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Proceedings Paper

Optical second-harmonic generation from silicon nanocrystals
Author(s): Michael C. Downer; Peter C. Figliozzi; Yingying Jiang; Liangfeng Sun; Brian Mattern; C. Woody White; Steve P. Withrow
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Paper Abstract

Optical second-harmonic generation (SHG)is used as a noninvasive probe of the interfaces of Si nanocrystals (SiNCs)embedded in an SiO2 matrix. We verify experimentally that the second-harmonic polarization P(2) has a quadrupolar form proportional to (E ·∇) E as proposed in recent models based on a locally noncentrosymmetric dipolar polarization averaged over the spherical NC interface. A two-beam sum-frequency geometry is found to enhance this polarization dramatically compared to a single-beam SHG geometry, yielding strong signals useful for scanning, spectroscopy and real time monitoring. Using this two beam geometry, we have produced non-invasive two dimensional SHG maps with few-micron resolution of 1-micron-thick layers of Si-NCs (3 and 5 nm average diameter)produced by ion implanting Si into SiO2. Samples were scanned over a 5mm x 5mm area with two non-collinear,orthogonally polarized,amplified Ti:S laser pulses (80 fs,810nm,100 μJ,1 kHz repetition rate) while detecting the generated SH signal in transmission. The SHG signal is sensitive to chemical modification of the Si/SiO2 interface and to local gradients in nanoparticle density.

Paper Details

Date Published: 4 December 2003
PDF: 8 pages
Proc. SPIE 5223, Physical Chemistry of Interfaces and Nanomaterials II, (4 December 2003); doi: 10.1117/12.511483
Show Author Affiliations
Michael C. Downer, Univ. of Texas/Austin (United States)
Peter C. Figliozzi, Univ. of Texas/Austin (United States)
Yingying Jiang, Univ. of Texas/Austin (United States)
Liangfeng Sun, Univ. of Texas/Austin (United States)
Brian Mattern, Univ. of Texas/Austin (United States)
C. Woody White, Oak Ridge National Lab. (United States)
Steve P. Withrow, Oak Ridge National Lab. (United States)

Published in SPIE Proceedings Vol. 5223:
Physical Chemistry of Interfaces and Nanomaterials II
Tianquan Lian; Hai-Lung Dai, Editor(s)

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