Theoretical study on quasi-confined optical phonon modes in a free-standing cylindrical GaN nanowire with ring geometry: A resonant Raman scattering

We have investigated quasi-confined (QC) optical resonant Raman scattering in GaN nanowires (NWs) with ring geometry. We consider the Fröhlich electron-phonon interaction in the framework of the dielectric continuum approach. The selection rules are studied. For small ring radius, our results show that the main contribution to the differential cross section (DCS) comes from high-frequency of the QC phonons, with a minor contribution from the LO phonons. The peak of the DCS is mainly attributed to the electron-QC coupling strength can get the maximum value as the anisotropic effect of wurtzite nitride crystal. Moreover, the lower orders of the QC phonons, the larger the DCS.