Energy distributions of field emitted electrons from few-layer graphene sheets with AB and ABC stacking
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ESSION “STATISTICAL MECHANICS, KINETICS AND QUANTUM THEORY OF CONDENSED MATTER”
Energy Distributions of Field Emitted Electrons from FewLayer Graphene Sheets with AB and ABC Stacking1 V. L. Katkov and V. A. Osipov Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, 141980 Russia Abstract—We study the effect of the band structure on the energy distributions of field emitted electrons from AB and ABC graphene multilayers. The characteristic subpeaks are found to appear for each type of stack ing. The experimental discovery of these peaks in field emission experiments from carbon fewlayer systems can provide important information about a type of stacking. DOI: 10.1134/S1063779610070105 1
1. INTRODUCTION Recently, freestanding carbon nanosheets (CNSs) have been synthesized on a variety of substrates by radio frequency plasma enhanced chemical vapor deposition [1, 2]. The sheets are consisting of several graphene layers and stand roughly vertical to the sub strate. It has been found that CNSs have good field emission characteristics with promising applications in vacuum microelectronic devices [3–6]. High emis sion total current at low threshold field enables using CNSs as an effective cold cathode material. There are two known forms of bulk graphite called as AB (Bernal) and ABC (rhombohedral) with differ ent stacking of layers. The AB phase is thermodynam ically stable and this form of graphite occurs naturally. At the same time, the ABC form was also experimen tally observed [7]. Thus, generally the CNSs synthe sized by radio frequency plasma enhanced chemical vapor deposition can have both types of stacking. Until now only the currentvolt age characteriza tion was used in studies of CNSs. At the same time, voltage dependent field emission energy distribution (VFEED) analysis is known as a powerful experimen tal method to interrogate the field emission. As com pared to classical I–V characterization, VFEED analysis can provide more information related to both inherent properties of the emitter and to the basic tun neling process [8]. In particular, in singlewalled car bon nanotubes (CNTs) the FEED has shown charac teristic peaks originated from the stationary waves in the cylindrical part of the nanotube [9]. Their number and sharpness were found to increase with the length of the tubes. Notice that short periodic variations were also observed in the thicknessdependent field emis sion current from ultrathin metal films (UMF) [10]. The calculated electron energy distribution curve characteristic of UMF was found to have “steps” which correspond with the quantized “normal” ener
gies [11]. The resonanttunneling peaks with specific microscopic tunneling mechanisms were also observed in field emission from nanostructured semi conductor cathodes [12]. A different example of the quantum size effect in CNTs, which originates from the intrinsic properties of the energy band structure, was revealed in field emission [13]. It is reasonable to expect manifestation
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