Journal cover Journal topic
Journal of Sensors and Sensor Systems An open-access peer-reviewed journal
J. Sens. Sens. Syst., 6, 163-170, 2017
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Regular research article
02 May 2017
H2S dosimeter with controllable percolation threshold based on semi-conducting copper oxide thin films
Christoph Seitz1, Giuliana Beck1, Jörg Hennemann1, Christian Kandzia2, Karl P. Hering2, Angelika Polity2, Peter J. Klar2, Andrej Paul3, Thorsten Wagner3, Stefanie Russ4, and Bernd M. Smarsly1 1Justus-Liebig-Universität Gießen, Physikalisch-Chemisches Institut, Heinrich-Buff-Ring 17, 35392 Gießen, Germany
2Justus-Liebig-Universität Gießen, I. Physikalisches Institut, Heinrich-Buff-Ring 16, 35392 Gießen, Germany
3Universität Paderborn, Naturwissenschaftliche Fakultät, Department Chemie, Warburger Straße 100, 33098 Paderborn, Germany
4Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
Abstract. Copper oxides, such as CuO and Cu2O, are promising materials for H2S detection because of the reversible reaction with H2S to copper sulfides (CuS, Cu2S). Along with the phase change, the electrical conductance increases by several orders of magnitude. On CuOx films the H2S reaction causes the formation of statistically distributed CuxS islands. Continuous exposition to H2S leads to island growth and eventually to the formation of an electrical highly conductive path traversing the entire system: the so-called percolation path. The associated CuOx ∕ CuxS conversion ratio is referred to as the percolation threshold. This pronounced threshold causes a gas concentration dependent switch-like behaviour of the film conductance. However, to utilize this effect for the preparation of CuO-based H2S sensors, a profound understanding of the operational and morphological parameters influencing the CuS path evolution is needed.

Thus, this article is focused on basic features of H2S detection by copper oxide films and the influence of structural parameters on the percolation threshold and switching behaviour. In particular, two important factors, namely the stoichiometry of copper oxides (CuO, Cu2O and Cu4O3) and surface morphology, are investigated in detail. CuOx thin films were synthesized by a radio frequency magnetron sputtering process which allows modification of these parameters. It could be shown that, for instance, the impact on the switching behaviour is dominated by morphology rather than stoichiometry of copper oxide.

Citation: Seitz, C., Beck, G., Hennemann, J., Kandzia, C., Hering, K. P., Polity, A., Klar, P. J., Paul, A., Wagner, T., Russ, S., and Smarsly, B. M.: H2S dosimeter with controllable percolation threshold based on semi-conducting copper oxide thin films, J. Sens. Sens. Syst., 6, 163-170, doi:10.5194/jsss-6-163-2017, 2017.
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