AVS 51st International Symposium
    Surface Science Monday Sessions
       Session SS-MoP

Paper SS-MoP14
Low Energy Electron Diffraction Study of Dodecanethiol Self-Assembled Monolayers Grown on Pt(100) and Pt(111) by Vapor Deposition

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: T.M. Sweeney, University of New Orleans
Authors: T.M. Sweeney, University of New Orleans
P.S. Robbert, University of New Orleans
C.A. Ventrice, Jr., University of New Orleans
H. Geisler, Xavier University
Correspondent: Click to Email
One of the most popular substrates for growing self-assembled monolayers (SAMs) is the Au(111) surface. This is primarily due to the fact that it does not oxidize during preparation of the SAMs from solution. However, gold is not compatible with conventional Si-based electronics due to its tendency to diffuse into Si. A more promising candidate for the integration of SAMs with Si-based electronic devices is the use of Pt for the growth of the SAMs. Therefore, we have performed a study of the growth of dodecanethiol SAMs on single-crystal Pt(100) and Pt(111) surfaces by vapor deposition in ultra-high vacuum. The clean Pt(100) surface exhibits a four-domain (5x1) reconstruction. Upon deposition of ~0.1 L of thiol, the (5x1) reconstruction is removed. Doses greater than a few Langmuir result in a weak (1x1) pattern, indicative of the growth of a disordered thiol overlayer on the unreconstructed Pt(100) surface. The clean Pt(111) surface does not exhibit a surface reconstruction. Deposition of ~0.1 L of thiol results in a sharp (2x2) LEED pattern, which indicates that the initial sticking coefficient is near unity and that the thiol molecules most likely have a standing up geometry. As with the Pt(100) surface, doses beyond a few Langmuir result in the formation of a weak (1x1) LEED pattern. In addition, we have initiated a study of the electronic properties of these SAMs using angle-resolved photoelectron spectroscopy. The results of these measurements will also be presented.