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

## TL;DR

A new laser sintering method enables precise fabrication of nanoscale metasurfaces without complex lithography.

## Contribution

A high-resolution laser-sintering strategy for direct writing of plasmonic metasurfaces is introduced.

## Key findings

- The method uses hot-electron-driven desorption and diffusion for subdiffraction-limited sintering of metal nanocrystals.
- A finite-temperature quantum-mechanical model predicts ligand desorption rates based on laser fluence.
- The technique enables fabrication of polarization-sensitive and wavelength-tunable optical metasurfaces.

## Abstract

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.