IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Thursday Sessions
       Session SC+SS+EL-ThM

Paper SC+SS+EL-ThM8
Adsorption and Thermal Decomposition of Iodoethane on Si(100)-2x1: Kinetically-Favored Adsorbate Ordering

Thursday, November 1, 2001, 10:40 am, Room 111

Session: Interaction of Hydrogen and Organics with Silicon
Presenter: A.V. Teplyakov, University of Delaware
Authors: A.V. Teplyakov, University of Delaware
K.M. Bulanin, University of Delaware
A.G. Shah, University of Delaware
Correspondent: Click to Email
The adsorption and chemical transformation of iodoethane were studied on a Si(100)-2x1 surface using multiple-internal reflection Fourier-transform infrared spectroscopy (MIR-FTIR). Although ethyl groups are stable on the Si(100)-2x1 surface at room temperature, thermal annealing studies suggest the formation of ethylene, a major hydrocarbon reaction product, accompanied by the loss of hydrogen, which is left on the surface until the temperature of recombinative desorption is reached. Adsorption of iodoethane on Si(100), followed by annealing to 570 K, leaves only hydrogen and iodine on the surface. MIR-FTIR spectroscopy shows that hydrogen is bound in several different types of site at temperatures between 295 K and 570 K. Annealing to higher temperatures produces a distribution dominated by a single hydrogen configuration. First-principles theory and polarization-dependent infrared spectra are consistent with the identification of this configuration as a dimer occupied by one hydrogen and one iodine atom. Calculations show that this configuration is not thermodynamically favored relative to other possible configurations. The observed ordering is attributed to kinetics, a consequence of slow pairing of iodine atoms.