Local Characterization of Field Emission Properties of Graphene Flowers

An experimental study about field emission properties of commercially available graphene flowers cloth is reported. Material characterization by means of x-ray diffraction, Raman spectroscopy, and x-ray photoemission spectroscopy confirms the formation of high quality vertical few-layers graphene nanosheets. A tip-anode setup is exploited in which nanomanipulated tungsten tip is used as the anode at controlled distance from the emitter in order to reduce the effective emitting area below 1 mu m(2), giving access to local characterization. A turn-on field as low as 0.07 V nm(-1) and field enhancement factor up to 32 for very small cathode-anode separation distances is demonstrated, in the range 400-700 nm. It is also shown that the turn-on field increases for increasing distances, while the field enhancement factor decreases. Finally, time stability of the field emission current is reported, evidencing a reduction of the fluctuations for lower current levels.