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Title: Synthesis and x-ray characterization of sputtered bi-alkali antimonide photocathodes

Advanced photoinjectors, which are critical to many next generation accelerators, open the door to new ways of material probing, both as injectors for free electron lasers and for ultra-fast electron diffraction. For these applications, the nonuniformity of the electric field near the cathode caused by surface roughness can be the dominant source of beam emittance. Therefore, improving the photocathode roughness while maintaining quantum efficiency is essential to the improvement of beam brightness. Here in this article, we report the demonstration of a bi-alkali antimonide photocathode with an order of magnitude improved roughness by sputter deposition from a K 2CsSb sputter target, using in situ and operando X-ray characterizations. We found that a surface roughness of 0.5 nm for a sputtered photocathode with a final thickness of 42 nm can be achieved while still yielding a quantum efficiency of 3.3% at 530 nm wavelength.
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [5] ;  [4] ;  [4] ;  [1] ;  [2] ; ORCiD logo [1] ; ORCiD logo [6] ;  [3] ;  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
  2. Stony Brook Univ., NY (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. Radiation Monitoring Devices, Watertown, MA (United States)
  5. Helmholtz-Zentrum Berlin (HZB), (Germany)
  6. Univ. of Chicago, IL (United States)
Publication Date:
Report Number(s):
BNL-200031-2018-JAAM
Journal ID: ISSN 2166-532X
Grant/Contract Number:
SC0012704; SC0017202; SC0017693
Type:
Accepted Manuscript
Journal Name:
APL Materials
Additional Journal Information:
Journal Volume: 5; Journal Issue: 11; Journal ID: ISSN 2166-532X
Publisher:
American Institute of Physics (AIP)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); National Institute of General Medical Sciences (NIGMS); National Institutes of Health (NIH); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION; Photocathodes; photodetectors; sputter deposition; accelerated beams; electron diffraction
OSTI Identifier:
1425174
Alternate Identifier(s):
OSTI ID: 1421047

Gaowei, M., Ding, Z., Schubert, S., Bhandari, H. B., Sinsheimer, J., Kuehn, J., Nagarkar, V. V., Marshall, M. S. J., Walsh, J., Muller, E. M., Attenkofer, K., Frisch, H. J., Padmore, H., and Smedley, J.. Synthesis and x-ray characterization of sputtered bi-alkali antimonide photocathodes. United States: N. p., Web. doi:10.1063/1.5010950.
Gaowei, M., Ding, Z., Schubert, S., Bhandari, H. B., Sinsheimer, J., Kuehn, J., Nagarkar, V. V., Marshall, M. S. J., Walsh, J., Muller, E. M., Attenkofer, K., Frisch, H. J., Padmore, H., & Smedley, J.. Synthesis and x-ray characterization of sputtered bi-alkali antimonide photocathodes. United States. doi:10.1063/1.5010950.
Gaowei, M., Ding, Z., Schubert, S., Bhandari, H. B., Sinsheimer, J., Kuehn, J., Nagarkar, V. V., Marshall, M. S. J., Walsh, J., Muller, E. M., Attenkofer, K., Frisch, H. J., Padmore, H., and Smedley, J.. 2017. "Synthesis and x-ray characterization of sputtered bi-alkali antimonide photocathodes". United States. doi:10.1063/1.5010950. https://www.osti.gov/servlets/purl/1425174.
@article{osti_1425174,
title = {Synthesis and x-ray characterization of sputtered bi-alkali antimonide photocathodes},
author = {Gaowei, M. and Ding, Z. and Schubert, S. and Bhandari, H. B. and Sinsheimer, J. and Kuehn, J. and Nagarkar, V. V. and Marshall, M. S. J. and Walsh, J. and Muller, E. M. and Attenkofer, K. and Frisch, H. J. and Padmore, H. and Smedley, J.},
abstractNote = {Advanced photoinjectors, which are critical to many next generation accelerators, open the door to new ways of material probing, both as injectors for free electron lasers and for ultra-fast electron diffraction. For these applications, the nonuniformity of the electric field near the cathode caused by surface roughness can be the dominant source of beam emittance. Therefore, improving the photocathode roughness while maintaining quantum efficiency is essential to the improvement of beam brightness. Here in this article, we report the demonstration of a bi-alkali antimonide photocathode with an order of magnitude improved roughness by sputter deposition from a K2CsSb sputter target, using in situ and operando X-ray characterizations. We found that a surface roughness of 0.5 nm for a sputtered photocathode with a final thickness of 42 nm can be achieved while still yielding a quantum efficiency of 3.3% at 530 nm wavelength.},
doi = {10.1063/1.5010950},
journal = {APL Materials},
number = 11,
volume = 5,
place = {United States},
year = {2017},
month = {11}
}