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Role of the Interfaces in Multiple Networked One-Dimensional Core–Shell Nanostructured Gas Sensors

Park, Sunghoon, Ko, Hyunsung, Kim, Soohyun, Lee, Chongmu
ACS Applied Materials & Interfaces 2014 v.6 no.12 pp. 9595-9600
ethanol, evaporation, indium, models, nanowires, zinc oxide
This study examined the gas sensing mechanism of multiple networked core–shell nanowire sensors. The ethanol gas sensing properties of In₂O₃/ZnO core–shell nanowires synthesized by the thermal evaporation of indium powder in an oxidizing atmosphere followed by the atomic layer deposition of ZnO were examined as an example. The pristine In₂O₃ nanowires and In₂O₃-core/ZnO-shell nanowires exhibited responses of ∼30% and ∼196%, respectively, to 1000 ppm ethanol at 300 °C. The response of the core–shell nanostructures to ethanol also showed a strong dependence on the shell layer width. The strongest response to ethanol was obtained with a shell layer thickness of ∼44 nm corresponding to 2λD, where λD is the Debye length of ZnO. The enhanced sensing properties of the core–shell nanowires toward ethanol can be explained based on the potential barrier-controlled carrier transport model combined with the surface depletion model; the former is predominant over the latter.