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Chemical and Electrical Passivation of Silicon (111) Surfaces through Functionalization with Sterically Hindered Alkyl Groups

Nemanick, E. Joseph and Hurley, Patrick T. and Brunschwig, Bruce S. and Lewis, Nathan S. (2006) Chemical and Electrical Passivation of Silicon (111) Surfaces through Functionalization with Sterically Hindered Alkyl Groups. Journal of Physical Chemistry B, 110 (30). pp. 14800-14808. ISSN 1520-6106. https://resolver.caltech.edu/CaltechAUTHORS:20170609-073705620

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Abstract

Crystalline Si(111) surfaces have been alkylated in a two-step chlorination/alkylation process using sterically bulky alkyl groups such as (CH_3)_2CH− (iso-propyl), (CH_3)_3C− (tert-butyl), and C_6H_5− (phenyl) moieties. X-ray photoelectron spectroscopic (XPS) data in the C 1s region of such surfaces exhibited a low energy emission at 283.9 binding eV, consistent with carbon bonded to Si. The C 1s XPS data indicated that the alkyls were present at lower coverages than methyl groups on CH_3-terminated Si(111) surfaces. Despite the lower alkyl group coverage, no Cl was detected after alkylation. Functionalization with the bulky alkyl groups effectively inhibited the oxidation of Si(111) surfaces in air and produced low (<100 cm s^(-1)) surface recombination velocities. Transmission infrared spectroscopy indicated that the surfaces were partially H-terminated after the functionalization reaction. Application of a reducing potential, −2.5 V vs Ag^+/Ag, to Cl-terminated Si(111) electrodes in tetrahydrofuran resulted in the complete elimination of Cl, as measured by XPS. The data are consistent with a mechanism in which the reaction of alkyl Grignard reagents with the Cl-terminated Si(111) surfaces involves electron transfer from the Grignard reagent to the Si, loss of chloride to solution, and subsequent reaction between the resultant silicon radical and alkyl radical to form a silicon−carbon bond. Sites sterically hindered by neighboring alkyl groups abstract a H atom to produce Si−H bonds on the surface.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/jp057070iDOIArticle
ORCID:
AuthorORCID
Nemanick, E. Joseph0000-0002-4650-6491
Brunschwig, Bruce S.0000-0002-6135-6727
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2006 American Chemical Society. Received 5 December 2005. Published online 13 July 2006. Published in print 1 August 2006. We gratefully acknowledge the NSF, Grant CHE-021358 and the Beckman Institute for support of this work.
Funders:
Funding AgencyGrant Number
NSFCHE-0213589
Caltech Beckman InstituteUNSPECIFIED
Issue or Number:30
Record Number:CaltechAUTHORS:20170609-073705620
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170609-073705620
Official Citation:Chemical and Electrical Passivation of Silicon (111) Surfaces through Functionalization with Sterically Hindered Alkyl Groups E. Joseph Nemanick, Patrick T. Hurley, Bruce S. Brunschwig, and Nathan S. Lewis The Journal of Physical Chemistry B 2006 110 (30), 14800-14808 DOI: 10.1021/jp057070i
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78042
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:09 Jun 2017 16:30
Last Modified:29 Oct 2020 19:27

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