Direct Writing of Nanostructured Metasurfaces by Hot-Electron-Driven Laser Sintering.

The precise fabrication of nanoscale metallic structures is pivotal to enabling progress in plasmonics, nanophotonics, and nanoelectronics. In this work, we introduce a high-resolution laser-sintering strategy for facile direct writing of plasmonic metasurfaces, avoiding the need for photolithography or ultrafast laser processing. This method exploits thermally assisted hot-electron-driven desorption and diffusion of aliphatic ligands to facilitate highly localized laser sintering of metal nanocrystals with subdiffraction-limited resolution down to ∼λ/5. A range of functional metasurface nanostructures are demonstrated. A finite-temperature quantum-mechanical model is proposed to predict the superlinear dependence of the ligand desorption rate on laser fluence. This hot-electron-driven sintering method proceeds without inducing the undesired degradation of the ligands, enabling sintering with properties comparable to those of bulk metals. The technique offers promise for the fabrication of polarization-sensitive, wavelength-tunable optical metasurfaces and presents a solution for rapid prototyping of nanodevices.