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“Meet the Master”Top Academic Forum Researcher. MATSUMOTO AKIRA from CEMES- CNRS-Université de Toulouse

By 2018-09-07

    Researcher Maxime Vallet is a materials scientist specialized in the structural and chemical characterization of materials. He obtained his PhD in 2014 at the PPrime Institute, Poitiers (France). He is currently working in CEMES-CNRS, Toulouse (France) as a research scientist.             He mainly uses transmission electron microscopy techniques such as bright/dark fields, HRTEM, HAADF-HRSTEM, EELS as well as in situ experiments. His presentation title is: Transmission electron microscopy: a powerful tool to study semiconductors at nanometer scale. Assisstant Prof. Wenbo Yu hosted this presentation.Prof. Yang Zhou, Prof. Shibo Li, Prof. Zhengying Huang, Associate Prof. Cuiwei Liu and other teaching faculties attended this lecture as well as graduate students from relevant majors.

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     In this academic lecture, Dr.Yu first briefly introduced the general information and academic achievements of researcher Maxime Vallet. Then Researcher Maxime Vallet primarily talked about investigation about the elastic properties of interfaces in the InAs/AlSb system both from experimental and theoretical points of view. The variations of lattice parameter through interfaces were studied by using the geometrical phase analysis (GPA) on atomic resolved images obtained from high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Negative strains ofabout 6% was measured at interfaces which are of the sameorder of magnitude as measured in an image generated froma model structure with perfect AlAs interfaces. We also discuss the relevance of strain measurement at the scale of an interface. The elastic properties of the InAs/AlSb heterostructure were also investigated by using the density functional theory (DFT). Firstly, asignificant deviation to the theory of linear elasticity was achieved in the stress-strain curves of bulk InAs, AlAs, InSb, and AlSb forstrain above 2.5% (in absolute value). This deviation was similar for these four binary compounds.Then we focused on the interfacial strains generated by perfect AlAs-likeand InSb-like interfaces in [InAs/AlSb]heterostructures with various InAs and AlSb layer thicknesses.The structuresof perfect Al-As (In-Sb) interfaces calculated by DFT and those predicted by applyingthe linear elasticity as in bulk AlAs (InSb) were in asurprisingly good agreement.

     Finally, we talked about his presentation and future collaborations.

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