Self-assembled growth of GaN nanowires

GaN nanowires (NWs) have been grown on Si(111) substrates by plasma-assisted molecular beam epitaxy. The morphology and optical properties of the NWs are influenced by the growth parameters as investigated by the scanning electron microscope. The nucleation process of GaN-NWs is explained in terms of nucleation density and wire evolution with time. The wire length in the nucleation stage shows a linear time dependence. The wire density increases rapidly with time and then it saturates. We explain GaN-NWs growth by making use of the diffusion-induced (D-I) mechanism that explains the dependence of the length on wire diameter for a deposition time longer than the nucleation stage.