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Femtosecond Far-Infrared Studies of Carrier Dynamics in Hydrogenated Amorphous Silicon and Silicon-Germanium Alloys

Published online by Cambridge University Press:  01 February 2011

A. V. V. Nampoothiri ,
B. P. Nelson  and
S. L. Dexheimer
A. V. V. Nampoothiri
Affiliation:
Department of Physics, Washington State University, Pullman, WA
B. P. Nelson
Affiliation:
National Renewable Energy Laboratory, Golden, CO
S. L. Dexheimer
Affiliation:
Department of Physics, Washington State University, Pullman, WA
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Abstract

We present femtosecond time-resolved studies of the photoexcited carrier response in the far-infrared spectral range in PECVD a-Si:H and a-SiGe:H thin films. The experiments are carried out using an optical pump / terahertz (THz) probe technique, in which a femtosecond pump pulse excites carriers in the sample and a time-delayed probe pulse measures the resulting change in the far-infrared optical properties as a function of time delay following the excitation. These measurements are sensitive to carrier processes at low energy, corresponding to a range of approximately 1 - 10 meV, a key energy scale in these materials. We find that the observed photoexcited carrier dynamics are consistent with trapping of carriers into band tail states on a picosecond time scale.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 762: Symposium A – Amorphous and Nanocrystalline Silicon-Based Films – 2003 , 2003 , A4.4
Copyright
Copyright © Materials Research Society 2003

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