AVS 47th International Symposium
    Surface Science Thursday Sessions
       Session SS3-ThM

Invited Paper SS3-ThM5
One-Dimensional Noble Metal Growth on Si(5 5 12)

Thursday, October 5, 2000, 9:40 am, Room 210

Session: Surface and Interface Structure II
Presenter: A.A. Baski, Virginia Commonwealth University
Authors: A.A. Baski, Virginia Commonwealth University
K.M. Jones, Virginia Commonwealth University
K.M. Saoud, Virginia Commonwealth University
Correspondent: Click to Email
Metal-semiconductor systems that exhibit 1-D growth have lately been of interest, particularly those that form nanometer-scale metal rows on a semiconductor. The recently discovered surface of Si(5 5 12) forms a single-domain reconstruction composed of row-like structures.@footnote 1@ providing a unique template for the growth of 1-D nanostructures. Our recent scanning tunneling microscopy (STM) studies show that noble metals such as Ag and Au deposited onto Si(5 5 12) and annealed indeed form a wide variety of well-ordered overlayer rows.@footnote 2@ At coverages below 0.25 monolayers (ML), both metals grow as monatomic rows with an inter-row spacing of ~5 nm. These metal rows preferentially nucleate along the more reactive Si tetramer rows of the surface reconstruction, leading to their growth in a periodic array. Scanning tunneling spectroscopy (STS) data show that Ag wires have a finite density of states at zero volts, indicating metallic behavior. At higher coverages and annealing temperatures, the underlying Si reconstruction is removed and the growth behavior of Ag and Au diverges. Up to ~0.5 ML, Ag forms sawtooth rows which evolve with coverage to an extremely well-ordered array of stepped double rows. Surprisingly, this phase has a significant band gap (1.25 V) compared to the clean Si surface (0.5 V). At comparable coverages and annealing temperatures, Au growth is usually less ordered; however, significantly elevated temperatures (>500C) lead to the creation of well-ordered facet planes [e.g. (7 7 15) and (225)]. For all coverages and annealing temperatures studied here, deposits of Au and Ag form row-like morphologies on the Si(5 5 12) surface, indicating the utility of this high-index surface as a template for the growth of 1-D nanostructures. @FootnoteText@ @footnote 1@ A. A. Baski, S. C. Erwin, and L. J. Whitman, Science 269, 1556 (1995). @footnote 2@ H.H. Song, K.M. Jones, and A.A. Baski, J. Vac. Sci. Technol. A 17(4), 1696 (1999).