Highly polarized Raman scattering anisotropy in single GaN nanowires

Single GaN nanowires and larger GaN ensembles are investigated by Raman spectroscopy. Spectra of nanowire ensembles prove the high crystal quality and are in agreement with selection rules for the wurtzite structure. Single nanowires are studied with a spatial resolution of the order of 400 nm for different polarization directions of the incident laser beam relative to the nanowire axis. In the single wire spectrum, only the A(1)(TO) was observed and the Raman intensity was suppressed for perpendicular polarization. These results confirm that Raman scattering in isolated GaN nanowires is governed by size effects.