Top-down lithographic method for inducing strain in carbon nanotubes

We demonstrate a method for inducing strain in carbon nanotubes using standard lithographic techniques. In this work, aligned nanotubes are partially suspended over trenches made by chemical etching. Strain-induced downshifts as high as 31 cm−1 are observed in the Raman spectra, roughly corresponding to 1.1% strain. We also observe significant shifts in the resonant transition energy Eii and an irreversible increase in the D band Raman intensity. The strains demonstrated using this technique are capable of creating significant bandgaps in metallic nanotubes, greater than kBT at room temperature, thereby making it possible to convert metallic nanotubes into semiconductors.