AVS 45th International Symposium
    Surface Science Division Monday Sessions
       Session SS1-MoM

Paper SS1-MoM9
HRPES Study of Acetylene Adsorption and Reaction with Si(100)-2x1 Surface

Monday, November 2, 1998, 11:00 am, Room 308

Session: Issues in Surface Electronic Structure
Presenter: S.H. Xu, Montana State University
Authors: S.H. Xu, Montana State University
Y. Yang, Montana State University
H. Cruguel, Montana State University
E. Rotenberg, Lawrence Berkeley National Laboratory
G.J. Lapeyre, Montana State University
J.T. Yates Jr., University of Pittsburgh
Correspondent: Click to Email
The adsorption and reaction of acetylene with Si(100)-2x1 surface has been studied using high resolution photoemission measurement the Si 2p, C 1s and valence band(VB)spectra as a function of acetylene coverage and post annealings at several temperatures. After the clean Si(100) surface is exposed to 0.5 ML acetylene, the surface state in valence bands is totally gone. Meanwhile, there is only one interface component in the Si 2p core line. These results indicate that the asymmetry of Si dimers is gone after acetylene adsorption, which is in excellent agreement with the tetra-@sigma@ model proposed by our previous photoelectron holographic results.@super [1]@ Significant changes in the electronic structure(Si 2p, C 1s and VB) are found after subsequent annealing of a saturation overlayer. Annealing at lower temperatures can induce a bit of acetylene desorption but most of the molecules decompose to C@sub 2@H@sub x@ (x=1, 0) and H species. After annealing at above 650 °C, there develops a surface state in valence bands and a Si 2p surface core-level component indicating some restoration of a Si(100)-2x1 structure. The C 1s line shows a single component indicating that a SiC compound forms on the Si surface. Both of the reacted components of the Si 2p and C 1s lines show that the SiC species form cluster-like feature. At the same time, the surface core-level components indicate that the clean surface Si dimers reappear on the silicon surface. This work is supported by NSF. The ALS of LBNL is supported by the DOE. [1]. G. J. Lapeyre et al., to be published.