Electronic transport in two dimensional graphene

Abstract

We provide a broad review of fundamental electronic properties of two-dimensional graphene with the emphasis on density and temperature dependent carrier transport in doped or gated graphene structures. A salient feature of our review is a critical comparison between carrier transport in graphene and in two-dimensional semiconductor systems (e.g. heterostructures, quantum wells, inversion layers) so that the unique features of graphene electronic properties arising from its gapless, massless, chiral Dirac spectrum are highlighted. Experiment and theory as well as quantum and semi-classical transport are discussed in a synergistic manner in order to provide a unified and comprehensive perspective. Although the emphasis of the review is on those aspects of graphene transport where reasonable consensus exists in the literature, open questions are discussed as well. Various physical mechanisms controlling transport are described in depth including long-range charged impurity scattering, screening, short-range defect scattering, phonon scattering, many-body effects, Klein tunneling, minimum conductivity at the Dirac point, electron-hole puddle formation, p-n junctions, localization, percolation, quantum-classical crossover, midgap states, quantum Hall effects, and other phenomena.

Graphene transport at high carrier densities using a polymer electrolyte gate

“…The upturn of resistivity observed at room temperature persists down to 4 K, since the resistivity at higher doping remains larger than the resistivity at for n = 2.5 × 10 13 /cm 2 and 6.2×10 13 /cm 2 respectively. This power-law dependence can be associated to a Bloch-Grüneisen regime, characterized by a strong suppression of the acoustic phonon scattering rate for T T BG , where T BG = 2 v s k F /k B is the Bloch-Grüneisen temperature, v s the speed of sound in graphene and k F the Fermi momentum [19]. The density of phonons being governed by the Bose-Einstein law, T BG defines the temperature scale below which the acoustic phonon absorption rate vanishes.…”

“…A density-dependent renormalization of the Fermi-velocity, v F can lead to corrections to an otherwise constant ρ 0 . The Fermi velocity is expected to be renormalized by direct electron-electron, Fröhlich, electron-phonon and electron-impurity interactions [4,19,[22][23][24][25][26]. The direct electron-electron interaction is responsible for an increase of the This limits the influence of a decrease of Fermi velocity on ρ(T ).…”

Competition between excitonic gap generation and disorder scattering in graphene

“…More recently, it becomes clear from extensive transport experiments that the minimum conductivity in undoped graphene is not universal but instead strongly sample-dependent [4,[36][37][38]. Regardless of the precise value of minimum conductivity, it seems that the undoped, gapless graphene is metallic and free of localization at experimentally accessible temperature [2][3][4], at least for weak disorder.…”

“…In region II, the disorder scattering wins, then the ground state is gapless and the Dirac fermions acquire a finite scattering rate. In region II, the accurate calculation of electric conductivity is a problem in debate [1,2]. To the leading order of the Kubo formula, the dc electric conductivity is known to be σ = 4e 2 /πh, which is independent of disorder and universal [17][18][19][20][21].…”

“…The low-energy elementary excitations in undoped graphene are massless Dirac fermions, which are believed to be responsible for the unusual physical properties of this material [1][2][3][4][5][6]. For clean undoped graphene, the density of states (DOS) of fermions N (ω) vanishes linearly near the Dirac point, so the Coulomb interaction between Dirac fermions is essentially unscreened [1,6,7].…”