Development of red and RGB µLEDs for microdisplays and high-speed communication
Background: MicroLEDs (µLEDs) are a promising technology for the development of high-brightness mini-displays (such as augmented reality glasses or smartwatches). Measuring less than 20 µm in size, these µLEDs are produced by etching a planar structure on sapphire that incorporates InxGa1-xN quantum wells. The emitted wavelength is directly tuned by the indium content x of the quantum wells (x ˜ 15% for blue, 25% for green, 35–40% for red). While nitride semiconductors offer excellent performance in the blue spectrum, efficiency drops sharply as the size of the µLEDs decreases. To overcome this issue, an innovative approach involves microwire technology with a core-shell geometry. This architecture preserves emission efficiency regardless of size and enables data transmission at GHz speeds (technology developed by the Grenoble-based startup Aledia). Despite their strong potential, core-shell microwire LEDs still face a major scientific challenge: achieving red emission. Indium incorporation remains limited to 25%, a threshold insufficient to reach red. This technological bottleneck is currently hindering the emergence of RGB trichromatic µLEDs. Our team has achieved pioneering results in this field, where we created the first InGaN core-shell quantum well at 15% for blue emission and 25% for green emission. Despite these advances, the challenge of achieving red emission remains.
Objectives: A new idea has emerged to go beyond 25% of In-content for core-shell microwire technology and thus aim for the first demonstration of red emission, which led to a patent application in 2025. Preliminary results have proven very promising results, and we wish to continue this work through a thesis with the three main objectives:
- Demonstrate red emission by varying the geometric parameters of the microwires (diameter, etc.)
- Produce red µLEDs
- Produce trichromatic RGB µLEDs in a single growth run
Collaborations: This project relies on close collaboration with the LTM (Laboratory of Microelectronics Technology) for the fabrication of GaN microwire arrays via etching process. Epitaxial studies of core/shell LEDs will be conducted at CEA’s PHELIQS facility using the MOCVD epitaxial setup, incorporating structural and optical analyses. The final step aims to fabricate microwire-based µLED devices using the expertise developed at the Néel Institute via the NanoFab cleanroom.
Why join this project? To gain expertise in epitaxy, semiconductor physics, and optoelectronics. To work in a dynamic and collaborative environment closely linked to the industrial sector. To contribute to the development of next-generation µLEDs for micro-displays and GHz communications.
PhD Funding: This thesis project is funded by the UGA’s Labex “µelectronics.”
Understanding and exploiting evolvability of biological systems
Directed evolution is a cornerstone of synthetic biology, yet its outcome is heavily constrained by the starting genotype. This latent capacity to innovate—termed evolvability—varies drastically across closely related proteins and microbial strains due to biophysical trade-offs and historical contingency. Financed by the ANR ProtEvol project, this thesis aims to systematically decipher and engineer the determinants of evolvability across two biological scales. At the macromolecular level, we will develop a novel, plasmid-free genomic diversification strategy to map the adaptive pathways of diverse ROK kinase homologs, leveraging AI and machine learning collaborations to extract predictive sequence features of functional promiscuity. Simultaneously, at the organismal scale, we will utilize the automated continuous-culture GM3 platform to evaluate how Escherichia coli strains with divergent pyruvate assimilation backgrounds evolve toward synthetic C1-formatotrophy. By combining high-throughput sequence diversification, machine learning, and automated evolution, this work will transform evolvability from an abstract evolutionary concept into a predictable, steerable parameter for industrial bioproduction.
Orbitronics: time scales involved in orbital to charge conversion processes
Orbitronics is an emerging research field spanning condensed matter physics and materials science to electrical engineering that focuses on the study and manipulation of the electron's orbital angular momentum (OAM). The key idea is to use the OAM of electrons as a means to store, transfer, and process information, similar to how spintronics leverages the electron's spin. Importantly, OAM can be generated by a wide range of material systems and with theoretically much higher efficiency than its spin counterpart, using cheap, environmentally friendly and abundant lightweight elements. Orbitronics thus has both a fundamental interest and technological perspectives that provide an innovative and multidisciplinary framework.
Here, we are targeting oxide interfaces as a rich playground to explore Rashba physics in 2D electron gases (2DEG) and in particular its ability to confert spin or orbit to charge via the Orbital Inverse Rashba Edelstein effect. The LaAlO3/SrTiO3 interface provides an ideal playground to explore this physics and in particular parameters such as crystal orientation and the (LaAlO3) tunnel barrier. These properties will be studied at low-temperature as angular momentum is injected in the dc regime by the spin Seebeck effect. The study will be extended to the ultra-fast regime of the orbital to charge conversion using ultra-fast laser-induced demagnetization of a magnetic layer deposited on top and the measurement of the resulting THz emission. Here, we want to identify the parameters responsible for the decrease in efficiency at the picosecond timescale noted in the first THz emission measurements. Our final aim is to measure the timescales associated to hot electrons and spin/orbital diffusion in this system, which will be the main activity of the PhD student.
Measurement and modelling of the chemical activity of complex fluid components in hydrometallurgy
Modern extraction processes rely on the optimal use of complex fluids, the detailed understanding of which remains too empirical. To overcome this, new multi-scale simulation software packages are being developed, with one of the unknowns at the mesoscopic scale, where the aggregation of molecules, interface structures, etc. are not well understood. Chemical activity is key here, as it controls exchange and transfer processes. Understanding it allows these software packages to be validated. It must therefore be possible to measure and analyse it reliably for each component, particularly volatile ones. We proposed to do this by measuring their partial pressures. An initial version of a microfluidic device was developed and patented, which allows the partial pressures of volatile components to be measured simultaneously by infrared spectroscopy in a hollow waveguide. This experimental prototype device has been validated on simple systems. The aim of this thesis is to demonstrate the application potential of this unique tool for the simulation and rapid development of processes, focusing on important concrete cases, both from an experimental and modelling point of view. This type of study would be completely new and would make it possible to experimentally verify the stability predictions of complex fluids for the first time.
The PhD student will first need to update the microfluidic brick. He/she will then use it to measure the chemical activities of the aforementioned complex fluids and will work with Jean-François Dufrèche to test/validate/further develop the software packages. Secondly, at NTU in Singapore and under the co-supervision of Professor Alex Yan Qingyu (https://personal.ntu.edu.sg/alexyan/ ), he/she will use the duplicate microfluidic platform currently being assembled to apply these results to the rapid development of a process for extracting a critical metal from recycled electronic components from printed circuit boards (SCARCE joint laboratory).
Expected results: publications, proprietary software package and possible patents on the new processes developed.
Uncovering the signaling roles of inositol polyphosphates in plant growth and development
Inositol polyphosphates (InsPs), particularly their pyrophosphate derivatives (PP-InsPs), are recently characterized as signaling molecules present in all eukaryotes. Extensive research has been conducted on the PP-InsP pathway revealing its impacts on organogenesis and various diseases such as cancer metastasis, obesity, and diabetes. Cellular PP-InsPs exist in low concentrations, complex isoforms, and turnover fast, therefore, making them a real challenge to monitor and to analyze. This restricts the PP-InsP study especially on defining their specific roles or putatively variable distribution among cells/tissues. To solve the problem, this project aims to create cellular reporters for monitoring PP-InsPs in real-time. Given the PP-InsP pathway is conserved, the development of the PP-InsP sensors in plants will have a broader impact on the study of to the fundamental characteristics of PP-InsP signaling in animals. For example, the transfer of the PP-InsP reporters to cancer cell lines for possibility to use it for better understanding of PP-InsP-regulated cancer metastasis in the future.
Non-invasively exploring the cerebellum microstructure with magnetic resonance
To better diagnose and monitor brain diseases, we need “non-invasive biopsies” to access the tissue cell-type composition and state without opening the skull. Magnetic resonance imaging (MRI) research efforts attempt to tackle the challenge but often lack cellular specificity because of the ubiquitous nature of water. Diffusion-weighted magnetic resonance imaging (dMRS) measures diffusion of intracellular and partly cell specific molecules in a region of interest, and forms a solid basis for resolving cell-types non-invasively. Among challenges, resolving signal contributions from the different cerebellar neurons could help monitor and understand neurodevelopmental and ataxic disorders. The cerebellum is a brain region representing 10% of the brain volume but containing more than half of the brain neurons, with the very large and complex Purkinje cells and the very small and round granule cells, both having very different functions and metabolism. The PhD project aims to disentangle these cells with complementary strategies: a classical dMRS approach and a quantum dMRS approach confronted to the state-of-the-art microstructure MRI methods.
Role of the JMY protein in human brain development and glioblastoma stem cell radioresistance: from brain organoids to therapeutic screening
The JMY protein is an important regulator of the actin cytoskeleton, involved in cell migration and morphogenesis. Expressed in the developing brain, it is associated with several key processes of neurogenesis, including neurite formation, dendritogenesis, myelination, and neuronal migration. However, its specific role in human brain development remains poorly characterized.
In parallel, our work demonstrates that JMY plays a central role in the pathophysiology of glioblastoma, a highly aggressive brain tumor. Following irradiation, glioblastoma stem cells increase their migratory and invasive capacities through a pathway involving HIF1a and JMY. This activation promotes the formation of actin-rich structures known as tumor microtubes, which are associated with therapeutic resistance.
This project aims to investigate JMY as a common regulator of neurodevelopment and tumor plasticity.
In a first axis, we will analyze the impact of JMY deficiency in human brain organoids derived from iPS cells, in order to assess its effects on proliferation, differentiation, neurogenesis, and cortical organization.
In a second axis, a high-throughput pharmacological screening will be conducted to identify inhibitors capable of blocking radiation-induced migration of glioblastoma tumor stem cells.
The expected results will improve our understanding of JMY’s role in the human brain and support the development of new strategies aimed at limiting glioblastoma recurrence after radiotherapy.
From Few-body to High-Energy antinuclei Collision Kinematics
Because rare antinuclei in space could carry information about exotic production mechanisms—including, potentially, dark-matter annihilation or decay—their study has become a high-impact frontier connecting nuclear physics, astroparticle physics, and collider measurements. Interpreting present and future antinuclei searches, however, is limited by a lack of key nuclear input data: low-energy scattering, annihilation, and breakup processes of antinuclei on ordinary matter are difficult to measure directly, precisely because producing and manipulating antinuclei is so challenging. This motivates a complementary, theory-driven strategy. Our project adopts a bottom-up approach: we will establish a controlled, ab initio description of the simplest low-energy antimatter nuclear systems and collisions, identify the underlying many-body mechanisms of annihilation, and then propagate these constraints to transport and event-level modeling at the many-body and higher-energy scales. In doing so, we aim to both deepen our understanding of matter–antimatter interactions at the nuclear level and deliver validated inputs for the simulation tools used in astroparticle and collider applications.
Two-way transfer between the two fields: In this project, we simplify the problem to the simplest case that can be treated by the ab initio method: in INCL the annihilation of the antideuteron is identified as an annihilation with a quasi-deuteron in a large target. Two key questions must be addressed in part using ab initio calculations:
1. Which quasi-deuteron will interact?
2. Which output channel will result?
Gyrokinetic modelling of the nonlinear interaction between energetic particle-driven instabilities and microturbulence in tokamak plasmas
Tokamak plasmas are strongly nonlinear systems far from thermodynamic equilibrium, in which instabilities of very different spatial scales coexist, ranging from large-scale macroscopic oscillations to microturbulence. The presence of energetic ions produced by fusion reactions or by auxiliary heating further enhances these instabilities through wave–particle resonances. Microturbulence is responsible for heat and particle transport in the thermal plasma, while instabilities driven by energetic particles can induce their radial transport and, consequently, their losses. Both phenomena degrade the performance of present tokamak plasmas, and possibly also those of burning plasmas such as ITER.
Recent results, however, show that these instabilities, which have long been studied separately, can interact nonlinearly, and that this interaction may lead to an unexpected improvement of plasma confinement.
The objective of this project is to investigate these multiscale interactions using the gyrokinetic code GTC, which is able to simultaneously simulate turbulence and energetic-particle-driven instabilities. This work aims to improve the understanding of the nonlinear mechanisms governing plasma confinement and to identify optimal regimes for future fusion plasmas.
The multiple roles of cohesin in genome stability
Cohesin, a ring-shaped protein complex, is crucial for genome stability, gene expression, sister chromatid cohesion, and DNA repair. It forms intrachromosomal loops during interphase, aiding in chromatin organization by bringing enhancers and promoters together. Cohesin also ensures sister chromatid cohesion during DNA replication and repairs double-strand breaks (DSBs). In response to DNA damage, cohesin binds to DSBs and enhances cohesion via damage-induced cohesion (DI-cohesion). Our recent findings show that cohesin tethers DSB ends through oligomer formation (Phipps et al., 2025).
This research project aims, in the frame of an ANR funded project, to explore how DNA damage influences cohesin’s functions in genome stability. The main hypothesis is that DNA damage activates distinct cohesin populations with specific roles critical for maintaining genome integrity. Using Saccharomyces cerevisiae as a model, the project focuses on three goals: analyzing the impact of DNA damage on cohesin composition and modifications, studying oligomerization in DSB tethering, and identifying the cohesin populations involved in DI-cohesion.
The methodology combines biochemical, genetic, and genomic approaches. Key tasks include identifying new cohesin interactors, analyzing cohesin in specific mutants, and investigating post-translational modifications.
This project aims to provide comprehensive insights into cohesin’s diverse roles in genome stability beyond traditional sister chromatid cohesion.