Lead free piezoelectric thin films for MEMS
As part of the TILPAC project (ANR grant), you will work on the development of lead-free piezoelectric materials for MEMS actuator applications. The materials deposited in thin layers will be integrated into test vehicles in order to evaluate their properties (electrical, ferroelectric, piezoelectric) and compare them to those of the reference material, PZT, with a view to integration into devices at industrial scale. Particular attention will also be paid to environmental impact aspects.
Quantum dot auto-tuning assisted by physics-informed neural networks
Quantum computers hold great promise for advancing science, technology, and society by solving problems beyond classical computers' capabilities. One of the most promising quantum bit (qubit) technologies are spin qubits, based on quantum dots (QDs) that leverage the great maturity and scalability of semiconductor technologies. However, scaling up the number of spin qubits requires overcoming significant engineering challenges, such as the charge tuning of a very large number of QDs. The QD tuning process implies multiple complex steps that are currently performed manually by experimentalists, which is cumbersome and time consuming. It is now crucial to address this problem in order to both accelerate R&D and enable truly scalable quantum computers.
The main goal of the postdoctoral project is to develop a QD automatic tuning software combining Bayesian neural networks and a QD physical model fitted on CEA-Leti’s device behavior. This innovative approach leveraging the BayNN uncertainty estimations and the predictive aspect of QD models will enable to achieve fast and non-ideality-resilient automatic QD tuning solutions.
Desigon of fully "on the fly" reconfigurable sensor interfaces based on network of oscillators
The availability of low-cost sensors and the development of 5G and 6G radios are responsible of a tremendous increase of the number of wireless sensor networks. It is highly necessary to design ultra-low power sensor interface ICs to limit the energy impact of such applications. One solution consists in placing Artificial Intelligence near the sensor (Edge-AI) to limit the transmission of useless information. In addition, the development of reconfigurable sensor interfaces ICs could help in decreasing the development cost of these applications. On top of that, getting solution of on-the-fly reconfigurable sensor interfaces could have a crucial impact on Edge-IA accuracy as it could bring the possibility to adapt the analog signal conditioning depending on the application context.
The postdoc candidate will contribute to the design of a CMOS integrated circuit able to condition a large number of sensors and which will be fully reconfigurable in gain, bandwidth, and that will implement reconfigurable ADCs and or reconfigurable neural network. For that purpose, the postdoc candidate will work on time-domain sensor interfaces based on Injection Locked Oscillators (ILOs) that have been already demonstrated at CEA Leti. The post doc candidate will have to design and test an oscillator network and will have to demonstrate its low-power behaviour as well as its on-the-fly configurability by maping an ultra-low power key word spotting application. The postdoc will take place in laboratory LGECA of CEA which is dedicated to analog mixed design for sensors applications.
Optomechanical resonators in chaotic regime for cryptography in optical datacoms
The aim of the post doc is to explore the use of optomechanical resonators placed in a chaotic regime to secure optical communications. It is part of a project from the CEA's research-at-risk program, selected in July 2024. A key point is to obtain a highly non-linear regime, favored by specific geometries, necessary for the richness of chaos. Exploiting the unique properties of chaos for secure data transfer will be explored by the postdoc as part of a working group.
With the advent of the quantum computer, current techniques for securing information exchange become largely compromised, necessitating the development of post-quantum cryptography techniques. Beyond software approaches, new hardware concepts have emerged, such as chaotic cryptography. In this context, it is becoming essential to develop chaos sources that are high-quality (richness of parameter space), compatible with existing communication systems and compact. While lasers are a well-known source of chaos, optomechanical systems seem particularly well suited to this application, as the mechanical domain provides an enriched parameter space, while retaining high data throughput and a direct connection with optical communications systems. The postdoc will explore the suitability of chaotic optomechanical devices for implementing hardware cryptography.
Simulation of thermal transport at sub-Kelvin
Thermal management in quantum computers is an urgent and crucial task. As the number of qubits rapidly scales, more electric circuits are placed close to qubits to operate them. Joule-heating of these circuits could significantly warm the qubit device, degrading its fidelity. With intensive activity in quantum computing at Grenoble, we (CEA-LETI, Grenoble, France) are looking for an enthusiastic post-doc researcher to study thermal transport at cryogenic temperature (sub-Kelvin).
The post-doc will apply the finite-element non-equilibrium Green’s function [1], developed in the group of Natalio Mingo at CEA-Grenoble, to simulate phonon transport in various designed structures. The simulation result promotes comparison with on-going experiments and constructive discussions in order to optimize the thermal management.
[1] C. A. Polanco, A. van Roekeghem, B. Brisuda, L. Saminadayar, O. Bourgeois, and N. Mingo, Science Advances 9, 7439 (2023).
Modeling of charge noise in spin qubits
Thanks to strong partnerships between several research institutes, Grenoble is a pioneer in the development of future technologies based on spin qubits using manufacturing processes identical to those used in the silicon microelectronics industry. The spin of a qubit is often manipulated with alternating electrical (AC) signals through various spin-orbit coupling (SOC) mechanisms that couple it to electric fields. This also makes it sensitive to fluctuations in the qubit's electrical environment, which can lead to large qubit-to-qubit variability and charge noise. The charge noise in the spin qubit devices potentially comes from charging/discharging events within amorphous and defective materials (SiO2, Si3N4, etc.) and device interfaces. The objective of this postdoc is to improve the understanding of charge noise in spin qubit devices through simulations at different scales. This research work will be carried out using an ab initio type method and also through the use of the TB_Sim code, developed within the CEA-IRIG institute. This last one is able of describing very realistic qubit structures using strong atomic and multi-band k.p binding models.
Design and fabrication of the magnetic control of 1.000 qubits arrays
Quantum computing is nowadays a strong field of research at CEA-LETI and in numerous institutes and companies around the world. In particular, RF magnetic fields allow to control the spin of silicon qubits, and pathway for large scale control is a real technological challenge.
The bibliographic analysis and the studies already carried out will able to draw out the pros and cons of the various existing solutions. In collaboration with integration, simulation and design staff, a proof of concept will be develloped and fabricated.
Development of large area substrates for power electronics
Improving the performance of power electronics components is a major challenge for reducing our energy consumption. Diamond appears as the ultimate candidate for power electronics. However, the small dimensions and the price of the substrates are obstacles to the use of this material. The main objective of the work is to overcome these two difficulties by slicing the samples into thin layers by SmartCut™ and by tiling these thin layers to obtain substrates compatible with microelectronics.
For this, various experiments will be carried out in a clean room. Firstly, the SmartCut™ process must be made more reliable. Characterizations such as optical microscopy, AFM, SEM, Raman, XPS, electrical, etc. will be carried out in order to better understand the mechanisms involved in this process.
The candidate might be required to work on other wide-gap materials studied in the laboratory such as GaN and SiC, which will allow him to have a broader view of substrates for power electronics.
Design of 2D Matrix For Silicum Quantum computing with Validation by Simulation
The objective is to design a 2D matrix structure for quantum computing on silicon in order to consider structures of several hundred physical Qubits.
In particular the subject will be focused on:
- The functionality of the structure (Coulomb interaction, RF and quantum)
- Manufacturing constraints (simulation and realistic process constraint)
- The variability of the components (Taking into account the variability parameter and realistic defectivity)
- The constraints induced on the algorithms (error correction code)
- Scalability of the structure to thousands of physical Qubits
The candidate will work within a project of more than fifty people with expertise covering the design, fabrication, characterization and modeling of spin qubits as well as related disciplines (cryoelectronics, quantum algorithms, quantum error correction, …)
Effect of TSV presence on BEOL reliability for 3-layer stacked CMOS image sensor (CIS)
Because conventional downsizing based on the empirical Moore's law has reached its limitations, an alternative integration technology, such as three-dimensional integration (3DI) is becoming the mainstream. The 3rd generation of CMOS image sensor (CIS) stacks up to 3 die interconnected by hybrid bonding and High Density Through Silicon Vias (HD-TSVs). Devices and circuits good functioning and integrity have to be maintained in such an integration especially in the close neighborhood of TSVs. Thermal budget, copper pumping, thin wafer warpage can lead to electrical yield and reliability concerns and must be investigated.
The work consists in evaluating the impact of TSV processing and proximity on BEOL and FEOL performance and reliability. Acquired data sets will help to define design rules and in particular a potential Keep-Out Zone (KOZ) and calibrate a finite element model (FFM).