Highly integrated SNO2 nanotubes using templated ZNO nanowires for low power gas sensors

We have developed highly sensitive, low power gas sensors consisting of beam-shaped, suspended microheaters and locally synthesized 1-D metal oxide nanostructures. In-situ localized hydrothermal synthesis method was utilized to grow ZnO nanowires on the Joule-heated region. Also, liquid phase deposition (LPD) process enabled to formulate SnO₂ thin film on the surface of ZnO nanowires and to etch ZnO out at the same time. Therefore, we could fabricate highly integrated and sensitive SnO₂ nanotubes on the selective region less than 50² μm². Due to the small and suspended heating area, operating power of the gas sensor was less than 10 mW at 300 °C. Also, the sensitivity (Rair/Rgas) of SnO₂ nanotubes for H₂S gas was around 6 times larger than that of pre-processed ZnO nanowires.