Enhanced Quantum-Radiofrequency Sensor
Through the Carnot SpectroRF exploratory project, CEA Leti is involved in radio-frequency sensor systems based on atomic optical spectroscopy. The idea behind the development is that these systems offer exceptional detection performance. These include high sensitivity´ (~nV.cm-1.Hz-0.5), very wide bandwidths (MHz- THz), wavelength-independent size (~cm) and no coupling with the environment. These advantages surpass the capabilities of conventional antenna-based receivers for RF signal detection.
The aim of this thesis is to investigate a hybrid approach to the reception of radio-frequency signals, combining atomic spectroscopy measurement based on Rydberg atoms with the design of a close environment based on metal and/or charged material for shaping and local amplification of the field, whether through the use of resonant or non-resonant structures, or focusing structures.
In this work, the main scientific question is to determine the opportunities and limits of this type of approach, by analytically formulating the field limits that can be imposed on Rydberg atoms, whether in absolute value, frequency or space, for a given structure. The analytical approach will be complemented by EM simulations to design and model the structure associated with the optical atomic spectroscopy bench. Final characterization will be based on measurements in a controlled electromagnetic environment (anechoic chamber).
The results obtained will enable a model-measurement comparison to be made. Analytical modelling and the resulting theoretical limits will give rise to publications on subjects that have not yet been investigated in the state of the art. The structures developed as part of this thesis may be the subject of patents directly exploitable by CEA.
Exploring the Strategic Benefits of 0V Storage for Na-ion Batteries
Recently deployed on a commercial scale, the Na-ion battery technology demonstrates excellent behaviour during medium or long-term storage at zero voltage. This characteristic offers numerous safety advantages during the transport, assembly and storage of cells and modules, as well as during emergency shutdowns in the event of external issues. But are there no consequences for battery performance?
This research project aims to study and better understand the electrochemical mechanisms at play when the potential difference across the terminals is maintained at 0 V.
Initially, advanced dynamic characterisation techniques will be used to analyse and compare the electrochemical, thermal and mechanical properties of battery materials. The results will enrich calendar and cycling ageing models at the cell scale, thereby improving their accuracy and reliability. Subsequently, tests will be conducted on mini-battery modules assembled in various electrical architectures to study cell behaviour during cycling and ageing, particularly in response to the application of negative voltage. Specific battery management system (BMS) solutions could then be proposed to address these issues.
The scientific approach will involve implementing advanced characterisation and instrumentation techniques, conducting ageing and safety tests to identify mechanisms, and developing ageing models. This approach will draw on the expertise and testing facilities of CEA-Liten at the Bourget du Lac site in Savoie.
Next-Gen Surface Analysis for Ultrathin Functional Materials
Advanced nanoelectronics and quantum devices rely on ultrathin oxides and engineered interfaces whose chemical composition, stoichiometry and thickness must be controlled with sub-nanometer precision. LETI is installing the first 300-mm multi-energy XPS–HAXPES tool with angle-resolved capability, enabling quasi in situ chemical metrology from deposition to characterization.
This PhD will develop quantitative, multi-energy and angle-resolved XPS/HAXPES methodologies for ultrathin oxides and oxynitrides, validate measurement accuracy, and establish robust protocols for quasi in situ transfer of sensitive layers. Applications include advanced CMOS stacks and quantum Josephson junctions, where sub-2 nm AlOx barriers critically determine device performance.
The project directly supports the development of next-generation quantum technologies, advanced photonics and energy-efficient microelectronics by improving the reliability and stability of nanoscale materials. The work will be carried out within a strong multi-partner framework.
Development of a 3D gel dosimetry method for quality control of radiotherapy treatment plans using ultra-high dose rate charged particle beams (FLASH)
Ultra-high-dose-rate FLASH radiotherapy is one of the most promising innovations of the last decade in radiation oncology. It has the potential to eradicate radioresistant tumours and reduce unwanted side effects, that in turn increases cure rates and improves patient quality of life. However, dosimetry infrastructure is lagging behind this clinical and technological advance, with current dosimeters no longer suitable and none of those under development achieving consensus.
The optically read dosimetric gel developed at LNHB-MD (CEA Paris-Saclay) is a promising candidate, as photon beam measurements have shown a linear response over a wide dose range (0.25 - 10 Gy) as well as independence in energy (6 - 20 MV) and dose rate (1 - 6 Gy/min). In addition, this water-equivalent dosimeter has the unique ability to provide three-dimensional measurements with high spatial resolution (< 1 mm) with an associated combined uncertainty of approximately 2% (k = 1). This dosimetry method has been validated for quality control of conventional radiotherapy treatment plans but has never been tested with FLASH beams.
This doctoral project aims to develop a 3D gel dosimetry method suitable for FLASH radiotherapy delivered by charged particle beams: (1) conventional energy electrons (= 10 MeV), (2) very high energy electrons (VHEE = 50 MeV), and (3) protons (= 100 MeV). For each of these types of beams, available at the Institut Curie in Orsay and also at Gustave Roussy in Villejuif, the validation of the dose distribution measured by gel will be carried out by comparison with measurements using other dosimeters (e.g. diamond, alanine) and Monte Carlo simulations.
This study will make a significant contribution to improving patient safety, optimising treatment efficacy and the future integration of FLASH radiotherapy into clinical practice.
Li alloys for all solid-state batteries with sulfide electrolyte
Using lithium metal as a negative electrode would significantly increase the energy density of current batteries. However, today, this material quickly leads to short circuits during charge/discharge cycles, mainly due to the formation of dendrites and the instability of the interface with the electrolyte. All-solid-state batteries, particularly with sulfide electrolytes, are a promising alternative, but the limitations of lithium metal remain. Lithium alloys appear to be a solution for improving mechanical and interfacial properties while maintaining good energy densities.
The objective of the PhD is to develop and select lithium alloys suitable for sulfide electrolytes batteries, then integrate them into all-solid-state cells in order to study degradation mechanisms. The work will be focused on the synthesis of the alloys, their shaping in thin films and their integration into cells. The alloys will be finely characterized and then electrochemically tested in laboratory cells and pouch cells. Finally, degradation phenomena, particularly at interfaces, will be studied using advanced post-mortem characterizations.
Reducing damage and loading in high aspect ratio III-V etching
The growing demand for III-V semiconductors in high-efficiency photovoltaics, quantum photonics, and advanced imaging technologies requires innovative and cost-effective fabrication methods. This PhD project focuses on developing plasma etching processes for In-based III-V semiconductors to produce high aspect ratio (HAR) structures on large wafers from 100 to 300 mm. The research addresses two key challenges: understanding how etching process windows evolve with material loading and process conditions (physical vs. chemical dominance), and minimizing electrical degradation induced by HAR etching, which is critical for device performance.
These challenges are fundamentally linked to the low volatility of In-based etch byproducts, the need to balance kinetic and thermal energy inputs to enhance etch selectivity, and the management of etch loading effects for large-scale production. The experimental approach will leverage CEA-Leti's state-of-the-art facilities, including the Photonics platform for 2–4-inch wafer processing, which enables masking strategies (hard mask deposition, photolithography) and low-temperature (150°C) etching.
Characterization will involve SEM for etch profile analysis, XPS for surface composition, and TEM-EDX for sidewall quality assessment. Damage evaluation will be performed using near-infrared photoluminescence decay to measure minority carrier lifetime and identify recombination centers. The work aims to develop optimized HAR etching processes (aspect ratios >10, critical dimensions <1 µm) for In-based III-V materials, investigate pulsed plasma techniques to reduce etch-induced damage, and provide insights into defect formation mechanisms to guide process optimization for industrial applications.
Introduction of innovative materials for sub-10nm contact realization
As part of the FAMES project and the European ChipACT initiative, which aim to ensure France’s and Europe’s sovereignty and competitiveness in the field of electronic nano-components, CEA-LETI has launched the design of new FD-SOI chips. Among the various modules being developed, the fabrication of electrical contacts is one of the most critical modules in the success of advanced node development.
For sub-10 nm node, the contact realization is facing a lot of challenges like punchthrough (due to low etch selectivity during contact etching), voids during metal deposition, self-alignment, and parasitic capacitance. New breakthrough approach has recently been proposed consisting in the deposition of new dielectric films with chemical gradient. This thesis focuses on the development (deposition an etching processes) of new gradient compounds incorporated into SiO2 to address the current issues.
Advanced characterization of defects generated by technological processes for high-performance infrared imaging
This thesis falls within the field of cooled infrared detectors. The CEA-LETI-MINATEC Infrared Laboratory specializes in the design and manufacture of infrared camera prototypes used in defense, astronomy, environmental monitoring, and satellite meteorology.
In this context of high-performance imaging, it is crucial to ensure optimal detector quality. However, manufacturing processes can introduce defects that can degrade sensor performance. Understanding and controlling these defects is essential to increase reliability and optimize processes.
The objective of the thesis is to identify and precisely characterize these defects using cutting-edge techniques, rarely combined, such as Laue microdiffraction and FIB-SEM nanotomography, enabling structural analysis at different scales. By linking the nature and origin of defects to manufacturing processes and quantifying their impact on performance, the doctoral student will contribute directly to improving the reliability and efficiency of next-generation infrared sensors.
The doctoral student will join a team covering the entire detector manufacturing chain and will actively participate in the development (LETI clean room) and structural characterization (CEA-Grenoble platform, advanced techniques) of samples. He/she will also be involved in electro-optical characterization in partnership with the Cooled Infrared Imaging Laboratory (LIR), which specializes in detailed analysis of active materials at cryogenic temperatures.
Advanced electrode materials by ALD for ionic devices
This work aims to develop Advanced ultrathin cunductive layers (<10nm) by ALD (Atomic Layer Deposition)for électrodes use(resistivity 100). The other challenge aims to reduce the ALD-based electrode layer thickness less than 5nm while still maintaining the advanced electric properties (resistivity in the mOhm range).
This work covers multiple aspects including inter alia ALD process, ALD precursors, Elementary characterization of intrinsec properties (physico-chemical, morphological and electrochemical) as well as integration on short loop 3D devices.
Superconducting silicide contacts on hyperdoped silicon by nanosecond pulsed-laser annealing
In the race towards building a quantum computer, there is a deep interest in fabricating devices based on the robust and scalable silicon FD-SOI technology. One example is the Josephson Field Effect Transistor (JoFET) whose operability relies on the high transparency of the interface between the superconducting source/drain regions and the semiconducting channel. Such transparency could be improved by doping the source/drain regions, and hence lowering the Schottky barrier height at the superconductor/semiconductor interfaces.
This PhD aims at developing highly transparent superconducting silicide contacts on a 300 mm production line using Nanosecond Pulsed Laser Annealing (NPLA). NPLA will play a key role for reaching extremely high doping concentrations in silicon [1,2], then forming the superconducting silicides (CoSi2, V3Si) with minimal thermal budget and related dopant deactivation. A particular focus will be devoted on the stresses during silicide formation and their impact on the superconducting critical temperature. Also, the distribution of dopants will be assessed by Atom Probe Tomography (APT), an advanced 3D imaging technique capable of imaging the distribution of dopants at the atomic scale [3]. Finally, electrical measurements on fabricated junctions and transistors will be carried out at low temperature (< 1 K) in order to evaluate the transparency of the superconducting contacts.