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The Influence of the Bonding Structure on Disorder and Band-Tails in a-B:H

Published online by Cambridge University Press:  21 February 2011

N. Bernhard ,
K. Eberhardt ,
M. B. Schubert  and
G. H. Bauer
N. Bernhard
Affiliation:
Institut fur Physikalische Elektronik, Universitat Stuttgart, Pfaffenwaldring 47, D-7000 Stuttgart 80, Germany
K. Eberhardt
Affiliation:
Institut fur Physikalische Elektronik, Universitat Stuttgart, Pfaffenwaldring 47, D-7000 Stuttgart 80, Germany
M. B. Schubert
Affiliation:
Institut fur Physikalische Elektronik, Universitat Stuttgart, Pfaffenwaldring 47, D-7000 Stuttgart 80, Germany
G. H. Bauer
Affiliation:
Institut fur Physikalische Elektronik, Universitat Stuttgart, Pfaffenwaldring 47, D-7000 Stuttgart 80, Germany
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Abstract

A thorough investigation of plasma-CVD amorphous hydrogenated boron (a-B:H) has been conducted with the main emphasis on how in this amorphous semiconductor the variation of the coordination number in comparison to a-Si:H influences the structural disorder and density of states in the band tails. a-B:H was deposited from different concentrations of B2 H6 diluted in H2 by both DC- and RF-plasma-CVD. The influence of the change of substrate temperature, pressure, flow and deposition power on the structural, optical and electronic properties of the material was examined. Raman-scattering and IR-absorption reveal the clear non-crystallinity of the deposited films. Almost all samples show some photoconductivity with a σphoto/σdark ratio from 10-1 to 3×101. Although a strong influence of some of the deposition parameters on bandgap and refractive index, hydrogen content, dark and photoconductivity was observed, the density of states in the band tails as measured by PDS was relatively high, showing always a rather flat Urbach slope of about 180 – 220 meV. An explanation for this unexpected almost uniform huge Urbach slope might be that even in the amorphous state the behaviour of boron is still dominated by its electron deficiency character which leads to a certain amount of three centre bonds (as seen in IR-absorption) and results in comparison to amorphous hydrogenated silicon in even stronger constraints of the amorphous network and obviously in more potential fluctuations.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 219: Symposium A – Amorphous Silicon Technology - 1991 , 1991 , 289
Copyright
Copyright © Materials Research Society 1991

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References

REFERENCES

1. Tsai, C. C., Phys. Rev. B 19, 2041 (1979)Google Scholar
2. Bagley, B. G., Aspnes, D. E., Adams, A. C., Benenson, R. E., J. Non-Cryst. Sol. 35 & 36, 441 (1980)Google Scholar
3. Cocks, F. H., Jones, P. L., Dimmey, L. J., Appl. Phys. Lett. 36, 970 (1980)CrossRefGoogle Scholar
4. Zalph, B. L., Dimmey, L. J., Park, H., Jones, P. L., Cocks, F. H., phys. stat. sol. a 62, K185 (1980)CrossRefGoogle Scholar
5. Schaffer, J. P., Park, H., Lind, J. H., Jones, P. L., phys. stat. sol. a 81, K51 (1984)CrossRefGoogle Scholar
6. Toyoda, H., Sugai, H., Isozumi, T., Okuda, T., Appl. Phys. Lett. 51, 798 (1987)CrossRefGoogle Scholar
7. Shirai, K., Gonda, S., J. Appl. Phys. 67, 6286 (1990)CrossRefGoogle Scholar
8. Ong, C. W., Chik, K. P., Wong, H. K., J. Non-Cryst. Sol. 114, 783 (1989)CrossRefGoogle Scholar
9. Phillips, J. C., Phys. Rev. Lett. 42, 1151 (1979); andCrossRefGoogle Scholar
in Proceedings of the 14th International Conference on the Physics of Semiconductors, edited by Stradling, R. A. (Plessy, Edinburgh, 1978)Google Scholar
10. See any standard textbook of inorganic chemistry, e. g. Christen, H. R., Grundlagen der allgemeinen und anorganischen Chemie (Sauerlander, Frankfurt, 1977), p. 545 Google Scholar
11. Ovshinsky, S. R., in Proceedings of the 7th International Conference on Amorphous and Liquid Semiconductors, edited by Spear, W. E. (Edinburgh, 1977), p. 519 Google Scholar
12. Blum, N. A., Feldman, C., Satkiewicz, F. G., phys. stat. sol. a 41, 481 (1977)CrossRefGoogle Scholar
13. Lehmann, W. J., Shapiro, I., Spectrochimica Acta 17, 396 (1961)CrossRefGoogle Scholar
14. Golikova, O. A., Zhubanov, M., and Mirlin, D. N., Sov. Phys. Sol. State 11, 1341 (1969)Google Scholar
15. Lannin, J. S., Sol. State Comm. 25, 363 (1978)CrossRefGoogle Scholar
16. Beckel, C. L., Vaughan, J. P., in Proceedings of the International Conference on the Physics and Chemistry of Boron and Boron-Rich Borides, edited by Emin, D. et al. (American Institute of Physics, New York, 1986), p. 305 Google Scholar
17. Katada, K., Jap. J. Appl. Phys. 3, 582 (1966)CrossRefGoogle Scholar
18. Badzian, A. R., Mat. Res. Bull. 2, 987 (1967)CrossRefGoogle Scholar
19. Grigorovici, R., J. Non-Cryst. Sol. 1, 303 (1969)CrossRefGoogle Scholar