The reduction of gate leakage of AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors by N2plasma pretreatment

Electrical performance of an AlGaN/GaN metal–insulator–semiconductor high electron mobility transistor (MISHEMT) with Al 2 O 3 as the gate insulator layers indicated that the gate leakage was decreased by two orders of magnitude after the Al 2 O 3 /AlGaN interface was pretreated by N 2 plasma. The Al 2 O 3 thin film was deposited by atomic layer deposition (ALD). Effects of N 2 plasma pretreatment on the electrical and structural properties of the Al 2 O 3 /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 N 2 plasma pretreatment, HRTEM measurements indicated that the thickness of an interfacial layer was reduced. XPS analysis confirmed that AlGaN oxides are greatly decreased during N 2 plasma pretreatment.