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Localized Liquid-Phase Synthesis of Porous SnO2 Nanotubes on MEMS Platform for Low-Power, High Performance Gas Sensors

Cho, Incheol, Kang, Kyungnam, Yang, Daejong, Yun, Jeonghoon, Park, Inkyu
ACS Applied Materials & Interfaces 2017 v.9 no.32 pp. 27111-27119
energy, nanotubes, nanowires, tin dioxide, zinc oxide
We have developed highly sensitive, low-power gas sensors through the novel integration method of porous SnO₂ nanotubes (NTs) on a micro-electro-mechanical-systems (MEMS) platform. As a template material, ZnO nanowires (NWs) were directly synthesized on beam-shaped, suspended microheaters through an in situ localized hydrothermal reaction induced by local thermal energy around the Joule-heated area. Also, the liquid-phase deposition process enabled the formation of a porous SnO₂ thin film on the surface of ZnO NWs and simultaneous etching of the ZnO core, eventually to generate porous SnO₂ NTs. Because of the localized synthesis of SnO₂ NTs on the suspended microheater, very low power for the gas sensor operation (<6 mW) has been realized. Moreover, the sensing performance (e.g., sensitivity and response time) of synthesized SnO₂ NTs was dramatically enhanced compared to that of ZnO NWs. In addition, the sensing performance was further improved by forming SnO₂–ZnO hybrid nanostructures due to the heterojunction effect.