High field emission enhancement of ZnO-nanorods via hydrothermal synthesis

We describe the synthesis of zinc oxide nanorods by a hydrothermal method in this paper. The reactants were zinc nitrate hexahydrate and hexamethylenetetramine (HMT, (CH2)6N4) and the solvent was absolute alcohol. The ZnO-nanostructures have been characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM): the nanorods had a length of 9–10 μm and a diameter 0.5 μm. From the field emission characteristics of the ZnO-nanorods the following properties were derived: a low turn-on electric field of 1.9 V/μm at a current density of 0.2 μA/cm2, maximum current density was 1 mA/cm2 at a threshold field of 7.4 V/μm and a field emission enhancement factor β of 2510. Furthermore, ZnO-nanorods show a higher stability and longer lifetime as compared with those of ZnO-nanoparticles and tetrapod ZnO-nanostructures.