‘Moth-head’ shaped structural defect

The photograph is an atomic force microscopy image of Indium Gallium Nitride and Gallium Nitride quantum well hetrostructures grown on Sapphire substrate by Metal Organic Vapour Phase Epitaxy for LED applications. The top layer was capped by Gallium Nitride. The morphology of this cap layer showed the presence of a structural defect whose shape appears as a Moth-head. The picture is added with some enhancement of brightness and contrast. Many thanks to Dr. Khaled Kaja, Applications Scientist of Bruker Nano Surface Division for his support to carry out the experiment and also to Strathclyde Institute of Pharmacy and Biomedical Sciences, where the work was carried out.