Metal oxide nanowire array gas sensor via block copolymer lithography combined with secondary sputtering phenomenon

Abstract

The metal oxide based gas sensor has many advantages of cost-effectiveness, high sensitivity, variety of mate-rial candidate, and high thermal stability. In this study, the highly aligned metal oxide NW array with small grain size was fabricated using block copolymer lithography combined with secondary sputtering phenomenon. Two types of NWs was fabricated, $WO_3$ for n-type and NiO NW for p-type and both types of sensors exhibited superior sensing performance to $C_2H_5OH$ gas ($R_{air}/R_{gas}$ = 3050 at 1000 ppm using $WO_3$ NWs and ($R_gas/R_air$ = 83 at 10 ppm using NiO NWs). Enhanced these sensing performances are attributed to an ultrathin (∼15 nm thickness), high-aspect-ratio (∼7.33) structure composed of ultra-small grains (∼5 nm size), generated by this new method.