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Epitaxial CoSi2/Porous-Si Strained Layer Structres Grown by Mbe

Published online by Cambridge University Press:  28 February 2011

Y. C. Kao ,
D. Jamieson ,
G. Bai ,
C. W. Nieh ,
T. L. Lin ,
B. J. Wu ,
H. Y. Chen  and
K. L. Wang
Y. C. Kao
Affiliation:
Device Research Laboratory, Electrical Engineering Department, University of California, Los Angeles, CA 90024
D. Jamieson
Affiliation:
California Institute of Technology, Pasadena, CA 91125
G. Bai
Affiliation:
California Institute of Technology, Pasadena, CA 91125
C. W. Nieh
Affiliation:
California Institute of Technology, Pasadena, CA 91125
T. L. Lin
Affiliation:
Device Research Laboratory, Electrical Engineering Department, University of California, Los Angeles, CA 90024 Now at: Jet Propulsion Laboratories, Pasadena, CA
B. J. Wu
Affiliation:
Device Research Laboratory, Electrical Engineering Department, University of California, Los Angeles, CA 90024
H. Y. Chen
Affiliation:
Device Research Laboratory, Electrical Engineering Department, University of California, Los Angeles, CA 90024
K. L. Wang
Affiliation:
Device Research Laboratory, Electrical Engineering Department, University of California, Los Angeles, CA 90024
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Abstract

CoSi2 epitaxial layers with thickness ranging from 24 nm to 170 nm have been grown onto porous Si substrates by molecular beam epitaxy. The X-ray rocking curves and transmission electron microscopy (TEM) are used to examine the strain relaxation and interface quality. Backscattering with channeling is used to characterize the crystallinity of the epilayers. The results show that it is necessary to grow a thin buffer Si layer in order to improve the interfacial sharpness and crystallinity of the epilayers; near perfect crystallinity is then obtained as the thickness of the CoSi2 films exceed 50 nm. TEM results reveal that both CoSi2/Si and CoSi2/porous-Si interfaces are flat and layer thickness is uniform. It is found by TEM that the dislocation density of CoSi2 grown on porous Si is much lower than that on single-crystal Si. For thin CoSi2 grown on porous Si, the TEM and strain measurement results imply that part of the film is pseudomorphic where no dislocations are observed. Average strains of CoSi2 films grown on porous Si substrates with thicknesses greater than 30 nm show a lower strains comparing to that on crystalline Si. This suggests that by using porous Si as substrates the stress energy in the epilayer can be accommodated by the Si buffer layer that bridged over the trenches of porous Si.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 91: Symposium A – Heteroepitaxy on Silicon II , 1987 , 473
Copyright
Copyright © Materials Research Society 1987

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References

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