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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/12327

Title: Enhanced thermionic energy conversion and thermionic emission from doped diamond films through methane exposure
Authors: Koeck, Franz A. M.
Nemanich, Robert J.
Balasubramaniam, Yaso
Haenen, Ken
Sharp, Jeff
Issue Date: 2011
Publisher: ELSEVIER SCIENCE SA
Citation: DIAMOND AND RELATED MATERIALS, 20(8). p. 1229-1233
Abstract: Thermionic electron emitters are a crucial component in applications ranging from high power telecommunication, electron guns, space thrusters and direct thermal to electrical energy converters. One key characteristic of diamond based electron sources is the negative electron affinity (NEA) properties of hydrogen terminated surfaces which can significantly reduce the emission barrier. Nitrogen and phosphorus doped diamond films have been prepared by plasma assisted chemical vapor deposition on metallic substrates for thermionic emitter application. Electron emission current versus temperature was measured and analyzed with respect to the Richardson-Dushman relation, with work function and Richardson constant deduced from the results. Initial emission measurements up to 500 degrees C in vacuum were followed by emitter characterization while the sample was exposed to methane. Vacuum measurements indicated a work function of 1.18 eV and 1.44 eV for phosphorus and nitrogen doped diamond films, respectively. Introduction of methane resulted in a significant increase of the emission current which was ascribed to contribution from ionization processes which increase charge transfer from the emitter surface. This phenomenon was utilized in a thermionic energy conversion structure by introduction of methane in the inter electrode gap where a two-fold increase in output power was observed upon introduction of the gaseous species. (C) 2011 Elsevier B.V. All rights reserved.
Notes: [Koeck, FAM; Nemanich, RJ] Arizona State Univ, Dept Phys, Tempe, AZ 85287 USA. [Balasubramaniam, Y; Haenen, K] Hasselt Univ, Inst Mat Res IMO, B-3590 Diepenbeek, Belgium. [Haenen, K] IMEC VZW, Div IMOMEC, B-3590 Diepenbeek, Belgium. [Sharp, J] Marlow Ind Inc, Dallas, TX 75238 USA. franz.koeck@asu.edu
URI: http://hdl.handle.net/1942/12327
DOI: 10.1016/j.diamond.2011.06.032
ISI #: 000295300800026
ISSN: 0925-9635
Category: A1
Type: Journal Contribution
Validation: ecoom, 2012
Appears in Collections: Research publications

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