Polarized Raman scattering from single GaP nanowires

We report the systematic investigation of polarized Raman scattering on individual crystalline GaP nanowires (NWs) with diameters 40 < d < 600 nm. At small diameter, d < 70 nm, the NWs are found to act like a nearly perfect dipole antenna that leads to a polarized scattering intensity function I(theta) similar to cos(4) theta where theta is the angle between NW axis and the incident laser polarization. For larger diameter (70 < d < 600 nm) NWs, some other different polar patterns were found. A simple theoretical approach which takes into account the Raman tensor and photon confinement in NWs was used to understand the experimental data.