Figure 1

Silicon particle characterization. (A) SEM and optical microscopy images of the porous silicon particles as prepared and (B) their size distribution. All scale bars in the insets correspond to 2 µm. (C) SEM image of a porous silicon colloid carved using the focused ion beam (FIB) technique. (D) EDX analysis of materials inside a silicon colloid as a function of the distance from the sphere center, normalized to the sphere radius (d = distance from the sphere center/sphere radius). The graph shows the counts for the Si and O peaks of the EDX spectra at five different points of analysis. The points were selected along a line travelling from the nucleus (d = 0) to the sphere surface (d = 1).