Synthesis of one-dimensional ZnO nanostructures and their field emission properties

This study fabricates one-dimensional ZnO nanostructures on a tin-doped indium oxide (ITO) glass substrate by thermal evaporation of Zn powder at 400 degrees C. The study finds that ZnO nanocones, ZnO nanorods and ZnO nanowires can be synthesized with a catalyst-free ITO glass, a Pt-coated ITO glass and an Au-coated ITO glass, respectively. The XRD and TEM investigations show that ZnO nanostructures possess good crystalline structures with growth direction along the c-axis of the crystal plane. Photoluminescence (PL) spectra of the ZnO nanocones and nanorods show a UV emission and a broad green emission at room temperature while the nanowires show a red-shifted UV and blue emissions. Field emission studies reveal ZnO nanorod arrays with a turn-on voltage of 3.4V mu m(-1) at a current density of 10 mu A cm(-2) and this work finds that morphology and growth direction of the ZnO nanostructures affect the field emission property.