Advanced analysis by microLaue diffraction.

Published : 15 July 2019

Installed at the European synchrotron (ESRF) in Grenoble, the Laue microdiffraction instrument unique in Europe allows probing the matter by diffraction of a polychromatic beam of a few hundred nanometers. The rate of acquisition of digital data (Laue diffraction diagram is constantly increasing and requires the development of software tools adapted to the maximum exploitation of the data. Several stages are necessary for the complete data processing to obtain the local features of mono or polycrystalline materials: orientation, lattice parameters, state of deformations. These quantities are essential for the control of elaboration processes, properties, and the longevity of the materials. Many physical and mechanical functions are governed by crystalline parameters (eg photonics, metallurgy) that are measured with extreme accuracy (1/10000). At the nanometer scale, the modification of these parameters has a direct impact on the performance of the devices developed in the laboratories. The increased need for precise characterization of complex materials studied at CEA, microstructures as well as micro and nano-objects requires to accelerate the time of data reduction and interpretation. The master course will consist of optimizing and proposing data processing chains based on image analysis algorithms, intelligent Laue diagram recognition and micro and nanostructure reconstruction.

In a thesis pursuit, these analyzes will focus on materials of interest to the CEA, in particular gallium nitride compounds (used in microLEDs and power transistors) and materials called phosphors, which are important in white LED lightnings. These Laue microdiffraction measurements can be combined with the acquisition of the light emission excited by the X-ray beam and thus achieve a novel correlation between the crystallographic structure and the optical emission.

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