Figure 2.

Cross-sectional view (a) and top view (b) of PSRF wafer FESEM images. The inset is a magnified cross-sectional view. (PSRF was prepared with a sinusoidal waveform ranging between 10 and 50 mA cm^-2 with a period of 6.9 s for 30 cycles in a 3:1 (v/v) solution of 49% aqueous hydrofluoric acid and ethanol.)