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Photoemission from Bialkali Photocathodes through an Atomically Thin Protection Layer
Fangze Liu1,2, Lei Guo3, Jeffrey DeFazio4
1Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, United States.
ACS Applied Materials & Interfaces
|December 22, 2021
Summary
Graphene encapsulation enhances the lifetime of alkali antimonide photocathodes. This protection allows for high quantum efficiency (QE) while maintaining performance, paving the way for more durable photodetectors and electron sources.
Area of Science:
- Materials Science
- Surface Science
- Quantum Electronics
Background:
- Alkali antimonide photocathodes offer high quantum efficiency (QE) but suffer from limited lifetimes due to reactivity and ion bombardment.
- Extending photocathode operational life is crucial for applications like photodetectors and free-electron lasers.
Purpose of the Study:
- To investigate graphene as a protective layer for enhancing the lifetime of bialkali photocathodes.
- To assess the impact of graphene encapsulation on photocathode quantum efficiency and photoelectron transmission.
Main Methods:
- Growing high-quality bialkali antimonide on suspended few-layer graphene substrates.
- Measuring photoemission properties and quantum efficiency through varying layers of graphene.
Main Results:
- Successful growth of bialkali antimonide on two-layer (2L) graphene with a peak QE of 15%.
- Demonstrated photoelectron transmission through 2L graphene with a QE of over 0.7% (5% transmission efficiency at 4.5 eV).
Conclusions:
- Atomically thin graphene layers can effectively protect photocathodes from degradation.
- Graphene encapsulation offers a viable strategy for creating robust bialkali photocathodes with both high QE and extended lifetimes.
