Figure 4.

SEM images of porous silicon prepared by metal-assisted etching using different fabrication strategies for gold nanoparticle arrays. (A) Si substrate cleaned with piranha solution and polymer matrix removed by plasma treatment, (B) substrate cleaned with piranha solution and polymer matrix removed by flame annealing, and (C) substrate cleaned with HF and polymer matrix removed by flame annealing. Insets are corresponding cross-sectional SEM images.