Effect of rare-earth Pr6O11 insulating layer on the electrical properties of Au/n-GaN Schottky electrode and its chemical and structural characterization

Abstract

An Au/Pr6O11/n-GaN metal/insulator/semiconductor (MIS) junction was prepared with a high-k praseodymium oxide insulator layer and probed its structural, chemical and electrical characteristics by XRD, TEM, XPS, I–V and C–V approaches. XRD, TEM and XPS examinations confirm the Pr6O11 film growth on n-type GaN surface. Electrical results demonstrate the fabricated junctions show a good rectifying nature with a low leakage current. The series resistance (RS) and shunt resistance (RSh) were derived for the Au/n-GaN Schottky electrode (SE) and MIS junction. MIS junction possesses a higher barrier height (BH) compared to the Au/n-GaN SE, implying the insulator layer altered the BH. By employing Cheung’s, Norde and surface potential plots, the BH, ideality factor and RS were evaluated and the results were comparable. Lower interface state density (NSS) was obtained for the MIS junction than the SE, which confirmed that the Pr6O11 insulator layer plays a vital role in lowering the NSS. Results demonstrated the Poole–Frenkel emission controls the current conduction mechanism in reverse-bias of both SE and MIS junction. Observations stated that the Pr6O11 thin film is a suitable high-k insulating material for the fabrication of GaN-based MIS devices.