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Metallization Of Thin Graphite Layers After Cs Deposition On 4H-Sic(0001) Surfaces

Published online by Cambridge University Press:  10 February 2011

H. Nienhaus  and
V. Van Elsbergen
H. Nienhaus
Affiliation:
Department of Chemical Engineering, University of California, Santa Barbara, CA 93106
V. Van Elsbergen
Affiliation:
Laboratorium für Festkörperphysik, Universitát Duisburg, D-47048 Duisburg, Germany
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Abstract

The interaction of cesium atoms with graphitized 4H-SiC(0001) surfaces was investigated by use of Auger electron, ultraviolet photoemission and high-resolution electron energy-loss spectroscopy (HREELS) as well as work function measurements with a Kelvin probe. The samples were annealed at temperatures well above 1300 K resulting in a formation of about two graphite layers on top of the SiC substrates. The corresponding low-energy electron diffraction image shows a () pattern. Cs deposition on graphitized SiC occurs in two subsequent stages. First, even small amounts of evaporated Cs lead to a spontaneous decrease in work function by 1.8 eV. The work function stays constant after further evaporation corresponding to an intercalation of Cs into the graphite overlayer. In the second stage Cs atoms are adsorbed on top of the Cs-intercalated compound resulting in a further decrease of work function. The graphite layer is effectively metallized by Cs evaporation. This is confirmed by a Fermi edge which is observed in the photoemission spectra even after the smallest dose applied. Moreover, the excitation of optical Fuchs-Kliewer phonons in SiC by HREELS is significantly quenched by the metallic overlayer and the electron energy-loss spectra exhibit features which are typical for thin homogeneous metal layers on surfaces of heteropolar semiconductors.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 483: Symposium E – Power Semiconductor Materials & Devices , 1997 , 229
Copyright
Copyright © Materials Research Society 1998

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