AVS 51st International Symposium
    Organic Films and Devices Thursday Sessions
       Session OF+NS-ThM

Paper OF+NS-ThM8
Structure of Self-Assembled Monolayers on Platinum

Thursday, November 18, 2004, 10:40 am, Room 304C

Session: Molecular Electronics
Presenter: D.Y. Petrovykh, University of Maryland, Naval Research Laboratory
Authors: D.Y. Petrovykh, University of Maryland, Naval Research Laboratory
H. Kimura-Suda, National Institute of Standards and Technology
A. Opdahl, National Institute of Standards and Technology
L.J. Richter, National Institute of Standards and Technology
R.D. Van Zee, National Institute of Standards and Technology
M.J. Tarlov, National Institute of Standards and Technology
L.J. Whitman, Naval Research Laboratory
Correspondent: Click to Email
We studied formation of self-assembled monolayers (SAMs) on polycrystalline platinum thin films using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), spectroscopic ellipsometry, and contact angle measurements. In particular we are interested in properties of SAMs on Pt with respect to their possible use as a substrate for Si-compatible molecular electronics. We find that SAMs formed on piranha-cleaned Pt from ethanoic solutions of n-alkanethiols have initial quality comparable to or better than that achieved under other conditions. The FTIR and XPS data indicate that films are formed with nearly normal orientation of alkane chains, have higher packing density than comparable SAMs/Au, and remain stable in ambient air for 3-5 days. XPS spectra of the S 2p region also show that SAMs/Pt are distinctly multicomponent. The main component, with the lowest binding energy, unambiguously corresponds to alkanethiol molecules adsorbed on Pt in a configuration similar to that for SAMs/Au. The minority higher binding energy components are not affected by exposure to good solvents and thus appear to correspond to different binding configurations related to surface roughness and oxidation (rather than to physisorbed molecules). Our results suggest that the use of oxide-free and atomically smooth Pt substrates may be necessary to attain a single-component, high-quality SAM on Pt.