Horizontally aligned single-walled carbon nanotubes can bridge wide trenches and climb high steps

The direct growth of horizontally aligned single-walled carbon nanotubes (HA-SWNTs) on the two basic structures of future SWNT-based nanodevices, i.e., trenches and steps, were demonstrated. The HA-SWNTs were found to be able to bridge trenches of varying widths (up to 1000 μm across) and to climb steps of varying heights (up to ∼1500 μm high). Observations of HA-SWNTs with periodical “beeline-curve-beeline” morphologies and HA-SWNTs which grew along step walls when climbing steps indicate that the popular “tip-floating” growth mechanism for HA-SWNTs should be modified because it is not always suitable for our HA-SWNTs. The consequence of HA-SWNTs being able to bridge wide trenches and to climb high steps suggests a promising way to fabricate nanodevices by directly integrating HA-SWNTs into three-dimensional device structures.