ABSTRACT
This chapter deals with approach which might be considered as being closely related to gradient index systems: silicon antireflection structures (SiARS) or black silicon. Silicon is mankind's most important and viable semiconductor, not only enabling powerful analog and digital electronics, but also cost-efficient optoelectronic light sources and sensors. The classical approach toward reflection suppression is to make use of antireflection coatings (ARC). In the simplest case, a good antireflection (AR) effect can be accomplished with a single-layer AR coating (SLAC), represented by a thin film of transparent material on top of the silicon, whose refractive index is between the indices of the incident medium and silicon. Metal-assisted chemical etching (MACE) is a comparably simple and cost-efficient method for black silicon fabrication and has thus attracted much attention lately, especially in the photovoltaic community. The possibility to create black silicon by repeated irradiation with short laser pulses is known since the 1980s, when first reliable, high-power laser systems became available.
