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Reference : UPR8011-ALACLA-003
Workplace : TOULOUSE
Date of publication : Friday, May 01, 2020
Type of Contract : FTC Scientist
Contract Period : 12 months
Expected date of employment : 1 July 2020
Proportion of work : Full time
Remuneration : From 2617 to 3017€ gross monthy salary, depending on experience
Desired level of education : PhD
Experience required : Indifferent
Your goal will be to characterize, understand and control, necessarily at the nanometre-scale, the change of structural/chemical and electrical characteristics of the GST layer of PCM devices, during the formation of intermediate states between the SET and RESET configurations. You will focus on devices using Ge-rich GST alloys since their higher transition temperatures (up to 380°C instead of 180°C for the canonical Ge2Sb2Te5) well match possible strategical applications. Understanding the origin of the intermediate conductivity states of these PCM cells will help our industrial partner STMicroelectronics (collaborator of the project) to optimize the composition of the material, the activation strategy (pulses) and the cell design in order to get the desired stability and low variability of the intermediate states at the wafer scale. The scientific strategy that you will adopt will be to manipulate the electrical properties of the cells, characterize their transport properties and investigate their structural and chemical characteristics at the atomic scale. Combining these complementary investigations is the only way to understand the microscopic nature of electrical conduction in the intermediate states of PCMs, a requirement for designing robust future non-von Neumann and neuromorphic devices.
You will manipulate (i.e., put in the SET, RESET or some intermediate state) and measure the electrical characteristics (impedance measurements) of the cells provided by STMicroelectronics using an experimental bench (already functioning). Once electrically characterized, you will locate and extract by FIB thin lamellas from the cells, suitable for TEM characterization. You will use advanced TEM techniques to fully characterize the structure and composition of the active part of the cell (dome). Then, you will try to correlate the electrical to the structural/elemental characteristics of the cells. Finally, you will contribute to build a model able to describe and simulate these electrical characteristics.
We are looking for a young doctor in Physics or Materials Science with demonstrated experience in materials science using advanced transmission electron microscopy techniques (HREM, STEM, ELS, EDX, in-situ…) and FIB. Some experience with electrical characterization would be a plus, but is not mandatory. Open minded and autonomous, he/she likes to “understand how things work”, has the will to take risks and develop exploratory and fundamental research in collaboration with a major industrial player in the field of advanced electronic devices.
The Centre d'Élaboration de Matériaux et d'Etudes Structurales (CEMES / CNRS) is a CNRS laboratory (CNRS UPR 8011.
CEMES is a laboratory for fundamental research in materials science, solid state physics, molecular chemistry. The scientific activities that are developed there cover a broad spectrum ranging from synthesis of (nano) materials and molecular systems, studying and modeling their structure and their physical properties (optical, mechanical, electronic and magnetic), their integration into devices, and the manipulation of these individual objects.
Most of the experimental work developed in CEMES relies on advanced instrumentation. An important part of the activities carried out in our laboratory is the instrumental and methodological developments in the key areas of CEMES that are the transmission electron microscopy (TEM), the near-field microscopy (SPM) and optical spectroscopy.
CEMES is collaborating with STMicroelectronics within a large European Project (IPCEI nano2022) (1) from which this position is granted. We have already set up a group of three permanent scientists of complementary expertise (experiments and theory, structural and electrical properties), one expert engineer from STMicroelectronics, one postdoc and one PhD student. You will complement this group.
Constraints and risks
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