directly onto TEM grids. Ni grids supporting SiO 2 films (approximately 10 nm thick, Ted Pella) were treated by APTES in the same manner as the SiO 2 /Si substrates, followed by Au particle deposition. The grids were imaged by TEM (Philips CM20, operating voltage 200 keV) before the CVD process to characterize the Au particles, and after the CVD process to characterize the grown nanowires and the particle±wire relationship.Patterned growth: Polymethylmethacrylate (PMMA) was first patterned by electron beam lithography (or photolithography) on a SiO 2 /Si substrate to form 5 î 5 mm wells (Figure 4 a). [11] The substrate was treated with APTES and soaked in a Au colloid solution so that Au particles were deposited into the wells (Figure 4 b). Removal of the PMMA in acetone affords Au particles that are confined in square islands (Figure 4 c). The substrate was then subjected to CVD growth.

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