High field response of gated graphene at THz frequencies

Abstract

We study the Fermi energy level dependence of nonlinear terahertz (THz) transmission of gated multi-layer and single-layer graphene transferred onto sapphire and quartz substrates. The two samples represent two limits of low-field impurity scattering: short-range neutral and long-range charged impurity scattering, respectively. We observe an increase in the transmission as the field amplitude is increased due to intraband absorption bleaching starting at fields above 8 kV/cm. This effect arises from a field-induced reduction in THz conductivity that depends strongly on the Fermi energy. We account for intraband absorption using a free carrier Drude model that includes neutral and charged impurity scattering as well as optical phonon scattering. We find that although the Fermi-level dependence in the monolayer and five-layer samples is quite different, both exhibit a strong dependence on the field amplitude that cannot be explained on the basis of an increase in the lattice temperature alone. Our results provide a deeper understanding of transport in graphene devices operating at THz frequencies and in modest kV/cm field strengths where nonlinearities exist.

arXiv comment10 pages, 8 figures

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• The effect of microscopic scattering on the nonlinear transmission of terahertz fields through monolayer graphene
• The effects of microscopic scattering on terahertz third harmonic generation in monolayer graphene
• Anisotropic ultrafast optical response of terahertz pumped graphene
• Polarization Effects of Electro-Optic Sampling and Over-Rotation for High Field THz Detection
• Pulse shaping in the terahertz frequency range for the control of photo-excited carriers in graphene