Photoemission characterization of N-polar III-nitride photocathodes as candidate bright electron beam sources for accelerator applications

L. Cultrera, E. Rocco, F. Shahedipour-Sandvik, L. D. Bell, J. K. Bae, I. V. Bazarov, P. Saha, S. Karkare, A. Arjunan

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish (US)
Article number124902
JournalJournal of Applied Physics
Volume131
Issue number12
DOIs
StatePublished - Mar 28 2022

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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