title: Theoretical investigation of the structure and coverage of the Si(111)-OCH3 surface.
abstract: The surface structure, strain energy, and charge profile of the methoxylated Si(111) surface, Si(111)-OCH3, has been studied using quantum mechanics, and the results are compared to those obtained previously for Si(111)-CH3 and Si(111)-C2H5. The calculations indicate that 100% coverage is feasible for Si(111)-OCH3 (similar to the methylated surface), as compared to only approximately 80% coverage for the ethylated surface. These differences can be understood in terms of nearest-neighbor steric and electrostatic interactions. Enthalpy and free energy calculations indicate that the formation of the Si(111)-OCH3 surface from Si(111)-H and methanol is favorable at 300 K. The calculations have also indicated the conditions under which stacking faults can emerge on Si(111)-OCH3, and such conditions are contrasted with the behavior of Si(111)-CH3 and Si(111)-CH2CH3 surfaces, for which stacking faults are calculated to be energetically feasible when etch pits with sufficiently long edges are present on the surface.
authors.affiliation: Division of Chemistry and Chemical Engineering, Kavli Nanoscience Institute and Beckman Institute, 210 Noyes Laboratory, 127-72, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Santiago D
authors.initials: SD
authors.lastname: Solares
authors.forename: David J
authors.initials: DJ
authors.lastname: Michalak
authors.forename: William A
authors.initials: WA
authors.lastname: Goddard
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Lewis