Fabrication of gas sensor based on p-type ZnO nanoparticles and n-type ZnO nanowires

This investigation studies the feasibility of synthesizing high-density transparent p-type ZnO nanoparticles and n-type ZnO nanowires on a glass substrate at 650 °C using the self-catalyzed vapor–liquid–solid method. The doping impurity is Sb, which reduces the concentration of electrons in n-type nanowires and increases the concentration of holes in p-type nanoparticles. XRD spectra clearly include a strong peak that is associated with the wurtzite structure and very weak peaks that are associated with Sb2O3. All XRD peaks of the ZnO sample shift by a small angle upon doping by Sb. The Hall effect indicates that ZnO nanowires and ZnO:Sb nanoparticles are n-type and p-type, respectively. The Sb atoms produce the Moiré pattern and cause stacked faults to form nanoparticles as determined by HRTEM. The reaction between ethanol and ionic oxygen species yield electrons, which increase the conductivity of the n-type nanowires and reduce the conductivity of the p-type nanoparticles. The responses of p-type ZnO nanoparticles/n-type ZnO nanowires to gas are dominated by those of p-type sensors at 25 °C and n-type sensors above 200 °C.