Mainz 2022 – wissenschaftliches Programm
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AKBP: Arbeitskreis Beschleunigerphysik
AKBP 7: Particle Sources
AKBP 7.1: Vortrag
Dienstag, 29. März 2022, 16:00–16:15, AKBP-H13
photocathodes for SRF photoinjectors: exploring GaN and multi-alkali options — •Chen Wang1,2, Sonal Mistry1, Julius Kühn1, Thorsten Kamps1,4, Qun Jin2, Michael Vogel2, Xin Jiang2, Jana Schaber3, Rong Xiang3, and Andre Arnold3 — 1HZB, Berlin, Germany — 2University of Siegen, Institute for Materials Engineering, Siegen, Germany — 3HZDR, Dresden, Germany — 4Humboldt University of Berlin, Berlin, Germany
Gallium nitride and multi-alkali antimonide photocathodes are two candidates for semiconducting photocathode materials for SRF photoinjectors. GaN photocathode has high thermal stability and can provides high QE under UV light, while multi-alkali antimonide provides high QE at visible wavelengths. The crystal quality and doping level of magnetron sputtered Mg doped GaN films are studied at University of Siegen, since they could affect the diffusion length of excited electrons and the electron affinity of the photocathode, which are related to QE of the sample. SEM and XRD methods are used to study the influence of substrates and sputtering conditions on crystal quality and structure. Doping levels are analyzed by hall effect measurement. QE measurements are conducted at HZDR and also in in-situ measurement chamber. Na-K-Sb photocathodes films are deposited on molybdenum substrates in UHV preparation chamber at HZB. The influence of deposition parameters is studied in order to optimize the growth procedure and to achieve better stability at higher temperature, which could benefit operational lifetime. The chemical compositions of films are analyzed by XPS, and then QE measurements are performed.