Tuning photoinduced terahertz conductivity in monolayer graphene: Optical-pump terahertz-probe spectroscopy
Language
en
Article de revue
This item was published in
Physical Review B: Condensed Matter and Materials Physics (1998-2015). 2014-10-16, vol. 90, n° 16, p. 165420 (1-9)
American Physical Society
English Abstract
Optical-pump terahertz-probe differential transmission measurements of as-prepared single layer graphene (AG) (unintentionally hole doped with Fermi energy E F at ∼ −180 meV), nitrogen doping compensated graphene (NDG) ...Read more >
Optical-pump terahertz-probe differential transmission measurements of as-prepared single layer graphene (AG) (unintentionally hole doped with Fermi energy E F at ∼ −180 meV), nitrogen doping compensated graphene (NDG) with E F ∼ −10 meV, and thermally annealed doped graphene (TAG) are examined quantitatively to understand the opposite signs of photoinduced dynamic terahertz conductivity σ . It is negative for AG and TAG but positive for NDG. We show that the recently proposed mechanism of multiple generations of secondary hot carriers due to Coulomb interaction of photoexcited carriers with the existing carriers together with the intraband scattering can explain the change of photoinduced conductivity sign and its magnitude. We give a quantitative estimate of σ in terms of controlling parameters—the Fermi energy E F and momentum relaxation time τ . Furthermore, the cooling of photoexcited carriers is analyzed using a supercollision model which involves a defect mediated collision of the hot carriers with the acoustic phonons, thus giving an estimate of the deformation potential.Read less <
English Keywords
Optical constants
Optical properties of graphene
Graphene
Spectroscopy of solid state dynamics
Origin
Hal imported