In-depth analysis of InAlN/GaN HEMT heterostructure after annealing using angle-resolved X-ray photoelectron spectroscopy
Résumé
During high-electron-mobility transistor elaboration process, a thermal treatment of In0.2Al0.8N (InAlN) barrier layer is performed in order to improve electrical performances. We showed previously that In0.2Al0.8N/GaN heterostructures, annealed at 850°C under O2 partial pressure, present a specific in-depth organization. Angle-resolved X-ray photoelectron spectroscopy is a powerful tool to precisely determine the spatial localization and relative position of the different interfaces, from InAlN until buried GaN layer. The proposed in-depth model of the stack evidences (1) an Al-rich surface oxide with embedded N2 molecules, (2) an interlayer of InAlN<1 governed by nitrogen lattice defects, (3) a stable In0.2Al0.8N matrix, and finally (4) the GaN buffer layer underneath.