Complex Chiral Colloids and Surfaces via High-Index Off-Cut Silicon

Silicon wafers are commonly etched in potassium hydroxide solutions to form highly symmetric surface structures. These arise when slow-etching {111} atomic planes are exposed on standard low-index surfaces. However, the ability of nonstandard high-index wafers to provide more complex structures by t...

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Bibliographic Details
Published in:Nano letters 2014-05, Vol.14 (5), p.2934-2940
Main Authors: McPeak, Kevin M, van Engers, Christian D, Blome, Mark, Park, Jong Hyuk, Burger, Sven, Gosálvez, Miguel A, Faridi, Ava, Ries, Yasmina R, Sahu, Ayaskanta, Norris, David J
Format: Article
Language:English
Subjects:
Circularity
Colloids
Cross-disciplinary physics: materials science
rheology
Dichroism
Etching
Exact sciences and technology
Gold
Materials science
Nanocrystalline materials
Nanoparticles
Nanoscale materials and structures: fabrication and characterization
Physics
Planes
Surface structure
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Summary:Silicon wafers are commonly etched in potassium hydroxide solutions to form highly symmetric surface structures. These arise when slow-etching {111} atomic planes are exposed on standard low-index surfaces. However, the ability of nonstandard high-index wafers to provide more complex structures by tilting the {111} planes has not been fully appreciated. We demonstrate the power of this approach by creating chiral surface structures and nanoparticles of a specific handedness from gold. When the nanoparticles are dispersed in liquids, gold colloids exhibiting record molar circular dichroism (>5 × 109 M–1 cm–1) at red wavelengths are obtained. The nanoparticles also present chiral pockets for binding.
ISSN:1530-6984
1530-6992
DOI:10.1021/nl501032j