AVS 45th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS2-TuA

Paper SS2-TuA7
ToF-SIMS Characterization of the Interaction Between Vapor-Deposited Al Atoms and an Ordered Array of Organic Functional Groups

Tuesday, November 3, 1998, 4:00 pm, Room 309

Session: Morton M. Traum Student Award Session
Presenter: G.L. Fisher, The Pennsylvania State University
Authors: G.L. Fisher, The Pennsylvania State University
A.E. Hooper, The Pennsylvania State University
R.L. Opila, Bell Laboratories, Lucent Technologies
D.L. Allara, The Pennsylvania State University
N. Winograd, The Pennsylvania State University
Correspondent: Click to Email
The room temperature vapor deposition of up to 4Å of Al metal onto monolayers of @omega@-functionalized alkanethiolate molecules, of structure HS-(CH@sub 2@)@sub n@-X, self-assembled on polycrystalline Au was studied using static ToF-SIMS, XPS and IRS. Deposited Al was found to be highly reactive with methylester organic functional groups (OFGs). The data indicate a titration of one Al atom per methylester OFG, and the ether bonds appear to be unperturbed. Thus, deposited Al reacts solely with carbonyl oxygen of the OFG forming a uniform dielectric with an Al-O-C bonding arrangement. Upon saturation of methylester OFGs with deposited Al, further deposition results in formation of metallic overlayers. Deposited Al was found to be unreactive with methyl OFGs. Instead, the deposited Al diffuses through the monolayer to the monolayer/Au interface via thermally activated transient defects. Here, the Al atoms are observed to disrupt the Au-S bonding to form stable Au-Al-S bonds that quench further transient defect formation. As the deposition progresses deposited Al is observed to form islands on top of the monolayer. Island formation in this case is a result of physisorbed Al; no chemical reaction is observed. Penetration of deposited Al through the methylester-terminated monolayer to the monolayer/Au interface was not observed. Reaction between deposited Al and the methylene backbone of methyl-terminated and methylester-terminated monolayers was not observed.