Characterization of SiNx/AlN passivation stack with epitaxial AlN grown on AlGaN/GaN heterojunctions by plasma-enhanced atomic layer deposition

Abstract

A SiNx/AlN dielectric stack, which has been shown to provide a practical, robust, and effective passivation for GaN-based lateral heterojunction power switching devices, was characterized in this work to provide insights on the mechanisms of its current collapse suppression ability. The interface between the SiNx/AlN passivation stack and the AlGaN/GaN structure was characterized by investigating the interface state distribution and its chemical composition. Such interface was found to have much less trap states and significantly less oxidation than that in the heterostructure passivated by an Al2O3/AlN stack, validating that SiNx/AlN passivation is superior to Al2O3/AlN passivation.