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Title: Active bialkali photocathodes on free-standing graphene substrates

Abstract

Here, the hexagonal structure of graphene gives rise to the property of gas impermeability, motivating its investigation for a new application: protection of semiconductor photocathodes in electron accelerators. These materials are extremely susceptible to degradation in efficiency through multiple mechanisms related to contamination from the local imperfect vacuum environment of the host photoinjector. Few-layer graphene has been predicted to permit a modified photoemission response of protected photocathode surfaces, and recent experiments of single-layer graphene on copper have begun to confirm these predictions for single crystal metallic photocathodes. Unlike metallic photoemitters, the integration of an ultra-thin graphene barrier film with conventional semiconductor photocathode growth processes is not straightforward. A first step toward addressing this challenge is the growth and characterization of technologically relevant, high quantum efficiency bialkali photocathodes on ultra-thin free-standing graphene substrates. Photocathode growth on free-standing graphene provides the opportunity to integrate these two materials and study their interaction. Specifically, spectral response features and photoemission stability of cathodes grown on graphene substrates are compared to those deposited on established substrates. In addition, we observed an increase of work function for the graphene encapsulated bialkali photocathode surfaces, which is predicted by our calculations. The results provide a unique demonstration of bialkalimore » photocathodes on free-standing substrates, and indicate promise towards our goal of fabricating high-performance graphene encapsulated photocathodes with enhanced lifetime for accelerator applications.« less

Authors:
 [1]; ORCiD logo [1];  [2];  [1];  [3];  [4];  [4]; ORCiD logo [1];  [5];  [4];  [6]; ORCiD logo [1]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. PHOTONIS USA Pennsylvania Inc., Lancaster, PA (United States)
  3. U.S. Naval Academy, Annapolis, MD (United States)
  4. Naval Research Lab., Washington, D.C. (United States)
  5. Naval Research Lab., Washington, D.C. (United States); U.S. Naval Academy, Annapolis, MD (United States)
  6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Louisville, Louisville, KY (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1372802
Report Number(s):
LA-UR-17-25087
Journal ID: ISSN 2397-7132
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
npj 2D Materials and Applications
Additional Journal Information:
Journal Volume: 1; Journal Issue: 1; Journal ID: ISSN 2397-7132
Publisher:
Springer Nature
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; material science; design, synthesis and processing; mechanical and structural properties and devices

Citation Formats

Yamaguchi, Hisato, Liu, Fangze, DeFazio, Jeffrey, Narvaez Villarrubia, Claudia W., Finkenstadt, Daniel, Shabaev, Andrew, Jensen, Kevin L., Pavlenko, Vitaly, Mehl, Michael, Lambrakos, Sam, Gupta, Gautam, Mohite, Aditya D., and Moody, Nathan A. Active bialkali photocathodes on free-standing graphene substrates. United States: N. p., 2017. Web. doi:10.1038/s41699-017-0014-6.
Yamaguchi, Hisato, Liu, Fangze, DeFazio, Jeffrey, Narvaez Villarrubia, Claudia W., Finkenstadt, Daniel, Shabaev, Andrew, Jensen, Kevin L., Pavlenko, Vitaly, Mehl, Michael, Lambrakos, Sam, Gupta, Gautam, Mohite, Aditya D., & Moody, Nathan A. Active bialkali photocathodes on free-standing graphene substrates. United States. doi:10.1038/s41699-017-0014-6.
Yamaguchi, Hisato, Liu, Fangze, DeFazio, Jeffrey, Narvaez Villarrubia, Claudia W., Finkenstadt, Daniel, Shabaev, Andrew, Jensen, Kevin L., Pavlenko, Vitaly, Mehl, Michael, Lambrakos, Sam, Gupta, Gautam, Mohite, Aditya D., and Moody, Nathan A. Thu . "Active bialkali photocathodes on free-standing graphene substrates". United States. doi:10.1038/s41699-017-0014-6. https://www.osti.gov/servlets/purl/1372802.
@article{osti_1372802,
title = {Active bialkali photocathodes on free-standing graphene substrates},
author = {Yamaguchi, Hisato and Liu, Fangze and DeFazio, Jeffrey and Narvaez Villarrubia, Claudia W. and Finkenstadt, Daniel and Shabaev, Andrew and Jensen, Kevin L. and Pavlenko, Vitaly and Mehl, Michael and Lambrakos, Sam and Gupta, Gautam and Mohite, Aditya D. and Moody, Nathan A.},
abstractNote = {Here, the hexagonal structure of graphene gives rise to the property of gas impermeability, motivating its investigation for a new application: protection of semiconductor photocathodes in electron accelerators. These materials are extremely susceptible to degradation in efficiency through multiple mechanisms related to contamination from the local imperfect vacuum environment of the host photoinjector. Few-layer graphene has been predicted to permit a modified photoemission response of protected photocathode surfaces, and recent experiments of single-layer graphene on copper have begun to confirm these predictions for single crystal metallic photocathodes. Unlike metallic photoemitters, the integration of an ultra-thin graphene barrier film with conventional semiconductor photocathode growth processes is not straightforward. A first step toward addressing this challenge is the growth and characterization of technologically relevant, high quantum efficiency bialkali photocathodes on ultra-thin free-standing graphene substrates. Photocathode growth on free-standing graphene provides the opportunity to integrate these two materials and study their interaction. Specifically, spectral response features and photoemission stability of cathodes grown on graphene substrates are compared to those deposited on established substrates. In addition, we observed an increase of work function for the graphene encapsulated bialkali photocathode surfaces, which is predicted by our calculations. The results provide a unique demonstration of bialkali photocathodes on free-standing substrates, and indicate promise towards our goal of fabricating high-performance graphene encapsulated photocathodes with enhanced lifetime for accelerator applications.},
doi = {10.1038/s41699-017-0014-6},
journal = {npj 2D Materials and Applications},
number = 1,
volume = 1,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}

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