Figures for MIJ-NSR Volume 3, Article 14 Figures Figure 1 Surface reconstruction and transitions between different ordering with GaN thickness and growth rate as parameters. The maximum thickness for the transition indicates the border between nitrogen and gallium rich growth.
Trenches can be seen on the surface, however, the area in between is smooth.
Both the layer surface and the GaAs substrate are shown, where part of the layer has been peeled off. The surface of the GaAs substrate is shown, revealing polycrystalline structure with hollows, where the GaN layer has been peeled off. The smooth backside of the peeled-off GaN layer is shown, revealing homogeneously distributed and randomly shaped hexagonal crystallites, originating from the GaAs substrate. The excess Ga has formed droplets which are trapped in trenches. It illustrates the columnar structure of small grains in the layer cross-section, while the surface part of the GaAs substrate shows neither indication of hollows, nor presence of polycrystalline structure.