Rugged bialkali photocathodes encapsulated with graphene and thin metal film
Abstract Protection of free-electron sources has been technically challenging due to lack of materials that transmit electrons while preventing corrosive gas molecules. Two-dimensional materials uniquely possess both of required properties. Here, we report three orders of magnitude increase in activ...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2023-02-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-023-29374-6 |
| _version_ | 1827984551971913728 |
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| author | Lei Guo Fangze Liu Kazuki Koyama Nolan Regis Anna M. Alexander Gaoxue Wang Jeffrey DeFazio James A. Valdez Anju Poudel Masahiro Yamamoto Nathan A. Moody Yoshifumi Takashima Hisato Yamaguchi |
| author_facet | Lei Guo Fangze Liu Kazuki Koyama Nolan Regis Anna M. Alexander Gaoxue Wang Jeffrey DeFazio James A. Valdez Anju Poudel Masahiro Yamamoto Nathan A. Moody Yoshifumi Takashima Hisato Yamaguchi |
| author_sort | Lei Guo |
| collection | DOAJ |
| description | Abstract Protection of free-electron sources has been technically challenging due to lack of materials that transmit electrons while preventing corrosive gas molecules. Two-dimensional materials uniquely possess both of required properties. Here, we report three orders of magnitude increase in active pressure and factor of two enhancement in the lifetime of high quantum efficiency (QE) bialkali photocathodes (cesium potassium antimonide (CsK2Sb)) by encapsulating them in graphene and thin nickel (Ni) film. The photoelectrons were extracted through the graphene protection layer in a reflection mode, and we achieved QE of ~ 0.17% at ~ 3.4 eV, 1/e lifetime of 188 h with average current of 8.6 nA under continuous illumination, and no decrease of QE at the pressure of as high as ~ 1 × 10–3 Pa. In comparison, the QE decreased drastically at 10–6 Pa for bare, non-protected CsK2Sb photocathodes and their 1/e lifetime under continuous illumination was ~ 48 h. We attributed the improvements to the gas impermeability and photoelectron transparency of graphene. |
| first_indexed | 2024-04-09T23:01:34Z |
| format | Article |
| id | doaj.art-3e1a2ba13f36467b81373faa1bb2e707 |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-04-09T23:01:34Z |
| publishDate | 2023-02-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-3e1a2ba13f36467b81373faa1bb2e7072023-03-22T10:55:48ZengNature PortfolioScientific Reports2045-23222023-02-011311910.1038/s41598-023-29374-6Rugged bialkali photocathodes encapsulated with graphene and thin metal filmLei Guo0Fangze Liu1Kazuki Koyama2Nolan Regis3Anna M. Alexander4Gaoxue Wang5Jeffrey DeFazio6James A. Valdez7Anju Poudel8Masahiro Yamamoto9Nathan A. Moody10Yoshifumi Takashima11Hisato Yamaguchi12Nagoya University Synchrotron Radiation Research Center (NUSR)Advanced Research Institute of Multidisciplinary Sciences, Beijing Institute of TechnologySchool of Engineering/Graduate School of Engineering, Nagoya UniversityLos Alamos National Laboratory (LANL)Los Alamos National Laboratory (LANL)Los Alamos National Laboratory (LANL)Photonis Defense Inc.Los Alamos National Laboratory (LANL)Los Alamos National Laboratory (LANL)Innovation Center for Applied Superconducting Accelerators, High Energy Accelerator Research Organization (KEK)Los Alamos National Laboratory (LANL)Nagoya University Synchrotron Radiation Research Center (NUSR)Los Alamos National Laboratory (LANL)Abstract Protection of free-electron sources has been technically challenging due to lack of materials that transmit electrons while preventing corrosive gas molecules. Two-dimensional materials uniquely possess both of required properties. Here, we report three orders of magnitude increase in active pressure and factor of two enhancement in the lifetime of high quantum efficiency (QE) bialkali photocathodes (cesium potassium antimonide (CsK2Sb)) by encapsulating them in graphene and thin nickel (Ni) film. The photoelectrons were extracted through the graphene protection layer in a reflection mode, and we achieved QE of ~ 0.17% at ~ 3.4 eV, 1/e lifetime of 188 h with average current of 8.6 nA under continuous illumination, and no decrease of QE at the pressure of as high as ~ 1 × 10–3 Pa. In comparison, the QE decreased drastically at 10–6 Pa for bare, non-protected CsK2Sb photocathodes and their 1/e lifetime under continuous illumination was ~ 48 h. We attributed the improvements to the gas impermeability and photoelectron transparency of graphene.https://doi.org/10.1038/s41598-023-29374-6 |
| spellingShingle | Lei Guo Fangze Liu Kazuki Koyama Nolan Regis Anna M. Alexander Gaoxue Wang Jeffrey DeFazio James A. Valdez Anju Poudel Masahiro Yamamoto Nathan A. Moody Yoshifumi Takashima Hisato Yamaguchi Rugged bialkali photocathodes encapsulated with graphene and thin metal film Scientific Reports |
| title | Rugged bialkali photocathodes encapsulated with graphene and thin metal film |
| title_full | Rugged bialkali photocathodes encapsulated with graphene and thin metal film |
| title_fullStr | Rugged bialkali photocathodes encapsulated with graphene and thin metal film |
| title_full_unstemmed | Rugged bialkali photocathodes encapsulated with graphene and thin metal film |
| title_short | Rugged bialkali photocathodes encapsulated with graphene and thin metal film |
| title_sort | rugged bialkali photocathodes encapsulated with graphene and thin metal film |
| url | https://doi.org/10.1038/s41598-023-29374-6 |
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