Tailoring the emissive properties of photocathodes through materials engineering: Ultra-thin multilayers
| Autor: | Rachel Seibert, Jeff Terry, Daniel Olive, Linda Spentzouris, Hasitha Ganegoda, Daniel Velazquez, Zikri Yusof, Kevin Logan, Amy Rice |
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| Rok vydání: | 2016 |
| Předmět: |
Free electron model
Reflection high-energy electron diffraction Materials science 010308 nuclear & particles physics business.industry General Physics and Astronomy Surfaces and Interfaces General Chemistry Condensed Matter Physics Laser 01 natural sciences Cathode Photocathode Surfaces Coatings and Films law.invention Pulsed laser deposition Optics law 0103 physical sciences Optoelectronics Quantum efficiency Work function 010306 general physics business |
| Zdroj: | Applied Surface Science. 360:762-766 |
| ISSN: | 0169-4332 |
| Popis: | We report on an experimental verification that emission properties of photocathodes can be manipulated through the engineering of the surface electronic structure. Ultrathin multilayered MgO/Ag(0 0 1)/MgO films were grown by pulsed laser deposition, tuning the thickness n of the flanking MgO layers to 0, 2, 3, and 4 monolayers. We observed an increase in quantum efficiency and simultaneous decrease in work function with layer thickness. The scale and trend direction of measurements are in good but not excellent agreement with theory. Angle resolved photoemission data for the multilayered sample n = 3 showed that the emission profile has a metallic-like momentum dispersion. Deviations from theoretical predictions [K. Nemeth et al., PRL 104, 046801 (2010)] are attributed to imperfections of real surfaces in contrast with the ideal surfaces of the calculation. Photoemissive properties of cathodes are critical for electron beam applications such as photoinjectors for Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). An ideal photoemitter has a high quantum efficiency, low work function, low intrinsic emittance and long lifetime. It has been demonstrated here that emission properties may be systematically tailored by control of layer thickness in ultrathin multilayered structures. The reproducibility of the emission parameters under specific growth conditions is excellent, even though the interfaces themselves have varying degrees of roughness. |
| Databáze: | OpenAIRE |
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