Dr. Stephan O. Hruszkewycz : Argonne National Laboratory, USA
"Hard X-ray Bragg Projection Ptychography : Mapping nanoscale lattice heterogeneity in crystalline thin films"
Abstract :
X-ray Bragg projection ptychography (BPP) is a robust approach for imaging lattice strain and distortion in thin films by combining coherent diffraction image reconstruction techniques with nanofocused x-ray scanning diffraction microscopy. This approach takes advantage of the fact that at the Bragg condition of a crystal, an observed area coherent diffraction pattern is the Fourier transform of a planar projection of the illuminated sample volume. Here, we will discuss how this projection property at a Bragg condition can be exploited with scanning coherent nano-focused x-ray diffraction and two-dimensional ptychographic phasing algorithms to image lattice features in nanostructured thin films projected onto a two-dimensional plane [1,2]. Bragg projection ptychography is well suited for studying structural heterogeneity in extended crystalline thin films. With relatively short acquisition times and nanoscale resolution, reconstructed planar projections of complex film density contain in-plane structural information that is difficult to obtain by other imaging techniques. Here, we will give experimental examples from our recent research in imaging strain in semiconductor device prototypes and local polarization in thin film ferroelectrics.
References :
[1] S. O. Hruszkewycz et al., Nano Letters 12, 5148 (2012).
[2] S. O. Hruszkewycz et al., Phys. Rev. Lett. 110, 177601 (2013).
Invitation : équipe SEMOX- Virginie Chamard -
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