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Photoconductivity of carbon aerogels

Published online by Cambridge University Press:  31 January 2011

M. Hosoya
Affiliation:
Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
G. Reynolds
Affiliation:
Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
M.S. Dresselhaus
Affiliation:
Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
R.W. Pekala
Affiliation:
Chemistry and Materials Science Department, Lawrence Livermore National Laboratory, Livermore, California 94550

Abstract

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Photoconductivity was measured on a series of carbon aerogels to investigate their electronic properties. Carbon aerogels are a special class of low-density microcellular foams, consisting of interconnected carbon particles (∼120 Å diameter) and narrow graphitic ribbons (∼25 Å width) intertwined within each particle. Both the dark- and photoconductivities show drastic changes in the temperature range 5–300 K, which are similar to those in a-Si and chalcogenide photoconductors. At high temperatures, the photoconductivity is dominated by the carrier recombination within each particle. The photoconductivity at low temperatures is dominated by the same carrier transport mechanism as that for the dark conductivity, which is based on hopping and tunneling transport. The activation energy values for transport and recombination identify the electronic structure of the particles among samples of different bulk density. The long decay time of the photoconductivity suggests a relaxation mechanism associated with the dangling bonds.

Type
Articles
Copyright
Copyright © Materials Research Society 1993

References

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