Enhancement of optical, electrical and sensing characteristics of ZnO nanowires for optoelectronic applications

In this work, the synthesis of undoped and Sn-doped ZnO nanowires using vapor transport technique is reported. The effects of Sn content on morphological, structural, optical, electrical and sensing characteristics of ZnO nanowire films were examined by utilizing various techniques. X-ray diffraction inferred that all undoped and Sn-doped ZnO films are indexed to single hexagonal phase and no additional phases for tin or tin oxides were presented. The estimated Sn at.% rations was proportionate with the Sn ratios utilized in the source ingots. The morphology of the undoped ZnO sample was nanowires with quite long and smooth surfaces. After Sn doping, the smoothness of the nanowires is reduced and agglomerations of particles are observed. A reduction in transmittance and an increase in reflectance were observed after Sn doping. The optical band gap reduced from 3.27 to 3.06 eV with the elevation of Sn doping percent from 0 to 7 at.%. Two characteristic emission peaks were seen in the spectra around 388 nm and 540 nm. The emission peaks were affected by the Sn doping ratio. All the nanowires films demonstrated the semiconductor type manner with two distinct activation energies. The Sn doping enhanced the sensitivity of the sensors toward NO2 gas.