Nano/micro double texturing of antireflective subwavelength structures on inverted pyramids

Antireflective Si subwavelength structures (SWSs) are fabricated after the texturing of nano-scale holes directly onto micro-scale inverted pyramid arrays. Thermally agglomerated Au catalysts and Au-assisted chemical etching adjusted the featured nanohole sizes that determined surface reflection. When nano-scale SWSs were textured into micro-scale inverted pyramids, the total reflectance was dramatically decreased to 2.9% in a wavelength region of 200-1100 nm. Additionally, the average specular reflectance value was below 3.6% up to the incident angle of 60°. The surface reflection was efficiently suppressed by combining the light trap of microstructures and anti-reflectance of nanostructures. This technique demonstrated the feasibility of nano/micro double textured structures for application in high-performance optical devices.