1. Fabrication process of Si nanopillar-arrays by self- assembled nanosphere etching

2. Fabrication process of the monodisperse SiO₂ nanospheres by two-step Stober method

3. (a) Effect of ammonia amount on particle size distribution of nanospheres; (b) Effect of TEOS amount on particle size distribution of nanospheres; (c) Fusion of the nanospheres found in the SEM image; (d) Particle size distribution of the SiO₂ nanosphere seed solution under the optimized synthesis condition

4. Effect of the last-step reaction time of the two-step Stober method on uniformity of SiO₂ nanospheres: (a) 1 h, (b) 2 h, (c) 3 h, (d) 4 h, (e) 5 h ; (f) Dependence of the average particle size and its distribution on reaction time; (g) SEM image of the SiO₂ nanospheres with reaction time of 4 h

5. (a) SEM image of the single-layer SiO₂ nanosphere on Si substrate (top view) and SEM images of the Si nanopillar-arrays from (b) top view and (c) side view

6. (a) Measured area for the light reflectance spectrum and (b) surface reflectance spectra of Si nanopillar-array samples