Photoconductivity of carbon aerogels

• Published in: Journal of materials research Vol. 8; no. 4; pp. 811 - 819
• Main Authors: Hosoya, M., Reynolds, G., Dresselhaus, M.S., Pekala, R.W.
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 01-04-1993; Materials Research Society
• Subjects: CARBON; Chemistry; Colloidal gels. Colloidal sols; Colloidal state and disperse state; COLLOIDS; DISPERSIONS; ELECTRIC CONDUCTIVITY; ELECTRICAL PROPERTIES; ELECTRONIC STRUCTURE; ELEMENTS; Exact sciences and technology; GELS; General and physical chemistry; MATERIALS SCIENCE; NONMETALS; PHOTOCONDUCTIVITY; PHYSICAL PROPERTIES; RECOMBINATION; TEMPERATURE RANGE 0000-0013 K; TEMPERATURE RANGE 0013-0065 K; TEMPERATURE RANGE 0065-0273 K; TEMPERATURE RANGE 0273-0400 K; TEMPERATURE RANGE 360606 > Other Materials > Physical Properties > (1992-); Temperature; Electrical conductivity; Electrical properties; Aerogel; Experimental study; Photoconductivity; Carbon
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/JMR.1993.0811

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.