Theoretical model of structure-dependent conductance crossover in disordered carbon

TL;DR

This paper presents a theoretical model analyzing how the sp^2/sp^3 bond ratio influences the conductance crossover in disordered amorphous carbon structures, revealing non-linear effects on transport properties and potential device tunability.

Contribution

It introduces a tight-binding model that captures the non-linear dependence of conductance on structural disorder and bond composition in amorphous carbon.

Findings

High electron transmission probability in sp^2-rich structures near the Fermi level.

Sharp increase in resistance with higher sp^3 content, saturating in wide bandgap regimes.

Potential for tuning device characteristics through structural control.

Abstract

We analyze the effects of sp^2/sp^3 bond-aspect ratio on the transport properties of amorphous carbon quasi-1D structures where structural disorder varies in a very non-linear manner with the effective bandgap. Using a tight-binding approach the calculated electron transmission showed a high probability over a wide region around the Fermi-level for sp^2-rich carbon and also distinct peaks close to the band edges for sp^3-rich carbon structures. This model shows a sharp rise of the structure resistance with the increase of sp^3C % followed by saturation in the wide bandgap regime for carbon superlattice-like structures and suggests the tuneable characteristic time of carbon-based devices.