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

Ramiz Zulkharnay; Paul W. May

doi:10.1039/D2TA09199B

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 journal › Article (Academic Journal) › peer-review

5 Citations (Scopus)

Abstract

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 language	English
Pages (from-to)	13432-13445
Number of pages	14
Journal	Journal of Materials Chemistry A
Volume	11
Issue number	25
Early online date	28 Apr 2023
DOIs	https://doi.org/10.1039/D2TA09199B
Publication status	E-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.

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5 Citations
2 Article (Academic Journal)

Oxygen-terminated diamond: insights into the correlation between surface oxygen configurations and work function values
Zulkharnay, R., Zulpukarova, G. & May, P. W., 15 Jun 2024, In: Applied Surface Science. 658, 9 p., 159776.
Research output: Contribution to journal › Article (Academic Journal) › peer-review

Open Access
5 Citations (Scopus)
Experimental studies of electron affinity and work function from titanium on oxidised diamond (100) surfaces
Fogarty, F., Fox, N. A. & May, P. W., 31 Dec 2022, In: Functional Diamond. 2, 1, p. 103-111 9 p.
Research output: Contribution to journal › Article (Academic Journal) › peer-review

Open Access

Cite this

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title = "Experimental evidence for large negative electron affinity from scandium-terminated diamond",

abstract = "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.",

author = "Ramiz Zulkharnay and May, {Paul W.}",

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: {\textcopyright} 2023 The Royal Society of Chemistry.",

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N2 - 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.

AB - 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.

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DO - 10.1039/D2TA09199B

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

Abstract

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Research output

Oxygen-terminated diamond: insights into the correlation between surface oxygen configurations and work function values

Experimental studies of electron affinity and work function from titanium on oxidised diamond (100) surfaces

Cite this