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Magnetic Field Alignment of Randomly Oriented, High Aspect Ratio Silicon Microwires into Vertically Oriented Arrays

Beardslee, Joseph A. and Sadtler, Bryce and Lewis, Nathan S. (2012) Magnetic Field Alignment of Randomly Oriented, High Aspect Ratio Silicon Microwires into Vertically Oriented Arrays. ACS Nano, 6 (11). pp. 10303-10310. ISSN 1936-0851. doi:10.1021/nn304180k. https://resolver.caltech.edu/CaltechAUTHORS:20130124-141635894

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Abstract

External magnetic fields have been used to vertically align ensembles of silicon microwires coated with ferromagnetic nickel films. X-ray diffraction and image analysis techniques were used to quantify the degree of vertical orientation of the microwires. The degree of vertical alignment and the minimum field strength required for alignment were evaluated as a function of the wire length, coating thickness, magnetic history, and substrate surface properties. Nearly 100% of 100 μm long, 2 μm diameter, Si microwires that had been coated with 300 nm of Ni could be vertically aligned by a 300 G magnetic field. For wires ranging from 40 to 60 μm in length, as the length of the wire increased, a higher degree of alignment was observed at lower field strengths, consistent with an increase in the available magnetic torque. Microwires that had been exposed to a magnetic sweep up to 300 G remained magnetized and, therefore, aligned more readily during subsequent magnetic field alignment sweeps. Alignment of the Ni-coated Si microwires occurred at lower field strengths on hydrophilic Si substrates than on hydrophobic Si substrates. The magnetic field alignment approach provides a pathway for the directed assembly of solution-grown semiconductor wires into vertical arrays, with potential applications in solar cells as well as in other electronic devices that utilize nano- and microscale components as active elements.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/nn304180kDOIUNSPECIFIED
http://pubs.acs.org/doi/abs/10.1021/nn304180kPublisherUNSPECIFIED
ORCID:
AuthorORCID
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2012 American Chemical Society. Received for review September 10, 2012; accepted October 20, 2012; published online October 20, 2012. This work was supported by the DOE “Light-Material Interactions in Energy Conversion” Energy Frontier Research Center under Grant DE-SC0001293. Research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. B.S. acknowledges the Beckman Institute of the California Institute of Technology for a postdoctoral fellowship.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE) Energy Frontier Research CenterDE-SC0001293
Caltech Beckman Institute postdoctoral fellowshipUNSPECIFIED
Subject Keywords:magnetic coatings; vapor−liquid−solid growth; Ni electrodeposition; X-ray diffraction; image analysis
Issue or Number:11
DOI:10.1021/nn304180k
Record Number:CaltechAUTHORS:20130124-141635894
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130124-141635894
Official Citation:Magnetic Field Alignment of Randomly Oriented, High Aspect Ratio Silicon Microwires into Vertically Oriented Arrays Joseph A. Beardslee, Bryce Sadtler, and Nathan S. Lewis ACS Nano 2012 6 (11), 10303-10310
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36574
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:25 Jan 2013 00:06
Last Modified:09 Nov 2021 23:23

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