2D layers of chalcogenide materials growth by van der Waals epitaxy for frugal electronics

Non-volatile magnetic memories (MRAMs), such as STT-MRAMs (Spin-torque Transfer MRAMs), appear to be extremely promising devices for reducing the energy consumption of memories. In this context, a very strong spin-orbit coupling at room temperature has been demonstrated in 2D heterostructures of Tellurium-based chalcogenide materials opening the way to new energy-efficient devices. On the other hand, thermoelectric devices based on the conversion of thermal energy into electrical energy are crucial to energy recovery systems. Again, the best thermoelectric materials near room temperature are Tellurium-based chalcogenide alloys. Therefore, mastering the synthesis of crystalline thin films of these Te-based chalcogenide materials is essential to enable a technological breakthrough in these two application areas.

Over the last few years, at LETI we have developed a unique expertise in the van der Waals epitaxial growth of Te-based chalcogenide films by the industrial magnetron co-sputtering technique. The objective of this internship and the following thesis is to extend this synthesis method to new pseudo 2D Bi-Sb-Te(Se) compounds intended for these new ultra-low power applications. The properties of these alloys will be studied using advanced structural characterizations (electron microscopy, synchrotron X-ray experiments, Raman and FTIR spectroscopy, Hall effect measurements, …) coupled with piezoelectric force microscopy (PFM) to analyze their ferroelectric properties.

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