Density-controllable growth of SnO2 nanowire junction-bridging across electrode for low-temperature NO2 gas detection
The junction-bridging structure of metal oxide nanowires (NWs) improves gas-sensing properties. In this study, an on-chip growth method was used to fabricate gas sensors, it easily and effectively controls NW junctions. SnO2 NWs were synthesized by thermal evaporation at 800 °C with tin powder as the source. The density of the NW junctions was controlled by changing the mass of the source material. A source material with large mass yielded high-density NW junctions. With electrode spacing of 20 μm, NW junctions were formed from the source material of larger than 2 mg. Gas sensing results revealed that the junction sensors exhibited a good response to NO2 gas at a concentration of 1–10 ppm. The sensors exhibited a good response to NO2 gas at low temperature of up to 100 °C and short response–recovery time (~20 s). The sensors also had good selectivity to NO2 gas. The response (R gas /R air) to 1 ppm NO2 was as high as 22 at 100 °C, whereas the cross gas responses (R air /R gas) to 10 ppm CO, 10 ppm H2S, 100 ppm C2H5OH, and 100 ppm NH3 were negligible (1.1–1.3).
KeywordsSnO2 Sensor Resistance Sensor Sample SnO2 Nanowires Nanostructured Semiconductor Metal Oxide
This study was financially supported by the National Foundation for Science and Technology Development project of Vietnam (code 103.02-2011.46).
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