Enhanced field-emission of silver nanoparticle-graphene oxide decorated ZnO nanowire arrays.

This work presents a new method to improve the field emission (FE) properties of semiconductors decorated with low-cost graphene oxide (GO) nanosheets and trace amounts of noble metal. The Ag/GO/ZnO composite emitter exhibited efficient FE properties with a low turn-on field of 1.4 V μm(-1) and a high field enhancement factor of 7018. The excellent FE properties of the Ag/GO/ZnO composite can be attributed to the tunneling effect of electrons through the heterojunction. The FE properties of the Ag/GO/ZnO composite are slightly better than those of the Ag/ZnO composite which forms an energy well that collects electrons on interfaces when an electric field is applied. This behavior is associated with heterostructures that offer more contact points and protrusions between ZnO nanowire arrays (NWAs) and Ag/GO, which leads to easier electron transfer. High-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterise the connection and evolution of the ZnO NWAs and Ag/GO composites.