Applied Microscopy

Korean Society of Microscopy (한국현미경학회)
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Enhanced Field Electron Emission from Dielectric Coated Highly Emissive Carbon Fibers

  • Almarsi, Ayman M. (Surface Physics and Materials Technology Laboratory, Department of Physics, Mu'tah University) ;
  • Hagmann, Mark J. (Department of Electrical and Computer Engineering, University of Utah) ;
  • Mousa, Marwan S. (Surface Physics and Materials Technology Laboratory, Department of Physics, Mu'tah University)
  • Received : 2016.07.21
  • Accepted : 2016.11.28
  • Published : 2017.03.30
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Abstract

This paper describes experiments aimed at characterizing the behavior of field electron emitters fabricated by coating carbon fibers with epoxylite resin. Polyacrylonitrile carbon fibers of type VPR-19, thermally treated at $2,800^{\circ}C$, were used. Each was initially prepared in a "uncoated" state, by standard electro polishing and cleaning techniques, and was then examined in a scanning electron microscope. The fiber was then baked overnight in a field electron microscope (FEM) vacuum chamber. Current-voltage characteristics and FEM images were recorded on the following day or later. The fiber was then removed from the FEM, coated with resin, "cured" by baking, and replaced in the FEM. After another overnight bake, the FEM characterization measurements were repeated. The coated fibers had significantly better performance than uncoated fibers. This confirms the results of earlier experiments, and is thought to be due in part to the formation of a conducting channel in the resin over layer. For the coated fiber, lower voltages were needed to obtain the same emission current. The coated fibers have current-voltage characteristics that show smoother trends, with greater stability and repeatability. No switch-on phenomena were observed. In addition, the emission images on the phosphor-coated FEM screen were more concentrated, and hence brighter.

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References

  1. American Chemical Society (2014) National Historic Chemical Landmarks [Internet]. Available from: https://www.acs.org/content/acs/en/education/whatischemistry/landmarks.html.
  2. Baker V S, Osborne A R, and Williams J (1974) The carbon-fiber field emitter. J. Phys. D: Appl. Phys. 7, 2105-2115. https://doi.org/10.1088/0022-3727/7/15/315
  3. Braun E, Smith J F, and Sykes D E (1975) Carbon fibers as field emitters. Vacuum 25, 425-426. https://doi.org/10.1016/0042-207X(75)90489-3
  4. Forbes R G (2004) Use of energy-space diagrams in free-electron models of field electron emission. Surf. Interface Anal. 36, 395-401. https://doi.org/10.1002/sia.1900
  5. Forbes R G (2008) Physics of generalized Fowler-Nordheim-type equations. J. Vac. Sci. Technol. B 26, 788-793. https://doi.org/10.1116/1.2827505
  6. Forbes R G, Al-Qudah A M, Alnawasreh S, Madanat M A, and Mousa M S (2016) Comparisons between apex-radius values extracted from Fowler-Nordheim plots and from SEM measurements, for carbon-based field emitters. 29th International Vacuum Nano electronics Conf., Canada, Vancouver, July 2016. Technical Digest (ISBN: 978-1-5090-2417-9) IEEE, Piscatory, NJ, 2014, p. 105.
  7. Forbes R G, Deane J H B, Fischer A, and Mousa M S (2015) Fowler Nordheim plot analysis: a progress report. Jo. J. Phys. 8, 125-147; arXiv 1504.06134v7.
  8. Fowler R H and Nordheim L (1928) Electron emission in intense electric fields. Proc. R. Soc. London A 119, 137-181.
  9. Huang X (2009) Fabrication and properties of carbon fibers materials. Materials 2, 2369-2403. https://doi.org/10.3390/ma2042369
  10. Latham R V and Mousa M S (1986) Hot electron emission from composite metal-insulator micropoint cathodes. J. Phys. D: Appl. Phys. 19, 699-713. https://doi.org/10.1088/0022-3727/19/4/021
  11. Madanat M A, Mousa M S, Al-Rabadi A N, and Fischer A (2015) Electron microscopy-based performance evaluation of various tungsten field emitter tips Apex radii. Jo. J. Phys. 8, 79-85.
  12. Morita K, Murata Y, Ishitani A, Murayama K, Ono T, and Nakajima A (1986) Characterization of commercially available PAN (polyacrylonitrile)-cased carbon fibers. Pure Appl. Chem. 58, 455-468. https://doi.org/10.1351/pac198658030455
  13. Mousa M S (1996) Electron emission from carbon fiber tips. Surf. Sci. 94/95, 129-135. https://doi.org/10.1016/0169-4332(95)00521-8
  14. Mousa M S (2007) Influence of a dielectric coating on electron emission from micropoint electron sources. Surf. Interface Anal. 39, 102-110. https://doi.org/10.1002/sia.2470
  15. Mousa M S and Kelly T F (2003) Stabilization of carbon-fiber cold field-emission cathodes with a dielectric coating. Ultramicroscopy 95, 125-130. https://doi.org/10.1016/S0304-3991(02)00307-8