Enhanced thermionic energy conversion and thermionic emission from doped diamond films through methane exposure

Franz A M Koeck, Robert Nemanich, Yasodhaadevi Balasubramaniam, Ken Haenen, Jeff Sharp

Research output: Contribution to journalArticle

26 Citations (Scopus)

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 °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.

Original languageEnglish (US)
Pages (from-to)1229-1233
Number of pages5
JournalDiamond and Related Materials
Volume20
Issue number8
DOIs
StatePublished - Aug 2011

Fingerprint

Thermionic emission
thermionics
thermionic emission
Diamond films
Methane
energy conversion
diamond films
Energy conversion
emitters
methane
Phosphorus
phosphorus
thermionic emitters
Nitrogen
Vacuum
direct power generators
negative electron affinity
Electron sources
nitrogen
Electron affinity

Keywords

  • Chemical vapor deposition
  • Diamond
  • Thermionic electron emission
  • Thermionic energy conversion

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Electrical and Electronic Engineering
  • Mechanical Engineering
  • Physics and Astronomy(all)
  • Chemistry(all)

Cite this

Enhanced thermionic energy conversion and thermionic emission from doped diamond films through methane exposure. / Koeck, Franz A M; Nemanich, Robert; Balasubramaniam, Yasodhaadevi; Haenen, Ken; Sharp, Jeff.

In: Diamond and Related Materials, Vol. 20, No. 8, 08.2011, p. 1229-1233.

Research output: Contribution to journalArticle

Koeck, Franz A M ; Nemanich, Robert ; Balasubramaniam, Yasodhaadevi ; Haenen, Ken ; Sharp, Jeff. / Enhanced thermionic energy conversion and thermionic emission from doped diamond films through methane exposure. In: Diamond and Related Materials. 2011 ; Vol. 20, No. 8. pp. 1229-1233.
@article{09b5d9531d5d4f18b6d6b5644a8504f3,
title = "Enhanced thermionic energy conversion and thermionic emission from doped diamond films through methane exposure",
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 °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.",
keywords = "Chemical vapor deposition, Diamond, Thermionic electron emission, Thermionic energy conversion",
author = "Koeck, {Franz A M} and Robert Nemanich and Yasodhaadevi Balasubramaniam and Ken Haenen and Jeff Sharp",
year = "2011",
month = "8",
doi = "10.1016/j.diamond.2011.06.032",
language = "English (US)",
volume = "20",
pages = "1229--1233",
journal = "Diamond and Related Materials",
issn = "0925-9635",
publisher = "Elsevier BV",
number = "8",

}

TY - JOUR

T1 - Enhanced thermionic energy conversion and thermionic emission from doped diamond films through methane exposure

AU - Koeck, Franz A M

AU - Nemanich, Robert

AU - Balasubramaniam, Yasodhaadevi

AU - Haenen, Ken

AU - Sharp, Jeff

PY - 2011/8

Y1 - 2011/8

N2 - 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 °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.

AB - 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 °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.

KW - Chemical vapor deposition

KW - Diamond

KW - Thermionic electron emission

KW - Thermionic energy conversion

UR - http://www.scopus.com/inward/record.url?scp=80051798383&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=80051798383&partnerID=8YFLogxK

U2 - 10.1016/j.diamond.2011.06.032

DO - 10.1016/j.diamond.2011.06.032

M3 - Article

AN - SCOPUS:80051798383

VL - 20

SP - 1229

EP - 1233

JO - Diamond and Related Materials

JF - Diamond and Related Materials

SN - 0925-9635

IS - 8

ER -