Wideband ‘black silicon’ for mid-infrared applications

In this paper, we investigate the absorption of mid-infrared light by low resistivity silicon textured via deep reactive ion etching. An analytical description of the wave propagation in black silicon texture is presented, showing agreement with the experiment and the computational analysis. We also study the dependence of absorption spectrum of black silicon structure on the electrical conductivity of silicon substrate. The structures investigated unveil wideband, all-silicon infrared absorbers applicable for infrared imaging and spectroscopy with simple CMOS compatible fabrication suitable for optoelectronic integration.