Author: Guo, L.Guo.
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THPMK116 NEA Surface Activation of GaAs Photocathode with CO2 4590
  • L.Guo. Guo
    UVSOR, Okazaki, Japan
  • H. Iijima
    Tokyo University of Science, Tokyo, Japan
  • M. Kuriki
    HU/AdSM, Higashi-Hiroshima, Japan
  • K. Uchida
    Cosylab Japan, Ibaraki, Japan
  NEA (negative electron affinity)-GaAs cathode is able to generate highly spin polarized electron beam more than 90%. The NEA activation is performed usually with Cs and O2 or NF3, but the exact structure of the NEA surface is not known. In this paper, we performed the NEA activation on a cleaned GaAs surface with CO2, CO, N2, and O2 gases and compared the results to improve our understanding on the NEA surface. We found that CO2 activated the cathode, but N2 and CO did not. By analyzing CO2 activation, we found that atomic oxygen activates the NEA surface and CO degrades the NEA surface simultaneously. We found that the NEA activation ability of atomic oxygen is almost a half of that of O2 molecule.*
*L. Guo, M. Kuriki, H. Iijima, K. Uchida. "NEA surface activation of GaAs photocathode with different gases", Surface Science 664C (2017) pp. 65-69.
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