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Composition and Structure of Epitaxial CaF2 Layers at the First Stages of Their Growth on Si(111)

Published online by Cambridge University Press:  17 March 2011

R. Würz ,
W. Bohne ,
W. Fuhs ,
J. Röhrich ,
M. Schmidt ,
A. Schöpke  and
B. Selle
R. Würz
Affiliation:
Hahn-Meitner-Institut, Silizium-Photovoltaik, Kekuléstrasse 5, 12489 Berlin, GERMANY Email: wuerz-r@hmi.de
W. Bohne
Affiliation:
Hahn-Meitner-Institut, Ionenstrahl-Labor, Glienicker Strasse 100, 14109 Berlin, GERMANY
W. Fuhs
Affiliation:
Hahn-Meitner-Institut, Silizium-Photovoltaik, Kekuléstrasse 5, 12489 Berlin, GERMANY
J. Röhrich
Affiliation:
Hahn-Meitner-Institut, Ionenstrahl-Labor, Glienicker Strasse 100, 14109 Berlin, GERMANY
M. Schmidt
Affiliation:
Hahn-Meitner-Institut, Silizium-Photovoltaik, Kekuléstrasse 5, 12489 Berlin, GERMANY
A. Schöpke
Affiliation:
Hahn-Meitner-Institut, Silizium-Photovoltaik, Kekuléstrasse 5, 12489 Berlin, GERMANY
B. Selle
Affiliation:
Hahn-Meitner-Institut, Silizium-Photovoltaik, Kekuléstrasse 5, 12489 Berlin, GERMANY
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Abstract

CaF2 films with thicknesses in the monolayer range (<20 Å) were grown on Si(111) by evaporation from a CaF2 source at UHV conditions. They were characterized ex-situ by Heavy-Ion Elastic Recoil Detection Analysis (HI-ERDA), RBS/Channeling, X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The F/Ca ratio of the films was found to depend on the growth temperature Ts and to deviate appreciably from the stoichiometric composition (F/Ca=2). Due to an interface reaction which leads to a CaF-interface layer a change from polycrystalline to epitaxial growth occurs at Ts=450°C. At higher temperature film growth started with a closed layer of CaF on top of which CaF2 layers with an increasing fraction of pinholes were formed. By means of a two-step process at different temperatures, the amount of pinholes could be strongly reduced. It was found, that buffer layers of CaF2 with a CaF interface layer introduced in Au/p-Si contacts enhance the barrier height by as much as 0.36eV to values of 0.64eV.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 696: Symposium N – Current Issues in Heteroepitaxial Growth--Stress Relaxation and Self Assembly , 2001 , N3.21
Copyright
Copyright © Materials Research Society 2002

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References

1. Olmstead, M. A. “Heteroepitaxy of Strongly Disparate Materials: From Chemisorption to Epitaxy in CaF2/Si(111)”, Thin Films: Heteroepitaxial Systems, ed. Liu, A. W. K. and Santos, M., (World Scientific, 1999) pp. 211–266 Google Scholar
2. Denlinger, J. D., Rotenberg, E., Hessinger, U., Leskovar, M. and Olmstead, M. A., Phys. Rev. B 51, 5352 (1995).Google Scholar
3. dell'Orto, T., Stasio, G. De, Capozi, M., Ottaviani, C., Quaresima, C. and Perfetti, P., Phys. Rev. B 48, 8823 (1993).Google Scholar
4. dell'Orto, T., Almeida, J., Terrasi, A., Marsi, M., Coluzza, C. and Margaritondo, G., Phys. Rev. B 50, 18189 (1994).Google Scholar
5. Franciosi, A. and Walle, C. G. Van de, Surf. Sci. Repts. 25, 1 (1996).Google Scholar
6. Bohne, W., Röhrich, J., Schmidt, M., Schöpke, A., Selle, B., and Würz, R., Appl. Surf. Sci. 179, 73 (2001).Google Scholar
7. Asano, T., Ishiwara, H., and Kaifu, N., Japan. J. Appl. Phys. 22, 1474 (1983).Google Scholar
8. Wollschläger, J., A. Klust and Pietsch, H., Appl. Surf. Sci. 123/124 496 (1998).Google Scholar
9. Tung, R. T., Phys. Rev. B 45, 13509 (1992).Google Scholar