Accueil > Production Scientifique > Thèses soutenues > Année 2021 > Soutenance de thèse de Rémi Bretel (jeudi 16 déc)
Soutenance de thèse de Rémi Bretel (jeudi 16 déc)
par - 10 décembre 2021
La thèse aura lieu dans la limite des places disponibles de l’amphithéâtre de l’ISMO.
Pour y assister, veuillez vous incrire :
https://docs.google.com/spreadsheets/d/1Wj0ORLCde4jzg6wERGhtOzgOOLLa_i-ESFxQ3r2ol7o/edit#gid=0
Elle sera également retransmise en visioconférence.
Contact pour demander le lien : seminaires.ismo@universite-paris-saclay.fr
Design and study of low dimensional systems decoupled from metallic surfaces for nano-optics
Organic molecules may become the building blocks of tomorrow’s electronics. Their size ( 1nm) is one order of magnitude smaller than the smallest components of silicon devices ( 10nm). An organic molecule can absorb light and transfer its energy to its neighbours via short-scale ( 1 to 10nm) resonant dipole-dipole coupling, a process that may be used to transfer information in highly miniaturized devices. Such a device could be a 1D nanowire along which molecular excitations (excitons) can propagate. Molecular self-assembly into 1D chains is therefore a critical aspect for this purpose. In addition, 2D semiconducting materials such as monolayer transition metal dichalcogenides (TMDs) have been drawing increasing attention as novel platforms for exciton generation and diffusion, with many potential applications to nano-optics and optoelectronics. In a first step of this PhD thesis, we study the growth of self-assembled 1D chains of a chiral molecule (quinacridone) under ultrahigh vacuum. Under these conditions, the formation of chains is partially guided by interactions with a monocrystalline Cu(111) surface ; however, the molecular electronic states are decoupled from the metallic substrate using thin films of alkali halides (less than 5 ML) or a single layer of boron nitride (a wide-bandgap 2D semiconductor). We study the growth modes and the structure of the chains using scanning tunneling microscopy (STM) and high resolution low energy electron diffraction (SPA-LEED). In a second step, we study the excitonic properties of monolayer TMDs exfoliated onto transparent conducting electrodes (ITO) at the nanoscale using an air-operated STM coupled with an optical microscope. Excitons are generated under the STM tip through inelastic tunneling current, and they may diffuse in the TMD material up to several micrometers away from the source.