AVS 50th International Symposium
    Surface Science Wednesday Sessions
       Session SS1-WeM

Paper SS1-WeM8
Coupling Reactions of Trifluoroethyl Iodide on GaAs(100)

Wednesday, November 5, 2003, 10:40 am, Room 328

Session: Adsorption on Semiconductor Surfaces
Presenter: N.K. Singh, The University of New South Wales, Australia
Authors: N.T. Kemp, The University of New South Wales, Australia
N. Paris, The University of New South Wales, Australia
N.K. Singh, The University of New South Wales, Australia
Correspondent: Click to Email
Alkyl coupling reactions studied to date have been restricted to gold, silver and copper surfaces, where the only coupling product formed has always been the corresponding higher alkane. In this paper we report, the coupling reactions of trifluoroethyl iodide on GaAs(100) which forms, not only the higher alkane, but a higher alkene as well. In this respect the alkyl coupling reactions on the GaAs surface differ from those on transition metal surfaces. Additionally, the ability of a semiconductor surface to catalyse carbon-carbon bond formation has not been reported previously by other researchers. The techniques of X-ray photoelectron spectroscopy and thermal desorption spectroscopy have been used to study the surface reactions of 2-iodo-1,1,1-trifluoroethane (CF@sub3@CH@sub2@I) on GaAs(100). Our results show that coupling of surface CF@sub3@CH@sub2@ species, generated via the dissociative adsorption of CF@sub3@CH@sub2@I, yields both CF@sub3@CH@sub2@CH@sub2@CF@sub3@ and CF@sub3@CH@sub2@CH=CF@sub2@. The coupling pathway competes with the disproportionation reactions of CF@sub3@CH@sub2@, to form CF@sub2@=CH@sub2@ as the major product of this pathway. In addition, we observe the formation of volatile etch products IF@subx@, GaI, AsI, GaF, AsF and As@sub2@. This paper will discuss the mechanisms by which these products form from the adsorbed CF@sub3@CH@sub2@ and I species, and the role that the GaAs surface plays in the reaction pathways proposed.