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 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.
- Received 30 December 2021
- Accepted 2 February 2022
DOI:https://doi.org/10.1103/PhysRevLett.128.114801
© 2022 American Physical Society
Physics Subject Headings (PhySH)
synopsis
Ultrathin Photocathode with High Efficiency
Published 18 March 2022
Researchers demonstrate a single-crystal photocathode that can emit electrons with higher efficiency than its predecessors.
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