Metal-Insulator Photocathode Heterojunction for Directed Electron Emission

Timothy C. Droubay, Scott A. Chambers, Alan G. Joly, Wayne P. Hess, Karoly Németh, Katherine C. Harkay, and Linda Spentzouris

Phys. Rev. Lett. 112, 067601 – Published 14 February 2014

Abstract

We use angle-resolved photoemission under ultraviolet laser excitation to demonstrate that the electron emission properties of Ag(001) can be markedly enhanced and redirected along the surface normal by the deposition of a few monolayers of epitaxial MgO. We observe new low-binding energy states with small spreads in their surface parallel momenta as a result of $MgO / Ag (001)$ interface formation. Under 4.66 eV laser excitation, the quantum efficiency of $MgO / Ag (001)$ is a factor of 7 greater than that of clean Ag(001), revealing the utility of such heterojunctions as advanced photocathodes.

Received 4 October 2013

DOI:https://doi.org/10.1103/PhysRevLett.112.067601

Authors & Affiliations

Timothy C. Droubay¹, Scott A. Chambers^1,*, Alan G. Joly¹, Wayne P. Hess¹, Karoly Németh^2,3, Katherine C. Harkay², and Linda Spentzouris^2,3

¹Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
²Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
³Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616, USA

^*sa.chambers@pnnl.gov

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Vol. 112, Iss. 6 — 14 February 2014

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