: (i) GaN/AlGaN structures that are used in nitride heterojunction field effect transistors; (ii) GaN/AlGaN/high-κ insulator structures for potential application in very small gate devices to suppress gate tunneling current; and (iii) GaN/AlGaN/polar insulator junctions with practical application for low source resistance regions. The physical parameters used for high-κ dielectrics and polarization charges reflect values typically found in ferroelectric materials. Our studies indicate that tailoring of junction properties is possible if a dielectric thicknesses of ∼20 Å can be achieved.