Superconducting RF Filters for Quantum Applications
Within the Quantum Devices Laboratory, you will work in an environment ranging from fundamental physics to new nano-electronics technologies, with a team that collaborates closely with quantum computing startups and physicists from CEA-IRIG and Institut Néel.
The operating conditions of qubits (cryogenic temperatures <= 1K, GHz frequencies , high signal density) require the development of suitable components and technological bricks. In particular, the passive radiofrequency components developed around the CEA-LETI superconducting interposer technology show extremely interesting electrical properties up to several GHz. These elements, including inductors available over wide value ranges, have already made it possible to establish the first proofs of concept for very compact and low-loss RF filters. The integration of superconducting materials now makes it possible to envisage the creation of new high-performance filters adapted to signal management in cryogenic environments.
You will be required to develop your expertise in the physics of materials and superconducting components. You will study the different superconducting filters that exist in the scientific literature. Using the models developed in the laboratory and the results of the RF measurements in which you will participate, and relying on 3D RF electromagnetic simulation, you will contribute to the design of different RF filters and functions that meet the needs of cryogenic applications.
3D Hybrid Synapses for Energy-Efficient and Adaptive Edge AI
This PhD thesis is part of the growing field of embedded AI for the Internet of Things (IoT), where constraints in energy, area, and connectivity require rethinking the learning mechanisms of neural networks. The goal is to design neuromorphic architectures based on 3D hybrid synapses combining FeRAM and ReRAM, within an in-memory computing framework. The objective is to enable local adaptation of the model—drawing from machine learning approaches and potentially compatible with plasticity mechanisms such as STDP, VDSP, etc.—while maintaining efficient inference adapted to naturally asynchronous information. The PhD student will develop a heterogeneous memory architecture, design an appropriate local learning protocol, and implement integrated circuit demonstrators. Experimental validation on edge-relevant tasks (e.g., sensory classification) will assess power consumption, network accuracy, and adaptability. Publications and patents are expected outcomes of the thesis.
Study of the stability of Si-CMOS Structures for the implementation of Spin Qubits
Silicon-based spin qubits in CMOS structures stand out for their compatibility with semiconductor technologies and their scalability potential. However, impurities and defects introduced during fabrication lead to noise and instability, which affect their performance.
The objective is to characterize devices fabricated at CEA-Leti, from room temperature to cryogenic temperatures, to evaluate their quality and understand the physical mechanisms responsible for their instability. The goal is to improve the design of the devices and ideally establish a method to identify the most promising devices without requiring measurements at very low temperatures.
The candidate should have skills in the following areas:
- Experimental physics and semiconductors.
- Algorithm programming and data analysis.
- Knowledge in nanofabrication, low-temperature physics, and quantum physics (desirable).
Innovative cooling solutions for 2.5D and 3D electronic systems
As electronic architectures become increasingly complex and dense, managing thermal dissipation is a critical challenge to ensure system reliability and performance. In constrained environments and demanding applications, localized hotspots require innovative cooling solutions compatible with advanced packaging integrations such as 2.5D and 3D. This PhD project is part of this dynamic and aims to explore wafer-level thermal management approaches, relying in particular on advanced 3D integration processes such as direct bonding.
The PhD candidate will contribute to the design and fabrication of test vehicles incorporating temperature sensors and active thermal structures. The main objective will be to assess the efficiency of novel cooling architectures, with a particular focus on integrating microfluidic channels within the stacks, combined with the use of high thermal conductivity materials. The work will include aspects of thermal (and possibly thermo-mechanical) modeling, cleanroom process development, and experimental characterization.
This research topic, at the crossroads of microelectronics and thermal management, offers a stimulating and interdisciplinary framework, closely aligned with emerging industrial needs in advanced packaging.
Physical modelling of Solid-State Batteries exposed to long cycling and fast-charge protocols
CEA-Leti, a leader in the development and manufacturing of integrated solid-state batteries, is collaborating with InjectPower, a cutting-edge start-up, to develop an innovative power solution for miniaturized implantable medical devices. Thin-film all-solid-state battery technology currently stands out as the leading choice for delivering high energy density and customizable form-factor power sources. However, despite this advantage, capacity retention during cycling remains insufficient, with the goal of 1,000 cycles and less than 10% capacity loss still unmet. Additionally, a comprehensive understanding of the physical mechanisms driving performance degradation in microbatteries is lacking.
During this PhD, you will contribute to the development and refinement of our physical model, focusing on accurately describing microbattery behavior during cycling and fast charging. You will also apply our physically informed Bayesian machine learning model to identify key factors that influence battery performance, including charge-discharge protocols, storage conditions, and device architecture. Model training and validation will be based on data collected from automatic probers on silicon wafers containing thousands of microbatteries.
In-situ Monitoring of RF Power Amplifier Circuits Aging for Eco-design and Extended Lifetime
The semiconductor industry, and more specifically the radio-frequency (RF) circuit sector, is facing critical challenges related to eco-design and eco-innovation. These challenges include the need to extend the lifetime of circuits while meeting the growing demands of emerging markets such as 5G and the future 6G. Among these circuits, power amplifiers (PA) play a central role, being both critical components in terms of energy efficiency and key targets for improving robustness against aging and enabling potential reuse.
In this context, in-situ aging monitoring of PAs appears to be a promising approach for developing innovative and sustainable solutions. This research topic is therefore fully aligned with eco-design strategies, leveraging advanced technological platforms such as current and future CMOS SOI technologies, while integrating industrial constraints through existing strategic collaborations with major partners of CEA Leti.
This thesis aims to design an innovative in-situ monitoring solution to evaluate and compensate for the aging of power amplifiers, thereby extending their lifetime through reuse and self-correction strategies. To achieve this, it will rely on methodologies and circuits specifically adapted to practical use cases. The ambition is thus to develop a new generation of robust and durable circuits, integrating intelligent aging management mechanisms. By adopting an eco-design approach, this work aims to address environmental challenges while enhancing the industrial competitiveness of CMOS SOI technologies.
Development of a transportable and high sensibility gamma/neutron spectro-imager to reconstruct and identify radioactive hotspots during decomissioning and dismantling operations
Radioactive hotspots reconstruction is a significant challenge when characterising radioelements in environments that have been impacted by radiological or nuclear activity. A thesis proposal aims to address this issue by developing a compact, highly sensitive multimodal instrument for assessing and characterising gamma-ray and neutron contributions. This system will help to meet the encountered challenges, during decommissioning and dismantling (D&D) operations, in nuclear industry sites. To do this, it will incorporate spectro-imaging specifications to ensure the identification and location of present radioelements. The state of art has already demonstrated the advantages and benefits of combining ionising radiations spectrometry and imaging. However, the suggested solutions show difficulties in deploying measurement systems (size, weight), as well as a sensitivity incompatible with the ground constraints. Results obtained in the frame of thesis works, carried out at SIMRI (Service Instrumentation et Métrologie des Rayonnements Ionisants), have led to the development of a gamma and neutron spectro-imager prototype.
Reliability of RF GaN transistors for 5G millimeter Wave applications
Gallium Nitride components are very good candidates for power amplification at Millimeter Wave frequencies such as 5G (~30GHz), due to their power density and energy efficiency. However, these technologies are commonly integrated on Silicon Carbide substrates, which are thermally efficient but expensive and have small diameters. CEA-LETI's GaN/Si technology provides world-class performance in Ka band, with power densities competing with GaN/SiC technologies. These devices, fabricated on 200mm Si substrates, are compatible with Silicon clean rooms and promise greater available volumes and lower costs. Furthermore, the Silicon-like back-end levels offer possibilities for dense heterogeneous integration with digital circuits, paving the way towards heterogeneous RF Integrated Circuits (RFICs).
However, few studies exist nowadays on the degradation mechanisms tied to these specific components with CMOS-compatible process: advanced barriers, in-situ MIS gates, ohmic contacts, etc... It is mandatory to know and master these effects to qualify the technology as well as better understand the device weaknesses and limitations.
The goal of this PhD is to evaluate the parasitic memory effects as well as the transistor aging under operational conditions using DC and RF measurements, linked to the device physics. The transistors will be subjected to various electrical stress conditions to model their DC & RF degradation: trapping effects measurements (BTI, DCTS), influence of the process and gate technology (Schottky vs MIS), the electrical confinement inside the structure (GaN:C, AlGaN back-barrier, etc…). Time Dependent Dielectric Breakdown (TDDB) measurements will be made on MIS gates from DC to RF domain, to study the time to breakdown increase with input signal frequency, in a similar manner than gate dielectrics in CMOS devices. Finally, electrical stresses in DC and RF conditions (RF CW stresses) will be performed to evaluate and model the transistor degradation under operational conditions.
Vertical GaN power devices development using localized epitaxy
This PhD offers a unique opportunity to enhance your skills in GaN power devices and develop cutting-edge architectures. You’ll work alongside a multidisciplinary team specializing in materials engineering, characterization, device simulation, and electrical measurements. If you’re eager to innovate, expand your knowledge, and tackle state-of-the-art challenges, this position is a valuable asset to your career!
Vertical GaN power components hold great promise for power applications beyond the kV range. Localized epitaxy of GaN enables the creation of thick structures on Si substrates at a competitive cost, with demonstrated success for diodes and pseudo-vertical transistors. However, this approach’s significant surface area limits the energy density of the devices. This PhD aims to develop denser, fully vertical components using layer transfer methods. You’ll study their electrical characteristics to monitor the impact of technological variations on their performance.
Throughout this PhD, you’ll gain comprehensive knowledge in microelectronics processes, electrical characterization, and TCAD (Technology Computer-Aided Design) simulation. You’ll collaborate with a multidisciplinary team including our partner CNRS-LTM and deepen your understanding of GaN power devices, all while being part of a lab dedicated to the development of wide-bandgap power devices. You will have the opportunity to write publications and patents.
Optimizing cryogenic super-resolution microscopy for integrated structural biology
Super-resolution fluorescence microscopy (“nanoscopy”) enables biological imaging at the nanoscale. This technique has already revolutionized cell biology, and today it enters the field of structural biology. One major evolution concerns the development of nanoscopy at cryogenic temperature (“cryo-nanoscopy”). Cryo-nanoscopy offers several key advantages, notably the prospect of an extremely precise correlation with cryo-electron tomography (cryo-ET) data. However, cryo-nanoscopy has not provided super-resolved images of sufficiently high quality yet. This PhD project will focus on the optimization of cryo-nanoscopy using the Single Molecule Localization Microscopy (SMLM) method with fluorescent proteins (FPs) as markers. Our goal is to significantly improve the quality of achievable cryo-SMLM images by (i) engineering and better understanding the photophysical properties of various FPs at cryogenic temperature, (ii) modifying a cryo-SMLM microscope to collect better data and (iii) developing the nuclear pore complex (NPC) as a metrology tool to quantitatively evaluate cryo-SMLM performance. These developments will foster cryo- correlative (cryo-CLEM) studies linking cryo-nanoscopy and cryo-FIB-SEM-based electron tomography.