Author: Pennington, C.A.
Paper Title Page
TUYD5 Epitaxial Alkali-Antimonide Photocathodes on Lattice-matched Substrates 289
  • P. Saha, S.S. Karkare
    Arizona State University, Tempe, USA
  • E. Echeverria, A. Galdi, J.M. Maxson, C.A. Pennington
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • E.J. Montgomery, S. Poddar
    Euclid Beamlabs, Bolingbrook, USA
  Alkali-antimonides photocathodes, characterized by high quantum efficiency (QE) and low mean transverse energy (MTE) in the visible range of spectrum, are excellent candidates for electron sources to drive X-ray Free Electron Lasers (XFEL) and Ultrafast Electron Diffraction (UED). A key figure of merit for these applications is the electron beam brightness, which is inversely proportional to MTE. MTE can be limited by nanoscale surface roughness. Recently, we have demonstrated physically and chemically smooth Cs3Sb cathodes on Strontium Titanate (STO) substrates grown via co-deposition technique. Such flat cathodes could result from a more ordered growth. In this paper, we present RHEED data of co-deposited Cs3Sb cathodes on STO. Efforts to achieve epitaxial growth of Cs3Sb on STO are then demonstrated via RHEED. We find that films grown epitaxially on substrates like STO and SiC (previously used to achieve single crystalline Cs3Sb) exhibit QE higher than the polycrystalline Cs3Sb cathodes, by an order of magnitude below photoemission threshold. Given the larger QE, lower laser fluence could be used to extract high charge densities, thereby leading to enhanced beam brightness.  
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DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD5  
About • Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 07 September 2022
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