Charge Transport in Chemically Doped 2D Graphene

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.

Figure 1

(a) Density of states of an ideal (dashed line) and boron-doped graphene sheets for several values of $C_d$. The zero of the energy has been set to the Fermi levels. (b),(c) local density of states on a boron (b) and nitrogen (c) impurity.

Figure 2

(a) Normalized time-dependent diffusion coefficient for a charge energy corresponding to the Dirac point, and several $C_d$. The closed symbols locate the position of the Dirac point (b) elastic mean free path as a function of energy for $C_d=0.5\%$, 1.0%, 2.0%, and 4.0%.

Figure 3

(a) Charge mobility at room temperature as a function of Fermi energy and $C_d$. Dotted lines correspond to the zero temperature limit. (b) Charge mobilities for electrons (dashed lines) and holes (dashed-dotted lines) as a function of the carrier density and for $C_d=0.5\%$.

Figure 4

(a) Semiclassical conductivity at room temperature as a function of energy and $C_d$. Dotted lines correspond to the zero temperature limit. (b) Semiclassical conductivities for electrons (dashed lines) and holes (dashed-dotted lines) as a function of the carrier density and for $C_d=0.5\%$.