Mechanical  and structural properties of nanostructures
The mechanical behavior of nanomaterials differs fundamentally from their bulk counterparts. In the absence of any preexisting defects, they may show ultra-high mechanical strengths reaching the ultimate limit of the material. In addition, plastic behavior instead of brittle fracture has been evidenced for low-dimensional semiconducting materials. The large elastic deformations accessible in nanomaterials further grant access to non-linear mechanical effects which are less well studied so far. Moreover, the nucleation of defects in such defect scarce nano-objects remains an open question. Elastic strain further alters the electronic band structure thus affecting the physical and chemical properties.
The MNO research team develops unique in situ and operando techniques to study the nano-mechanical and catalytic behavior of nanostructures using synchrotron X-ray diffraction [refs]. Defects within nano-objects are further investigated by TEM, Bragg coherent X-ray diffraction imaging as well as by atomistic simulations [refs].
 
Materials of interest: simple FCC (Au, Pd, Cu…) and BCC (Fe) metals, and semiconductors (Si, Ge, Si_xGe_1-x, ZnO, GaN)

1. In situ nano-mechanical tests coupled with synchrotron X-ray diffraction
2. In situ and operando imaging of nanostructures during catalytic reaction coupled with synchrotron X-ray diffraction
3. Atomistic simulations
4. Defects (TEM, Bragg coherent X-ray diffraction imaging)
5. Coupling mechanical strain with physical properties (piezoelectricity, catalysis, …)

Strain in microelectronics
Microelectronic devices are composed of many functional materials (semiconductors, dielectric, conductors), which differ not only by their electronic properties but also by their thermomechanical properties. Very large mechanical stresses occur in these devices and depend on the way they are deposited, the temperature (difference in thermal expansion coefficients), the nature of interfaces (epitaxy is looked for in some cases), the geometry or the working conditions (stretchable device). These stresses are a serious concern for the reliability of devices and therefore their measurement at the desired scale and their mitigation are important. Stresses may also be beneficial and sought after since they can enhance the mobility of charge carriers (strain engineering).

1. Strain in microelectronic materials and devices (strain engineering, through-silicon-vias)
2. Reactivity, Stress and Interdiffusion in nanostructures: silicides, Si_xGe_1-x nanostructures
3. Thin films, texture, residual stress, surface stress
4. Phase change materials
5. Organic electronics and photovoltaics on flexible substrates
    

Research projects

Present projects

• ANR PRC DINACS ("Defects in nanocrystals: Coherent Diffraction imaging and simulation")
• ANR PRC LATINO ("Non-linear electromechanical effects in ZnO nanowires for enhanced energy conversion")
• ANR PRC NANOTRIP ("Transformation-induced plasticity in zirconia-based ceramics at the nanoscale")
• ANR PRC Get-Yt
• ANR PRCI StreeARtNano ("Développement de conducteurs métalliques étirables basés sur le réarrangement atomique aux interfaces CFC/CC")
• IRP DASEIN (University of California, Santa Barbara, CA, USA)

Previous projects (within the last 5 years)

• ANR PRC SESAME
• ANR JCJC CHARLINE
• PRC CNRS-MosT (Technion, Haifa, Israel)
• PHC PROCOPE (University of Siegen, Germany)
• PHC PROCOPE (Friedrich-Alexander University Erlangen-Nürnberg, Germany)
• AMIDEX PhD Collogium MEMS (University of Pennsylvania, Philadelphia (PA, USA))
• ANR PRC MecaniX ("Mécanique des Nano-objets étudiée In situ par diffraction X: étude in situ des déformations et des défauts (diffraction cohérente des rayons X) au cours d’un chargement mécanique (AFM)")
• ANR PRC BiDuL ("BrIttle to DUctile transition in silicon at Low dimensions")
• ANR PRC MOON
• CATRENE COCOA
• Several CIFRE PhD contracts with STMicroelectronics
• CAPES-COFECUB (UNESP, Ilha Solteira, Brazil)
• BQR NanoDiff