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

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• Device Model for Graphene Bilayer Field-Effect Transistor
• Amplification of surface plasmons in graphene-black phosphorus injection laser heterostructures
• Negative photoconductivity and hot-carrier bolometric detection of terahertz radiation in graphene-phosphorene hybrid structures
• Coulomb electron drag mechanism of terahertz plasma instability in n+-i-n-n+ graphene FETs with ballistic injection
• Effect of Coulomb carrier drag and terahertz plasma instability in p+-p-i-n-n+ graphene tunneling transistor structures
• Collision-dominated spin transport in graphene and Fermi liquids
• Ballistic injection terahertz plasma instability in graphene n+-i-n-n+ field-effect transistors and lateral diodes
• Electron-hole collision-limited resistance of gapped graphene
• Exact eigenstate analysis of finite-frequency conductivity in graphene