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256 Sputter Growth of Alkali Antimonide Photocathodes: An In Operando Materials Analysis.

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Description: Proceedings of IPAC2015, May 3-8, 2015; Richmond VA TUPHA003 Abstract: Alkali antimonide photocathodes are a strong contender for the cathode of choice for next-generation photon sources such as LCLS II or the XFEL. These materials have already found extensive use in photodetectors and image intensifiers. However, only recently have modern synchrotron techniques enabled a systematic study of the formation chemistry of these materials. Such analysis has led to the understanding that these materials are inherently rough when grown through traditional sequential deposition; this roughness has a detrimental impact on the intrinsic emittance of the emitted beam. Sputter deposition may provide a path to achieving a far smoother photocathode, while maintaining reasonable quantum efficiency. We report on the creation and vacuum transport of a K2CsSb sputter target, and its use to create an ultra-smooth (sub nm roughness) cathode with a 2% quantum efficiency at 532 nm.

Harish Bhandari
Henry J Frisch
Susanne Schubert
John Smedley


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