Hostname: page-component-848d4c4894-m9kch Total loading time: 0 Render date: 2024-04-30T13:54:52.309Z Has data issue: false hasContentIssue false

Femtosecond Carrier Dynamics in Nanocrystalline Silicon Films: The Effect of the Degree of Crystallinity

Published online by Cambridge University Press:  17 March 2011

K.E. Myers
Affiliation:
Department of Physics and Materials Science Program, Washington State University, Pullman, WA
Q. Wang
Affiliation:
National Renewable Energy Laboratory, Golden, CO
S.L. Dexheimer
Affiliation:
Department of Physics and Materials Science Program, Washington State University, Pullman, WA
Get access

Abstract

We present studies of the ultrafast dynamics of photoexcited carriers in HWCVD nanocrystalline silicon thin films to address the underlying physics of carrier relaxation and recombination processes in this heterogeneous material. The degree of crystallinity is controlled by varying the H-dilution during deposition, yielding materials with increasingly larger grain size and crystalline fraction at higher dilution values. Time-resolved measurements of the carrier dynamics were made using a femtosecond pump-probe method, in which a short pump pulse excites carriers in the sample and a time-delayed probe pulse measures the resulting change in the optical properties as a function of the pump-probe delay time. Photoexcitation of carriers with pulses 35 fs in duration centered at 1.55 eV results in a net induced absorbance signal in the near-infrared that is analyzed in terms of a multi-component response that includes contributions from the silicon crystallites and the amorphous matrix.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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. Han, D., Yue, G., Lorentzen, J.D., Lin, J., Habuchi, H., and Wang, Q., J. Appl. Phys., 87, 1882 (2000).Google Scholar
2. Moon, J.A. and Tauc, J., J. Appl. Phys., 73, 4571 (1993), and references therein.Google Scholar
3. Myers, K.E., and Dexheimer, S.L., to be published.Google Scholar
4. Fauchet, P.M., Hulin, D., Vanderhaghen, R., Mourchid, A., and Nighan, J. W. L., J. Non-Cryst. Solids, 141, 76 (1992).Google Scholar
5. Esser, A., Seibert, K., Kurz, H., Parsons, G.N., Wang, C., Davidson, B.N., Lucovsky, G., and Nemanich, R.J., Phys. Rev. B 41, 2879 (1990).Google Scholar
6. Shkrob, I.A. and Crowell, R.A., Phys. Rev. B 57, 12207 (1998).10.1103/PhysRevB.57.12207Google Scholar
7. Young, J.E., Nelson, B.P., and Dexheimer, S.L., MRS Symposium Proceedings, vol. 609 (2000).Google Scholar
8. Schiff, E.A, J. Non-Cryst. Solids, 190, 1 (1995).Google Scholar