CaltechAUTHORS
  A Caltech Library Service

Spectroscopic Studies of the Modification of Crystalline Si(111) Surfaces with Covalently-Attached Alkyl Chains Using a Chlorination/Alkylation Method

Bansal, Ashish and Li, Xiuling and Yi, Sang I. and Weinberg, W. H. and Lewis, Nathan S. (2001) Spectroscopic Studies of the Modification of Crystalline Si(111) Surfaces with Covalently-Attached Alkyl Chains Using a Chlorination/Alkylation Method. Journal of Physical Chemistry B, 105 (42). pp. 10266-10277. ISSN 1520-6106. https://resolver.caltech.edu/CaltechAUTHORS:20170515-141841951

[img] PDF (Surface Characterizations by X-ray Photoelectron Spectroscopy) - Supplemental Material
See Usage Policy.

304Kb

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:20170515-141841951

Abstract

A two-step procedure, involving radical-initiated chlorination of the Si surface with PCl_5 followed by reaction of the chlorinated surface with alkyl-Grignard or alkyl-lithium reagents, has been developed to functionalize crystalline (111)-oriented H-terminated Si surfaces. The surface chemistry that accompanies these reaction steps has been investigated using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), temperature programmed desorption spectroscopy (TPDS), high-resolution electron energy loss spectroscopy (HREELS), infrared (IR) spectroscopy in both glancing transmission (TIR) and attenuated total multiple internal reflection (ATR) modes, ellipsometry, and contact angle goniometry. The XPS data show the appearance of the Cl signal after exposure to PCl_5 and show its removal, and concomitant appearance of a C 1s signal, after the alkylation step. Auger electron spectra, in combination with TPD spectroscopy, demonstrate the presence of Cl after the chlorination process and its subsequent loss after thermal desorption of Si−Cl fragments due to heating the Si surface to 1200 K. High-resolution XP spectra of the Si 2p region show a peak corresponding to Si−Cl bond formation after the chlorination step, and show the subsequent disappearance of this peak after the alkylation step. IR spectra show the loss of the perpendicularly polarized silicon monohydride (Si−H) vibration at 2083 cm^(-1) after the chlorination step, whereas HREELS data show the appearance of vibrations due to Si−Cl stretches upon chlorination of the Si surface. The HREELS data furthermore show the disappearance of the Si−Cl stretch and the appearance of a Si−C vibration at 650 cm^(-1) after alkylation of the Si surface. Ellipsometric measurements indicate that the thickness of the alkyl overlayer varies monotonically with the length of the alkyl group used in the reactant. Contact angle and IR measurements indicate that the packing of alkyl groups in the monolayers produced by this method is less dense than that found in alkylthiol monolayers on Au. As determined by XPS, the alkylated surfaces show enhanced resistance to oxidation by various wet chemical treatments, compared to the H-terminated Si surface. The two-step reaction sequence thus provides a simple approach to functionalization of (111)-oriented, H-terminated silicon surfaces using wet chemical methods.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/jp010284pDOIArticle
http://pubs.acs.org/doi/abs/10.1021/jp010284pPublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/jp010284pPublisherSupporting Information
ORCID:
AuthorORCID
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2001 American Chemical Society. Received: January 24, 2001; In Final Form: May 23, 2001; Publication Date (Web): October 3, 2001. We acknowledge the NSF, Grant No. CHE-997456, for support of this work. Si wafers polished on both sides were generously provided by Mr. Daniel L. McDonald of Wacker Siltronic Corp. We also acknowledge Dr. Steve Doig for constructing the surface IR apparatus and Dr. Alan Rice for assistance with, and technical support of, the UHV equipment.
Funders:
Funding AgencyGrant Number
NSFCHE-9974562
Issue or Number:42
Record Number:CaltechAUTHORS:20170515-141841951
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170515-141841951
Official Citation:Spectroscopic Studies of the Modification of Crystalline Si(111) Surfaces with Covalently-Attached Alkyl Chains Using a Chlorination/Alkylation Method Ashish Bansal, Xiuling Li, Sang I. Yi, W. H. Weinberg, and Nathan S. Lewis The Journal of Physical Chemistry B 2001 105 (42), 10266-10277 DOI: 10.1021/jp010284p
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77463
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:16 May 2017 03:39
Last Modified:03 Oct 2019 17:57

Repository Staff Only: item control page