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This content will become publicly available on April 3, 2019

Title: Free-Standing Bialkali Photocathodes Using Atomically Thin Substrates

This study reports successful deposition of high quantum efficiency (QE) bialkali antimonide K 2CsSb photocathodes on graphene films. The results pave the way for an ultimate goal of encapsulating technologically relevant photocathodes for accelerator technology with an atomically thin protecting layer to enhance lifetime while minimizing QE losses. A QE of 17% at ≈3.1 eV (405 nm) is the highest value reported so far on graphene substrates and is comparable to that obtained on stainless steel and nickel reference substrates. The spectral responses of the photocathodes on graphene exhibit signature features of K 2CsSb including the characteristic absorption at ≈2.5 eV. Materials characterization based on X-ray fluorescence and X-ray diffraction reveals that the composition and crystal quality of these photocathodes deposited on graphene is comparable to those deposited on a reference substrate. Quantitative agreement between optical calculations and QE measurements for the K 2CsSb on free suspended graphene and a graphene-coated metal substrate further confirms the high-quality interface between the photocathodes and graphene. In conclusion, a correlation between the QE and graphene quality as characterized by Raman spectroscopy suggests that a lower density of atomistic defects in the graphene films leads to higher QE of the deposited K 2CsSb photocathodes.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [3] ;  [5] ;  [6] ;  [7] ;  [3] ;  [1] ;  [6]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Photonis USA Pennsylvania Inc., Lancaster, PA (United States)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
  4. Argonne National Lab. (ANL), Argonne, IL (United States)
  5. Max Planck Inst. for Physics, Munich (Germany)
  6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States
  7. Naval Research Lab. (NRL), Washington, DC (United States). Materials Science and Technology Division
Publication Date:
Report Number(s):
BNL-207987-2018-JAAM
Journal ID: ISSN 2196-7350
Grant/Contract Number:
SC0012704; AC02-06CH11357; AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Advanced Materials Interfaces
Additional Journal Information:
Journal Volume: 5; Journal Issue: 13; Journal ID: ISSN 2196-7350
Publisher:
Wiley-VCH
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 36 MATERIALS SCIENCE; accelerator technology; antimonide photocathodes; bialkali; gas barrier; graphene
OSTI Identifier:
1466595
Alternate Identifier(s):
OSTI ID: 1431140