Formation of carbon nanotube semiconductor-metal intramolecular junctions by self-assembly of vacancy defects

Atomistic processes of carbon nanotube semiconductor-metal intramolecular junction formation are investigated by tight-binding molecular dynamics simulations and first-principles total energy calculations. We show that the junctions can be formed by reconstruction of vacancy clusters through a series of generalized Stone-Wales transformations [Chem. Phys. Lett. 128, 501 (1986)]. Our simulations suggest a mechanism for synthesis of carbon nanotube semiconductor-metal intramolecular junctions with specific locations and controlled sizes and show the possibility of application to nanoelectronic devices. Our simulations study also provides a microscopic explanation to the superplastic deformation in single-wall carbon nanotubes.