Method for determining the residual electron- and hole- densities about the neutrality point over the gate-controlled n leftrightarrow p transition in graphene

The Hall effect, and the diagonal resistance, which indicates a residual resistivity $\rho_{xx} \approx h/4e^{2}$, are experimentally examined over the p$\leftrightarrow$n transition about the nominal neutrality point in chemical vapor deposition (CVD) grown graphene. A distribution of neutrality potentials is invoked in conjunction with multi-carrier conduction to model the experimental observations. From the modeling, we extract the effective residual electron- and hole- densities around the nominal neutrality point. The results indicate mixed transport due to co-existing electrons and holes in large area zero-band gap CVD graphene devices, which indicates domain confined ambipolar currents broadly over the gate-induced n $\leftrightarrow$ p transition.