A cesium-iodide surface treatment for enhancement of negative electron affinity photocathode chemical robustness
Abstract
Photocathodes activated to negative electron affinity with a cesium-based activation layer, such as GaAs and GaN, can be used for generating spin-polarized electron beams, but their extreme sensitivity to chemical poisoning limits their operational lifetimes. This work demonstrates that applying and subsequently heating a cesium iodide (CsI) coating can produce a more durable activation layer lacking iodine, but rich in stable cesium suboxides (formal O oxidation state >−2), which significantly extend the dark lifetimes of both GaAs and GaN photocathodes. Through x-ray photoelectron spectroscopy, we examine the stability and formation of these Cs suboxides, which exhibit remarkable resistance to chemical poisoning. Additionally, we investigate the subsequent surface quality using atomic force microscopy. Our findings show that CsI-based surface treatments not only prolong photocathode lifetime but also maintain high spin polarization, positioning this method as a promising approach for enhancing photocathode durability in demanding applications.
Article Details
Journal Info
Journal of Applied Physics
American Institute of Physics
Authors (12)
S. J. Levenson
Cornell Laboratory for Accelerator-Based Sciences and Education (CLASSE), Cornell University 1 , Ithaca, New York 14850,
M. B. Andorf
Cornell Laboratory for Accelerator-Based Sciences and Education (CLASSE), Cornell University 1 , Ithaca, New York 14850,
M. A. Reamon
Cornell Laboratory for Accelerator-Based Sciences and Education (CLASSE), Cornell University 1 , Ithaca, New York 14850,
I. V. Bazarov
Cornell Laboratory for Accelerator-Based Sciences and Education (CLASSE), Cornell University 1 , Ithaca, New York 14850,
A. Galdi
Department of Industrial Engineering, University of Salerno 6 , 84084 Fisciano, SA,
Q. Zhu
Department of Chemistry, Cornell University 3 , Ithaca, New York 14853,
M. A. Hines
Department of Chemistry, Cornell University 3 , Ithaca, New York 14853,
J. Encomendero
School of Electrical and Computer Engineering, Cornell University 4 , Ithaca, New York 14853,
V. V. Protasenko
School of Electrical and Computer Engineering, Cornell University 4 , Ithaca, New York 14853,
D. Jena
School of Electrical and Computer Engineering, Cornell University 3 , Ithaca, New York 14853,
H. G. Xing
School of Electrical and Computer Engineering, Cornell University 3 , Ithaca, New York 14853,
J. M. Maxson
Cornell Laboratory for Accelerator-Based Sciences and Education (CLASSE), Cornell University 1 , Ithaca, New York 14850,