▎ 摘　　要

One of the critical technologies for the development of a compact high-power terahertz (THz)-VEDs is the requirement of efficient cathodes with emission density in excess of 1000 A/cm(2). In view of this, it is proposed to develop graphene-based field emitters with low electrical resistivity. Average similar to 100-nm ultrathin free-standing reduced graphene oxide (rGO) films (4 mm x 4 mm) were developed using modified hummers method followed by hydrothermal technique and thermal reduction. The I - V characterization of the developed film was carried out in specially designed UHV chamber in closely spaced diode (CSD) mode. The maximum current density obtained from the rGO film was similar to 500 A/cm(2) at 4 V/mu m. Further improvement in the current density was achieved by doping tungsten (W) into rGO film using dc sputtering followed by thermal annealing. The average resistivity of the film was found to be very low similar to 15 x 10(-7) Omega-m, due to the uniform doping of W nanoparticles into the film. The emission characterization result showed that this W-rGO film could deliver a maximum current density in excess of 1500 A/cm(2) at 4 V/mu m, which makes it a potential candidate for use in THz-VEDs applications.