The reduction of gate leakage of AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors by N2 plasma pretreatment

Abstract

Electrical performance of an AlGaN/GaN metal–insulator–semiconductor high electron mobility transistor (MISHEMT) with Al2O3 as the gate insulator layers indicated that the gate leakage was decreased by two orders of magnitude after the Al2O3/AlGaN interface was pretreated by N2 plasma. The Al2O3 thin film was deposited by atomic layer deposition (ALD). Effects of N2 plasma pretreatment on the electrical and structural properties of the Al2O3/AlGaN interface were investigated by C–V measurements, high-resolution transmission electron microscopy (HRTEM) and x-ray photoelectron spectroscopy (XPS). The C–V measurements showed that the electrical property was improved after N2 plasma pretreatment, HRTEM measurements indicated that the thickness of an interfacial layer was reduced. XPS analysis confirmed that AlGaN oxides are greatly decreased during N2 plasma pretreatment.