Study on the coalescence of dislocation-free GaN nanowires on Si and SiOx

The authors have studied the epitaxial growth and structural characterization of coalesced GaN nanowire arrays formed directly on Si and SiOx substrates. It was observed that the coalescence can be induced by the tilting or the enhanced lateral growth of the nanowires. Dislocations at the coalescence interface are largely localized, leading to the formation of nearly defect-free GaN microcrystals. In addition, high quality GaN epilayers can be grown directly on SiOx with buffer layer less than 1 μm by optimizing the growth parameters in nanowire nucleation and coalescence stages.