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The Electronic Transport Mechanism in Amorphous Tetrahedrally-Coordinated Carbon Films

Published online by Cambridge University Press:  10 February 2011

J. P. Sullivan ,
T. A. Friedmann ,
R. G. Dunn ,
E. B. Stechel ,
P. A. Schultz ,
M. P. Siegal  and
N. Missert
J. P. Sullivan
Affiliation:
Sandia National Laboratories, MS 1421, Albuquerque, NM 87185–1421
T. A. Friedmann
Affiliation:
Sandia National Laboratories, MS 1421, Albuquerque, NM 87185–1421
R. G. Dunn
Affiliation:
Sandia National Laboratories, MS 1421, Albuquerque, NM 87185–1421
E. B. Stechel
Affiliation:
Sandia National Laboratories, MS 1421, Albuquerque, NM 87185–1421
P. A. Schultz
Affiliation:
Sandia National Laboratories, MS 1421, Albuquerque, NM 87185–1421
M. P. Siegal
Affiliation:
Sandia National Laboratories, MS 1421, Albuquerque, NM 87185–1421
N. Missert
Affiliation:
Sandia National Laboratories, MS 1421, Albuquerque, NM 87185–1421
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Abstract

The electronic transport mechanism in tetrahedrally-coordinated amorphous carbon was investigated using measurements of stress relaxation, thermal evolution of electrical conductivity, and temperature-dependent conductivity measurements. Stress relaxation measurements were used to determine the change in 3-fold coordinated carbon concentration, and the electrical conductivity was correlated to this change. It was found that the conductivity was exponentially proportional to the change in 3-fold concentration, indicating a tunneling or hopping transport mechanism. It was also found that the activation energy for transport decreased with increasing anneal temperature. The decrease in activation energy was responsible for the observed increase in electrical conductivity. A model is described wherein the transport in this material is described by thermally activated conduction along 3-fold linkages or chains with variable range and variable orientation hopping. Thermal annealing leads to chain ripening and a reduction in the activation energy for transport.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 498: Symposium AA – Covalently Bonded Disordered Thin-Film Materials , 1997 , 97
Copyright
Copyright © Materials Research Society 1998

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References

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