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Measurement of Two Deep H Bonding Levels in Device Quality Glow Discharge a-SI:H

Published online by Cambridge University Press:  15 February 2011

A. H. Mahan ,
E. J. Johnson ,
R. S. Crandall  and
H. M. Branz
A. H. Mahan
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401
E. J. Johnson
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401
R. S. Crandall
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401
H. M. Branz
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401
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Abstract

We present the results of H effusion studies on device-quality glow discharge deposited hydrogenated amorphous silicon (a-Si:H) films. We measure the decrease in the amount of Si-H infrared absorption as pieces of an a-Si:H sample are annealed isothermally at temperatures from 425°C to 500°C, until more than 95% of the initial H is evolved. We use the rate equation for loss of H due to annealing to calculate the activation energy for H effusion. For anneals below 500°C we observe two distinct rate processes, a fast process corresponding to release of ∼ 70% of the total H (∼10 at. %) contained in the sample, and a slower process corresponding to effusion of the remainder. The fast loss process yields an activation energy of ∼1.4 eV; this is the energy level widely observed in diffusion coefficient measurements. A similar analysis for the slow loss process yields an activation energy of ∼2.1 eV and a diffusion constant prefactor higher than that for the fast loss process. We suggest that this slow component represents the first determination of the energy depth of the “isolated” H component commonly observed in nuclear magnetic resonance experiments.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 377: Symposium A – Amorphous Silicon Technology 1995 , 1995 , 413
Copyright
Copyright © Materials Research Society 1995

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References

REFERENCES

1. Beyer, W. in Tetrahedrally Bonded Amorphous Semiconductors, edited by Adler, D. and Fritzsche, H. (Plenum, NY, 1985) p. 129.Google Scholar
2. Beyer, W. and Wagner, H., J. Appl. Phys. 53, 8745 (1982).Google Scholar
3. Carlson, D. E. and Magee, C.W., Appl. Phys. Lett. 33, 81 (1978).Google Scholar
4. Branz, H. M., Asher, S. E. and Nelson, B. P., Phys. Rev. B 47, 7061 (1993).Google Scholar
5. Carlos, W. E. and Taylor, P. C., Phys. Rev. B 26, 3605 (1982).Google Scholar
6. Reimer, J. A., Vaughan, R. W. and Knights, J. C., Solid State Comm. 37, 161 (1981),.Google Scholar
7. Jackson, W., J. non-Cryst. Solids 164–166, 263 (1993).Google Scholar
8. Jackson, W. B., Nickel, N. H., Johnson, N. M., Pardo, F., and Santos, P. V., MRS Symp. Proc. 336, 311 (1994).Google Scholar
9. Branz, H. M., Asher, S., Xu, Y. and Kemp, M., this conference.Google Scholar
10. Mahan, A. H., Johnson, E. J., and Webb, J. D., MRS Symp. 297, 103 (1993).Google Scholar
11. Abelson, J. R., private communication.Google Scholar
12. Langford, A. A., Fleet, M. L., Nelson, B. P., Lanford, W. A., and Maley, N., Phys. Rev. B 45, 13367 (1992).Google Scholar
13. Zellama, K., Germain, P., Squelard, S., Bourdon, B., Fontenille, J., and Danielou, R., Phys. Rev. B 23, 6648 (1981).Google Scholar
14. Han, D., private communication.Google Scholar
15. The presence of either a surface evolution barrier or a highly depleted surface region, through which the H must pass in order to evolve, has no effect on how we determine our Ea, since we are measuring only the relative number of (isolated) Si-H bonds left in the sample as it is annealed. These barriers or depleted regions, however, probably do influence the (D0) slow. since this H must certainly traverse these highly defective regions to leave the sample after the bonds are broken.Google Scholar
16. In both works, the reference energy was the energy to excite the H to the transport level, and not to the vacuum level.Google Scholar
17. Jackson, W. B. and Tsai, C. C., Phys. Rev. B 40, 5235 (1992).Google Scholar
18. A careful re-examination of the data of ref. 14 suggests that the assumption of each ruptured (isolated) Si-H bond leaving behind one dangling bond is not a valid one.Google Scholar
19. Beyer, W. and Wagner, H., MRS Symp. Proc. 336, 323 (1994).Google Scholar
20. Gleason, K. K., Petrich, M. A. and Reimer, J. A., Phys. Rev. B 36, 3259 (1987).Google Scholar
21. Taylor, P. C., private communication.Google Scholar