Size-dependent Fano Interaction in the Laser-etched Silicon Nanostructures

Rajesh Kumar,Hs Mavi,Ak Shukla,Vd Vankar

doi:10.1007/s11671-008-9120-x

Rajesh Kumar, Hs Mavi + Show 2 more

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https://doi.org/10.1007/s11671-008-9120-x

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Abstract

Photo-excitation and size-dependent Raman scattering studies on the silicon (Si) nanostructures (NSs) prepared by laser-induced etching are presented here. Asymmetric and red-shifted Raman line-shapes are observed due to photo-excited Fano interaction in the quantum confined nanoparticles. The Fano interaction is observed between photo-excited electronic transitions and discrete phonons in Si NSs. Photo-excited Fano studies on different Si NSs show that the Fano interaction is high for smaller size of Si NSs. Higher Fano interaction for smaller Si NSs is attributed to the enhanced interference between photo-excited electronic Raman scattering and phonon Raman scattering.

Highlights

Raman scattering from the silicon (Si) nanostructures (NSs) has been extensively studied in recent years [1,2,3,4]
Asymmetry and broadening in Raman line-shape is attributed to the quantum confinement of phonons in Si NSs [12,13,14,15]
The Raman line-shapes from the Si NSs are investigated as a function of Si NSs size and excitation laser power density

Summary

Introduction

Raman scattering from the silicon (Si) nanostructures (NSs) has been extensively studied in recent years [1,2,3,4]. Observed Raman line-shapes from the Si NSs are asymmetrically broadened and red-shifted from its counterpart for the bulk Si. Most authors have fitted the first-order experimental Raman band to an asymmetrical line-shape first proposed by Richter et al [5] and modified by Campbell et al [6]. Most authors have fitted the first-order experimental Raman band to an asymmetrical line-shape first proposed by Richter et al [5] and modified by Campbell et al [6] In this model, the asymmetry and red-shift in the Raman peak have been attributed to the confinement of phonons in the Si NSs. Many others [3, 4] have explained the asymmetry and downshift in the Raman line-shape in terms of a combined effect of quantum confinement and laser heating. Effect of the quantum confinement on Fano resonance is not studied yet and needs further studies to elucidate the behavior of Fano interaction as a function of Si NSs size and laser power density

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