Effect of 6 MeV electron beam irradiation on the field emission current noise behavior of graphene

Arc discharge synthesized graphene cold cathodes were fabricated using electrophoresis on gold coated silicon substrate. As fabricated cold cathodes were irradiated with 6 MeV electron beam with the fluence of 5×10¹⁴, 7×10¹⁴, 1×10¹⁵ e^-/cm² and characterized using field emission scanning electron microscopy and Raman spectroscopy. Furthermore, the effect of electron beam irradiation on the field emission current noise was investigated using a Fast Fourier Transform analyzer at the base pressure of ~1×10^-8 mbar. The electron irradiated graphene cathode exhibits `step´ like fluctuations in the field emission current-time traces. The power spectra, pre and post irradiation, show 1/f^α type of behavior, with a between 0.7-0.82. The observed variation in the turn on electric field and step like fluctuations in the field emission current are explained on the basis of structural modifications due to electron irradiation and various surface processes.