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Title: Tailoring the emissive properties of photocathodes through materials engineering: Ultra-thin multilayers

In this paper, we report on an experimental verification that emission properties of photocathodes can be manipulated through the engineering of the surface electronic structure. Ultrathin multilayered MgO/Ag(0 0 1)/MgO films were grown by pulsed laser deposition, tuning the thickness n of the flanking MgO layers to 0, 2, 3, and 4 monolayers. We observed an increase in quantum efficiency and simultaneous decrease in work function with layer thickness. The scale and trend direction of measurements are in good but not excellent agreement with theory. Angle resolved photoemission data for the multilayered sample n = 3 showed that the emission profile has a metallic-like momentum dispersion. Deviations from theoretical predictions [K. Németh et al., PRL 104, 046801 (2010)] are attributed to imperfections of real surfaces in contrast with the ideal surfaces of the calculation. Photoemissive properties of cathodes are critical for electron beam applications such as photoinjectors for Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). An ideal photoemitter has a high quantum efficiency, low work function, low intrinsic emittance and long lifetime. It has been demonstrated here that emission properties may be systematically tailored by control of layer thickness in ultrathin multilayered structures. Lastly, the reproducibility of themore » emission parameters under specific growth conditions is excellent, even though the interfaces themselves have varying degrees of roughness.« less
Authors:
 [1] ;  [1] ;  [1] ; ORCiD logo [2] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Illinois Institute of Technology, Chicago, IL (United States)
  2. Illinois Institute of Technology, Chicago, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-17-24546
Journal ID: ISSN 0169-4332
Grant/Contract Number:
AC52-06NA25396; SC0007952
Type:
Accepted Manuscript
Journal Name:
Applied Surface Science
Additional Journal Information:
Journal Volume: 360; Journal Issue: PB; Journal ID: ISSN 0169-4332
Publisher:
Elsevier
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Pulsed laser deposition; RHEED; Epitaxy; Photocathode; Work function; Quantum efficiency
OSTI Identifier:
1467324
Alternate Identifier(s):
OSTI ID: 1358799

Velazquez, Daniel, Seibert, Rachel, Ganegoda, Hasitha, Olive, Daniel Thomas, Rice, Amy, Logan, Kevin, Yusof, Zikri, Spentzouris, Linda, and Terry, Jeff. Tailoring the emissive properties of photocathodes through materials engineering: Ultra-thin multilayers. United States: N. p., Web. doi:10.1016/j.apsusc.2015.11.064.
Velazquez, Daniel, Seibert, Rachel, Ganegoda, Hasitha, Olive, Daniel Thomas, Rice, Amy, Logan, Kevin, Yusof, Zikri, Spentzouris, Linda, & Terry, Jeff. Tailoring the emissive properties of photocathodes through materials engineering: Ultra-thin multilayers. United States. doi:10.1016/j.apsusc.2015.11.064.
Velazquez, Daniel, Seibert, Rachel, Ganegoda, Hasitha, Olive, Daniel Thomas, Rice, Amy, Logan, Kevin, Yusof, Zikri, Spentzouris, Linda, and Terry, Jeff. 2015. "Tailoring the emissive properties of photocathodes through materials engineering: Ultra-thin multilayers". United States. doi:10.1016/j.apsusc.2015.11.064. https://www.osti.gov/servlets/purl/1467324.
@article{osti_1467324,
title = {Tailoring the emissive properties of photocathodes through materials engineering: Ultra-thin multilayers},
author = {Velazquez, Daniel and Seibert, Rachel and Ganegoda, Hasitha and Olive, Daniel Thomas and Rice, Amy and Logan, Kevin and Yusof, Zikri and Spentzouris, Linda and Terry, Jeff},
abstractNote = {In this paper, we report on an experimental verification that emission properties of photocathodes can be manipulated through the engineering of the surface electronic structure. Ultrathin multilayered MgO/Ag(0 0 1)/MgO films were grown by pulsed laser deposition, tuning the thickness n of the flanking MgO layers to 0, 2, 3, and 4 monolayers. We observed an increase in quantum efficiency and simultaneous decrease in work function with layer thickness. The scale and trend direction of measurements are in good but not excellent agreement with theory. Angle resolved photoemission data for the multilayered sample n = 3 showed that the emission profile has a metallic-like momentum dispersion. Deviations from theoretical predictions [K. Németh et al., PRL 104, 046801 (2010)] are attributed to imperfections of real surfaces in contrast with the ideal surfaces of the calculation. Photoemissive properties of cathodes are critical for electron beam applications such as photoinjectors for Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). An ideal photoemitter has a high quantum efficiency, low work function, low intrinsic emittance and long lifetime. It has been demonstrated here that emission properties may be systematically tailored by control of layer thickness in ultrathin multilayered structures. Lastly, the reproducibility of the emission parameters under specific growth conditions is excellent, even though the interfaces themselves have varying degrees of roughness.},
doi = {10.1016/j.apsusc.2015.11.064},
journal = {Applied Surface Science},
number = PB,
volume = 360,
place = {United States},
year = {2015},
month = {11}
}