Probing charge scattering mechanisms in suspended graphene by varying its dielectric environment

Abstract

Graphene with high carrier mobility μ is required both for graphene-based electronic devices and for the investigation of the fundamental properties of graphene's Dirac fermions. It is largely accepted that the mobility-limiting factor in graphene is the Coulomb scattering off of charged impurities that reside either on graphene or in the underlying substrate. This is true both for traditional graphene devices on SiO2 substrates and possibly for the recently reported high-mobility suspended and supported devices. An attractive approach to reduce such scattering is to place graphene in an environment with high static dielectric constant κ that would effectively screen the electric field due to the impurities. However, experiments so far report only a modest effect of high-κ environment on mobility. Here, we investigate the effect of the dielectric environment of graphene by studying electrical transport in multi-terminal graphene devices that are suspended in liquids with κ ranging from 1.9 to 33. For non-polar liquids (κ<5) we observe a rapid increase of μ with κ and report a record room-temperature mobility as large as ~60,000 cm2/Vs for graphene devices in anisole (κ=4.3), while in polar liquids (κ>18) we observe a drastic drop in mobility. We demonstrate that non-polar liquids enhance mobility by screening charged impurities adsorbed on graphene, while charged ions in polar liquids cause the observed mobility suppression. Furthermore, using molecular dynamics simulation we establish that scattering by out-of-plane flexural phonons, a dominant scattering mechanism in suspended graphene in vacuum at room temperature, is suppressed by the presence of liquids. We expect that our findings may provide avenues to control and reduce carrier scattering in future graphene-based electronic devices.

To Appear in Nature Communications (2012)

References in corpus (18)

• Electric Field Effect in Atomically Thin Carbon Films
• The Raman Fingerprint of Graphene
• Ultrahigh electron mobility in suspended graphene
• Boron nitride substrates for high-quality graphene electronics
• Suspended Graphene: a bridge to the Dirac point
• Doping graphene with metal contacts
• Micrometer-scale ballistic transport in encapsulated graphene at room temperature
• Charged Impurity Scattering in Graphene
• Atomic Structure of Graphene on SiO2
• A self-consistent theory for graphene transport
• Temperature dependent transport in suspended graphene
• Quantum Hall Ferromagnetism in Graphene
• Electron scattering on microscopic corrugations in graphene
• Enhancement of Carrier Mobility in Semiconductor Nanostructures by Dielectric Engineering
• Limits on electron quality in suspended graphene due to flexural phonons
• Tuning the effective fine structure constant in graphene: opposing effects of dielectric screening on short- and long-range potential scattering
• The environment of graphene probed by electrostatic force microscopy
• Transport in suspended graphene

Cited by in corpus (7)

• Colloquium: Graphene spectroscopy
• Carrier screening, transport, and relaxation in 3D Dirac semimetals
• Excitons and trions in monolayer transition metal dichalcogenides: A comparative study between the multiband model and the quadratic single-band model
• Flexural phonon scattering induced by electrostatic gating in graphene
• Influence of interface dipole layers on the performance of graphene field effect transistors
• Quantum corrections to transport in graphene: a trajectory-based semiclassical analysis
• Device Chemistry of Graphene Transistors