Fabrication of ZnO nanowires using nanoscale spacer lithography for gas sensors

ZnO nanowire arrays were fabricated by nanoscale spacer lithography (NSL) and the electrical characterization and gas sensing were carried out to evaluate the performance of the nanowire devices based on the NSL method. Arrays successfully formed without any defects or contamination suggest that the dimensions and positions of the ZnO nanowires can be controlled by adjusting the thickness of the ZnO layer and the etch depth of the sacrificial oxide layer. ZnO shows high resistance to air and the resistance is decreased due to the loss of electrons to the conduction band of the ZnO. The ZnO nanowires show a much higher sensitivity compared to the ZnO thin film for both H₂ and CO. The results also show that an increase in gas sensitivity of the nanowires can be attributed to the higher surface-to-volume ratio than that of the thin film.