Self-assembled monolayer islands masked chemical etching for broad-band antireflective silicon surfaces

We report a simple and low-cost nonlithographic approach to fabricate tapered silicon arrays for broad-band antireflective coatings. Wafer-scale, subwavelength-structured pyramidal arrays are directly patterned on Si using mixed self-assembled monolayers consisting of octadecyltrichlorosilane islands as KOH etching masks. We have investigated the effects of etching conditions (such as temperature and pH of solution and etching time) on antireflective properties. The reflectivity of Si surfaces can be suppressed to below 3.8% in the waveband of 300-2000 nm. This technique combines the simplicity of self-assembly and cost benefits of chemical etching, which is promising for reducing the manufacturing cost of crystalline silicon solar cells and optical devices.