In our past studies on SiC power devices, the analysis of electrical performances on diodes [1] (idem for future MOSFETs) must take into account the impact of material's defects at the epitaxy and substrate level.
Initially, the thesis work will consist of setting up tools dedicated to our needs in the SiC team. The specifications for these tools have already been established as part of the internship currently underway within the LAPS laboratory. These AI tools will be able to be trained on already existing datasets (SiC diode batches: with electrical data, defect mappings) and complete the previous manually carried out analyses.
In a second phase, the use of the developed tools will be applied to new manufactured and characterized batches. The range of data will then be completed by considering new component architectures (diodes and power MOSFETs), new material characterizations (defects characterization from other tools being installed at Leti, or even with external collaborators: see Line Pilot WBG, see Soitec), new entries (images of defectivity, obtained during the components fabrication in the clean rooms).
Note that the approach applies i) in the case of power to other materials (GaN, diamond, Ga2O3...), ii) also potentially to any component on semiconductor (memory, transistor, photonic, quantum...).

Timing is a key function in electronic circuits. Beyond on-chip signals synchronization, it also allows the synchronization of wireless data transmissions. Accurate time references require stable frequency sources, which also benefit to sensor applications. The gold standard for time or frequency generation is still quartz resonators, which are however bulky and difficult to miniaturize. Research is therefore still ongoing to provide high quality factor (> 10,000) resonators, ideally capable of operating at frequencies of several GHz. A key to reach such high quality factors is to confine strongly the mechanical vibration of micro-size structures in order to make them insensitive to external perturbations. Recently, the field of topological acoustics has demonstrated the capability to confine elastic waves in very small volumes concentrated at the interface between periodic structure, and to provide extremely high quality factor resonances.
This PhD position focuses on exploiting topologically protected modes in piezoelectric microstructures to provide next generations of high quality factor resonators, which may be used in oscillators or even filter circuits. Leveraging the know-how of CEA Leti in the design and fabrication of such components, the PhD will be part of an international collaboration with well established academic laboratories (Politecnico di Milano, Imperial College FEMTO-ST Institute) and industrial partners.
The candidate will model and design structures supporting topologically protected modes, combinining finite element simulations with simplified numerical approaches which reduce computation times. He will follow the fabrication of demonstrators in collaboration with the process integration teams in the CEA Leti clean rooms, and carry on measurements of the proposed resonators.

Switches based on phase change materials (PCM) demonstrate excellent RF performance (FOM <10fs) and can be co-integrated into the BEOL of CMOS processes. However, their reliability is still very little studied today. Failure modes such as heater breakage, segregation, or the appearance of cavities in the material are shown during endurance tests, but the mechanisms of these failures are not discussed. The objective of this thesis will therefore be to study the failure modes and mechanisms for different operating conditions (endurance, hold, power). The analysis will be carried out through electrical and physical characterizations and accelerated aging methods will be implemented.