Enhanced Raman Scattering from Individual Semiconductor Nanocones and Nanowires

Abstract

We report strong enhancement (approximately 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.

Raman spectroscopy of wurtzite and zinc-blende GaAs nanowires: Polarization dependence, selection rules, and strain effects

“…Furthermore, experiments on silicon nanocones showed that the enhancement in the Raman scattering, due to the enhanced internal field, decreases with the nanowires diameter and increases with the wavelength of the excitation, features which suggest a resonant nature. 31 This is consistent with photoluminescence ͑PL͒ experiments. Indeed, it is observed that the light is preferentially absorbed when the incident light is polarized along the nanowire axis.…”

“…Indeed, the highly anisotropic shape of the nanowires can lead to angular dependencies of the modes, which otherwise would not be expected from the selection rules. [29][30][31] Additionally, modes such as the ones associated with surface phonons have been detected. [32][33][34][35] In this work, scanning Raman spectroscopy is performed on GaAs nanowires with zinc-blende and wurtzite structures.…”

Internal field induced enhancement and effect of resonance in Raman scattering of InAs nanowires

“…9 A strong enhancement of local/internal field in dielectric nanostructures, like silicon nanowires and nanocones of varying diameters was experimentally observed. 10 In a recent report, 11 resonant Raman scattering measurements were carried out to probe the electronic band structure near the E 1 gap of InAs NWs, which are mostly of wurtzite (WZ) phase. The variation of the integral intensity of the phonon modes with laser excitation energy reveals redshifted E 1 gap of the WZ NWs compared to bulk InAs, of zinc-blende (ZB) phase.…”

Raman Spectroscopy on Semiconductor Nanowires

“…As it will be shown in the following, this is partly due to the one-dimensionality and to the small diameter of the nanowires, as it has been reported in literature (Cao et al, 2007;Livneh et al, 2007;Papadimitriou & Nassiopoulou, 1998;Pauzauskie et al, 2005;Duesberg et al, 2006;Fréchette & Carraro, 2006;Cao et al, 2006;Xiong et al, 2006). Xiong et al found that nanowires with a diameter d<<λ/4, with λ the wavelength of the excitation, show a dipolar behavior.…”

“…Additionally, polarization dependent experiments on single carbon nanotubes and/or nanowires have shown that the physics behind Raman scattering of such one-dimensional nanostructures can differ significantly from the bulk (Frechette et al, 2006;Livneh et al, 2006;Cao et al, 2006). Indeed, the highly anisotropic shape of the nanowires can lead to angular dependencies of the modes which otherwise would not be expected from selection rules (Frechette et al, 2006;Livneh et al, 2006;Cao et al 2006).…”