Nano-Cold-Cathode\nElectron Source Based on Plasmon-Mediated\nEmission

To address the developmental requisites of the emerging\ngeneration\nof vacuum micro- and nanoelectronic devices, cathode electron sources\nare evolving toward enhanced efficiency, heightened brightness, diminished\nenergy consumption, and enhanced tunability. The pursuit of nano-cold-cathodes\nwith plasmon-enhanced properties emerges as a potent strategy to realize\nthese objectives. In this study, we propose a novel large-current,\nhigh-brightness needle-like nano-cold-cathode electron source designed\nwith photoelectric synergistic excitation. This cathode is constructed\nusing a composite material comprising plasmonic gold (Au) nanoparticles\nand a high-melting-point metal tungsten (W) needle. The resulting\nAu-on-W needle nano-cold-cathode demonstrates outstanding electron\nemission characteristics: under the synergistic excitation of an electrostatic\nfield below ∼0.35 V μm<sup>–1</sup> and an average\nlaser intensity of ∼10 W cm<sup>–2</sup>, the source\nachieved an emission current surpassing 830 nA and a reduced brightness\nof ∼1.1 × 10<sup>10</sup> A m<sup>–2</sup> sr<sup>–1</sup> V<sup>–1</sup>. This performance marks a remarkable\nenhancement, improving by one and 2 orders of magnitude when compared\nto W needle nano-cold-cathodes and commercial Schottky point electron\nsource cathodes, respectively, thus underscoring its significant superiorities.\nIn this photoelectric synergistic excitation mode, the Au-on-W cathode\ndemonstrates tunable electron emission characteristics in response\nto the intrinsic properties of the incident laser, including frequency,\namplitude, and polarization. These features can be achieved through\nthe direct modulation of the structural features of the Au-on-W nano-cold-cathodes.\nThis research endeavors to establish the groundwork for the development\nof a new class of tunable high-performance cathode electron source\ndevices.