AVS 63rd International Symposium & Exhibition
    2D Materials Focus Topic Thursday Sessions
       Session 2D-ThP

Paper 2D-ThP12
Tuning the Electronic Structure of Metallic Single Crystal Surfaces through Ultra Thin Hetero-Junctions for Photocathode Applications

Thursday, November 10, 2016, 6:00 pm, Room Hall D

Session: 2D Materials Poster Session
Presenter: ZhengRong Lee, Illinois Institute of Technology
Authors: Z.R. Lee, Illinois Institute of Technology
R. Seibert, Illinois Institute of Technology
D. Velázquez, Illinois Institute of Technology
L. Spentzouris, Illinois Institute of Technology
J. Terry, Illinois Institute of Technology
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The development of photocathodes for the next generation of state-of-the-art laser-driven photoinjectors requires the use of photoemissive materials with specific characteristics depending upon their application (FELs, ERLs, Wakefield acceleration, etc.). The ability to tune the emissive properties of photocathodes to match the requirememts of the specific accelerator device could have a important impact in research and development. In this work we show that such photoemissive tunability can be achieve thorugh the engineering of single crystal metallic surfaces by coating them with metal-insulator heterojunctions of various thicknesses. Ultrathin multilayered MgO/Ag(001)/MgO films were grown by pulsed laser deposition, tuning the thickness n of the flanking MgO layers to 0, 2, 3, and 4 monolayers. We observed an increase in quantum efficiency and simultaneous decrease in work function with layer thickness. The scale and trend direction of measurements are in good but not excellent agreement with theory. Angle resolved photoemission data for the multilayered sample n = 3 showed that the emission profile has a metallic-like momentum dispersion. Deviations from theoretical predictions [K. Németh et al., PRL 104, 046801 (2010)] are attributed to imperfections of real surfaces in contrast with the ideal surfaces of the calculation.