Van Der Waals-Layered Chalcogenide Superlattice for innovative low power phase-change memories

Published : 27 February 2019

Phase-change memories (PCMs) are the best candidates for replacing Flash memories, universal memories (SCMs) and neuromorphic circuits for artificial intelligence. Nevertheless, PCMs exhibit too programming currents limiting their use for the future genration of resistive memories. For this purpose, using van der Waals-layered GeTe/Sb2Te3 super-lattice heterostructures with iPCMs (interfacial PCM) instead of bulk GeSbTe PCM material is a very promising way. Although performance improvement with iPCMs is admitted, the origin of the resistive transition mechanism remains unclear. This is mainly related to the lack of robust description of their structure at the atomic scale. In this context, recently we have been able to describe for the first time the structure of superlattices used in iPCM devices at the atomic scale (Ph.D. Kowalczyk 2015-2018 / # Small 2018, 1704514). In order to be able to go further with this system, there is still a lot of work to understand and control the atomic structure of the latter. For this purpose the phD student will study the van der Waals growth conditions of these super lattices by means co-sputtering in industrial microelectronic 200 mm tools with a particular emphasis on their electronic properties (iPCM memory test devices, magnetotransport/Hall, resistivity, atomic structure by electron microscopy techniques and X-ray diffraction …). The goal will be to ultimately highlight the physical mechanism behind the resistive transition in iPCMs devices. This understanding is essential to be able to propose new systems of vdW heterostructures aiming at improving further iPCM performances but also to develop new technological applications (topological insulators in spintronics, photonics, thermal …).

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