Projet de thèse en Chimie Physique
Sous la direction de Juliette Mangeney et de Qingyuan Jin.
Thèses en préparation à Paris Sciences et Lettres en cotutelle avec l'East China Normal university - ECNU , dans le cadre de Physique et Chimie des Matériaux , en partenariat avec LABORATOIRE PIERRE AIGRAIN (laboratoire) et de Ecole normale supérieure (établissement de préparation de la thèse) depuis le 01-09-2016 .
Graphene based materials THz technology
The terahertz (THz) frequency domain is a very specific region of the electromagnetic spectrum: THz rays are low-energy, non-ionizing and can penetrate a wide variety of non-conducting materials. THz radiation is of importance to fundamental science and has many promising applications in wide areas of science and technology, such as astronomy, chemistry, bio-security and high bandwidth communications. However, scientific progress in the THz frequency range is hampered by the lack of compact powerful sources and high-sensitive detectors. A material that might enable to overcome these technological limitations is graphene. Thanks to its gap-less electronic band structure, high electron mobility and the linear electronic dispersion, graphene possesses in fact many properties that are highly attractive for the development of the new THz technology. However, recent investigations have shed light on the large detrimental role of Auger recombination processes for the development of graphene-based THz devices, as they limit the lifetime of optical gain to few hundreds of femtoseconds and hinder the efficiency of the carrier multiplication. This proposed PhD project aims at exploring novel strategies to reduce Auger recombination processes in graphene-based structures. Our approach will be based on the investigation monolayer graphene on a high-dielectric constant layer integrated into a Tamm cavity. This design might allow the realization of next generation compact THz lasers, as predicted by recent studies. In fact, long-lived optical THz gain and the emission of THz coherent radiation is expected in such structures, thanks to the combined effect of the high-dielectric constant layer, which screens the Coulomb interaction in the graphene layer by inducing an electrostatic background-potential, and microcavity, which enhance the carrier-light interaction.