Electronic transport through defective semiconducting carbon nanotubes

Abstract

We investigate the electronic transport properties of semiconducting (m, n) carbon nanotubes (CNTs) on the mesoscopic length scale with arbitrarily distributed realistic defects. The study is done by performing quantum transport calculations based on recursive Green's function techniques and an underlying density-functional-based tight-binding model for the description of the electronic structure. Zigzag CNTs as well as chiral CNTs of different diameter are considered. Different defects are exemplarily represented by monovacancies and divacancies. We show the energy-dependent transmission and the temperature-dependent conductance as a function of the number of defects. In the limit of many defetcs, the transport is described by strong localization. Corresponding localization lengths are calculated (energy dependent and temperature dependent) and systematically compared for a large number of CNTs. It is shown, that a distinction by (m−n)mod 3 has to be drawn in order to classify CNTs with different bandgaps. Besides this, the localization length for a given defect probability per unit cell depends linearly on the CNT diameter, but not on the CNT chirality. Finally, elastic mean free paths in the diffusive regime are computed for the limit of few defects, yielding qualitatively same statements.

An improved Green’s function algorithm applied to quantum transport in carbon nanotubes

“…We get R = 0.52 (1 + N/1.1) for the diffusion regime and G = 0.032 exp(−N/29) for the localization regime, giving the dimensionless elastic mean free path (normalized to the average defect distance) N mfp = 1.1 and the dimensionless localization length N loc = 29. Further results of electron transport through arbitrary chiral CNTs can be found in our comprehensive study [Tei18b].…”

“…Examples suitable for using DFTB are systems with random disorder [Mar07,Bie08,Flo08,Tei14,Gre14,Tei18a,Tei18b]. They are often treated with recursive or iterative techniques.…”

Quantum transport in graphene nanoribbon networks: complexity reduction by a network decimation algorithm

“…Proficient algorithms benefit from this subdivision and result in a linear scaling with the number of atoms. For example, the recursive Green's function formalism (RGF) [10,11] has been widely used for similar calculations of linear chains [16][17][18][19][20][21][22]. Two slightly different versions of the RGF, the renormalization decimation scheme (RDS) and forward iteration scheme (FIS) are utilized [37] and adopted to the networks studied here, as shown in figure 3.…”

“…Nevertheless, many quantum studies have been done using efficient recursive approaches [8][9][10][11], e.g. describing the influence of metal contacts [12][13][14][15] or imperfections [16][17][18][19][20][21][22]. For even larger systems like networks [23][24][25] or whole transistors [7] (semi)-classical approaches are used.…”

Alleviating defects in perovskites using single-walled carbon nanotubes

“…Therefore, we reviewed SWCNTs applications to PSCs from the standpoint of the defect control by categorising their functions. For SWCNTs, purity is paramount because impurity leads to charge recombination that noticeably undermines device performance [52]. Moreover, the methods of CNT production are important as there are various types of SWCNTs.…”