Synthesis and characterization of ZnO NWAs/graphene composites for enhanced optical and field emission performances

We demonstrate ZnO nanowire arrays (NWAs) and ZnO NWAs/graphene composites grown on ZnO seed layers on Cu substrate via a hydrothermal method and graphene film layer chemically synthesized at low pressure chemical vapor deposition. In the case of the Cu substrate covered with graphene layer, the uniform and vertically aligned ZnO NWAs/graphene composites with the average diameter of 80 nm grown on ZnO seed layers were obtained and growth mechanism of that has been proposed. The photoluminescence (PL) spectra of ZnO NWAs/graphene composites shows enhanced intensity of UV emission and decreased intensity of visible emission. In addition, field emission measurements reveal that the ZnO NWAs/graphene composites have a lower turn-on field of 1.74 V/μm and higher field enhancement factor of 12130 in comparison to that of graphene film layer and ZnO NWAs, which demonstrate ZnO NWAs/graphene composites are characteristic of having excellent emitting behavior in field emission technology.