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Atomic Structure and Chemistry of Si/Ge Interfaces Determined by Z-Contrast Stem

Published online by Cambridge University Press:  25 February 2011

M. F. Chisholm ,
S. J. Pennycook  and
D. E. Jesson
M. F. Chisholm
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6024
S. J. Pennycook
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6024
D. E. Jesson
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6024
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Abstract

The technique of Z-contrast STEM provides a fundamentally new and powerful approach to determining the atomic scale structure and chemistry of interfaces. The images produced do not show contrast reversals with defocus or sample thickness, there are no Fresnel fringe effects at interfaces, and no contrast from within an amorphous phase. Such images are unambiguous and intuitively interpretable. In this paper, the technique has been used to directly image subnanometer interdiffusion in ultrathin (SimGen)p superlattices. The Z-contrast image of a (Si8Ge2)p superlattice grown by MBE at 400°C clearly shows significant broadening of the Gerich layer. Also, film formation and misfit accommodation in epitaxial Ge films on (001)Si produced by implantation and oxidation of Si wafers was studied. It was found that the Ge films, which are constrained to grow layer-by-layer, remain completely coherent with the Si substrate to a thickness of 5–6 nm. This is 3 to 6 times thicker than the observed critical thickness for Ge films grown on Si by MBE. It is observed that misfit accommodating dislocations nucleate at the film surface as Shockley partials. The Z-contrast images show these partials can combine to form perfect dislocations whose cores are found to lie entirely in the elastically softer Ge film.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 159: Symposium C – Atomic Scale Structure of Interfaces , 1989 , 447
Copyright
Copyright © Materials Research Society 1990

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References

REFERENCES

1. Jesson, D. E., Pennycook, S. J., and Chisholm, M. F., these proceedings.Google Scholar
2. Pennycook, S. J., Berger, S. D., and Culbertson, R. J., J. Microsc. 144, 229 (1986).Google Scholar
3.See ref. in Pearsall, T. P., CRC Critical Reviews in Solid State and Materials Science 15, 551 (1989).Google Scholar
4. Fathy, D., Holland, O. W., and White, C. W., Appl. Phys. Lett. 51, 1337 (1987).Google Scholar
5. Lockwood, J., Dharma-Wardona, M. W. C., Aers, G. C., and Baribeau, J.-M., Appl. Phys. Lett. 52, 2040 (1988).Google Scholar
6. Chew, N. G. and Cullis, A. G., Appl. Phys. Lett. 44, 142 (1984) and Ultramicroscopy 23, 175 (1987).Google Scholar
7. Abstreiter, G., Eberl, K., Friess, E., Wegscheider, W., and Zachai, R., J. Cryst. Growth 95, 431 (1989).Google Scholar
8. Jesser, W. A. and Matthews, J. W., Philos. Mag. 17, 461 (1968).Google Scholar