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:

Yamaguchi, Hisato ^[1]; Liu, Fangze  ^[1];

• Search DOE PAGES for author "Liu, Fangze"
• Search DOE PAGES for ORCID "0000-0003-3114-5280"

DeFazio, Jeffrey ^[2]; Narvaez Villarrubia, Claudia W. ^[1]; Finkenstadt, Daniel ^[3]; Shabaev, Andrew ^[4]; Jensen, Kevin L. ^[4]; Pavlenko, Vitaly  ^[1];

• Search DOE PAGES for author "Pavlenko, Vitaly"
• Search DOE PAGES for ORCID "0000-0001-8550-9209"

Mehl, Michael ^[5]; Lambrakos, Sam ^[4]; Gupta, Gautam ^[6]; Mohite, Aditya D.  ^[1];

• Search DOE PAGES for author "Mohite, Aditya D."
• Search DOE PAGES for ORCID "0000-0001-8865-409X"

Moody, Nathan A.  ^[1]

• Search DOE PAGES for author "Moody, Nathan A."
• Search DOE PAGES for ORCID "0000-0001-6568-7841"

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+ Show Author Affiliations

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:

Thu Jun 01 00:00:00 EDT 2017

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:

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