Epitaxial Growth of Single Crystalline GaN Nanowires on (0001) Al₂O₃

Summary

Well-aligned single crystalline GaN nanowires were epitaxially grown on Al₂O₃ by molecular beam epitaxy. Controlled growth of the nanowires is achieved by tuning the V/III ratio during growth. Oxidised single crystalline catalyst droplets of a cubic symmetry are observed on the top surface of the nanowires. Adaptation of the cubic lattice on the wurtzite tip is realized via the introduction of a dense network of misfit dislocations at the interface. The {100} lattice spacing of the oxide droplets is found to be very close to its strain-free value, indicating almost full relaxation by the misfit dislocation network.