Soft lithography allows for the simple and low-cost fabrication of nanopatterns with different\nshapes and sizes over large areas. However, the resolution and the aspect ratio of the nanostructures\nfabricated by soft lithography are limited by the depth and the physical properties of the stamp.\nIn this work, silicon nanobelts and nanostructures were achieved by combining soft nanolithography\npatterning with optimized reactive ion etching (RIE) in silicon. Using polymethylmethacrylate (PMMA)\nnanopatterned layers with thicknesses ranging between 14 and 50 nm, we obtained silicon nanobelts\nin areas of square centimeters with aspect ratios up to ~1.6 and linewidths of 225 nm. The soft\nlithographic process was assisted by a thin film of SiOx (less than 15 nm) used as a hard mask and\nRIE. This simple patterning method was also used to fabricate 2D nanostructures (nanopillars) with\naspect ratios of ~2.7 and diameters of ~200 nm. We demonstrate that large areas patterned with\nsilicon nanobelts exhibit a high reflectivity peak in the ultraviolet C (UVC) spectral region (280 nm)\nwhere some aminoacids and peptides have a strong absorption. We also demonstrated how to tailor\nthe aspect ratio and the wettability of these photonic surfaces (contact angles ranging from 8.1 to\n96.2ââ??¦) by changing the RIE power applied during the fabrication process.
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