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Stress and nanostructuration

This thematic is devoted to the role of the internal stresses in the growth and properties of thin layers, multilayers and quantum dots which are involved in optoelectronic, magnetic or microelectronic devices. In these nanostructures, stresses are due to the presence of interfaces, of lattice mismatches (epitaxial stress), or are generated during the process (thermal stresses…).

Internal stresses result in a modification of the crystalline symmetry and of the physical properties. They intervene in the growth mechanisms and are likely to affect the device stability.

We also study how internal stresses can be exploited for the nanotructuration, i.e. the spatial organisation of nano-objects, thanks to self-assembly processes (competition between molecule-molecule interactions and molecules-surface interaction, Stranski-Krastanov growth mode…) and to the use of specific surfaces (non conventional orientation, surface etching…).

We develop experimental studies (transmission electron microscopy, optical and Raman micro-spectroscopy), modelling at the atomic scale, and new methods for measuring stress and strain. The nanostructures studied include semiconductors, metallic oxides, and hybrid organic-inorganic systems.

Research topics:

Key-words:

epitaxy, self-organisation, elastic relaxation, plastic relaxation, III-V semiconductor, gallium nitride, GaN, organic-inorganic system, TEM, Raman, DFT, Kinetic Monte Carlo.