Simple fabrication of ultrahigh aspect ratio nanostructures for enhanced antireflectivity

In this work, the authors present a novel fabrication process to create periodic nanostructures with aspect ratio as high as 9.6. These nanostructures reduce spectral reflectance of silicon to less than 4% over the broad wavelength region from 200 to 2000 nm. At the visible range of the spectrum, from 200 to 650 nm, reflectivity is reduced to less than 0.1%. The aspect ratio and reflectance performance that the authors achieved have never been reported before for ordered tapered nanostructures, to our knowledge.