AVS 45th International Symposium
    Surface Science Division Monday Sessions
       Session SS-MoP

Paper SS-MoP24
Hydrogen Diffusion and Desorption from the Si(100)-2x1 Surface

Monday, November 2, 1998, 5:30 pm, Room Hall A

Session: Surface Science Division Poster Session
Presenter: E.J. Buehler, University of North Carolina, Chapel Hill
Authors: E.J. Buehler, University of North Carolina, Chapel Hill
J.J. Boland, University of North Carolina, Chapel Hill
Correspondent: Click to Email
The mechanisms of hydrogen diffusion on the Si(100) surface and desorption from the 2x1 monohydride surface are being studied using high temperature scanning tunneling microscopy. Several desorption mechanisms have been proposed in the literature to explain the observed first-order kinetics, large energy barrier to adsorption, and similarity between hydrogen molecules desorbing from the decomposition of the mono- and dihydride phases. The possible role of surface defects has also been discussed. Using high temperature imaging conditions at which the tip does not induce desorption, we have observed pairs of vacant dangling bond (DB) sites on the surface following desorption. The spatial distribution of DB’s on the surface shows no correlation with the locations of steps and defects. A particular surface feature has been identified, however, which may be a stable intermediate formed during the hydrogen desorption process. The structure and stability of this intermediate are discussed, as is the possible role of this feature in hydrogen desorption.