Spectroscopic characterization of alkylsilanes on metal and oxide surfaces

Persistent Link:
http://hdl.handle.net/10150/282578
Title:
Spectroscopic characterization of alkylsilanes on metal and oxide surfaces
Author:
Cai, Mei, 1967-
Issue Date:
1997
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The research projects described in this Dissertation were designed to investigate the interfacial chemistry of alkylsilanes on metal and oxide surfaces, specifically Ag and silica, respectively. A variety of surface analysis tools, including FTIR and Raman spectroscopies, electrochemistry, ellipsometry, and x-ray photoelectron spectroscopy, have been applied to study important aspects of bonded alkylsilane structures. Two model silica surfaces were designed and fabricated as substrates for the attachment of alkylsilanes. The first model silica surface employs self-assembled monolayers of hydrolyzed and condensed (3-mercaptopropyl)trimethoxysilane (3MPT) on Ag surfaces. The Ag substrate is used to provide a small enhancement to the Raman scattering at the interface. Octadecyltrichlorosilane (OTS) and dimethylchlorooctadecylsilane (DOS) are covalently bonded to these surfaces. Monolayers of OTS on 3MPT-modified Ag surfaces are ordered, while submonolayers of DOS, the maximum coverage achievable, are disordered. Results obtained from this study demonstrate the importance of van der Waals interactions and siloxane cross-linking in promoting an ordered alkylsilane structure. The second model silica surface studied is based on thin silica films prepared through sol-gel technology. These are prepared by spin-coating prehydrolyzed solutions of tetratmethoxysilane (TMOS) onto 3MPT-modified Ag surfaces. These surfaces are designed to contribute to an understanding of the partitioning process associated with alkylsilane stationary phases in reversed-phase liquid chromatography (RPLC). OTS layers covalently attached to such surfaces were studied previously in this laboratory. In this Dissertation, the sol-gel methodology used is improved to enable silica films in the ultrathin (< 100 Å) regime to be fabricated. These substrates allow study of model stationary phases of DOS. Both FTIR and Raman spectroscopies indicate that the DOS alkyl chains on silica are disordered, consistent with previous notions about monomeric alkylsilane stationary phases in RPLC. Further characterization of these thin silica films reveals them to be non-porous, dielectric, and homogeneous. Their dielectric strengths are found to be equivalent to or better than those from device-quality thermally grown silica. This research expands application of the well-defined sol-gel technology to the fabrication of ultrathin silica films that may be useful as insulating layers in the microelectronics and semiconductor industries.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Chemistry, Analytical.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Chemistry
Degree Grantor:
University of Arizona
Advisor:
Pemberton, Jeanne E.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleSpectroscopic characterization of alkylsilanes on metal and oxide surfacesen_US
dc.creatorCai, Mei, 1967-en_US
dc.contributor.authorCai, Mei, 1967-en_US
dc.date.issued1997en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe research projects described in this Dissertation were designed to investigate the interfacial chemistry of alkylsilanes on metal and oxide surfaces, specifically Ag and silica, respectively. A variety of surface analysis tools, including FTIR and Raman spectroscopies, electrochemistry, ellipsometry, and x-ray photoelectron spectroscopy, have been applied to study important aspects of bonded alkylsilane structures. Two model silica surfaces were designed and fabricated as substrates for the attachment of alkylsilanes. The first model silica surface employs self-assembled monolayers of hydrolyzed and condensed (3-mercaptopropyl)trimethoxysilane (3MPT) on Ag surfaces. The Ag substrate is used to provide a small enhancement to the Raman scattering at the interface. Octadecyltrichlorosilane (OTS) and dimethylchlorooctadecylsilane (DOS) are covalently bonded to these surfaces. Monolayers of OTS on 3MPT-modified Ag surfaces are ordered, while submonolayers of DOS, the maximum coverage achievable, are disordered. Results obtained from this study demonstrate the importance of van der Waals interactions and siloxane cross-linking in promoting an ordered alkylsilane structure. The second model silica surface studied is based on thin silica films prepared through sol-gel technology. These are prepared by spin-coating prehydrolyzed solutions of tetratmethoxysilane (TMOS) onto 3MPT-modified Ag surfaces. These surfaces are designed to contribute to an understanding of the partitioning process associated with alkylsilane stationary phases in reversed-phase liquid chromatography (RPLC). OTS layers covalently attached to such surfaces were studied previously in this laboratory. In this Dissertation, the sol-gel methodology used is improved to enable silica films in the ultrathin (< 100 Å) regime to be fabricated. These substrates allow study of model stationary phases of DOS. Both FTIR and Raman spectroscopies indicate that the DOS alkyl chains on silica are disordered, consistent with previous notions about monomeric alkylsilane stationary phases in RPLC. Further characterization of these thin silica films reveals them to be non-porous, dielectric, and homogeneous. Their dielectric strengths are found to be equivalent to or better than those from device-quality thermally grown silica. This research expands application of the well-defined sol-gel technology to the fabrication of ultrathin silica films that may be useful as insulating layers in the microelectronics and semiconductor industries.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectChemistry, Analytical.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorPemberton, Jeanne E.en_US
dc.identifier.proquest9831857en_US
dc.identifier.bibrecord.b38625453en_US
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