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Ultralow-voltage field-ionization discharge on whiskered silicon nanowires for gas-sensing applications

Nature Materials volume 10, pages 135–140 (2011)Cite this article

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A Corrigendum to this article was published on 21 February 2011

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Abstract

Several hundred million volts per centimetre of electric-field strength are required to field-ionize gas species. Such fields are produced on sharp metallic tips under a bias of a few kilovolts. Here, we show that field ionization is possible at dramatically lower fields on semiconductor nanomaterials containing surface states, particularly with metal-catalysed whiskers grown on silicon nanowires. The low-voltage field-ionization phenomena observed here cannot be explained solely on the basis of the large field-amplification effect of suspended gold nanoparticles present on the whisker tips. We postulate that field penetration causes upward band-bending at the surface of exposed silicon containing surface states in the vicinity of the catalyst. Band-bending enables the valence electron to tunnel into the surface states at reduced fields. This work provides a basis for development of low-voltage ionization sensors. Although demonstrated on silicon, low-voltage field ionization can be detected on any sharp semiconductor tip containing proper surface states.

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Figure 1: Field ionization dynamics.
Figure 2: Nanowires used to measure anomalous semiconductor-assisted gas ionization.
Figure 3: Current–voltage curves.
Figure 4: Energy-band diagrams for FI on a semiconductor surface.
Figure 5: Sensitivity and the effect of gas admixtures on the low-voltage field-ion current.

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  • 01 February 2011

    In the version of this Article originally published, the corresponding author and the Acknowledgements were incorrect. These errors have now been corrected in the HTML and PDF versions of the text.

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Acknowledgements

The work reported herein was partially supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada, a University of California CITRIS research grant funded by Hewlett Packard Labs, NSF grant 0547679 and an Army Research Office (ARO) research grant 55176-EL-DRP. R.B.S. would like to thank J. Y. Oh for help with nanowire synthesis, Logeeswaran VJ for help with the vacuum chamber set-up and A. Ghogha for help with statistical analysis.

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Authors and Affiliations

  1. Department of Electrical and Computer Engineering, University of California—Davis, 2064 Kemper Hall, Davis, California 95616-5294, USA

    Ramin Banan Sadeghian & M. Saif Islam

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  1. Ramin Banan Sadeghian
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Contributions

R.B.S. designed and carried out experiments, analysed data and wrote the manuscript. M.S.I. supervised the project, analysed data and edited the manuscript. Both authors discussed the results, and commented on the manuscript.

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Correspondence to M. Saif Islam.

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Banan Sadeghian, R., Saif Islam, M. Ultralow-voltage field-ionization discharge on whiskered silicon nanowires for gas-sensing applications. Nature Mater 10, 135–140 (2011). https://doi.org/10.1038/nmat2944

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