Synthesis of anti-reflective and hydrophobic Si nanorod arrays by colloidal lithography and reactive ion etching

Si nanorod arrays (NRAs) mimicking moth-eye structures were fabricated with colloidal lithography and reactive ion etching. Compared with that on polished surface, the reflectance on NRA structures is significantly reduced by more than 10 times. The reflectance is decreased with the height of the NRAs. The anti-reflection (AR) ability of the NRAs is accompanied with broad band, omnidirectional, and polarization-insensitive characteristics. The enhancement of surface hydrophobicity is also observed with increasing height of the NRAs. A detailed experimental analysis of the height-dependent AR and self-cleaning characteristics will benefit the design and optimization processes of Si nanowire-based optoelectronic devices.