It was recalled that, although the presence of axial screw dislocations in helical nanowires and nanotubes was known to be due to the growth process, their effect upon the electronic properties remained unexplored. Relying upon objective molecular dynamics simulations coupled to density functional tight-binding models, and supporting density functional theory calculations, significant screw-dislocation-induced band-gap modifications were predicted. The effect originated in the highly distorted cores and were expected to be present at radii larger than those considered in these simulations (maximum of about 2nm) as well as in other materials. The observed band-gap dependences upon the size of the Burgers vector and wall thickness were expected to motivate new strategies for growing, via the screw dislocation mechanism, stable nanostructures having desired band gaps.

Electrically Active Screw Dislocations in Helical ZnO and Si Nanowires and Nanotubes. Akatyeva, E., Kou, L., Nikiforov, I., Frauenheim, T., Dumitricǎ, T.: ACS Nano, 2012, 6[11], 10042-9