Effect of Surface Treatment on Electrical Properties of GaN Metal Insulator-Semiconductor Devices with Al2O3 Gate Dielectric

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, O-2 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 x 10(12) 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.