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

Paper SS3-ThM7
Stability and Nuclear Formation of Si(111)-7x7 Structure as Determined from Charge Redistribution in Surface Layers

Thursday, October 5, 2000, 10:20 am, Room 210

Session: Surface and Interface Structure II
Presenter: K. Miyake, University of Tsukuba, Japan
Authors: K. Miyake, University of Tsukuba, Japan
T. Kaikoh, University of Tsukuba, Japan
Y.J. Li, University of Tsukuba, Japan
R. Morita, Hokkaido University, Japan
M. Yamashita, Hokkaido University, Japan
H. Shigekawa, University of Tsukuba, Japan
Correspondent: Click to Email
Reconstruction of the Si(111) surface has been extensively studied by various experiments as well as theoretical considerations. And 7x7 structure has been concluded to be the most stable phase on the Si(111) surface in equilibrium condition. In fact, the 7x7 phase is completed on the well annealed surface, and phase transition between high-temperature "1x1" and 7x7 phases was directly observed around the critical temperature by using scanning tunneling microscopy (STM). The dimer-adatomstacking-fault (DAS) structure proposed by Takayanagi et al., @footnote 1@ which is compatible with the experimental and theoretical results, is widely accepted as the model for the Si(111)-7x7 reconstructed surface structure. And atomic arrangement of the DAS structure in the static form is now well established. However, since the DAS structure involves few surface layers and is very complicated, dynamics of the surface, mechanism for the formation and stabilizing processes of the structure, has not yet been completely clarified, and is still attracting considerable attention. By considering the charge transfer from adatoms to rest atoms, we can analyze the structure of the dimer and stacking-fault (DS) layers in the Si(111) dimer-adatomstacking-fault (DAS) structure in a subunit level. In comparison with the modified model of Vanderbilt, corner holes with the completed DS structure in the second layer, completed corner hole, was confirmed to play a key role not only in the mechanism to stabilize the DAS structure, but also in the formation process of it; formation of the completed corner hole works as a rate limiting process for the growth of the DAS structure.@footnote 2@ This mechanism was shown to be quite consistent with the experimental results which had been obtained by STM on the quenched and HBO@SUB 2@ molecules irradiated Si(111) surface.@footnote 3@ Phase transition from Si(111)-7x7 to the B-induced @sr@3x@sr@3 structure, and the structure near the step edge was analyzed in detail. @FootnoteText@ @footnote 1@K. Takayanagi et al, J. Vac. Sci. Technol., A 3 (1985) 1502. @footnote 2@K. Miyake et al., Surf. Sci., 429 (1999) 260-273. @footnote 3@K. Miyake et al., Jpn. J. Appl. Phys., 38 (1999) 3841.