Single atomic layer protective barrier for Cu photocathodes

ORAL

Abstract

We describe an initial study to evaluate the efficacy of single-layer graphene and hexagonal boron nitride (hBN) films on photoemission properties of Cu cathodes. Many cathode material systems can benefit from a protective, passivating surface layer, so long as this layer does not significantly hinder the emission of the electron beam or increase beam emittance. Graphene and hBN are known to be excellent barriers for protecting transition metal surface, as well as reducing the work function of these metals. We utilize Cu, a well-known photoemitter and growth substrate for graphene and hBN, as a platform for understanding the key features as a passivating layer for photocathodes. Photoelectric work function and quantum efficiency were measured by UV-Vis photoemission yield spectra. The protected Cu photocathodes exhibit lower work function and higher quantum efficiency. These cathodes are also resilient to degradation when subjected to atmospheric conditions. Moreover, the validation of graphene/hBN-photocathode compatibility opens a new route to the lifetime-extension for photocathodes, especially for those more fragile III–V or alkali-antimonide semiconductor families.

*The authors acknowledge the support from the Los Alamos National Laboratory Laboratory, Project No. 20150394DR.

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Presenters

  • Fangze Liu

    • MPA-11: Materials Synthesis and Integrated Devices, Los Alamos National Laboratory

Authors

  • Fangze Liu

    • MPA-11: Materials Synthesis and Integrated Devices, Los Alamos National Laboratory

  • Hisato Yamaguchi

    • MPA-11: Materials Synthesis and Integrated Devices, Los Alamos National Laboratory
    • Los Alamos National Laboratory

  • Vitaly Pavlenko

    • AOT-AE: Accelerators and Electrodynamics, Los Alamos National Laboratory

  • Mark Hoffbauer

    • C-CDE: Chemical Diagnostics and Engineering, Los Alamos National Laboratory

  • Kevin Jensen

    • Naval Research Laboratory
    • U.S. Naval Research Laboratory

  • Claudia Villarrubia

    • MPA-11: Materials Synthesis and Integrated Devices, Los Alamos National Laboratory

  • Aditya Mohite

    • MPA-11: Materials Synthesis and Integrated Devices, Los Alamos National Laboratory
    • Los Alamos National Laboratory
    • Los Alamos National Lab
    • Materials Physics and Applications Division, Los Alamos National Laboratory

  • Nathan Moody

    • AOT-AE: Accelerators and Electrodynamics, Los Alamos National Laboratory
    • Los Alamos National Laboratory