Ab initio study of negative electron affinity on the scandium-terminated diamond (100) surface for electron emission devices

Ramiz Zulkharnay*, Neil L. Allan, Paul W. May

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

6 Citations (Scopus)

Abstract

Surface modification of diamond with the addition of (sub)monolayer of metals or other electropositive adsorbates than the bulk carbon can result in negative electron affinity (NEA). Surface coverages of up to one-monolayer (<1 ML) of scandium on clean, oxygenated and nitrogenated diamond (100) surfaces were studied via plane-wave density functional theory (DFT) calculations. Adsorption of Sc on diamond is energetically favourable; for example, 0.25 ML coverage of Sc on the oxygenated diamond (100) surface has an extremely large calculated adsorption energy per adsorbate atom of −8.68 eV. Moreover, the majority of stable Sc-adsorption configurations possess NEA, with the most negative values of −3.73 eV, – 3.02 eV and −1.75 eV being found for 0.25 ML Sc coverage on the oxygenated, bare and nitrogenated diamond surfaces, respectively. These results predict that Sc termination on diamond should provide a thermally stable surface with large NEA, and is therefore a highly promising candidate for thermionic and other electron-emission applications.

Original languageEnglish
Pages (from-to)176-185
Number of pages10
JournalCarbon
Volume196
DOIs
Publication statusPublished - 30 Aug 2022

Bibliographical note

Funding Information:
RZ would like to acknowledge the funding scheme of the Government of the Republic of Kazakhstan under the Bolashak International programme. This work was carried out using the computational facilities of the Advanced Computing Research Centre, University of Bristol (http://bris.ac.uk/acrc/).

Funding Information:
RZ would like to acknowledge the funding scheme of the Government of the Republic of Kazakhstan under the Bolashak International programme. This work was carried out using the computational facilities of the Advanced Computing Research Centre, University of Bristol ( http://bris.ac.uk/acrc/ ).

Publisher Copyright:
© 2022

Keywords

  • Density functional theory
  • Diamond
  • Negative electron affinity
  • Scandium
  • Surface
  • Thermionic electron emission

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