AVS 50th International Symposium
    Surface Science Thursday Sessions
       Session SS1-ThM

Paper SS1-ThM6
Equilibrium Morphologies for Cl-roughened Si(100) at 700 - 750 K: Experiments and Monte Carlo Modeling

Thursday, November 6, 2003, 10:00 am, Room 310

Session: Patterned Growth and Etching of Semiconductors
Presenter: G.J. Xu, University of Illinois at Urbana-Champaign
Authors: G.J. Xu, University of Illinois at Urbana-Champaign
K.S. Nakayama, University of Illinois at Urbana-Champaign
B.R. Trenhaile, University of Illinois at Urbana-Champaign
C.M. Aldao, University of Illinois at Urbana-Champaign
J.H. Weaver, University of Illinois at Urbana-Champaign
Correspondent: Click to Email
Adsorbed halogen atoms on Si(100)-(2x1) can induce roughening at temperatures where material removal (etching) is minimal. Variable temperature scanning tunneling microscopy was used to follow roughening at 700 - 750 K for surfaces with 0.1 - 0.99 ML of Cl. Dimer vacancies and Si adatoms were observed at short times, and at longer times the progression toward a state of dynamic equilibrium was traced. Once dynamic equilibrium was reached, the appearance of individual pits and regrowth islands changed but their densities and mean sizes did not. The results show that the roughness depends non-linearly on Cl coverage with surfaces having 0.3 ML being nearly ten times rougher than those with 0.1 ML. The importance of Cl-free dimers is stressed, and the role of Cl as an impediment for vacancy and adatom diffusion is demonstrated. Roughening is attributed mainly to adsorbate-adsorbate repulsive interactions. Further insight can be gained from Monte Carlo simulations, where the consequences of adsorbate-adsorbate interactions are explored and the resulting morphologies are compared with those experimentally observed. While adsorbate-adsorbate interactions may be the main driving force responsible for roughening, contributions from other interactions cannot be ruled out.