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WEXC07 |
Nucleation of Single Crystal Photocathode on Atomically Thin Graphene Substrate Using Co-Deposition of Cesium Telluride |
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- M. Gaowei, J. Cen, J. Sinsheimer, J. Walsh
BNL, Upton, New York, USA
- A.M. Alexander, F. Liu, V.N. Pavlenko, J. Smedley, H. Yamaguchi
LANL, Los Alamos, New Mexico, USA
- J.P. Biswas
Stony Brook University, Stony Brook, USA
- D.P. Juarez-Lopez
The University of Liverpool, Liverpool, United Kingdom
- S. Mistry
HZB, Berlin, Germany
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
For the past decades, cesium telluride (CsTe) has been chosen as the electron source material for high bunch charge, high repetition rate superconducting radio frequency electron injectors. The application of cesium telluride photocathode has been reported by accelerators all over the world. Alkali based semiconductor photocathode material has always been vapor deposited thin films, with amorphous or very limited crystalline phases. The fragility of alkali-based photocathode partially comes from its disordered and unstable structure. The limited crystallinity also limits the quantum efficiency to improve. Therefore, growing large crystal or even single crystal of the alkali-based photocathode material is the goal of many scientific projects these days. Nucleation of cesium telluride crystalline phase was observed via co-deposition method on atomically thin graphene substrate, which is is a recognized sign of the first step of the formation of single crystal. In situ and operando X-ray characterization has been performed on this process and the results in the evolution of crystal structure, chemical stoichiometry as well as the surface morphology and quantum efficiency are reported.
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| WEPAB112 |
Performance Characterisation of a Cu (100) Single-Crystal Photocathode |
2860 |
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- L.A.J. Soomary, D.P. Juarez-Lopez, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
- L.B. Jones, T.C.Q. Noakes
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
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The search for high performance photocathode electron sources is a priority in the accelerator science community. The surface characteristics of a photocathode define important factors of the photoemission including the intrinsic emittance, the quantum efficiency and the work function of the photocathode. These factors in turn define the electron beam performance which are measurable as emittance, brightness and energy spread. We have used ASTeC’s Multiprobe (SAPI)* to characterise and analyse photocathode performance using multiple techniques including XPS, STM, and LEED imaging, and their Transverse Energy Spread Spectrometer (TESS)** to measure mean transverse energy (MTE). We present characterisation measurements for a Cu (100) single-crystal photocathode sample with data from SAPI confirming the crystallographic face and showing surface composition and roughness, supported by data from TESS showing the photocathode electron beam energy spread.
* B.L. Militsyn, 4-th EuCARD2 WP12.5 meeting, Warsaw, 14-15 March 2017
**Proc. FEL’13, TUPPS033, 290-293
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Poster WEPAB112 [0.814 MB]
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| DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB112
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| About • |
paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 22 August 2021 |
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