AVS 51st International Symposium
    Surface Science Wednesday Sessions
       Session SS2-WeM

Paper SS2-WeM5
Si Epitaxial Growth on Br-Si(100): How Steric Repulsive Interactions Dictate Overlayer Development

Wednesday, November 17, 2004, 9:40 am, Room 210C

Session: Semiconductor Surface and Interface Structure
Presenter: G.J. Xu, University of Illinois at Urbana-Champaign
Authors: G.J. Xu, University of Illinois at Urbana-Champaign
J.H. Weaver, University of Illinois at Urbana-Champaign
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Scanning tunneling microscopy results show the consequences of Si adatom deposition onto Br-saturated Si(100)-(2x1). Those adatoms undergo an exchange reaction with Br but they are immobile at room temperature. In the low coverage regime, annealing to 650 K leads to dimerization, limited ordering, and the formation of short Si chains. Adatom capture by those chains produces features of even and odd numbers of atoms. Annealing at 700 K eliminates the odd chains, but diffusion is highly constrained by Br site blocking. With increased Si coverage, there is further nucleation of chains and chain growth. The local patterning of the Si chains reveals the influence of the strong steric repulsive interactions of Br as out-of-phase structures were favored over in-phase structures around any given chain. Eventually, those interactions favor adlayer (3x2) patches rather than (2x1) islands. Second layer chains appear after the deposition of ~0.3 ML, with layer-2 nucleation at antiphase domain boundaries of layer-1. Bromine loss was observed, even at 650 K, and it is probably tied to the dynamics of atom exchange involved with Si diffusion on a saturated surface.