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Broadband Dielectric Spectroscopy Detection of Volatile Organic Compounds with ZnO Nanorod Gas Sensors



Papa K. Amoah, Pengtao Lin, Helmut Baumgart, Yaw S. Obeng, Rhonda R. Franklin


Metal-oxide semiconductor gas sensors based on chemical resistivity necessarily involve making electrical contacts to the sensing materials. These contacts are imperfect and introduce errors into the measurements. In this paper, we demonstrate the feasibility of using contactless broadband dielectric spectroscopy (BDS)-based metrology in gas monitoring that avoids distortions in the reported resistivity values due to probe use, and parasitic errors, (i.e., tool-measurand interactions). Specifically, we show how radio frequency (RF) propagation characteristics can be applied to study discrete processes on metal-oxide sensing material, such as zinc oxide (i.e. ZnO) surfaces, when exposed to a redox-active gas. Specifically, we have used BDS to investigate the initial oxidization of ZnO gas sensing material in air at temperatures below 200 °C, and to show that the technique affords new mechanistic insights that are inaccessible with the traditional resistance-based measurements.
Journal of Physics D-Applied Physics


contactless broadband microwaves, semiconductor metal oxide, ZnO, sensing, volatile organic compounds (VOC), depletion layer


Amoah, P. , Lin, P. , Baumgart, H. , Obeng, Y. and Franklin, R. (2021), Broadband Dielectric Spectroscopy Detection of Volatile Organic Compounds with ZnO Nanorod Gas Sensors, Journal of Physics D-Applied Physics, [online],, (Accessed May 22, 2024)


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Created January 28, 2021, Updated October 12, 2021