Synthesis and characterization of ZnO nano/microfibers thin films by catalyst free solution route

Zinc oxide (ZnO) nano/microfibrous thin films were successfully synthesized by a catalyst free solution route on glass and Si substrates. X-ray diffraction study revealed the formation of ZnO nanofibers of hexagonal crystalline structure. The texture coefficient of different planes varied with annealing temperature and that of the (0 0 2) plane was the highest for films annealed at temperature ∼873 K. Scanning electron micrograph showed the well formation of ZnO nano/microfibers with an average diameter ∼500 nm and having an average aspect ratio ∼150. UV-Vis-NIR spectroscopic study for the films deposited on glass substrates showed the high transmittance in the visible and near-infrared region. It was also observed that the band gap energy decreased as the films were annealed at higher temperature. The band gap energies of nanostructured ZnO thin films were determined to be in the range 3.03-3.61 eV. The photoluminescence study showed an UV emission peak at ∼397 nm, a visible blue-green emission peak at ∼468 nm and a green emission peak at ∼495 nm. Field emission properties of nanofiber ZnO thin film showed considerably low turn-on field around 1.4 V/μm. The emission current was as high as ∼70 μA at the field of 3.6 V/μm.