Fig. 3.

The assembly of SWNTs depends critically on the surface functional groups. (a–c) AFM tapping mode topographic images of a series of substrates with 1-μm MHA dot arrays passivated with MUO (a), ODT (b), and PEG-SH (c). These dots show that ODT is the superior passivation layer. (d–f) AFM phase images of a second series of 2-μm dots of MUO (d), AUT (e), and PEG-SH (f), passivated with ODT. None of these show the optimized SWNT assembly observed for the MHA∕ODT system in b. (Insets) Shown are zoom-in images of a selected dot. All images were taken at a scan rate of 0.5 Hz. The height scale is 20 nm, and the phase lag is 10°.