Enhancing quantum efficiency of ultraviolet photocathodes using surface plasmon nanostructures

Ultraviolet (UV) photocathodes are indispensable for solar-blind detection in industrial monitoring, astronomy, and biomedical applications. However, the quantum efficiency (QE) of traditional alkali-metal telluride cathodes, such as cesium telluride (Cs2Te), remains constrained by the inherent trade-off between photon absorption depth and electron escape probability. To address this challenge, we introduce plasmonic nanostructures into Cs2Te photocathodes and systematically investigate their effects using finite-difference time-domain simulations. We compare nanoparticle arrays and nanograting structures with a planar reference. The results show that both plasmonic designs significantly enhance UV absorption and local field intensity, while nanogratings yield superior performance in the short-wavelength region. Moreover, the research finds a 38% increase in QE for the nanograting structure compared to the planar structure. These findings establish a theoretical basis for plasmon-assisted UV photocathode design and provide new insights into the development of high-efficiency solar-blind photodetectors.