Practical utilization of carbon nanotubes (CNTs) in nanoscale devices requires their directed placement on a substrate. Controlled placement has been achieved by a combination of the highly selective adsorption of single walled CNTs (SWNTs) onto open regions of amino-functionalized SiO 2 in a polymeric resist, followed by liftoff. Careful selection of the surfactant used to suspend the SWNTs as well as other processing parameters allow controlled placement in high yield. This technique may provide a path for the large-scale fabrication of CNT-based devices and circuits.

On an upward curve? The curvature of an elastically deformed nanowire pinned to a flat surface contains information about the maximum static friction force, and hence the shear stress, between the nanowire and the surface. Here, InAs nanowires are bent in a controlled manner using the tip of an atomic force microscope (see image). The shear stress can be obtained from a simple analysis according to the standard theory of elasticity.

Bent nanowires lying on a planar substrate (see image) have shapes determined by an interplay between internal stresses and friction with the substrate. By analyzing the shapes of InAs nanowires manipulated with an AFM tip, we study quantitatively how static and sliding friction vary with the nanowire diameter. The contact area is truly mesoscopic.

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