AVS 49th International Symposium
    Surface Science Thursday Sessions
       Session SS+EL-ThA

Paper SS+EL-ThA6
Surface Modification without Desorption: Recycling of Cl on Si(100)-(2x1)

Thursday, November 7, 2002, 3:40 pm, Room C-112C

Session: Growth & Etching on Semiconductor Surfaces
Presenter: K.S. Nakayama, University of Illinois at Urbana-Champaign
Authors: K.S. Nakayama, University of Illinois at Urbana-Champaign
E. Graugnard, University of Illinois at Urbana-Champaign
J.H. Weaver, University of Illinois at Urbana-Champaign
Correspondent: Click to Email
We demonstrate the structural consequences of thermally activated reactions of Cl on Si(100)-(2x1). We used scanning tunneling microscopy at room temperature to obtain atomic-resolution images of the surface before and after thermal processing. We show surface modification under conditions where Cl is recycled rather than desorbed as SiCl@sub 2@. In this unexpected reaction, the surface roughens as dimer vacancies are produced. First, a dimer with 2 Cl atoms, 2SiCl, converts to SiCl@sub 2@ + Si. This allows the destabilized, bare Si atom to escape onto the terrace. At temperatures where the desorption is negligible, the SiCl@sub 2@ unit decays as the Cl atoms can move to other active sites of the Si surface, allowing the second Si atom to escape. The result is a dimer vacancy, Si atoms on the terrace that can form self-organized regrowth structures, and Cl that is able to participate in another pitting event. Access to this unexpected roughening pathway is controlled by the Cl concentration and temperature. This previously overlooked process represents an important component of Si(100) surface processing.