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Title: Comparison of CsBr and KBr coated Cu photocathodes. Effects of laser irradiation and work function changes

Abstract

Thin films (7 nm layers) of CsBr and KBr were deposited on Cu(100) to investigate photoemission properties of these potential photocathode materials. After thin film deposition and prolonged laser ultraviolet (UV) irradiation (266 nm picosecond laser) photoemission quantum efficiency increases by factors of 26 and 77 for KBr/Cu(100) and CsBr/Cu(100) photocathodes, respectively. Immediately following thin film deposition, a decrease in work function is observed, compared to bare Cu, in both cases. Quantum efficiency enhancements are attributed to the decrease in photocathode work function, due to the deposition of alkali halide thin films, and photo-induced processes, that introduce defect states into the alkali halide bandgap, induced by UV laser irradiation. It is possible that alkali metal formation occurs during UV irradiation and that this further contributes to photoemission enhancement. Our results suggest that KBr, a relatively stable alkali-halide, has potential for photocathode applications.

Authors:
 [1];  [1];  [1];  [1];  [1];  [2];  [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Stanford Univ., CA (United States)
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1072853
Report Number(s):
PNNL-SA-92864
Journal ID: ISSN 0003-6951; 47670
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 102; Journal Issue: 7; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; Environmental Molecular Sciences Laboratory

Citation Formats

He, Weidong, VilayurGanapathy, Subramanian, Joly, Alan G., Droubay, Timothy C., Chambers, Scott A., Maldonado, Juan R., and Hess, Wayne P. Comparison of CsBr and KBr coated Cu photocathodes. Effects of laser irradiation and work function changes. United States: N. p., 2013. Web. doi:10.1063/1.4793214.
He, Weidong, VilayurGanapathy, Subramanian, Joly, Alan G., Droubay, Timothy C., Chambers, Scott A., Maldonado, Juan R., & Hess, Wayne P. Comparison of CsBr and KBr coated Cu photocathodes. Effects of laser irradiation and work function changes. United States. https://doi.org/10.1063/1.4793214
He, Weidong, VilayurGanapathy, Subramanian, Joly, Alan G., Droubay, Timothy C., Chambers, Scott A., Maldonado, Juan R., and Hess, Wayne P. 2013. "Comparison of CsBr and KBr coated Cu photocathodes. Effects of laser irradiation and work function changes". United States. https://doi.org/10.1063/1.4793214.
@article{osti_1072853,
title = {Comparison of CsBr and KBr coated Cu photocathodes. Effects of laser irradiation and work function changes},
author = {He, Weidong and VilayurGanapathy, Subramanian and Joly, Alan G. and Droubay, Timothy C. and Chambers, Scott A. and Maldonado, Juan R. and Hess, Wayne P.},
abstractNote = {Thin films (7 nm layers) of CsBr and KBr were deposited on Cu(100) to investigate photoemission properties of these potential photocathode materials. After thin film deposition and prolonged laser ultraviolet (UV) irradiation (266 nm picosecond laser) photoemission quantum efficiency increases by factors of 26 and 77 for KBr/Cu(100) and CsBr/Cu(100) photocathodes, respectively. Immediately following thin film deposition, a decrease in work function is observed, compared to bare Cu, in both cases. Quantum efficiency enhancements are attributed to the decrease in photocathode work function, due to the deposition of alkali halide thin films, and photo-induced processes, that introduce defect states into the alkali halide bandgap, induced by UV laser irradiation. It is possible that alkali metal formation occurs during UV irradiation and that this further contributes to photoemission enhancement. Our results suggest that KBr, a relatively stable alkali-halide, has potential for photocathode applications.},
doi = {10.1063/1.4793214},
url = {https://www.osti.gov/biblio/1072853}, journal = {Applied Physics Letters},
issn = {0003-6951},
number = 7,
volume = 102,
place = {United States},
year = {Wed Feb 20 00:00:00 EST 2013},
month = {Wed Feb 20 00:00:00 EST 2013}
}