Optical Modulation Effects on Nonlinear Electron Transport in Graphene in Terahertz Frequency Range

Abstract

We describe very fast electron dynamics for a graphene nanoribbon driven by a control electromagnetic field in the terahertz regime. The mobility as a function of bias possesses a large threshold value when entering a nonlinear transport regime. This value depends on the temperature, electron density, impurity scattering strength, nanoribbon width and correlation length for the line-edge roughness. An enhanced electron mobility beyond this threshold has been observed, which is related to the initially-heated electrons in high energy states with a larger group velocity. However, this mobility enhancement quickly reaches a maximum governed by the Fermi velocity in graphene and the dramatically increased phonon scattering. Super-linear and sub-linear temperature dependences of the mobility are seen in the linear and nonlinear transport regimes, which is attributed separately to the results of sweeping electrons from the right Fermi edge to the left one through elastic scattering and moving electrons from low-energy states to high-energy ones through field-induced electron heating. The threshold field is pushed up by a decreased correlation length in the high field regime, and is further accompanied by a reduced magnitude in the mobility enhancement. This implies an anomalous high-field increase of the line-edge roughness scattering with decreasing correlation length due to the occupation of high-energy states by field-induced electron heating. Additionally, a self-consistent device modeling has been proposed for graphene transistors under an optical modulation on its gate, which employs Boltzmann moment equations up to the third order for describing fast carrier dynamics and full wave electromagnetics coupled to the Boltzmann equation for describing spatial-temporal dependence of the total field.

References in corpus (11)

• The electronic properties of graphene
• Graphene photodetectors for high-speed optical communications
• Room Temperature All Semiconducting sub-10nm Graphene Nanoribbon Field-Effect Transistors
• Charged Impurity Scattering in Graphene
• Photocurrent imaging and efficient photon detection in a graphene transistor
• Friedel oscillations, impurity scattering and temperature dependence of resistivity in graphene
• Mobility in Semiconducting Graphene Nanoribbons: Phonon, Impurity, and Edge Roughness Scattering
• Conductance Quantization in Graphene Nanoribbons
• Electronic transport properties of graphene nanoribbons
• Diffusive transport in graphene: the role of interband correlation
• Comparison of inelastic and quasi-elastic scattering effects on nonlinear electron transport in quantum wires

Cited by in corpus (3)

• Interplay of Lorentz-Berry forces in position-momentum spaces for valley-dependent impurity scattering in alpha-T3 lattices
• Surface Plasmon Instability Leading to Emission of Radiation
• Disentangling surface and bulk transport in topological-insulator $p$-$n$ junctions