This study investigates the scattering mechanisms and minimum conductivity in graphene samples with varying levels of disorder. The researchers measured the conductivity of 19 graphene devices, ranging from high to low mobility, and compared the experimental data with theoretical calculations based on charged impurity scattering. They found that the impurity concentration in the samples varies from \(2 \times 10^{11}\) to \(15 \times 10^{11}\) cm\(^{-2}\). In low carrier density, the conductivity ranges from \(2\) to \(12e^2/h\), attributed to the residual density induced by inhomogeneous charge distribution. The shape of the conductivity curves suggests that high mobility samples contain short-range disorder, while low mobility samples are dominated by long-range scatterers. The minimum conductivity values observed in the samples are between \(2\) and \(12e^2/h\), which is significantly higher than the universal value of \(4e^2/h\) predicted by some theories. The study concludes that density inhomogeneities across the graphene sheet may be responsible for the observed spread in conductivity.This study investigates the scattering mechanisms and minimum conductivity in graphene samples with varying levels of disorder. The researchers measured the conductivity of 19 graphene devices, ranging from high to low mobility, and compared the experimental data with theoretical calculations based on charged impurity scattering. They found that the impurity concentration in the samples varies from \(2 \times 10^{11}\) to \(15 \times 10^{11}\) cm\(^{-2}\). In low carrier density, the conductivity ranges from \(2\) to \(12e^2/h\), attributed to the residual density induced by inhomogeneous charge distribution. The shape of the conductivity curves suggests that high mobility samples contain short-range disorder, while low mobility samples are dominated by long-range scatterers. The minimum conductivity values observed in the samples are between \(2\) and \(12e^2/h\), which is significantly higher than the universal value of \(4e^2/h\) predicted by some theories. The study concludes that density inhomogeneities across the graphene sheet may be responsible for the observed spread in conductivity.