Physics of perovskite materials for medical radiography: experimental study of photoconduction gain
X-rays is the most widely used medical imaging modality. It is used to establish diagnostics, monitor the evolution of pathologies, and guide surgical procedures.
The objective of this thesis is to study a perovskite type semiconductor material for its use as a direct X-ray sensor. Perovskite-based matrix imagers demonstrate improved spatial resolution and increased signal, and can thus help improve patient treatment. Prototype X-ray imagers manufactured at the CEA already provide radiographic images but their performances are limited by the instability of the sensor material.
You job will be to study the mechanisms responsible for the photoconduction gain and photocurrent drift of thick perovskite layers from both a theoretical and an experimental standpoint. To this end, you will adapt the electro-optical characterization benches of the laboratory, conduct experiments and analyze the data collected. You will also have the opportunity to perform advanced characterizations with specialized laboratories within the framework of national and international collaborations. The results of this thesis will provide a better understanding of the material properties and guide its ellaboration to produce high-performance X-ray imagers.
Thermomechanical study of heterostructures according to bonding conditions
For many industrial applications, the assembly of several structures is one of the key stages in the manufacturing process. However, these steps are generally difficult to carry out, as they lead to significant increases in warpage. Controlling stresses and strains generated by heterostructures is however imperative. We proposes to address this subject using both experimental exploration and simulation through thermomechanical studies in order to predict and anticipate problems due to high deformations.
Design and implementation of cryogenic electronics for signal acquisition at cryogenic temperatures
The aim of our proposed thesis is to demonstrate that it is possible to integrate at cryogenic temperatures the entire instrumentation chain for reading and controlling quantum components at cryogenic temperatures
qubits. In other words, we are seeking to place in-situ, in the cryostat and as close as possible to the quantum components
(qubits), all the systems that are currently located outside. In addition, to achieve a major breakthrough
we are aiming for a fully programmable microwave chain (> 2 GHz). This is the subject of an ongoing thesis
financed by the Agence Innovation Défense (AID) and the Commissariat à l'Énergie Atomique (CEA) and a RAPID-type project application.
RAPID type project.
As part of this thesis, we will start at a few hundred MHz. Several main problems
are identified and need to be solved, including
- design and integration of chiplets in System-in-Packages (SiPs) compatible with cryogenic temperatures ;
- interfacing and integrating the Analog to Digital Converter (ADC), Digital to Analog
Converter (DAC) and processing components;
- manage high data rates (several tens of Gbit/s per qubit);
- maximum roundtrip latency of 200 ns;
- energy management (a few tens of mW budget per qubit);
- choice of cryogenic stages adapted to the different processing stages;
- choice of independent technologies