Figure 24

Nanoparticle placement using electrostatic funneling scheme. (A) SEM image of Au nanoparticles (diameter ∼20 nm) placed along the centers of silicon oxide lines using the electrostatic funneling scheme. (B) Zero-dimensional placement of individual nanoparticles (∼20 nm diameter) onto the square-shaped pattern. Note that only one nanoparticle is placed in the center of each square-shaped pattern due to the repulsive electrostatic interactions between charged nanoparticles. (C) Nanoparticle placement in a step structure. Au nanoparticles (diameter ∼50 nm) are placed along the center line of the exposed silicon oxide sidewall (dark stripe). For all SEM images: the patterns in dark, silicon oxide functionalized with APTES SAMs; the bright area, gold surface functionalized with MHA SAMs. The Au nanoparticles appear as bright dots. (Reprinted with permission from Reference [82]. Copyright 2007 American Chemical Society.)