Nitrogen Oxide (NO<sub>2</sub>) Gas Sensing Performance of ZnO Nanoparticles (NPs)/Sapphire-Based Sensors

Abstract

The interesting ZnO nanoparticles (NPs)-based sensor devices are fabricated on sapphire substrates to study the nitrogen oxide (NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) gas sensing performance. The postheat treatment process is not used to avoid the undesired agglomeration phenomenon. Different concentrations (0.1 and 0.01 wt%) of ZnO NPs are employed to produce the studied NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas sensors. Experimentally, studied devices demonstrate good NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensing responses $\sim 100$ (at 5 ppm NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /air, 473 K). Especially, an extremely low sensing limit of 10 ppb NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /air is obtained for the studied devices. This value is superior to those of previously reported results from other NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensors. The studied sensor devices also show the advantages of low cost, easy fabrication, and compact potentiality to integrate with other high-speed and optoelectronic devices. Therefore, the studied devices give the promise for high-performance NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> monitoring applications.