ELECTRON-IMPURITY SCATTERING IN DOPED SINGLE LAYER GRAPHENE

Abstract

We calculated electron-impurity scattering rate (ℏ/τ) as a function of quasiparticle energy (ε) for doped single layer graphene (SLG), bilayer graphene (BLG) and two-dimensional electron gas (2DEG) at zero temperature. (ℏ/τ) of SLG has been computed analytically as well as numerically. Computed results show that ℏ/τ of SLG; (a) tends to zero at ε = 0 and, (b) it exhibits peak at ≈1.6εf, where εf is Fermi energy. Contrary to this, ℏ/τ of 2DEG and BLG show their maximum values at ε = 0 and decline thereafter on increasing ε to attain a minimum at around ε equal to Fermi energy. We thus find that ℏ/τ versus ε of SLG displays an entirely different behavior than that of BLG and 2DEG, suggesting that electron-impurity scattering process in SLG sharply differs from those in BLG and 2DEG. Further, computed ℏ/τ of SLG exhibits a large variation in its magnitude over the energy range of 0 ≤ ε ≤ 3εf. Estimation of resistivity within Boltzmann transport theory involves an scattering rate averaged over all possible values of ε. It can therefore be inferred that the computation of resistivity with the use of ℏ/τ at ε = εf for comparing the computed results with experimental data can be highly misleading. Scattering rates of SLG, BLG and 2DEG are found increasing on enhancing the impurity concentration.