Improved field emission property of graphene by laser irradiation

Graphene oxide (GO) can be reduced to graphene by either laser irradiation or thermal annealing. To improve the field emission (FE) property, a pulse CO2 laser has been employed to irradiate GO films prepared by electrophoretic deposition (EPD). By varying the laser irradiation time, we were able to fabricate emitters with varied field enhancement factor. It has been found that the FE properties of laser irradiated films with optimized time 15 s were better than that of thermal annealed samples. The turn-on field (Eto) at 0.01 mA/cm2 was reduced from 3.4 to 2.4 V/μm, and the threshold field (Eth) at 1 mA/cm2 was reduced from 6.8 to 5.1 V/μm. Scanning electron microscopy (SEM) was taken to reveal the change of morphology after laser ablation, and it shows that the laser irradiation made great deal of graphene edges vertical to the substrate, which remarkably enhanced the FE properties. This kind of effective and convenience method made the graphene films as a potential field emitter for vacuum microelectronic devices.