Theoretical Investigation of the Structure and Coverage of the Si(111)−OCH_3 Surface
Santiago D. Solares, David J. Michalak, William A. Goddard III, Nathan S. Lewis
Abstract
The surface structure, strain energy, and charge profile of the methoxylated Si(111) surface, Si(111)−OCH_3, has been studied using quantum mechanics, and the results are compared to those obtained previously for Si(111)−CH_3 and Si(111)−C_2H_5. The calculations indicate that 100% coverage is feasible for Si(111)−OCH_3 (similar to the methylated surface), as compared to only ∼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)−OCH_3 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)−OCH_3, and such conditions are contrasted with the behavior of Si(111)−CH_3 and Si(111)−CH_2CH_3 surfaces, for which stacking faults are calculated to be energetically feasible when etch pits with sufficiently long edges are present on the surface.
Group Members
Solares, S. D., Michalak, D. J., III, W. A. G., & Lewis, N. S. (2006). Theoretical Investigation of the Structure and Coverage of the Si(111)−OCH_3 Surface. *J. Phys. Chem. B*, *110*(16), 8171-8175.