Enhanced quantum efficiency from optical interference in alkali antimonide photocathodes: Modeling and experimental results
Abstract
We present measurements of enhanced quantum efficiency (QE) in thin film alkali antimonide photocathodes from optical interference in the cathode-substrate multilayer. Modulations in the spectral response are observed over a range of visible wavelengths and are shown to increase the QE by more than a factor of two at specific wavelengths. We present a model describing the QE modulations based on the three step photoemission process incorporating cases of both constant density of states and density functional theory-derived density of states and show that the calculated results are in good agreement with the measurements. Model predictions demonstrate that QE can be enhanced by more than a factor of 5 by optimization of cathode and substrate layer thicknesses. Additionally, these calculations reveal that optical interference can yield higher quantum efficiencies in thin films compared to thick, optically dense films. We model the QE vs excitation wavelength of multiple alkali antimonide compounds at different thicknesses. We then discuss the advantages of this interference effect for electron accelerators.
Article Details
Journal Info
Journal of Applied Physics
American Institute of Physics
Authors (15)
C. Pennington
Cornell Laboratory for Accelerator-based Sciences and Education 1 , Ithaca, New York 14853,
E. Echeverria
Cornell Laboratory for Accelerator-based Sciences and Education 1 , Ithaca, New York 14853,
A. Flint
Cornell Laboratory for Accelerator-based Sciences and Education 1 , Ithaca, New York 14853,
N. Gonzalez
Cornell Laboratory for Accelerator-based Sciences and Education 1 , Ithaca, New York 14853,
T. Wu
T. Arias
Cornell Laboratory for Accelerator-based Sciences and Education 1 , Ithaca, New York 14853,
K. P. Mondal
Brookhaven National Laboratory 3 , Upton, New York 11973,
K. Evans-Lutterodt
Brookhaven National Laboratory 3 , Upton, New York 11973,
M. Gaowei
Brookhaven National Laboratory 3 , Upton, New York 11973,
J. Smedley
SLAC National Accelerator Laboratory 4 , Menlo Park, California 94025,
P. Bhattacharyya
Arizona State University 5 , Tempe, Arizona 85004,
S. Karkare
Arizona State University 5 , Tempe, Arizona 85004,
A. Galdi
Department of Industrial Engineering, University of Salerno 6 , 84084 Fisciano, SA,
A. Bartnik
Cornell Laboratory for Accelerator-based Sciences and Education 1 , Ithaca, New York 14853,
J. Maxson
Cornell Laboratory for Accelerator-based Sciences and Education 1 , Ithaca, New York 14853,