Ultra-low reflectance, high absorption microcrystalline silicon nanostalagmite.

In this work, microcrystalline silicon nanostalagmite [μc-SiNS] arrays have been successfully fabricated on glass by catalytic etching process through a template. The template, polystyrene [PS] nanospheres, with diameter and density of 30 to approximately 50 nm and 1010/cm2, respectively, was obtained by a modified nanophase separation of PS-containing block copolymer. The length of μc-SiNS could be controlled by the duration of etching time. The μc-SiNS exhibits ultra-low reflection approximately 0.3% and absorption around 99% over 300 to 800 nm in wavelength. Reflection is also suppressed for a wide range of angles of incidence in wide range of wavelength. This indicates the extensive light-trapping effect by the μc-SiNS and could possibly harvest a large amount of solar energy at infrared regime.