Thèses

Vendredi 28 Mai 2021 à 14h00.

Scintillation Properties of II-VI Semiconductor Nanocrystals Heterostructures

''Scintillatoris a kind of converter transforming the energetic photon or particle (ionizing radiation) into low energy UV/visible photons. The scintillator in the form of nanocrystals(NCs) has been received great attention to achieve the fast timing radiation detection. However, until now the scintillation mechanism in nanocrystals is still ambiguous.
In this thesis, we focused on the investigation of energy deposition and relaxation process in semiconducting nanocrystals under X-rays excitation. Two types of hetero-structural NCs are successfully synthesized: spherical quantum wells (SQWs) and nanoplatelets (NPLs). Through steady state fluorescence spectroscopy and time resolved techniques, we compared temporally and spectrally radiative recombination produced following photoexcitation and X-rays ionizing radiation. We achieved the identification and assignment of the excitonic species, and also demonstrated the important role of the multiexcitons formation by the carrier multiplication during the energetic electron relaxation. Additionally, we have experimentally and theoretically studied the evolution of excitonic species as a function of particle size, showing that the fraction of excitonic species is insensitive to particle size. Our observations provide a better understanding of the scintillation mechanisms involved in nanostructures and will contribute to the development and applications of the nano-scintillators, particularly in the field of hybrid scintillation materials.

Directeurs de thèse/ thesis director : Christophe Dujardin, Benoit Mahler

Membres du jury / members of the jury :
Audrey POTDEVIN Maître de Conférences, Univ Clermont-Auvergne
Martin NIKL Chercheur, Institute of Physics, Academy of Sciences
Franck LEPINE Directeur de Recherche, Univ lyon 1
Frédéric LEROUGE Maître de Conférences, ENS Lyon
Anna VEDDA Professeure, Univ Milan
Christophe DUJARDIN Professeur, Univ lyon 1
Benoit MAHLER Chargé de recherches, CNRS
Sandrine ITHURRIA Maître de Conférences, ESPCI

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