Web Release Date: November 4,
Structure, Bonding Nature, and Binding Energy of Alkanethiolate on As-Rich GaAs (001) Surface: A Density Functional Theory Study
Department of Electrical and Computer Engineering, Centre de Recherche en Nanofabrication et Nanocaractériasation (CRN2), Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
Received: July 23, 2006
In Final Form: October 5, 2006
Abstract:
Chemisorption of alkanethiols on As-rich GaAs (001) surface under a low coverage condition was studied using first principles density functional calculations in a periodic supercell approach. The thiolate adsorption site, tilt angle and its direction are dictated by the high directionality of As dangling bond and sulfur 3p orbital participating in bonding and steric repulsion of the first three CH2 units from the surface. Small charge transfer between thiolate and surface, strong dependence of total energy on tilt angle, and a relatively short length of 2.28 Å of the S-As bond indicate the highly covalent nature of the bonding. Calculated binding energy of 2.1 eV is consistent with the available experimental data.
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