Improved interface properties of GaN metal-oxide-semiconductor device with non-polar plane and AlN passivation layer

Abstract

Utilizing a non-polar plane substrate and an ultra-thin AlN passivation layer results in significantly improved interface properties of a GaN metal-oxide-semiconductor (MOS) device. After depositing an Al2O3 gate dielectric layer on GaN substrates with polar c-plane and non-polar m-plane surfaces, it is found that the devices on the non-polar surface show much better interface properties than those on the polar surface. To further improve the interface properties, an amorphous ultra-thin AlN layer is deposited on the substrate before the Al2O3 deposition. The interface properties of both devices on the c-plane and m-plane are dramatically improved by the AlN passivation layer. The interface trap density of the Al/Al2O3/AlN/GaN MOS capacitor on the non-polar surface is reduced by two orders of magnitude compared to that on the polar surface.