Broadband and quasi-omnidirectional antireflection Si subwavelength structure based on alumina nano-template directly formed on SiO2/Si

Wafer-scaled cost-effective technique for subwavelength structured (SWS) surface by means of anodic porous alumina masks directly formed on SiO₂/Si substrates is demonstrated. Combined with ion beam etching and induced coupled plasma etching, SWS surface with a period of 100nm and a height of 200-300nm was achieved on 2 inch polished single crystalline Si wafer. A lower reflectivity below 6% was observed over broadband (350-1200nm) at broad view (0°-45°). Such surface should improve the performance of solar cells and detectors. The fabrication technique can be widely employed to other heterogeneous substrate and achieve SWS functional surface.