Antireflective nanostructures fabricated by reactive ion etching method on pyramid-structured silicon surface

In this paper, pyramid-structured silicon wafers were etched in a reactive ion etching system at room temperature and without any negative voltage pulses to obtain antireflective nanostructures. The effects of the etching time, etching power and the flow ratio of the SF6 and O2 (FSF6/FO2) on the morphologies and reflective properties of the etched samples were studied. Scanning electron microscope was used to investigate the morphologies of etched samples. The surface reflectance measurements were carried out using UV–vis-NIR spectrophotometer. A reflectance of 4.72% from the etched surface in the wavelength range of 400–800 nm was obtained under etching time of 20 min, etching power of 150 W and FSF6/FO2 of 18 sccm/6 sccm. Meanwhile, samples etched with FO2 lower than 6 sccm can’t get low reflective silicon structure. Besides, the results show that overlong etching time of 30 min and too big etching power of 225 W would make the nanostructures too sparse to obtain a low reflectance.