Coulomb Blockade in Graphene Nanoribbons

We propose that recent transport experiments revealing the existence of an energy gap in graphene nanoribbons may be understood in terms of Coulomb blockade. Electron interactions play a decisive role at the quantum dots which form due to the presence of necks arising from the roughness of the graphene edge. With the average transmission as the only fitting parameter, our theory shows good agreement with the experimental data.

Figure 1

Illustration of a graphene ribbon with a disordered edge leading to the formation of necks and dots along the ribbon. Coulomb blockade takes place when the charge moves from dot to dot.

Figure 2

Comparison between experimental data of Ref. 17 and the theoretical result (full line): $E_g^{-1}=BW{e}^{CW}$, obtained from Eq. (4) with $B=0.001(\mathrm{meV}\times \mathrm{nm}{)}^{-1}$ and $C=0.023{\mathrm{nm}}^{-1}$.