Conductance of carbon nanotubes functionalized with gold clusters during CO adsorption

TL;DR

This paper models the electronic conductance of gold-cluster functionalized carbon nanotubes during CO gas exposure using NEGF formalism, revealing how dopants influence conductance and sensor fluctuations.

Contribution

It provides a detailed theoretical analysis of conductance changes in functionalized SWCNTs during CO adsorption, including fluctuation analysis via autocorrelation functions.

Findings

Dopants significantly alter the conductance of SWCNTs during CO exposure.

Theoretical conductance calculations agree with experimental data.

Fluctuations in sensor response are characterized by autocorrelation functions.

Abstract

We investigate the time-dependent electronic transport in single-walled carbon nanotubes (SWCNTs) functionalized with Au clusters on CO gas exposure. Using a tight-binding Hamiltonian and the nonequilibrium Green's function (NEGF) formalism the time-dependent zeroth and first order contributions to the current are calculated. The zeroth order contribution is identified as the time-dependent Landauer formula in terms of the slow time variable, whereas the first order contribution is found to be small. The Green's function for the SWCNT is derived using the equation of motion and Dyson equation technique. The conductance is explicitly evaluated by considering a form for the hopping integral which accounts for the effect of dopants on the charge distribution of the carbon atoms and the nearest-neighbor distance. The effect of dopants is also studied in terms of fluctuations by calculating the autocorrelation function for the experimental and theoretical data. These calculations allow direct comparison with the experiment and demonstrate how the presence of dopants modifies the conductance of the SWCNT measured experimentally and provide the only study of fluctuations in the sensor response in terms of the autocorrelation function.