Comparative effects of synthesis parameters on the NO2 gas-sensing performance of on-chip grown ZnO and Zn2SnO4 nanowire sensors

Abstract

Large-scale fabrication, sensitivity and selectivity are important considerations for the practical applications of metal-oxide nanowire (NW) gas sensors fabricated by thermal evaporation. This paper reports the effect of the distance between the source and the microelectronic chips on the gas-sensing properties of ZnO and Zn2SnO4 NW sensors fabricated by on-chip growth via thermal evaporation. Results indicate that the placement of the microelectrode chips in the range of 2–6 cm results in a similar response for ZnO NW sensors but an order of magnitude difference in response for Zn2SnO4 NW sensors as measured at 10 ppm NO2. The response of Zn2SnO4 NW sensors is significantly higher than that of ZnO NW sensors. Similar to that of ZnO NW sensors, the NW–NW junction density of Zn2SnO4 NW sensors strongly affects their NO2 gas-sensing performance. The selectivity of Zn2SnO4 NW sensors is much better than that of ZnO NW sensors under testing with interference gases, such as CO, H2, H2S and NH3.