Highly sensitive VOC sensors using NiO-decorated ZnO nanowire networks: the effect of radial p-n junction

The pristine, NiO-decorated, and NiO-doped ZnO nanowires were prepared by vapor phase reaction and their gas sensing characteristics were investigated. The decoration of p-type NiO on n-type ZnO nanowires significantly enhanced the responses to volatile organic compounds such as C2H5OH and HCHO. In contrast, the doping of NiO into the lattice of ZnO NW deteriorated the gas sensing characteristics. The enhanced gas sensing characteristics of NiO-decorated ZnO nanowires were explained by the extension of the electron depletion layer due to the formation of nanoscale p-n junctions between p-type NiO and n-type ZnO