Quantum dots from irradiated carbon nanotubes

We modeled by finite-temperature tight-binding molecular dynamics the welding of crossed (5,5) metallic nanotubes, as demonstrated in recent electron-beam irradiation experiments. By studying the correlation between the atomic and electronic structure of the simulated systems, three classes of junctions among metallic nanotubes were individuated, as a function of the degree and type of disorder created by the irradiation in the junction region. The three classes of junction display, respectively, ohmic cunduction, hopping conduction, and quantum confinement, indicating the formation of a quantum dot contacted to metallic nanowires by tunnel barriers. Implications for molecular-electronics and quantum-computing devices based on arrays of such quantum dots are elaborated and discussed.