Effect of Coulomb scattering on graphene conductivity

Abstract

The effect of Coulomb scattering on graphene conductivity in field effect transistor structures is discussed. Inter-particle scattering (electron-electron, hole-hole, and electron-hole) and scattering on charged defects are taken into account in a wide range of gate voltages. It is shown that an intrinsic conductivity of graphene (purely ambipolar system where both electron and hole densities exactly coincide) is defined by strong electron-hole scattering. It has a universal value independent of temperature. We give an explicit derivation based on scaling theory. When there is even a small discrepancy in electron and hole densities caused by applied gate voltage the conductivity is determined by both strong electron-hole scattering and weak external scattering: on defects or phonons. We suggest that a density of charged defects (occupancy of defects) depends on Fermi energy to explain a sub-linear dependence of conductivity on a fairly high gate voltage observed in experiments. We also eliminate contradictions between experimental data obtained in deposited and suspended graphene structures regarding graphene conductivity.

4 pages, 3 figures, to be published in JETP Lett

References in corpus (9)

• Ultrathin epitaxial graphite: 2D electron gas properties and a route toward graphene-based nanoelectronics
• Giant Intrinsic Carrier Mobilities in Graphene and Its Bilayer
• Graphene Nano-Ribbon Electronics
• Carrier transport in 2D graphene layers
• Transport measurements across a tunable potential barrier in graphene
• Highly-ordered graphene for two dimensional electronics
• On the minimal conductivity of graphene
• Voltage and temperature dependencies of conductivity in gated graphene
• Interplay of Coulomb and electron-phonon interactions in graphene