Variabilité multicentrique de l’estimée du volume tumoral métabolique total en TEP au FDG dans le cadre du PHRC multicentrique RTEP7

International audienc

THz absorption in Graphene Quantum Dots

International audienceWe study the optical response of multilayer graphene quantum dots at THz frequencies. We fabricate 73 nm diameter graphene quantum dots in an array of ~1mm 2 size. We demonstrate optical absorbance of these graphene quantum dots from 0.85 to 4.7 THz and study the absorption dependence with the temperature from 4K to 300 K

Energy levels and THz optical properties in Graphene Quantum Dots

International audienceOwing to their energy level splitting in the meV range, large graphene quantum dots (size ~100 nm) are very attractive candidates for THz technology. Whereas their electronic properties have been widely studied by transport measurements, only very few works have been focused on their interaction with THz radiation. Here, we report a theoretical and experimental investigation of the optical properties at THz frequencies of large graphene quantum dots. Using a tight-binding modeling, we show the existence of spatially extended mixed-states that should couple efficiently to THz photons. Furthermore, we experimentally demonstrate THz optical absorption of an array of circular 75 nm-diameter graphene quantum dots at 4K and 300K

Evidence of Fermi level pinning at the Dirac point in epitaxial multilayer graphene

International audienceWe investigate the temperature-dependent conductivity of epitaxial multilayer graphene using THz time-domain spectroscopy and find evidence that the Fermi level in quasineutral graphene layers is pinned at the Dirac point by midgap states. We demonstrate that the scattering mechanisms result from the interplay between midgap states that dominate in the vicinity of the Dirac point and short-range potentials that govern at higher energies (>8 meV). Our results highlight the potential of multilayer epitaxial graphene for probing low-energy Dirac particles and also for THz optics