The Parameters of the Field Emission Model and the Fabrication of Zinc Oxide Nanorod Arrays/Graphene Film

Abstract

A large-scale growth of zinc oxide (ZnO) nanorod arrays on graphene sheets was fabricated by a hydrothermal technique, and the Fowler–Nordheim theory was used to build a model to describe the properties of the arrays’ field emission. The results indicated that the morphological characteristics of the ZnO nanorods grown on the graphene sheets can be easily tuned by varying the reaction time and concentrations of the reaction solution. The regular ordered ZnO nanorods arrays on the graphene sheets were obtained under the appropriate experimental conditions. Further, this composite cathode was demonstrated to possess excellent field emission properties due to the outstanding mechanical and electrical properties of graphene. The field emission current density of the composite cathode reached 1,448 μA cm–2 at the electric field of 16.5 V μm–1. The key parameter, field enhancement factor, reached 6,366, while the pure graphene cathode field is about 1,660. These specific nanorod arrays with enhancement of the field emission properties would be useful to sensor or modulator units for accessing networks.

Tuneable effects of pyrrolic N and pyridinic N on the enhanced field emission properties of nitrogen-doped graphene

“…4(a) that the turn-on E , defined at the current density of 1 μA cm −2 , was 7.95 V μm −1 and the current density was 7.3 μA cm −2 of PG, which is comparable to the reported values for graphene films prepared by the CVD method, as shown in Table 1. 40–44 In general, the doping of nitrogen has an enhancing effect on the field emission properties of graphene. Interestingly, the enhancing effect is not linear, and it is optimal when the introduced urea mass is 20 mg, with a turn-on E of 6.38 V μm −1 and a current density of 42.6 μA cm −2 .…”

“…One can find numerous graphene-based field emitters with different structures, such as vertically curved graphene, 8,9 graphene/carbon nanotube, graphene/ZnO, and graphene/nanoparticles. 10–12 For material modification, doping graphene with heteroatoms (boron, nitrogen, etc .) is a common way to tune the electronic and mechanical properties of graphene, 13,14 thus improving carrier mobility and decreasing the work function.…”