Theoretical model: Disorder and transport in amorphous nitrogenated carbon ribbons

Abstract

We investigate the origin of the nitrogen induced conductance cross-over in quasi-one dimensional disordered carbon structures through the analysis of resonant transmission features of electrons. The tight-binding model of the electronic structure of carbon was employed to calculate the transmission coefficients in the presence of structural disorder, which was controlled by changing the sp3 bond alternation as well as a hopping disorder parameter for the sp2 regions. The incorporation of nitrogen atoms in carbon networks was modeled as a combination of disorders which vary both in correlated and uncorrelated manners. By changing the bond alternation of sp3 − C sites correlated with the (incorporated) nitrogen site disorder, we establish the tunable characteristics of the resonance peaks inside the gap. Under proposed non-linear variation of the disorder parameter, the calculated resistance of the carbon structures was found to increase initially with the resonance energy followed by a decrease due to the appearance of resonant peaks close to the band edges. Resonant peaks associated with C and N sites in these structures show a conductance cross-over with the variation of nitrogen concentration in these structures. This work will be useful for developing nano-electronic devices based on nitrogen doped disordered graphene heterostructures.