Author: Forrest, T.
Paper Title Page
MOPFI081 Correlating Structure and Function - In situ X-ray Analysis of High QE Alkali-antimonide Photocathodes 464
  • J. Smedley, K. Attenkofer, S.G. Schubert
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi, X. Liang, E.M. Muller, M. Ruiz-Osés
    Stony Brook University, Stony Brook, USA
  • T. Forrest, H.A. Padmore, T. Vecchione, J.J. Wong
    LBNL, Berkeley, California, USA
  • J. Xie
    ANL, Argonne, USA
  Funding: The authors wish to acknowledge the support of the US DOE, under Contract No. KC0407-ALSJNT-I0013, DE-AC02-98CH10886 and DE-SC0005713. Use of CHESS is supported by NSF award DMR-0936384.
Alkali antimonide photocathodes have high quantum efficiency and low emittance when illuminated by visible light, and are thought to be well suited for use in high-brightness photoinjectors of 4th generation light sources. Here we report on the growth of multi-alkali K2CsSb cathodes on [100] silicon substrates measured using in-situ X-ray diffraction (XRD) and X-ray reflection (XRR). Correlations between cathode structure and growth parameters and the resulting quantum efficiency (QE) are also explored. The best cathodes have a QE at 532 nm in excess of 6% and are structurally textured K2CsSb with grain sizes in excess of 20 nm. In an attempt to reduce the complexity of the current growth methodology we are also making alkali antimonides in parallel via the reaction of bulk materials in an inert environment. This approach has the advantage that the desired stoichiometry can be obtained exactly. Initial diffraction results from prepared bulk materials are promising and show the formation of well reacted K3Sb. In the future we intend to transfer this material to smooth thin photocathode films by either sputtering or pulsed laser deposition.