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

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 (R-S) and shunt resistance (R-Sh) 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 R-S were evaluated and the results were comparable. Lower interface state density (N-SS) was obtained for the MIS junction than the SE, which confirmed that the Pr6O11 insulator layer plays a vital role in lowering the N-SS. 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.