Effect of surface treatment on electrical properties of GaN metal–insulator–semiconductor devices with Al2O3 gate dielectric

Abstract

This research proposes an economical and effective method of 1-octadecanethiol (ODT) treatment on GaN surfaces prior to Al2O3 gate dielectric deposition. GaN-based metal–insulator–semiconductor (MIS) devices treated by HCl, O2 plasma and ODT are demonstrated. ODT treatment was found to be capable of suppressing native oxide and also of passivating the GaN surface effectively; hence the interface quality of the device considerably improved. The interface trap density of Al2O3/GaN was calculated to be around 3.0 × 1012 cm−2 eV−1 for devices with ODT treatment, which is a relatively low value for GaN-based MIS devices with Al2O3 as the gate dielectric. Moreover, there was an improvement in the gate control characteristics of MIS-HEMTs fabricated with ODT treatment.