Fabrication of Pyramid/Nanowire Binary Structure on n-Type Silicon Using Chemical Etching

A pyramid and nanowire binary structure of n-type monocrystalline silicon surface was fabricated by two-step chemical etching process. The nanowire surface is formed by electroless etching in HF-AgNO3 aqueous solution after being textured in KOH/IPA solution. Optical absorption was compared between this structure and that of random pyramid arrays. The effective reflectance calculated between 400 and 1100 nm decreased from approximate to 40% to approximate to 15% after pyramidal texturing and approximate to 4% after formation of vertically aligned nanowires with a length less than 1 mu m. This simple and low-cost surface structuring technique holds high potential for the manufacture of terrestrial silicon solar cells with reduced optical losses.