Guided Growth of Epitaxially Coherent GaN Nanowires on SiC

We report the guided growth of highly coherent, horizontal GaN nanowires (NWs) on atomically flat singular SiC (0001) and on periodically stepped vicinal SiC (0001) substrates. On singular SiC (0001) the NWs grow in six symmetry-equivalent directions, while on vicinal SiC (0001) the NWs grow only in the two directions parallel to the atomic step edges. All of the NWs have the same epitaxial relations with the substrate on both singular and vicinal (0001). Owing to the low mismatch (∼3.4%) with the substrate, the NWs grow highly coherent, with a much lower density of misfit dislocations than previously observed on sapphire. This is also the first observation of NW VLS growth along atomic steps. Epitaxially coherent guided NWs have potential uses in many fields, including high-power electronics, light-emitting diodes (LEDs), and laser diodes.