Wafer-scale broadband antireflective silicon fabricated by metal-assisted chemical etching using spin-coating Ag ink

We report broadband antireflective disordered subwavelength structures (d-SWSs), which were fabricated on 4-inch silicon wafers by spin-coating Ag ink and metal-assisted chemical etching. The antireflection properties of the d-SWSs depend on its dimensions and heights, which were changed by the sintering temperature of the spin-coated Ag ink and etching time. The fabricated d-SWSs drastically reduced surface reflection over a wide range of wavelengths and incident angles, providing good surface uniformity. The d-SWSs with the most appropriate geometry for practical solar cell applications exhibit only 1.23% solar-weighted reflectance in the wavelength range of 300-1100 nm and average reflectance <5% up to an incident angle of 55 in the wavelength range of 300-2500 nm. This simple and low-cost nanofabrication method for antireflection could be of great importance in optical device applications because it allows mass production without any lithography processes or sophisticated equipment. (C) 2011 Optical Society of America