title: Towards graphane field emitters.
abstract: We report on the improved field emission performance of graphene foam (GF) following transient exposure to hydrogen plasma. The enhanced field emission mechanism associated with hydrogenation has been investigated using Fourier transform infrared spectroscopy, plasma spectrophotometry, Raman spectroscopy, and scanning electron microscopy. The observed enhanced electron emissionhas been attributed to an increase in the areal density of lattice defects and the formation of a partially hydrogenated, graphane-like material. The treated GF emitter demonstrated a much reduced macroscopic turn-on field (2.5 V μm-1), with an increased maximum current density from 0.21 mA cm-2(pristine) to 8.27 mA cm-2(treated). The treated GFs vertically orientated protrusions, after plasma etching, effectively increased the local electric field resulting in a 2.2-fold reduction in the turn-on electric field. The observed enhancement is further attributed to hydrogenation and the subsequent formation of a partially hydrogenated structured 2D material, which advantageously shifts the emitter work function. Alongside augmentation of the nominal crystallite size of the graphitic superstructure, surface bound species are believed to play a key role in the enhanced emission. The hydrogen plasma treatment was also noted to increase the emission spatial uniformity, with an approximate four times reduction in the per unit area variation in emission current density. Our findings suggest that plasma treatments, and particularly hydrogen and hydrogen-containing precursors, may provide an efficient, simple, and low cost means of realizing enhanced nanocarbon-based field emission devicesviathe engineered degradation of the nascent lattice, and adjustment of the surface work function.
authors.affiliation: Display R&D Center , School of Science and Engineering , Southeast University , Nanjing 210096 , P. R. China . Email: lw@seu.edu.cn; School of Information Engineering , Nanjing Normal University Taizhou Collage , Taizhou , 225300 , P. R. China.
authors.forename: Shuyi
authors.initials: S
authors.lastname: Ding
authors.affiliation: Electrical Engineering Division , Department of Engineering , Cambridge University , Cambridge , CB3 0FA , UK . Email: mtc35@cam.ac.uk.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Cole
authors.affiliation: National Centre for Nanoscience & Technology , Beijing , 100190 , P. R. China . Email: daiq@nanoctr.cn.
authors.forename: Chi
authors.initials: C
authors.lastname: Li
authors.affiliation: School of Information Engineering , Nanjing Normal University Taizhou Collage , Taizhou , 225300 , P. R. China.
authors.forename: Yanhuai
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Electrical Engineering Division , Department of Engineering , Cambridge University , Cambridge , CB3 0FA , UK . Email: mtc35@cam.ac.uk.
authors.forename: Clare M
authors.initials: CM
authors.lastname: Collins
authors.affiliation: Electrical Engineering Division , Department of Engineering , Cambridge University , Cambridge , CB3 0FA , UK . Email: mtc35@cam.ac.uk.
authors.forename: Moon H
authors.initials: MH
authors.lastname: Kang
authors.affiliation: Electrical Engineering Division , Department of Engineering , Cambridge University , Cambridge , CB3 0FA , UK . Email: mtc35@cam.ac.uk.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Parmee
authors.affiliation: Display R&D Center , School of Science and Engineering , Southeast University , Nanjing 210096 , P. R. China . Email: lw@seu.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Lei
authors.affiliation: Display R&D Center , School of Science and Engineering , Southeast University , Nanjing 210096 , P. R. China . Email: lw@seu.edu.cn.
authors.forename: Xiaobing
authors.initials: X
authors.lastname: Zhang
authors.affiliation: National Centre for Nanoscience & Technology , Beijing , 100190 , P. R. China . Email: daiq@nanoctr.cn.
authors.forename: Qing
authors.initials: Q
authors.lastname: Dai
authors.affiliation: Electrical Engineering Division , Department of Engineering , Cambridge University , Cambridge , CB3 0FA , UK . Email: mtc35@cam.ac.uk; Quantum Nanoelectronics Research Center , Tokyo Institute of Technology , Tokyo , Japan.
authors.forename: William I
authors.initials: WI
authors.lastname: Milne
authors.affiliation: Display R&D Center , School of Science and Engineering , Southeast University , Nanjing 210096 , P. R. China . Email: lw@seu.edu.cn.
authors.forename: Baoping
authors.initials: B
authors.lastname: Wang