Field Emission from Novel Room Temperature Grown Carbon Based Multilayered Cathodes
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Field emission from novel room temperature grown carbon based multilayered cathodes B.S.Satyanarayana@, K.Nishimura* and A.Hiraki. KUT Academic & Industrial Collaboration Centre, Kochi University of Technology, Kochi, 782-8502, Japan. * Kochi Prefectural Industrial Tech. Centre, 3992-3, Nunoshida, Kochi, 781-5101, Japan. @ Also- Sistec Co Ltd, Nankoku-Shi, Kochi, 783 0014, Japan. ABSTRACT
Low field electron emission from novel room temperature grown multilayered cold cathodes were studied. The cathodes consisted of a layer of nanocrystalline diamond and a layer of nanocluster carbon films. The nanocrystalline diamond was first coated on to the substrate. The nanocluster carbon films and the tetrahedral amorphous carbon films were then deposited on the nanocrystalline diamond coated substrates using the cathodic arc process at room temperature. The heterostructured microcathodes were observed to exhibit electron emission currents of 1µA/cm2 at fields as low as 1 V/µm. The effect of the nanoseeded diamond size and concentration and the properties of different nanocluster carbon films on emission characteristics is presented.
INTRODUCTION
There is an increasing interest in carbon based nanostructured materials like the nanodiamond[1-3], nanotubes[4,5], and nanocluster or nanostructured carbon[6-10] for possible use as electron emitters. The interest stems from the feasibility of diverse applications, which include field emission displays, electron-beam lithography, electron and ion guns, sensors, electron microscopes and microprobes, low & medium power microwave sources, micro and pico satellite propulsion systems, high power devices and Tera hz communication devices. The need is for electron emitters capable of emitting high emission currents at low fields accompanied by a high emission site density. Further the material process should be such that, it can be used for deposition on low cost substrates, easily scaled for large area growth and compatible with other material process technologies. However most materials mentioned above are grown at high temperatures, some have poor adhesion to the substrate and also patterned growth could be a problem. Coming to the understanding of the emission behaviour, many models have been proposed to explain the emission mechanism and factors influencing emission in the case of the diverse nano-carbon based flat cathode materials[11-23]. The main factors influencing emission from carbon films seem to be a) field enhancement factor, b) highly conducting sp2 bonded nanostructured carbon, in it’s various manifestations and c) the presence of sp3 bonded material in the sp2 matrix, irrespective of the process of growth or the main material grown. Based on the present understanding of the science and technology of carbon based field emitters, it would be difficult to clearly define and tailor the emitter. The material growth process parameters seems to be the only controlling factor and the emitter site derived is D15.5.1
random. It would be desirable to exactly tailor the emitters a
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