AVS 46th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS-TuP

Paper SS-TuP22
Surface Modification in Heteroepitaxy : Laminar, Crystalline Silicon on CaF@sub 2@

Tuesday, October 26, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: B.R. Schroeder, University of Washington
Authors: B.R. Schroeder, University of Washington
S. Meng, University of Washington
A. Bostwick, University of Washington
E. Rotenberg, Lawrence Berkeley National Laboratory
M.A. Olmstead, University of Washington
Correspondent: Click to Email
CaF@sub 2@/silicon heterostructures are strong candidates for obtaining visible light emission from silicon. However, the heteroepitaxial growth of laminar, crystalline silicon on CaF@sub 2@(111) substrates is hindered by two factors 1) CaF@sub 2@ surface energy is much lower than that of Si and 2) a strong etching reaction between Si and F. We have overcome these difficulties through surface modification 1) use of arsenic as a surfactant 2) electron irradiation to remove surface fluorine. Low energy (40 eV) electron irradiation removes fluorine (amount of F removed scales linearly with the electron dose) but the films become extremely reactive with oxygen and/or water vapor (even under UHV conditions). Arsenic termination stabilizes this surface and serves as a surfactant for the subsequent silicon growth. X-ray photoelectron spectroscopy shows Ca-Si bonds at the interface and As-Si bonds at the surface. The silicon surface has a bulk-like termination, characteristic of Si(111):As, as evidenced by the 1X1 LEED pattern. X-ray photoelectron diffraction shows that the grown silicon layer is crystalline, rotated 180@super o@ with respect to the CaF@sub 2@ substrate (Type B interface), and completely covers the CaF@sub 2@. Supported by DOE grant DE-FG03-97ER45646/A002.