Carbon nanotube quantum dots

We present a theoretical study of the local electronic properties of quantum-dot nanotubes composed of different isolated nanotubes joined via modelled junctions (defect pairs composed of heptagon and pentagon along the axial direction of pure nanotubes). The heterostructures are studied following a single pi-band tight-binding Hamiltonian and adopting real-space renormalization techniques within the Green's function formalism. The conductance of semiconducting and metallic dots is analysed as a function of the dot sizes for energies close to the Fermi level. Different transport regimes are found depending upon the electronic nature of the dot and also on the contacts.