Influence of thermal annealing on the structural and optical properties of GaN/AlN quantum dots

The influence of the post-growth thermal annealing on the structural and optical properties of GaN/AlN quantum dots (QDs) is reported. X-ray techniques suggest smooth and high quality interfaces of the stacked multilayer structures for the as-grown and annealed samples without any period thickness change. High-angle annular dark field images by scanning transmission electron microscopy show an intermixing between the GaN QDs and AlN spacers after annealing. The QDs recombination shifts to lower energies (red shift) for big dots and to higher energies (blue shift) for small dots, reflecting two competitive processes taking place during the thermal annealingFCT-PTDC/FIS/66262/2006FCT-PTDC/CTM/ 100756/2008FCT-SFRH/BD/45774/2008FCT-SFRH/BD/44635/2008Ciência 200