Field emission from zinc oxide nanorod bundles grown on silicon nanoporous pillar array

► A ZnO nanorod bundle array was grown on silicon nanoporous pillar array (Si-NPA). ► The field-emission properties of ZnO/Si-NPA was studied. ► The turn-on field of ZnO/Si-NPA was 4.6 V/μm, with a field enhancement factor of ∼1700. ► ZnO/Si-NPA might be a promising electron-emitting source.