Morphologies and optical properties of black silicon by room temperature reactive ion etching

Abstract Black Silicon (BS) nanostructures fabricated by Reactive Ion Etching at Room Temperature (RT-RIE) are presented. We discuss the influence of the plasma process parameters on the silicon etching and their influence on the shape of the nanostructures constituting the BS. Furthermore, we study - both experimentally and using modeling by finite difference time domain (FDTD) method – how to increase absorptance in the visible and NIR regions using light trapping effect based on a fine control of the BS morphology. Absorptance higher than 99 % is reached with a strong angular acceptance. This paper proposes an optimized process to fabricate high aspect ratio and high absorptance BS using a room temperature process.