|MOPLH11||Nanostructured Photocathodes for Spin-Polarized Electron Beams||196|
Funding: Work supported by US DOE Office of Science, Office of Nuclear Physics, SBIR grant DESC0019559. CNM work supported by US DOE Office of Science, Basic Energy Sciences, contract DE-AC02-06CH11357.
We present progress on incorporation of nanopillar arrays into spin-polarized gallium arsenide photocathodes in pursuit of record high tolerance to ion back-bombardment. Our goal is to exceed the 400 Coulomb record for a high polarization milliampere-class electron source set at Jefferson Laboratory in 2017, while maintaining high quantum efficiency (QE) and spin polarization with a superlattice. Because the Mie effect is resonant, uniformity and careful control over nanostructure geometry is key. We report excellent uniformity and straight sidewall geometry with improved optical absorption using a painstakingly optimized inductively coupled plasma reactive ion etch. We also report the application of Kerker theory to spin-polarized photocathode nanopillar arrays, setting new requirements on nanostructure dimensions to avoid spoiling spin polarization. Finally, we also report initial steps toward re-establishing U.S. production of strained superlattice photocathodes towards integration with nanopillar arrays.
|DOI •||reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH11|
|About •||paper received ※ 03 September 2019 paper accepted ※ 12 September 2019 issue date ※ 08 October 2019|
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