High Brightness of Electron Beams from Graphene Edge
Jeff Tsung Hui Tsai1*, Li-Jie Chen1, Tzu-Hua Chen1
1Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung, Taiwan
* Presenter:Jeff Tsung Hui Tsai
In this paper, we fabricated freestanding graphene edge probes as electron sources with the testing of the field emission properties and revels the electron beam brightness from such novel electron source. We use solid carbon source to synthesis graphene on copper foils. These copper foils were then transferred into a structure with the graphene protrusion form the Cu substrate and made the freestanding graphene edge emitter. In order to increase the emission performance, we use the tungsten heater to increase the temperature of graphene. The field emission experiments are performed in our lab-assembled measurement system. This system contains three parts: The cathode heater with the emitter, the pin-hold anode and the phosphorous screen. The field emission performance of freestanding graphene edge emitter was compared with the pure tungsten wire and the pure copper, respectively, in such measurement system. We then utilized a sharp edge of a metal blade to inference the electron beams which from the graphene edge. The Fresnel interference pattern was observed from such configuration. We then enable to calculated the brightness of this electron beam. According to the total emission current, spaces of the interference pattern, we are able to conclude the brightness of freestanding graphene edge emitter was determined to 2.2x1010 Am-2sr-1V-1 . The electron beam utility and high brightness obtained from this prototype electron source is higher than that of commercial tungsten or LaB6 field emission sources. The highest value of beam brightness from our graphene emitter is even one order higher than the prototype carbon nanotube emitter.

Keywords: Electron beam, Field emission, Graphene