Molybdenum Monocrystalline Material for Ultraviolet Plasmonics

ABSTRACT Ultraviolet (UV) plasmonics has great potential in the applications of nano‐optoelectronic devices, food safety, and medical diagnosis. However, the reliable fabrication of high‐quality UV plasmonic materials remains a challenge. The commonly used UV plasmonic materials, such as Al and Pd, suffer from their poor morphological stability, surface roughness, and crystalline quality. In this study, we demonstrate a millimeter‐scale ultrasmooth molybdenum (Mo) monocrystal with a root‐mean‐square roughness of 0.282 nm, prepared via thermal evaporation deposition, exhibiting exceptional UV plasmonic performance. The growth mechanism of the Mo monocrystalline film is revealed using molecular dynamics methods. Additionally, highly repeatable plasmonic nanostructures are fabricated via focused ion beam milling and hole‐mask colloidal lithography. Such structures exhibit surface plasmon polariton (SPP) and localized surface plasmon resonance (LSPR) properties in the UV range. At the Mo‐air interface, the ratio of SPP propagation length to the decay length in dielectric materials reaches 12.74, and the field enhancement of LSPR has been shown to reach 102 times. The developed Mo monocrystalline material therefore exhibits promising plasmonic characteristics in the UV band, which together with its high melting point, strong structural stability, and excellent thermal conductivity, makes it promising for constructing UV plasmonic devices.