IPAC2015 - List of Authors (Schubert, S.G.)

Paper	Title	Page
WEPWA032	CsK2Sb Growth Studies: Towards High Quantum Efficiency and Smooth Surfaces	2566
	S.G. Schubert, M. Gaowei, J. Sinsheimer, J. Smedley BNL, Upton, Long Island, New York, USA Z. Ding, E.M. Muller SBU, Stony Brook, New York, USA J. Kühn HZB, Berlin, Germany H.A. Padmore, J.J. Wong LBNL, Berkeley, California, USA J. Xie ANL, Argonne, Illinois, USA
	Funding: This work was supported by the US DOE, under Contracts DE-AC02-05CH11231, DE-AC02-98CH10886, KC0407-ALSJNT-I0013, DE-FG02-12ER41837 and the German BMBF, Helmholtz-Association and Land Berlin. The properties of CsK2Sb, make this material an ideal candidate as photocathode for electron injector use. Producing photocathodes with quantum efficiencies with 7% and greater at 532 nm poses no challenge, nevertheless the traditional growth mechanisms, which are based on a sequential deposition of Antimony, Potassium and Cesium at a temperature gradient yield a rough surface with a rms roughness in the range of 25 nm. Surface roughness’s in this region impacts the emittance. At an accelerating field of 3 MV/m an rms surface roughness of 25 nm is the dominant effect on emittance and will limit injector performance. Studies are performed to optimize roughness. Various growth procedures are exploited and the surface roughness compared.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA032
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TUPHA003	Sputter Growth of Alkali Antimonide Photocathodes: An in Operando Materials Analysis	1965
	J. Smedley, K. Attenkofer, M. Gaowei, J. Sinsheimer, J. Walsh BNL, Upton, Long Island, New York, USA H. Bhandari Radiation Monitoring Devices, Watertown, USA Z. Ding, E.M. Muller SBU, Stony Brook, New York, USA H.J. Frisch Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA H.A. Padmore, S.G. Schubert, J.J. Wong LBNL, Berkeley, California, USA
	Funding: Work supported by U.S. DoE, under KC0407-ALSJNT-I0013 and SBIR grant # DE-SC0009540. NSLS was supported by DOE DE-AC02-98CH10886, CHESS is supported by NSF & NIH/NIGMS via NSF DMR-1332208 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 adequate 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPHA003
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Paper

Title

Page

CsK2Sb Growth Studies: Towards High Quantum Efficiency and Smooth Surfaces

2566

S.G. Schubert, M. Gaowei, J. Sinsheimer, J. Smedley
BNL, Upton, Long Island, New York, USA
Z. Ding, E.M. Muller
SBU, Stony Brook, New York, USA
J. Kühn
HZB, Berlin, Germany
H.A. Padmore, J.J. Wong
LBNL, Berkeley, California, USA
J. Xie
ANL, Argonne, Illinois, USA

Funding: This work was supported by the US DOE, under Contracts DE-AC02-05CH11231, DE-AC02-98CH10886, KC0407-ALSJNT-I0013, DE-FG02-12ER41837 and the German BMBF, Helmholtz-Association and Land Berlin.
The properties of CsK2Sb, make this material an ideal candidate as photocathode for electron injector use. Producing photocathodes with quantum efficiencies with 7% and greater at 532 nm poses no challenge, nevertheless the traditional growth mechanisms, which are based on a sequential deposition of Antimony, Potassium and Cesium at a temperature gradient yield a rough surface with a rms roughness in the range of 25 nm. Surface roughness’s in this region impacts the emittance. At an accelerating field of 3 MV/m an rms surface roughness of 25 nm is the dominant effect on emittance and will limit injector performance. Studies are performed to optimize roughness. Various growth procedures are exploited and the surface roughness compared.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA032

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPHA003

Sputter Growth of Alkali Antimonide Photocathodes: An in Operando Materials Analysis

1965

J. Smedley, K. Attenkofer, M. Gaowei, J. Sinsheimer, J. Walsh
BNL, Upton, Long Island, New York, USA
H. Bhandari
Radiation Monitoring Devices, Watertown, USA
Z. Ding, E.M. Muller
SBU, Stony Brook, New York, USA
H.J. Frisch
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
H.A. Padmore, S.G. Schubert, J.J. Wong
LBNL, Berkeley, California, USA

Funding: Work supported by U.S. DoE, under KC0407-ALSJNT-I0013 and SBIR grant # DE-SC0009540. NSLS was supported by DOE DE-AC02-98CH10886, CHESS is supported by NSF & NIH/NIGMS via NSF DMR-1332208
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 adequate 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPHA003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)