IPAC2011 - List of Authors (Padmore, H.A.)

Paper	Title	Page
THPC136	High Efficiency Visible Photocathode Development	3206
	J. Smedley, K. Mueller, T. Rao BNL, Upton, Long Island, New York, USA K. Attenkofer, S.W. Lee ANL, Argonne, USA I. Ben-Zvi, X. Liang, E.M. Muller, M. Ruiz-Oses Stony Brook University, Stony Brook, USA H.A. Padmore, T. Vecchione LBNL, Berkeley, California, USA
	Alkali antimonide cathodes are critical both for high average current photoinjectors for energy recovery linacs and for high quantum efficiency photodetectors. These cathodes have historically been plagued by extreme vacuum sensitivity, non-reproducibility and poor lifetime. We report on ongoing efforts to improve the performance of alkali antimonides (principally K2CsSb). Cathodes have been fabricated which have a QE of 7% at 532 nm. The films are much more resistant to oxygen and water exposure than previously thought, with a 50% yield lifetime of 20 hrs at 2 pBar partial pressure of water. Several analysis techniques have been employed in this study, including in-situ x-ray diffraction during growth to measure grain size and texture, measurement of transverse momentum distribution of the emitted electrons, and measurement of the stoichiometry of the films via x-ray fluorescence. An extensive study of the growth parameters, including both transparent and metallic substrates, sputtered and evaporated films, variation of growth time and temperatures and post-growth annealing processes, is currently underway.

Paper

Title

Page

High Efficiency Visible Photocathode Development

3206

J. Smedley, K. Mueller, T. Rao
BNL, Upton, Long Island, New York, USA
K. Attenkofer, S.W. Lee
ANL, Argonne, USA
I. Ben-Zvi, X. Liang, E.M. Muller, M. Ruiz-Oses
Stony Brook University, Stony Brook, USA
H.A. Padmore, T. Vecchione
LBNL, Berkeley, California, USA

Alkali antimonide cathodes are critical both for high average current photoinjectors for energy recovery linacs and for high quantum efficiency photodetectors. These cathodes have historically been plagued by extreme vacuum sensitivity, non-reproducibility and poor lifetime. We report on ongoing efforts to improve the performance of alkali antimonides (principally K2CsSb). Cathodes have been fabricated which have a QE of 7% at 532 nm. The films are much more resistant to oxygen and water exposure than previously thought, with a 50% yield lifetime of 20 hrs at 2 pBar partial pressure of water. Several analysis techniques have been employed in this study, including in-situ x-ray diffraction during growth to measure grain size and texture, measurement of transverse momentum distribution of the emitted electrons, and measurement of the stoichiometry of the films via x-ray fluorescence. An extensive study of the growth parameters, including both transparent and metallic substrates, sputtered and evaporated films, variation of growth time and temperatures and post-growth annealing processes, is currently underway.