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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 ,
Q. Wang  and
S.L. Dexheimer
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
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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
Information
MRS Online Proceedings Library (OPL) , Volume 664: Symposium A – Amorphous and Heterogeneous Silicon-Based Films-2001 , 2001 , A16.5
Copyright
Copyright © Materials Research Society 2001

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References

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