The size of the dots could thus be controlled by changing the exposure time under nitrogen plasma, but can also be varied with the substrate temperature and the amount of deposited GaN. As the dots and the tip apex exhibit similar radius, AFM is not very precise for determining the shape of the dots. When rotating the sample, these facets appear to have a six-fold symmetry. A careful analysis of High Resolution Electron Microsopy images allows us to measure the thickness of the two-dimensional GaN wetting layer. After this elastic relaxation that occurs during the first stages of growth, it is believed that a slower plastic relaxation takes place. Further work will concern the photoluminescence and cathodoluminescence of the GaN dots.
Calculations have to be performed in order to correlate their optical and morphological properties.
L. Leprince, E. Andre, O. Vatel, Appl. P Hacke, G Feuillet, H Okumura, S Yoshida, Appl. Figure 1 . Figure 2 . Figure 3 .