We report on a numerical study of electronic transport in chemically doped 2D graphene materials. By using ab initio calculations, a self-consistent scattering potential is derived for boron and nitrogen substitutions, and a fully quantum-mechanical Kubo-Greenwood approach is used to evaluate the resulting charge mobilities and conductivities of systems with impurity concentration ranging within [0.5, 4.0]%. Even for a doping concentration as large as 4.0%, the conduction is marginally affected by quantum interference effects, preserving therefore remarkable transport properties, even down to the zero temperature limit. As a result of the chemical doping, electron-hole mobilities and conductivities are shown to become asymmetric with respect to the Dirac point.

We report on a numerical study of quantum transport in disordered two dimensional graphene and graphene nanoribbons. By using the Kubo and the Landauer approaches, transport length scales in the diffusive (mean free path and charge mobilities) and localized regimes (localization lengths) are computed, assuming a short range disorder (Anderson-type). The electronic systems are found to undergo a conventional Anderson localization in the zero-temperature limit, in agreement with localization scaling theory. Localization lengths in weakly disordered ribbons are found to strongly fluctuate depending on their edge symmetry, but always remain several orders of magnitude smaller than those computed for 2D graphene for the same disorder strength. This pinpoints the role of transport dimensionality and edge effects.

We compute the subband structure of several group IV and III-V $⟨001⟩$-, $⟨110⟩$-, and $⟨111⟩$-oriented nanowires using $s{p}^3$ and $s{p}^3{d}^5{s}^{*}$ tight-binding models. In particular, we provide the band gap energy of the nanowires as a function of their radius $R$ in the range $R=1–20\mathrm{nm}$. We then discuss the self-energy corrections to the tight-binding subband structure, that arise from the dielectric mismatch between the nanowires (with dielectric constant ${\epsilon }_{\mathrm{in}}$) and their environment (with dielectric constant ${\epsilon }_{\mathrm{out}}$). These self-energy corrections substantially open the band gap of the nanowires when ${\epsilon }_{\mathrm{in}}>{\epsilon }_{\mathrm{out}}$, and decrease slower $(\propto 1∕R)$ than quantum confinement with increasing $R$. They are thus far from negligible in most experimental setups. We introduce a semi-analytical model for practical use. This semianalytical model is found in very good agreement with tight-binding calculations when ${\epsilon }_{\mathrm{in}}>{\epsilon }_{\mathrm{out}}$.

Strongly enhanced thermoelectric properties are predicted for graphene nanoribbons (GNRs) with optimized pattern. By means of nonequilibrium Green's function atomistic simulation of electron and phonon transport, we analyze the thermal and electrical properties of perfect GNRs as a function of their width and their edge orientation to identify a strategy likely to degrade the thermal conductance while retaining high electronic conductance and thermopower. An effect of resonant tunneling of electrons is detected in mixed GNRs consisting of alternate zigzag and armchair sections. To fully benefit from this effect and from strongly reduced phonon thermal conductance, a structure with armchair and zigzag sections of different widths is proposed. It is shown to provide a high thermoelectric factor of merit ZT exceeding unity at room temperature.