Effect of annealing on AlN/GaN quantum dot heterostructures: Advanced ion beam characterization and X-ray study of low-dimensional structures

Multilayers consisting of six GaN quantum dot (QD) layers separated by AlN spacer layers were grown by molecular beam epitaxy. Structural properties and the effects of thermal annealing were analyzed using X-ray diffraction (XRD), X-ray reflection (XRR) and Rutherford backscattering spectrometry/Channeling (RBS/C). Annealing was performed in nitrogen atmosphere for 20 min at temperatures between 1000 and 1200 • C. The GaN QDs on the surface were destroyed at temperatures ≥1100 • C while the AlN spacer layers protected the deeper lying QD layers. The multilayer structure was well preserved for all studied temperatures. Indications of interdiffusion in the interfaces were found. Thickness fluctuations were evidenced by XRR