Graphene-film electron field emitters for THz VEDs

M. Sattorov, D. Hong, V. Dixit, S.-H. Min, Y. J. Yoo, S.-Y. Park, and G.-S. Park
Int’l Vacuum Electronics Conference (IVEC),22 (2024)
DOI: 10.1109/IVECIVESC60838.2024.10694844

Abstract

While field electron emitters have seen notable advancements enhancing their applications in diverse fields , challenges such as inconsistent emission , material degradation , and the complexities of nanoscale fabrication persist as significant barriers . This report introduces a graphene electron field emitter as a promising candidate for the sheetbeam electron source for developing compact , high -power terahertz (THz) sources. Since the discovery of graphene, there has been a continuous pursuit to leverage its superior properties by restoring its exceptional characteristics in film or paper forms , often referred to as reduced graphene oxide (rGO ). Typically, the material properties of rGO are constrained by the oxidation process, but they can be enhanced limitedly through a general high-temperature annealing process .In this report , a turbostratically stacked 2.5-D graphene film (TGF), fashioned through an innovative binder -free gelation technique , has showcased superior performance in both material and field emission properties. This includes an electrical conductivity of
1.95× 10^6 S·m^-1, electron mobility of 818 cm^2·V^-1·s^-1, thermal conductivity of 2000 W ·m^- 1·K^-1, and current exceeding 10 mA with a current density over 300 A cm^-2. Additionally , the TGF maintained a 10% current degradation after 25 days of continuous DC operation at 1.5 mA. The film used is typically about 300 nm in thickness and 1-2 cm in width. Utilizing this graphene electron field emitter , we are progressing in the development of a THz vacuum electron device.