Nanoheteroepitaxy of GaN on AlN/Si(111) nanorods fabricated by nanosphere lithography

Nanoheteroepitaxy (NHE) of GaN on an AlN/Si(111) nanorod structure was investigated by metal-organic chemical vapor deposition. Silica nanosphere lithography was employed to fabricate a periodic hexagonal nanorod array with a narrow gap of 30nm between the nanorods. We were successful in obtaining a fully coalesced GaN film on the AlN/Si(111) nanorod structure. Transmission electron microscopy revealed that threading dislocation (TD) bending and termination by stacking faults occurred near the interface between GaN and the AlN/Si(111) nanorods, resulting in the reduction of TD density for the NHE GaN layer. The full width at half-maximum of the X-ray rocking curve for (102) plane of the NHE GaN was found to decrease down to 728arcsec from 1005arcsec for the GaN layer on a planar AlN/Si(111) substrate, indicating that the crystalline quality of the NHE GaN was improved. Also, micro-Raman measurement showed that tensile stress in the NHE GaN layer was reduced significantly as much as 70% by introducing air voids between the nanorods. •We propose a nanoheteroepitaxy of GaN on AlN/Si(111) nanorod substrates.•Nanosphere lithography was employed to fabricate the AlN/Si(111) nanorod substrate.•A continuous and high quality GaN film was selectively grown on the substrate.•The residual stress in the GaN film was reduced as much as 70% by embedded voids.