Field emission from tetrahedral amorphous carbon films with various surface morphologies |
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| Affiliation: | 1. Department of Physics, Zhongshan University, Guangzhou S10275, People''s Republic of China;2. Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, People''s Republic of China;1. School of Mechanical and Production Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore;2. School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore;1. Department of Physics, University of Durham, Durham DH1 3LE, UK;2. Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK;3. Cavendish Laboratories, University of Cambridge, Cambridge CB3 OHE, UK;1. Department of Engineering, Cambridge University, Cambridge, CB2 1PZ, UK;2. Department of Physics and Interdisciplinary Research Centre in Surface Science, University of Liverpool, Liverpool, L69 3BX, UK;1. Universitat de Barcelona, Departament de F?́sica Aplicada i Òptica, Av. Diagonal 647, Barcelona E-08028, Spain;2. Engineering Department, University of Cambridge, Trumptington Street, Cambridge CB2 1PZ, UK |
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| Abstract: | Field emission properties of tetrahedral amorphous carbon films prepared by filtered cathodic vacuum arc technique have been compared with different surface morphologies. With fewer cycles of conditioning, field emission from relatively rough granular ta-C films on nickel-coated silicon substrates was routinely improved, due to a local field enhancement resulting from both a ‘protrusion-on-protrusion’ geometry and a relatively high sp2 content in the film. A 2-MeV ion implantation machine was also employed to intentionally produce local graphitic channels in smooth ta-C films with a high fraction of sp3 content on bare silicon. A relatively low threshold field was obtained from the ta-C film implanted at a dose of 1012 cm?2, which still remained an extremely smooth surface. However, for the highly graphitic sample implanted with a higher dose of over 4×1013 cm?2, no electron field emission was observed, even under a very high electric field of 40 V μm?1. Therefore, a suitable sp2 content in an sp3 matrix, resulting in graphitic conductive channels in amorphous carbon films to produce a local field enhancement, may be the main factor in obtaining low threshold fields. Furthermore, protrusive structures could further increase the field enhancement factor, due to a ‘protrusion-on-protrusion’ geometry. |
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