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Single-Crystal Alkali Antimonide Photocathodes: High Efficiency in the Ultrathin Limit

Cornell Affiliated Author(s)

Author

C.T. Parzyck
A. Galdi
J.K. Nangoi
W.J.I. Debenedetti
J. Balajka
B.D. Faeth
H. Paik
C. Hu
Tomas Arias
M.A. Hines
D.G. Schlom
K.M. Shen
J.M. Maxson

Abstract

The properties of photoemission electron sources determine the ultimate performance of a wide class of electron accelerators and photon detectors. To date, all high-efficiency visible-light photocathode materials are either polycrystalline or exhibit intrinsic surface disorder, both of which limit emitted electron beam brightness. In this Letter, we demonstrate the synthesis of epitaxial thin films of Cs3Sb on 3C-SiC (001) using molecular-beam epitaxy. Films as thin as 4 nm have quantum efficiencies exceeding 2% at 532 nm. We also find that epitaxial films have an order of magnitude larger quantum efficiency at 650 nm than comparable polycrystalline films on Si. Additionally, these films permit angle-resolved photoemission spectroscopy measurements of the electronic structure, which are found to be in good agreement with theory. Epitaxial films open the door to dramatic brightness enhancements via increased efficiency near threshold, reduced surface disorder, and the possibility of engineering new photoemission functionality at the level of single atomic layers. © 2022 American Physical Society.

Date Published

Journal

Physical Review Letters

Volume

128

Issue

11

URL

https://www.scopus.com/inward/record.uri?eid=2-s2.0-85126962453&doi=10.1103%2fPhysRevLett.128.114801&partnerID=40&md5=621b2a9c3673230701a9a773f07dd410

DOI

10.1103/PhysRevLett.128.114801

Group (Lab)

Kyle Shen Group
Tomas Arias Group

Funding Source

DMR-2039380
PHY-1549132
DMR-1719875
DMR-2104427

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