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Tue Gunst: Mobility of graphene in a perpendicular electric field

posted 4 Jul 2016, 06:17 by info admin
DTU Nanotech, Technical University of Denmark

The electron mobility, limited by electron-phonon scattering, is an important optimal performance indicator of emerging 2D materials [1,2]. One of the advantages of two-dimensionality is that it allows very precise control of the carrier density by a gate, which further enables tuning of the electron-phonon interaction [1]. Graphene has an extremely high carrier mobility, partly due to the fortunate planar symmetry making scattering from the highly occupied acoustic flexural phonons (ZA) impossible. Gating a graphene device breaks the horizontal mirror symmetry and reintroduces scattering from ZA vibrations. I examine the effect in several electrode geometries and argue why this scattering mechanism is a limiting factor at moderate to high carrier densities. In addition, I will discuss the temperature dependence of the carrier mobility and show how this depends on the gate configuration employed.

[1] Dmitri K. Efetov and Philip Kim. “Controlling Electron-Phonon Interactions in Graphene at Ultrahigh Carrier Densities,” Phys. Rev. Lett., 105(25):256805, December 2010. 
[2] T. Gunst, T. Markussen, K. Stokbro, M. Brandbyge. “First-principles method for electron-phonon coupling and electron mobility:Applications to 2D materials” Physical Review B, 93, 035414 (2016).

Tue Gunst is a Post Doc developing nanoscale design tools at DTU Nanotech, Technical University of Denmark. Atomic scale computational methods is developed in close collaboration with the industry partner QuantumWise. His research is focused on electrical characterization, including heat transport and effects of the electron-phonon interaction, in nanoscale devices. He received his PhD in 2013 from DTU Nanotech studying thermoelectric applications and current-induced forces in nanostructured graphene.