Enhanced Raman Scattering from Individual Semiconductor Nanocones and Nanowires*

We report strong enhancement ($\sim $10$^{3})$ of the spontaneous Raman scattering from individual silicon nanowires and nanocones as compared with bulk Si. The observed enhancement is diameter ($d)$, excitation-wavelength ($\lambda _{laser})$, and incident polarization state-dependent, and is explained in terms of a resonant behavior involving incident electromagnetic radiation and the structural dielectric cross-section. The variation of the Raman enhancement with $d$, $\lambda _{laser}$ and polarization is shown to be in good agreement with model calculations of scattering from an infinite dielectric cylinder.