Low temperature onset for thermionic emitters based on nitrogen incorporated UNCD films

Franz A M Koeck, Robert Nemanich

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Thermionic electron emission is a key phenomenon utilized in a variety of applications, from communications, space propulsion to direct energy conversion. Doped diamond films with a negative electron affinity (NEA) surface characteristic present a reduced effective work function for electron emission. Our prior research has indicated a work function of ∼ 1.5 eV for nitrogen doped diamond films prepared by microwave plasma CVD. The focus of this study is on the role of the interfacial or nucleation layer. A thermionic emitter was fabricated with a nitrogen incorporated ultra-nanocrystalline diamond (UNCD) nucleation layer and a nitrogen doped diamond surface layer with hydrogen termination. The film exhibited a resistance that decreased with temperature suggesting the role of the dopant, and thermionic electron emission was observed at temperatures < 250 °C. An analysis based on the Richardson-Dushman equation indicated an emission barrier of < 1.3 eV with a Richardson constant of ∼ 0.8 A/cm2 K2.

Original languageEnglish (US)
Pages (from-to)232-234
Number of pages3
JournalDiamond and Related Materials
Issue number2-3
StatePublished - Feb 2009


  • Chemical vapor deposition
  • Diamond growth
  • Doping
  • Field emission

ASJC Scopus subject areas

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


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