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Gas sensing with long, diffusively contacted single-walled carbon nanotubes

Anupama B Kaul

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A carbon nanotube thermal-conductivity-based pressure or gas sensor is described, which utilizes 5–10 µm long, diffusively contacted single-walled nanotubes (SWNTs). Low temperature electrical transport measurements for these tubes were suggestive of a thermally activated hopping mechanism for electron localization, where a hopping energy of ~39 meV was computed. A negative differential conductance regime was also detected in suspended tubes, released using critical point drying, at high bias voltages. The pressure or gas sensitivity increased more dramatically as the bias power was increased up to 14 µW, which was interpreted in the context of the high optical phonon density in the suspended SWNTs. Such devices are promising for use as pressure sensors, as well as for the chemical identification of species having differing gas thermal conductivities.


PACS

07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing

65.80.+n Thermal properties of small particles, nanocrystals, nanotubes

72.20.Ee Mobility edges; hopping transport

66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves

73.63.Fg Nanotubes

82.80.-d Chemical analysis and related physical methods of analysis

Subjects

Condensed matter: electrical, magnetic and optical

Semiconductors

Instrumentation and measurement

Condensed matter: structural, mechanical & thermal

Nanoscale science and low-D systems

Chemical physics and physical chemistry

Dates

Issue 15 (15 April 2009)

Received 16 January 2009, in final form 4 March 2009

Published 24 March 2009



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