Density-functional study of strain effects on the electronic band structure and transport properties of the graphene nanoribbons (GNR) is presented. We apply a uniaxial strain $\left(\epsilon \right)$ in the $x$ (nearest-neighbor) and $y$ (second-nearest-neighbor) directions, related to the deformation of zigzag- and armchair-edge GNRs (AGNR and ZGNR), respectively. We calculate the quantum conductance and band structures of the GNR using the Wannier function in a strain range from $-8\mathrm{\%}$ to $+8\mathrm{\%}$ (minus and plus signs show compression and tensile strain). As strain increases, depending on the AGNR family type, the electrical conductivity changes from an insulator to a conductor. This is accompanied by a variation in the electron and hole effective masses. The compression ${\epsilon }_x$ in ZGNR shifts some bands to below the Fermi level $\left(E_f\right)$ and the quantum conductance does not change but the tensile ${\epsilon }_x$ causes an increase in the quantum conductance to $10e^2/h$ near the $E_f$. For transverse direction, it is very sensitive to strain and the tensile ${\epsilon }_y$ causes an increase in the conductance while the compressive ${\epsilon }_y$ decreases the conductance at first but increases it later.

• Received 31 October 2009

DOI:https://doi.org/10.1103/PhysRevB.81.125409