AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP6
Defect Structures on the Si(5 5 12)-2x1 Surface

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: A.S. Sun, Virginia Commonwealth University
Authors: A.S. Sun, Virginia Commonwealth University
K.M. Jones, Virginia Commonwealth University
E.S. Bowman, Virginia Commonwealth University
A.A. Baski, Virginia Commonwealth University
Correspondent: Click to Email
Scanning tunneling microscopy (STM) studies of the high-index Si(5 5 12)-2x1 reconstructed surface show that it forms a single domain of row-like structures. It has therefore been proposed as a viable template for metallic nanowire growth. In this work, we use STM to characterize two common surface defects that may influence its application as such a template. The most commonly observed surface defects are disruptions in the periodicity of the Si(5 5 12) unit cell. The Si(5 5 12) unit cell can be considered as a combination of one (7 7 17) and one (337) unit cell. In up to 20 percent of the (5 5 12) units, an extra or missing (337) subunit appears, resulting in a non-uniform surface periodicity. Because there is a dominance of either extra or missing (337) units on a given sample, sample preparation conditions appear to play an important role. Another type of defect observed on the Si(5 5 12) surface is the presence of adsorbed dimers. These dimers have a typical coverage of 10-15 percent, and exist as single dimers or in clusters up to ~10 dimers long. Statistics taken from STM data indicate that as the dimer cluster size increases, the number of clusters decreases exponentially. A Monte Carlo model of 1D clusters has been used to correlate the distribution of these dimer defects with their relative "hopping" probabilities on different surface sites.@footnote 1@ We find that single dimers have a strong preference to remain attached to the ends of existing clusters. A better understanding of both the adsorbed dimer and (337) unit cell defects should lead to a more controlled preparation of Si(5 5 12) as a growth template. @FootnoteText@ @footnote 1@ E. S. Bowman, M. F. Bishop, T. McMullen, and A. A. Baski, Cluster and Nanostructure Interfaces, edited by P. Jena (World Scientific, New York, 2000), p. 569-574, in press.