Field emission and photoluminescence of ZnO nanocombs

Abstract

Three kinds of new comb-shape nanostructures of ZnO have been grown on single silicon substrates without catalyst-assisted thermal evaporation of Zn and active carbon powders. The morphology and structure of the prepared nanorods are determined on the basis of field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD). The growth mechanism of the ZnO nanocombs can be explained on the basis of the vapor–solid (VS) processes. In nanocombs 1 and nanocombs 2, the comb teeth grow along [0001] and the comb stem grows along [\(01\overline{1}0\)], while in nanocombs 3, nanoteeth grow along [\(01\overline{1}0\)] and stem grows along [0001]. The photoluminescence and field-emission properties of ZnO nanocombs 1–3 have been investigated. The turn-on electric field of ZnO nanocombs 1–3, which is defined as the field required to producing a current density of 10 μA/cm2, is 9, 7.7 and 7.1 V/μm, respectively. The field-emission performance relies not only on the tip’s radius of curvature and field enhancement factor, but also on the factor evaluating the degree of the screening effect.