Rapid Anisotropic Chemical Etching for Quick Formation of Novel Octagonal Pyramids on Silicon Surface for Photovoltaics

A novel octagonal micro pyramid structure was formed by etching a monocrystalline silicon wafer (100) by employing a wet chemical anisotropic etching process. The main objective is to reduce the silicon wafer's front surface reflectance, improve surface morphology, enhance wettability, and increase the coverage area of the octagonal pyramids on the surface of silicon wafers. The reaction time of the etching process was kept precise under strict observation and control. The experimental results demonstrate a significant reduction in silicon wafers' optical surface reflectance, achieving the lowest reflectance of 8.87%, along with improved surface morphology, periodicity, and coverage of more than 88%. While adding hydrofluoric acid together with magnetic stirring (mechanical agitation) at 300 rpm was advantageous in forming the octagonal silicon pyramid with a high etch rate of 0.41 um/min and significantly reducing the reaction time.