Towards Graphane Field Emitters
Royal Society of Chemistry
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Ding, S., Cole, M., Li, C., Zhou, Y., Collins, C., Kang, M., Parmee, R., et al. (2015). Towards Graphane Field Emitters. RSC Advances, 5 105111-105118. https://doi.org/10.1039/C5RA20771A
Here we report on the improved the field emission performance of graphene foam (GF) following transient exposure to hydrogen plasma. The enhanced field emission mechanism associated with these treated has been investigated using Fourier Transform Infrared spectroscopy, plasma spectrophotometry, Raman spectroscopy, and scanning electron microscopy and has 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), with an increased maximum current density from 0.21 mA/cm2 (pristine) to 8.27 mA/cm2 (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 and the constitute macro molecules, 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 approximately four times reduction in the per unit area variation in emission current density. Our findings suggest that plasma treatments, and particularly those employing hydrogen and hydrogen-containing precursors, may provide an efficient, simple, and low costs means of realizing enhanced nanocarbon-based field emission devices via the engineered degradation of the nascent lattice and adjustment of the surface work function.
field electron emission, plasma, graphene, graphane, hydrogenation
For assistance in ATR FTIR and EDXRF measurements we thank Dr Bob Keighley and Dr Ralph Vokes of Shimadzu Corp; and for plasma optical spectrophotometry analysis, Dr Thomas Schűtte of PLASUS GmbH. This work is supported by National Key Basic Research Program 973(2010CB327705), National Natural Science Foundation Project (51120125001, 51002031, 61101023, 51202028), Foundation of Doctoral Program of Ministry of Education (20100092110015), an EPSRC Impact Acceleration grant, and the Research Fund for International Young Scientists from NSFC (510501101 42, 51350110232). MT Cole thanks the Oppenheimer Trust for their generous financial support.
External DOI: https://doi.org/10.1039/C5RA20771A
This record's URL: https://www.repository.cam.ac.uk/handle/1810/252807
Rights Holder: EPSRC