Hostname: page-component-77c89778f8-9q27g Total loading time: 0 Render date: 2024-07-22T09:26:13.460Z Has data issue: false hasContentIssue false
  • English
  • Français

Structural Relaxation and Structural Memory at Amorphous Silicon Dangling Bonds

Published online by Cambridge University Press:  16 February 2011

Howard M. Branz  and
Peter A. Fedders
Howard M. Branz
Affiliation:
National Renewable Energy Laboratory, Golden, Co 80401
Peter A. Fedders
Affiliation:
Department Of Physics, Washington University, St. Louis, Mo 63130
Get access

Abstract

We examine the energy and time scales of configurational relaxation around the dangling bond defect, D, in hydrogenated Amorphous silicon (a-Si:H). After D captures or emits charge, its bond angle, electron energy eigenvalues and local structural environment all change. This determines the measured electronic energy levels; we use previous theoretical results and experimental data to estimate the density of gap states in the different atomic configurations of D. We also describe D relaxation effects observed in experiments, including the very slow relaxations found in recent transient capacitance measurements. To explain the unusual T-independent kinetics of transient capacitance carrier emission, we propose a model of “structural memory” in a-Si:H. After carrier capture, neighbors of D retain memory of their pre-capture configuration for seconds at 300K. The rate-limiting step to carrier emission is an effectively one-dimensional random walk of these neighbors through their configuration space and back to the pre-capture configuration. The final, activated, step of emission is very rapid. We describe analytic and monte Carlo calculations that support the structural memory Model and propose possible microscopic Mechanisms.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 336: Symposium A – Amorphous Silicon Technology - 1994 , 1994 , 129
Copyright
Copyright © Materials Research Society 1994

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Cohen, J. D., Leen, T. M., and Rasmussen, R. J., Phys. Rev. Lett. 69, 3358 (1992).Google Scholar
2. Carlen, M. W., Salamon, S. J., Xu, Y., and Crandall, R. S., unpublished.Google Scholar
3. Han, D., Melcher, D. C., Schiff, E. A., and Silver, M., Phys. Rev. B 48, 8658 (1993).Google Scholar
4. Graf, W., Wolf, M., Leihkamm, K., Ristein, J., and Ley, L., J. Non-Cryst. Solids 164–166, 195 (1993).Google Scholar
5. Ansari, A., Berendzen, J., Bowne, S. F., Frauenfelder, H., Iben, I. E. T., Sauke, T. B., Shyamsunder, E., and Young, R. D., Proc. Nati. Acad. Sci. USA 82, 5000 (1985).Google Scholar
6. Palmer, R. G., Stein, D. L., Abrahams, E., and Anderson, P. W., Phys. Rev. Lett. 53, 958 (1984).Google Scholar
7. Ogielski, A. T. and Stein, D. L., Phys. Rev. Lett. 55, 1634 (1985).Google Scholar
8. Tajima, M., Okushi, H., Yamasaki, S., and Tanaka, K., Phys. Rev. B 33, 8522 (1986).Google Scholar
9. Branz, H. M., Phys. Rev. B 39, 5107 (1989).Google Scholar
10. Fedders, P. A., Fu, Y., and Drabold, D. A., Phys Rev Lett 68, 1888 (1992).Google Scholar
11. Norberg, R. E., Fedders, P. A., Bodart, J., Corey, R., Paul, W., Turner, W. A., and Jones, S. J., Journal of Non-Crystalline Solids 137&138, 71 (1992).Google Scholar
12. Branz, H. M. and Schiff, E. A., Phys. Rev. B 48, 8667 (1993).Google Scholar
13. LeComber, P. G. and Spear, W. E., Phil. Mag. Lett. 53, L1 (1986).Google Scholar
14. Austin, I. G., Nashashibi, T. S., Searle, T. M., LeComber, P. G., and Spear, W. E., J. Non-Cryst. Sol. 32, 373 (1979).Google Scholar
15. Adler, D., in Semiconductors and Semimetals, Vol. 21A, 21A. edited by Pankove, J. I. (Academic, Orlando, 1984), p. 291.Google Scholar
16. Bar-Yam, Y. and Joannopoulos, J. D., Phys. Rev. Lett. 56, 2203 (1986).Google Scholar
17. Fedders, P. A. and Carlsson, A. E., Phys. Rev. B 39, 1134 (1989). Tight-binding calculations yield a linear dependence of energy eigenvalue on bond angle for the (O/+) transition of D.Google Scholar
18. McMahon, T. J. and Tsu, R., Appl. Phys. Lett. 51, 412 (1987).Google Scholar
19. See Ref. 9 for a review of optical and luminescence data in doped a-Si:H.Google Scholar
20. Zhong, F. and Cohen, J. D., Phys. Rev. Lett. 71, 597 (1993).Google Scholar
21. Fedders, P. A., unpublished.Google Scholar