IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Thursday Sessions
       Session SS4-ThP

Paper SS4-ThP1
Surface Stress of Thin Epitaxial CaF@sub 2@ Films on Si(111)

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Semiconductor Morphology Poster Session
Presenter: M. Bierkandt, Universität Hannover, Germany
Authors: P. Zahl, Universität Hannover, Germany
A. Klust, Universität Hannover, Germany
M. Bierkandt, Universität Hannover, Germany
J. Wollschläger, Universität Hannover, Germany
M. Horn- von Hoegen, Universität GH Essen, Germany
Correspondent: Click to Email
In this paper we present the first elastic properties characterisation of ultrathin epitaxial grown calcium fluoride films (thickness up to five molecular layers) using SSIOD (Surface Stress Induced Optical Defection@footnote 1@). This experimental technique will be explained and demonstrated by Hydrogen ad-/desorption on Si(111). From the large difference in thermal expansion coefficients@footnote 2@ between CaF@sub 2@ and Si a change in volume misfit from 0.5% at room temperature up to 2.5% at 1000 K takes place. The analysis of stress increase during growth at different temperatures (e.g. misfits) allows estimating the stress at the Si/CaF@sub 2@ interface. A change of the surface reconstruction at approx. 900K between 1 and 3 TL is detectable by SSIOD. Furthermore, the measurements are showing, that although at 600K a relaxed and stress free thin films can be grown, a volume lattice misfit of approx 1.5% exists. @FootnoteText@ @footnote 1@ P. Zahl, "Oberflächenspannung auf Si(111): Heteroepitaxie von Ge und CaF@sub 2@, Adsorption von H und Sb", Logos Verlag Berlin 2000, ISBN 3-89722-571-9 @footnote 2@ M. A. Olmstead, in: Thin Films: Heteroepitaxial Systems, Chapter: "Heteroepitaxy of Strongly Disparate Materials: From Chemisorption to Epitaxy in CaF@sub 2@/Si(111)", pp. 211-266. World Scientific Publishing, Singapore, 1999 @footnote 3@ Ohmi, S. K. Tsutsui, S. Furukawa; Jpn. J. Appl. Phys., 33:1121, 1994 @footnote 4@ J. Wollschläger, A. Klust, H. Pietsch; Appl.Surf.Sci., 123/124:496-500, 1998.