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Hydrogen Sensing with Diameter- and Chirality-Sorted Carbon Nanotubes

Ganzhorn, Marc and Vijayaraghavan, Aravind and Dehm, Simone and Hennrich, Frank and Green, Alexander A. and Fichtner, Maximilian and Voigt, Achim and Rapp, Michael and von Löhneysen, Hilbert and Hersam, Mark C. and Kappes, Manfred M. and Krupke, Ralph (2011):
Hydrogen Sensing with Diameter- and Chirality-Sorted Carbon Nanotubes.
In: ACS Nano, 5 (3), pp. 1670-1676, ISSN 1936-0851,
[Online-Edition: http://dx.doi.org/10.1021/nn101992g],
[Article]

Abstract

The work function of palladium is known to be sensitive to hydrogen by the formation of a surface dipole layer or Pd hydride. One approach to detect such a change in the work function can be based on the formation of a Schottky barrier between the palladium metal and a semiconductor. Here, we study the hydrogen sensitivity of Schottky barrier field-effect transistors made for the first time from diameter- and chirality-sorted semiconducting single-walled carbon nanotubes (s-SWNTs) in contact with Pd electrodes. We observe an unrivaled 100-fold change in the on-state conductance at 100 ppm H2 compared to air for devices with s-SWNT and diameters between 1 and 1.6 nm. Hydrogen sensing is not observed for devices of Pd-contacted few-layer graphene (FLG), as expected due to the absence of a significant Schottky barrier. Unexpectedly, we observe also a vanishing sensitivity for small-diameter SWNTs. We explain this observation by changes in the nanotube work function caused by spillover and chemisorption of atomic hydrogen onto small-diameter nanotubes. We also observe that long-term sensing stability is only achieved if the gate voltage is inverted periodically. Under constant gate bias, the sensitivity reduces with time, which we relate to gate screening by accumulated charges in the substrate.

Item Type: Article
Erschienen: 2011
Creators: Ganzhorn, Marc and Vijayaraghavan, Aravind and Dehm, Simone and Hennrich, Frank and Green, Alexander A. and Fichtner, Maximilian and Voigt, Achim and Rapp, Michael and von Löhneysen, Hilbert and Hersam, Mark C. and Kappes, Manfred M. and Krupke, Ralph
Title: Hydrogen Sensing with Diameter- and Chirality-Sorted Carbon Nanotubes
Language: English
Abstract:

The work function of palladium is known to be sensitive to hydrogen by the formation of a surface dipole layer or Pd hydride. One approach to detect such a change in the work function can be based on the formation of a Schottky barrier between the palladium metal and a semiconductor. Here, we study the hydrogen sensitivity of Schottky barrier field-effect transistors made for the first time from diameter- and chirality-sorted semiconducting single-walled carbon nanotubes (s-SWNTs) in contact with Pd electrodes. We observe an unrivaled 100-fold change in the on-state conductance at 100 ppm H2 compared to air for devices with s-SWNT and diameters between 1 and 1.6 nm. Hydrogen sensing is not observed for devices of Pd-contacted few-layer graphene (FLG), as expected due to the absence of a significant Schottky barrier. Unexpectedly, we observe also a vanishing sensitivity for small-diameter SWNTs. We explain this observation by changes in the nanotube work function caused by spillover and chemisorption of atomic hydrogen onto small-diameter nanotubes. We also observe that long-term sensing stability is only achieved if the gate voltage is inverted periodically. Under constant gate bias, the sensitivity reduces with time, which we relate to gate screening by accumulated charges in the substrate.

Journal or Publication Title: ACS Nano
Volume: 5
Number: 3
Uncontrolled Keywords: single-walled carbon nanotube; chirality; diameter; hydrogen; sensing; sorting; Schottky barrier field-effect transistor
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Fachgebiet Molekulare Nanostrukturen
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 08 Nov 2011 11:26
Official URL: http://dx.doi.org/10.1021/nn101992g
Identification Number: doi:10.1021/nn101992g
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