Photoemission characterization of N-polar III-nitride photocathodes as candidate bright electron beam sources for accelerator applications
Abstract
We report on the growth and characterization of a new class of photocathode structures for use as electron sources to produce high brightness electron beams for accelerator applications. The sources are realized using III-nitride materials and are designed to leverage the strong polarization field, which is characteristic of this class of materials when grown in their wurtzite crystal structure, to produce a negative electron affinity condition without the use of Cs, possibly allowing these materials to be operated in radio frequency guns. A Quantum Efficiency (QE) of about 1 × 10 - 3 and an emitted electrons' Mean Transverse Energy (MTE) of about 100 meV are measured at a wavelength of 265 nm. In a vacuum level of 3 × 10 - 10 Torr, the QE does not decrease after more than 24 h of continuous operation. The lowest MTE of about 50 meV is measured at 300 nm along with a QE of 1.5 × 10 - 5. Surface characterizations reveal a possible contribution to the MTE from surface morphology, calling for more detailed studies.
- Publication:
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Journal of Applied Physics
- Pub Date:
- March 2022
- DOI:
- 10.1063/5.0076488
- arXiv:
- arXiv:2110.01533
- Bibcode:
- 2022JAP...131l4902C
- Keywords:
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- Physics - Accelerator Physics;
- Physics - Applied Physics
- E-Print:
- will be submitted to Journal of Applied Physics