AVS 46th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS3+EM-WeM

Paper SS3+EM-WeM2
Si Surface Passivation: Si(111):GaSe versus Si(111):As

Wednesday, October 27, 1999, 8:40 am, Room 604

Session: Surface Electronic Structure
Presenter: A. Bostwick, University of Washington
Authors: A. Bostwick, University of Washington
S. Meng, University of Washington
B.R. Schroeder, University of Washington
E. Rotenberg, Lawrence Berkeley National Laboratory
F.S. Ohuchi, University of Washington
M.A. Olmstead, University of Washington
Correspondent: Click to Email
Heteroepitaxy on Si(111)7x7 requires removal of the deep reconstruction and accompanying dangling bonds. One way to passivate the Si(111) surface and remove the reconstruction is exposure to As, forming Si(111):As 1x1.@footnote 1@ The initial chemisorption of GeSe on Si(111)7x7 surfaces also results in a nearly ideally terminated 1x1 surface, quite similar to Si(111):As. Ga and Se occupy bulk Si sites, with Ga directly above Si (T1 site) and Se forming three back-bonds to Ga (H3 site). This (1x1) structure is the same as half a bulk GaSe layer, and initiates GaSe heteroepitaxy on Si(111). The very small (less than 0.1 eV) Si 2p core level shift shows the interface silicon to be in a bulk-like environment with minimal charge transfer, in contrast to As terminated silicon (0.75 eV shift). Electron counting arguments predict a lone-pair state on the Si(111):GaSe 1x1 surface, very similar to the As case. We observe such a state with angle-resolved ultraviolet photoemission spectroscopy. It has a similar E(k) dispersion to Si(111):As, though a somewhat larger bandwidth. We find a second surface state between this lone-pair state and the first bulk state, which we attribute to Ga-Se bonds. In addition, the zone-center bulk state, degenerate in bulk Si, is split by about 0.5 eV. This surprising result is not found for Si(111):As. We tentatively attribute the splitting to the Si-Ga interaction. @FootnoteText@ M. A. Olmstead, R. D. Bringans, R. I. G. Urhberg and R. Z. Bachrach, Phys. Rev. B 34, 6401 (1986).