Size Effects in Mechanical Deformation and Fracture of Cantilevered Silicon Nanowires

Elastic modulus and fracture strength of vertically aligned Si [111] nanowires (ø = 100−700 nm) in an as-grown state have been measured using a new, multipoint bending protocol in an atomic force microscope. All wires showed linear elastic behavior, spring constants which scale with (length)3, and b...

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Bibliographic Details
Published in:Nano letters 2009-02, Vol.9 (2), p.525-529
Main Authors: Gordon, Michael J, Baron, Thierry, Dhalluin, Florian, Gentile, Pascal, Ferret, Pierre
Format: Article
Language:English
Subjects:
Catalytic methods
Condensed Matter
Condensed matter: structure, mechanical and thermal properties
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Materials Science
Mechanical and acoustical properties of condensed matter
Mechanical properties of nanoscale materials
Methods of nanofabrication
Nanocrystalline materials
Nanoscale materials and structures: fabrication and characterization
Physics
Quantum wires
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Summary:Elastic modulus and fracture strength of vertically aligned Si [111] nanowires (ø = 100−700 nm) in an as-grown state have been measured using a new, multipoint bending protocol in an atomic force microscope. All wires showed linear elastic behavior, spring constants which scale with (length)3, and brittle failure at the wire-substrate junction. The “effective” Young’s modulus increased slightly (100 → 160−180 GPa) as wire diameter decreased, but fracture strength increased by 2−3 orders of magnitude (MPa → GPa). These results indicate that vapor−liquid−solid grown wires are relatively free of extended volume defects and that fracture strength is likely controlled by twinning and interfacial effects at the wire foot. Small wires (100 nm) grown with a colloidal catalyst were the best performers with high modulus (∼180 GPa) and fracture stress >1 GPa.
ISSN:1530-6984
1530-6992
DOI:10.1021/nl802556d