Experimental evidence for large negative electron affinity from scandium-terminated diamond

Ramiz Zulkharnay*, Paul W. May

*Corresponding author for this work

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


Negative electron affinity (NEA) or low-work function conditions of wide-band gap materials play a crucial role in developing effective electron-emission devices, field-effect transistors (FETs), and energy converters. Single-crystal diamond with electropositive surface terminating groups can exhibit NEA and has been proposed for possible thermionic emission devices. Here, a report on the in situ observation of large NEA from scandium-terminated diamond is presented. A quarter monolayer of Sc was deposited via electron beam evaporation onto bare diamond (100) and (111) surfaces. The variations of surface structure, electron affinity (EA) and work function (WF) were measured following each annealing step in vacuo at temperatures up to 900 °C. The magnitudes of the EA were found to be dependent upon the surface orientation and annealing temperature, the most negative measured being −1.45 eV and −1.13 eV for the diamond (100) and (111) surfaces, respectively. These values show that these two Sc–diamond surfaces have the highest negative EA for a metal adsorbed onto bare diamond measured to date, as well as being thermally stable up to 900 °C. This study unveils structural and electronic insights into tuning the adsorbate–diamond interface and further expands the potential candidate material map for effective electron-emission applications.

Original languageEnglish
Pages (from-to)13432-13445
Number of pages14
JournalJournal of Materials Chemistry A
Issue number25
Early online date28 Apr 2023
Publication statusE-pub ahead of print - 28 Apr 2023

Bibliographical note

Funding Information:
RZ wishes to acknowledge the funding scheme of the Government of the Republic of Kazakhstan under the Bolashak International program. The authors acknowledge the use of the University of Bristol NanoESCA facility. DFT calculations were carried out using the BlueCrystal Phase 4 high-performance computing cluster of the Advanced Computing Research Centre, University of Bristol.

Publisher Copyright:
© 2023 The Royal Society of Chemistry.


Dive into the research topics of 'Experimental evidence for large negative electron affinity from scandium-terminated diamond'. Together they form a unique fingerprint.

Cite this