Development of 4D-STEM with variable tilts
The development of 4D-STEM (Scanning Transmission Electron Microscopy) has profoundly transformed transmission electron microscopy (TEM) by enabling the simultaneous recording of spatial (2D) and diffraction (2D) information at each probe position. These so-called “4D” datasets make it possible to extract a wide variety of virtual contrasts (bright-field imaging, annular dark-field imaging, ptychography, strain and orientation mapping) with nanometer-scale spatial resolution.
In this context, 4D-STEM with variable beam tilts (4D-STEMiv) is an emerging approach that involves sequentially acquiring electron diffraction patterns for different incident beam tilts. Conceptually similar to precession electron diffraction (PED), this method offers greater flexibility and opens new possibilities: improved signal-to-noise ratio, faster two-dimensional imaging at higher spatial resolution, access to three-dimensional information (orientation, strain, phase), and optimized coupling with spectroscopic analyses (EELS, EDX).
The development of 4D-STEMiv thus represents a major methodological challenge for the structural and chemical characterization of advanced materials, particularly in the fields of nanostructures, two-dimensional materials, and ferroelectric systems.
Infertility is a growing problem in all developed countries. The standard methods for the diagnostic of male infertility examine the concentration, motility and morphological anomalies of individual sperm cells. However, 40% of male infertility cases remain unexplained with the standard diagnostic tools.
In this thesis, we will explore the possibility to determine the male infertility causes from the detailed analysis of 3D trajectories and morphology of sperms swimming freely in the environment mimicking the conditions in the female reproductive tract. For this challenging task, we will develop a dedicated microscope based on holography for fast imaging and tracking of individual sperm cells. Along with classical numerical methods, we will use up-to date artificial intelligence algorithms for improving the imaging quality as well as for analysis of multi-dimensional data.
Throughout the project we will closely collaborate with medical research institute (CHU/IAB) specialized in Assisted Reproductive Technologies (ART). We will be examining real patient samples in order to develop a new tool for male infertility diagnosis.
Development and multiparametric monitoring of a microfluidic chip of the blood-brain barrier model
The blood-brain barrier (BBB) protects the brain by controlling exchanges between the blood and nervous tissue. However, current models struggle to accurately reproduce its complexity. This thesis aims at developing and evaluating a microfluidic chip of BBB model incorporating a real-time monitoring system that combines simultaneous optical and electrical measurements. The device will enable the study of permeability, transendothelial resistance and cellular response to various pharmacological or toxic stimuli. By combining microtechnologies, cell co-cultures and integrated sensors, this model of biological avatar will offer a more physiological and dynamic approach than conventional in vitro systems to improve understanding of the diffusion/permeation phenomena of therapeutic molecules. This project will contribute to the development of predictive tools for neuropharmacology, toxicology and research into neurodegenerative diseases.
Integrated material–process–device co-optimization for the design of high-performance RF transistors on advanced nanometer technologies
This PhD research focuses on the integrated co-optimization of materials, fabrication processes and device architectures to enable high-performance RF transistors on advanced nanometer-scale technologies. The work aims to understand and improve key RF figures of merit—such as transit frequency, maximum oscillation frequency, noise behaviour and linearity—by establishing clear links between material choices, process innovations and transistor design.
The project combines experimental development, structural and electrical characterization, and advanced TCAD simulations to analyse the strengths and limitations of different integration schemes, including FD-SOI and emerging 3D architectures such as GAA and CFET. Particular attention will be given to the engineering of optimized spacers, gate stacks, junction placement and epitaxial source/drain materials in order to minimize parasitic effects and enhance RF efficiency.
By comparing planar and 3D device platforms within a unified modelling and characterization framework, the thesis aims to provide technology guidelines for future generations of energy-efficient RF transistors targeting applications in 5G/6G communications, automotive radar and low-power IoT systems.
Understanding the origin of charge noise in quantum devices
Thanks to strong collaborations between teams from several research institutes and the cleanroom facilities at CEA-LETI, Grenoble has been a pioneer in the development of spin qubit devices as a platform for quantum computing. The lifetime of these spin qubits is highly sensitive to fluctuations in the qubit's electrical environment, known as charge noise. Charge noise in spin qubit devices potentially originates from trapping/detrapping events within the amorphous and defective materials (e.g., SiO2, Si3N4). This PhD project aims to better understand the origin of this noise through numerical simulations, and guide the development of quantum devices towards lower noise levels and higher quality qubits.
The goal of this PhD position is to improve the understanding of noise in spin qubit devices through multi-scale simulations going from the atomistic to the device level. The PhD candidate will use codes developed at CEA for the numerical modeling of spin qubits and will leverage supercomputing facilities to perform the simulations. Depending on the candidate’s profile and interests, code development may be considered. The work will also involve collaborations with experimentalists to validate simulation methods and to aid in the interpretation of experimental results.
Instrumented PCB for predictive maintenance
The manufacturing of electronic equipment, and more specifically Printed Circuit Boards (PCBs), represents a significant share of the environmental impact of digital technologies, which must be minimized. Within a circular economy approach, the development of monitoring and diagnostic tools for assessing the health status of these boards could feed into the product’s digital passport and facilitate their reuse in a second life. In a preventive and prescriptive maintenance perspective, such tools could extend their lifespan by avoiding unnecessary periodic replacement in applications where reliability is a priority, as well as adapting their usage to prevent premature deterioration.
This PhD proposes to explore innovative instrumentation of PCBs using ‘virtual’ sensors, advanced estimators powered by measurement modalities (such as piezoelectric, ultrasonic, etc.) that could be integrated directly within the PCBs. The objective is to develop methods for monitoring the health status of the boards, both mechanically (fatigue, stresses, deformations) and electronically.
A first step will consist of conducting a state-of-the-art review and simulations to select the relevant sensors, define the quantities to be measured, and optimize their placement. Multi-physics modeling and model reduction will then make it possible to link the data to PCB integrity indicators characterizing its health status. The approach will combine numerical modeling, experimental validations, and multiparametric optimization methods.
Electron beam probing of integrated circuits
The security of numerical systems relies on cryptographic chains of trust starting from the hardware up to end-user applications. The root of chain of trust is called a “root of trust” and takes the form a dedicated Integrated Circuit (IC), which stores and manipulates secrets. Thanks to countermeasures, those secrets are kept safe from extraction and tampering from attackers.
Scanning Electron Microscope (SEM) probing is a well-known technique in failure analysis that allows extracting such sensitive information. Indeed, thanks to a phenomenon known as voltage contrast, SEM probing allows reading levels of transistors or metal lines. This technique was widely used in the 90s on ICs frontside, but progressively became impractical with the advance of manufacturing technologies, in particular the increasing number of metal layers. Recent research work (2023) showed that SEM-based probing was possible from the backside of the IC instead of frontside. The experiments were carried-out on a quite old manufacturing technology (135 µm). Therefore, it is now essential to characterize this threat on recent technologies, as it could compromise future root of trusts and the whole chains of trust build on top of them.
The first challenge of this PhD is to build a reliable sample preparation process allowing backside access to active regions while maintaining the device functional. The second challenge is to characterize the voltage contrast phenomenon and instrument the SEM for probing active areas. Once the technique will be mature, we will compare the effect of the manufacturing technology against those threats. The FD-SOI will be specifically analyzed for potential intrinsic benefits against SEM probing.
Development of multiplexed photon sources for quantum technologies
Quantum information technologies offers several promises in domains such as computation or secured communications. Because of their robustness against decoherence, photonic qubits are particularly interesting for quantum communications applications, even at room temperature. They also offers an alternative to other qubits technologies for quantum computing. For the large-scale deployment of those applications, it is necessary to have cheap, compact and scalable devices. To reach this goal, silicon photonics platform is attractive. It allows implementing key components such as generation, manipulation and detection of photonic qubits. On the silicon platform, the photonic qubits are generated by pair through non linear process. has several benefits, such as working at room temperature, the ability to generate heralded single photon, or undistiguishable photons with spatially distinct sources.
The goal of this thésis is to work on the development, the fabrication monitoring, and the characterization in the laboratory of multiplexed photon sources on silicon chips to overcome the limits in the process of photon generation with one source. In order to achieve a full integration on chip, it is also essential to properly filter unwanted light in order to keep only the photons that are of interest. As a consequence you will also focus on the development of intgrated filters with high rejection rate.
Injection-Locked Oscillators based Liquid Neural Networks for Generative Edge Intelligence
This PhD aims to design analog liquid neural networks for generative edge intelligence. Current neuromorphic architectures, although more efficient through in-memory computing, remain limited by their extreme parameter density and interconnection complexity, making their hardware implementation costly and difficult to scale. The Liquid Neural Networks (LNN), introduced by MIT at the algorithmic level, represent a breakthrough: continuous-time dynamic neurons capable of adjusting their internal time constants according to the input signal, thereby drastically reducing the number of required parameters.
The goal of this PhD is to translate LNN algorithms into circuit-level implementations, by developing ultra-low power time-mode cells based on oscillators that reproduce liquid dynamics, and interconnecting them into a stable, recurrent architecture to target generative AI tasks. A silicon demonstrator will be designed and validated, paving the way for a new generation of liquid neuromorphic systems for Edge AI.
Analysis and design of dispersion-engineered impedance surfaces
Dispersion engineering (DE) refers to the control of how electromagnetic waves propagate in a structure by shaping the relationship between frequency and phase velocity. Using artificially engineered materials and surfaces, this relationship can be tailored to achieve non-conventional propagation behaviors, enabling precise control of dispersive effects in the system. In antenna design, dispersion engineering can enhance several key aspects of radiation performance, including gain bandwidth, beam-scanning accuracy, and in general the reduction of distortions that arise when the operating frequency changes. It can also enable additional functionalities, such as multiband operation or multifocal behavior in lens- and reflector-based antennas.
This thesis aims to investigate the underlying physics governing the control of phase and group velocities in two-dimensional artificial surfaces with frequency-dependent effective impedance properties. A particular emphasis will be placed on spatially fed architectures, such as transmitarrays and reflectarrays, where dispersion plays a crucial role. The objective is to derive analytical formulations within simultaneously control of both group and phase delay, develop general models, and assess the fundamental limitations of such systems in radiation performance. This work is especially relevant for high-gain antenna architectures, where the state of the art remains limited. Current dispersion-engineered designs are mostly narrowband, and no compact high-gain solution (> 35 dBi) has yet overcome dispersion-induced degradations, which lead to gain drop and beam squint.
The student will develop theoretical and numerical tools, investigate new concepts of periodic unit cells for the impedance surfaces, and design advanced antenna architectures exploiting principles such as true-time delay, shared-aperture multiband operation, or near-field focsuing with minimized chromatic aberrations. The project will also explore alternative fabrication technologies to surpass the constraints of standard PCB processes and unlock new dispersion capabilities.