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Communication Dans Un Congrès Année : 2023

Novel approach for displacement and strain mapping from HR-(S)TEM images of crystalline materials

Résumé

A large number of nanostructures of different type (precipitates, nanocrystals, 3D islands and 2D layers) are widely used in modern microelectronics. For example, Si and Ge nanocrystals buried in the gate oxide of MOSFET transistors are promising candidates for the large-scale, low-power integration in non-volatile semiconductor nanomemories. Metal Ag and Ag doped nanoparticles embedded into a dielectric matrix or AsSb nanoinclusions buried in the low-temperature grown (Al, Ga)(As, Sb) semiconductor films can be used to enhance and manipulate electromagnetic fields. The localization of electrons and holes within self-assembled epitaxial InGaAs quantum dots offers fascinating opportunities for both basic and applied research. Chemical composition, unit cell structure, and intrinsic strain all influence the optical and electrical properties of such nanostructures. As a result, such parameters should be assessed with subnanometer spatial resolution and high precision. Strain and atom displacements are particularly concerned in complex oxides because they alter spontaneous polarization and may result in the polarization reversal. Complex oxides are made up of more than two types of sublattices, each of which can be strained and/or shifted differently, although sharing a common Bravais lattice. Thus, strain and atomic displacements must be measured for each sub-lattice individually and in relation to others. Here, we propose a method for the reciprocal space treatment of high-resolution transmission electron microscopy (HR-TEM) and high-resolution scanning transmission electron microscopy (HR-STEM) images. Named “Absolute strain” (AbStrain), it allows for quantification and mapping of interplanar distances and angles, displacement fields and strain tensor components with reference to a user-defined virtual real lattice, as well as for their correction from the image distortions specific to HR-TEM and HR-STEM imaging. The mathematical formalism for AbStrain will be presented. When a crystal is made up of two or more types of atoms, the technique for extracting images of the sub-lattices and measuring absolute and polarization related displacements will be described. We will demonstrate a successful application of AbStrain to HR-TEM and HR-STEM images of nanocrystals and nanolayers. The advantages of AbStrain with respect to existing methods like geometric phase analysis and “peak finding” will be discussed.
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Dates et versions

hal-04258683 , version 1 (25-10-2023)

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  • HAL Id : hal-04258683 , version 1

Citer

Nikolay Cherkashin. Novel approach for displacement and strain mapping from HR-(S)TEM images of crystalline materials: Absolute quantitative mapping of strain and displacement fields in HR-TEM and HR-STEM images of crystals with reference to a virtual real lattice. Microscopy of Semi-Conducting Materials Conference 2023, Thomas Walther, Rachel A Oliver, Apr 2023, Cambridge (GB), United Kingdom. ⟨hal-04258683⟩
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