Disorder effect on conductance in a doped C60 molecular bridge

Abstract

In this work, we study electrical conductance in a C60 molecular nanobridge with randomly point dopants sandwiched between two (5,5) carbon nanotubes (CNTs) in two cases with opened end and closed end. Two different ways of coupling C60 fullerene through one and five carbon atoms to the uncap- and cap-edges are considered in each case. Our calculations are based on the Green's function technique in the tight-binding approximation. The CNT surface self-energy is also obtained, analytically. The effects of contacts, various strengths of random disorder, cage type, and the bond dimerization on the conductance are investigated. Our results indicate that the appearance of conductance resonances is a manifestation of resonant states of CNT caps, which lie within the molecular HOMO-LUMO gap and consequently they change by disorder concentration. By controlling the disorder concentration, bond dimerization, and contact geometries, this kind of system can explain the extended states from the localized states. The numerical results can serve as a base for developments in designing nanoelectronic devices.