Novel fabrication of an SnO₂ nanowire gas sensor with high sensitivity

We fabricated a nanowire-based gas sensor using a simple method of growing SnO₂ nanowires bridging the gap between two pre-patterned Au catalysts, in which the electrical contacts to the nanowires are self-assembled during the synthesis of the nanowires. The gas sensing capability of this network-structured gas sensor was demonstrated using a diluted NO₂. The sensitivity, as a function of temperature, was highest at 200°C and was determined to be 18 and 180 when the NO₂ concentration was 0.5 and 5 ppm, respectively. Our sensor showed higher sensitivity compared to different types of sensors including SnO₂ powder-based thin films, SnO ₂ coating on carbon nanotubes or single/multiple SnO₂ nanobelts. The enhanced sensitivity was attributed to the additional modulation of the sensor resistance due to the potential barrier at nanowire/nanowire junctions as well as the surface depletion region of each nanowire.