Léa LA SPINA : " High-frequency guided elastic waves in thin films of lithium niobate on sapphire"

Abstract : This thesis is part of the ANR MAXSAW project, which aims to develop new components operating in the RF domain, adapted to the new 5G frequencies. Surface acoustic wave (SAW) filters are widely used to distinguish the different frequencies of RF signals. Unfortunately, the frequency of conventional SAW filters is limited to 3.7 GHz. Epitaxial thin films of LiNbO3 on sapphire host guided acoustic waves that meet the demand for higher frequencies and efficiency. We first produced LiNbO3 thin films on sapphire substrates. Thin films of good crystalline quality were obtained. We also studied their acoustic properties using simulations, and confirmed the frequencies achievable with these structures. The, we simulated, designed and characterized SAW resonators based on LiNbO3 thin films deposited on sapphire, and compared them with the state of the art. Promising acoustic devices were obtained. Finally, an application to the MAXSAW project is presented. 

Jury Composition  :

M. Solal Marc, DocteurHDR, Qorvo Inc., Reporter
Mme. Clement Lorenzo Marta, Professeure des Universités, UPM, Reporter
M. Muralt Paul, Professeur Émérite, EPFL, Reviewer
M. Devolder Thibaut, Directeur de recherche, C2N-CNRS, Reviewer
Mme. Gourdon Catherine, Directrice de recherche, INSP-CNRS, Reviewer
M. Margueron Samuel, Professeur des Universités, ENSMM, PhD Director
Mme. Bartasyte Ausrine, Professeure des Universités, UFC, PhD Co-director
M. Laude Vincent, Directeur de recherche, FEMTO-ST-CNRS, PhD Co-directeur

Localization : Amphithéâtre JJ-Gagnepain, Bâtiment TEMIS