Field emission of graphene oxide decorated ZnO nanorods grown on Fe alloy substrates

Graphene oxides (GO) are decorated on the top surface of ZnO nanorods (NRs) grown on Fe alloy substrates for efficient field emission. The GO decorated ZnO NRs acting as cold electron emitters exhibit excellent field emission performance with the turn-on field E_to as low as 1.63 V/μm and the threshold field E_thr down to 3.12 V/μm. ZnO NRs grown on the alloy substrates have a low interfacial resistance and intend to enhance electrical conduction. A schottky contact of Fe-ZnO and matched Fermi levels of ZnO-GO interface contribute to the enhanced current emission efficiency. Besides, some nanometer-scaled sharp protrusions have been formed in the GO sheets, and GO itself owns abundant C-O-C oxygen functional groups that also help to improve the field emission current. A straight line Fowler-Nordheim plot of the field emission current from the emitter is obtained and the effective work function for the decorated GO sheets is calculated from the slope with a value below 1.5 eV. Finally, field emission mechanism of the GO decorated ZnO NRs has been proposed. This work may help the development of the practical electron sources and advanced optronic devices based on GO field emitters.