Laser direct writing of nanoreliefs in Sn nanofilms

High-resolution $(\sim 200\mathrm{nm})$ nanoreliefs, which possess a controllable height change ($\Delta h$, up to film thickness) and transmittance or reflectance, have been successfully fabricated in $12\text{-}\mathrm{nm}$-thick Sn films by using $532\mathrm{nm}$ pulsed laser direct writing. Different from current micro/nanofabrication techniques, the height change of the nanoreliefs is generated by a laser-induced-thickening process. The majority of the height change comes from a balling and coarsening effect rather than oxidation of grains. Because both optical density and $\Delta h$ of the nanoreliefs are almost linear to laser power, the optical images can highly resemble the topographic images. This technique is useful for fabricating complicated nanorelief structures and fine images.