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Stability and Relaxation of Point Defects in amorphous silicon

Published online by Cambridge University Press:  25 February 2011

Raymond Lutz
Affiliation:
Département de physique et Groupe de recherche en physique et technologie des couches minces, Université de Montréal, C.P. 6128, Suce. A, Montréal, Québec, Canada H3C 3J7
Laurent J. Lewis
Affiliation:
Département de physique et Groupe de recherche en physique et technologie des couches minces, Université de Montréal, C.P. 6128, Suce. A, Montréal, Québec, Canada H3C 3J7
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Abstract

We have used molecular-dynamics to investigate the stability and relaxation of point defects — vacancies and interstitials — in a model of amorphous silicon, with the interactions between atoms described by the Stillinger-Weber empirical potential. The annihila-tion of point defects has been proposed as an important mechanism by which relaxation proceeds in amorphous silicon. Starting with a Wooten-Winer-Weaire model of a-Si, we “manually” create vacancies in the structure by removing a number of randomly-selected four-fold coordinated atoms. The system is then allowed to relax. Our calculations reveal unambiguously that, of a number of vacancies introduced in the model at low temperature, roughly a third are stable; these anneal out upon heating at room temperature. The vacancies seem, in most cases, to consist of a relatively large empty volume bounded by four atoms of which at least one is undercoordinated. Our study of interstitials seems to indicate that they diffuse through a “jump-and-bump” process, eventually annihilating when a large enough, properly coordinated, vacant volume is encountered.

Type
Research Article
Copyright
Copyright © Materials Research Society 1993

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References

REFERENCES

1. See for instance Lannin, J. S., Phys. Today 41 (7), 28 (1988).Google Scholar
2. Roorda, S., Sinke, W. C., Poate, J. M., Jacobson, D. C., Dierker, S., Dennis, B. S., Eaglesham, D. J., Spaepen, F., and Fuoss, P., Phys. Rev. B 44, 3702 (1991).Google Scholar
3. Roorda, S., Hakvoort, R. A., van Veen, A., Stolk, P. A., and Saris, F. W., in Phase formation and modification by beam-solid interactions, ed. by Was, G.S., Rehn, L.E., and Follstaedt, D.M., Mat. Res. Soc. Symp. Proc. Vol. 235 (MRS, Pittsburgh, 1992), p. 39.Google Scholar
4. van den Hoven, G. N., Liang, Z. N., Niesen, L., and Custer, J. S., Phys. Rev. Lett. 68, 3714 (1992).Google Scholar
5. Weber, T. A. and Stillinger, F. H., Phys. Rev. B 31, 5265 (1985).Google Scholar
6. Lutz, R. and Lewis, L. J., Phys. Rev. B, in press.Google Scholar
7. Mousseau, N. and Lewis, L. J., Phys. Rev. B. 43, 9810 (1991); Phys. Rev. B 41, 3702 (1990).Google Scholar
8. Wooten, F., Winer, K., and Weaire, D., Phys. Rev. Lett. 54, 1392 (1985).CrossRefGoogle Scholar
9. Lutz, R. and Lewis, L. J., in preparation.Google Scholar