An Ultraviolet Plasmon-Enhanced Molybdenum Nanocone Field-Emission Array Cold-Cathode Electron Source

Abstract

Ultraviolet (UV) plasmon-enhanced field emission offers a route toward dynamically tunable cold-cathode electron sources operating under low-light-intensity excitation. However, cathode materials and structures that simultaneously exhibit outstanding UV plasmonic and high field-emission performance still require further development. In this study, a Mo nanocone array cold cathode is proposed and fabricated for photoelectric co-excited electron emission with UV plasmonic enhancement. The Mo nanocone array supports localized surface plasmon resonance (LSPR) in the UV region, and the high-energy electrons generated by the resonance, together with the localized near-field effect, synergistically enhance cold-cathode electron emission. Surface-enhanced Raman scattering (SERS) measurements demonstrate that the array exhibits the strongest enhancement under 325 nm excitation, supporting the wavelength-dependent optical response of the Mo nanocone array associated with its UV-LSPR characteristics. Under photoelectric co-excitation at a low light intensity on the order of W cm–2, the Mo nanocone array cold cathode achieves emission current and brightness increases of 314.2% and 300% relative to pure electric field excitation, respectively. Meanwhile, the effective work function decreases by 0.23 eV. The wavelength-dependent electron emission current agrees with the photocurrent contribution from plasmon decay-generated carriers, supporting that the enhanced electron emission originates from the designed UV plasmonic resonance. Furthermore, deep-UV plasmon-enhanced Mo nanocone arrays targeting shorter wavelengths (266 and 160 nm) are designed. This study provides a viable strategy toward developing UV plasmon-enhanced cold-cathode electron sources with tailorable emission characteristics, which presents potential for application in short-wavelength vacuum micro/nanoelectronic devices.