Electron Mobility in Single-layer Graphene

Analytical expressions for the low-field mobility of the two dimensional electrons in mono layer graphene are obtained on base of quantum kinetic approach that is based on the one-particle density matrix and the model non-equilibrium distribution function in form of the shifted Fermi distribution. We consider the gated graphene with the Fermi level that is biased by applying an external voltage to the gate. In this case, the confining potential has the shape of a triangle well that can be written in terms of Airy functions. Screened acoustic, optic phonons and ionized impurities are considered as scattering mechanisms. Calculations show that in the semiconductors with Dirac spectrum of charge carriers mobility for scattering by acoustic phonons and ionized impurities does not depend on the electron effective mass. Both effective mass of electrons and scattering rate by non-polar optic phonons reach minimum for electron energy close to the Dirac point. A comparison of the temperature dependences of the calculated and experimental mobility data shows that in the temperature range under consideration, at T < 400 K mobility is determined by the scattering of electrons by ionized impurities. The acoustic and out-of-plane optical phonons (ZO phonons) determine the electron mobility at higher temperatures. Results of mobility calculations are compared with known experimental data.