Black silicon with sub-percent reflectivity: Influence of the 3D texturization geometry

In this paper we study the impact of the three-dimensional geometry of a micro/nanostructured silicon surface on its reflectivity under incident electromagnetic (EM) illumination. We simulate the optical reflectance of 3D micro/nano silicon cones of different dimensions. Based on the favorable simulation results, maskless textured silicon, called “black silicon” is processed by deep reactive ion etching (DRIE) under cryogenic temperatures. By varying the process parameters, we fabricate conical black silicon substrates with excellent anti-reflective behavior. Notable among the results, one of the samples exhibits the lowest reflectivity in the optical wavelength published to date for plasma-etched black-silicon.