AVS 47th International Symposium
    Semiconductors Monday Sessions
       Session SC+EL+SS-MoA

Paper SC+EL+SS-MoA5
STM Study of Self-Assembled Quantum-Dot Arrays of Sn on Si(111)-(7x7) Surface

Monday, October 2, 2000, 3:20 pm, Room 306

Session: Reactions on Semiconductors
Presenter: M. Yoon, The Pennsylvania State University
Authors: M. Yoon, The Pennsylvania State University
R.F. Willis, The Pennsylvania State University
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The adsorption and diffusion mechanisms of Sn on the Si(111)-(7x7) at sub-monolayer coverages have been studied by scanning tunneling microscopy (STM). It is found that the preference of Sn adsorbates on the faulted-halves of the 7x7 unit cell is dependent on adsorbate coverage up to @THETA@ ~ 0.3 monolayer (ML). At higher coverages (~0.3 - 0.5 ML), the tin atoms cluster together on both halves of the 7x7 unit cell, forming a two-dimensional array of self-assembled quantum dots. This is in contrast to the behavior recently reported@footnote 1@ for Tl condensation on Si(111)-(7x7). In this latter case, the element occupies faulted half-cells preferentially and the surface remains metallic. In the present case, the Sn clusters are semiconducting, the surface showing an energy bandgap which increases with increasing coverage. The surface returns to metallic behavior as the number of Sn atoms approaches that of one monolayer of Si. @FootnoteText@ @footnote 1@L. Vitali, M. G. Ramsey, and F. P. Netzer, Phys. Rev. Lett. 83, 316 (1999).