IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Nanotubes: Science and Applications Topical Conference Friday Sessions
       Session NT+EL+NS-FrM

Paper NT+EL+NS-FrM6
Field Emission in Cylindrical Geometry with Carbon Nanotube Cathodes: Characterization and Application to Luminescent Tubes

Friday, November 2, 2001, 10:00 am, Room 133

Session: Nanotubes: Field Emission
Presenter: I. Arfaoui, IPE, Switzerland
Authors: J.-M. Bonard, Ecole Polytechnique Fédérale de Lausanne, Switzerland
M. Croci, Ecole Polytechnique Fédérale de Lausanne, Switzerland
O. Noury, Ecole Polytechnique Fédérale de Lausanne, Switzerland
T. Stöckli, Ecole Polytechnique Fédérale de Lausanne, Switzerland
A. Chatelain, Ecole Polytechnique Fédérale de Lausanne, Switzerland
I. Arfaoui, IPE, Switzerland
Correspondent: Click to Email
There have been in the past some attemps to realize tubular lighting elements with field emitters to offer a mercury-free alternative to incandescent or fluorescent lamps. To ensure a uniform light emission from the cylindrical anode, the cathode itself must be cylindrical, and the problem of depositing field emitters on a non-planar surface has up-to-now prevented the demonstration of such devices. We report here on the successful realization of a field emission diode in a cylindrical geometry, with multiwall carbon nanotubes deposited on the metallic cathode as the electron sources. The deposition was carried out by chemical vapor deposition of acetylene over metallic wires, and we observed a significant influence of the wire material. The field emitters show excellent performances: electron emission is observed below 1 kV and currents up to 1 A cm@super -2@ can be obtained. The cathodes can be used to realize luminescent mercury-free tubes: our most recent tube has a length of 30 cm and a diameter of 4 cm, and reaches luminances equivalent to those of commercial fluorescent elements. We show also that the cylindrical geometry allows one to gain information on the different parameters involved in the field emission. Space-charge related problems and the influence of residual gas pressure have been addressed. Field emission microscopy measurements show also that modifications of the structure of the nanotubes can occur during the emission, especially during or following heating. Spectacular observations of the failure of single nanotube emitters also offer direct clues to the degradation mechanism.