Atomic Resolution Inline Holography of Quantum Materials

Characterization plays a critical role in the discovery of quantum materials, which is still challenging despite tremendous progress being made during past decades. Extending the study of point defects from 2D materials to crystals and thin films, probing novel charge states and complex structures, for example, are all difficult problems that require novel characterization approaches. Here we explore inline holography for quantitative defect imaging and defect analysis based on the collection and analysis of coherent convergent beam electron diffraction (CBED) patterns using an aberration corrected electron probe. At large convergence angles, the CBED patterns can be considered as Gabor’s inline hologram formed by a spherical wave, while at smaller convergence interference between CBED disks provide phase information that forms the basis for electron ptychography[1,2]. With fast electron detectors, four-dimensional (4D, two-dimensional scan and diffraction pattern) diffraction data as in 4D-STEM can be collected efficiently with high signal/noise ratio[3]. All of these provide fertile ground for revisiting Gabor’s original idea of inline holography. This talk will highlight our recent progress in developing atomic resolution inline holography using the combination of an aberration corrected STEM and EMPAD detector. Examples will be provided related to point defect detection in heavily doped semiconductors. The experimental study will be compared to dynamical diffraction simulations. The reconstruction algorithms will be proposed and discussed, as well as prospects[4].<br/>References<br/>[1] J. M. Rodenburg, in Advances in Imaging and Electron Physics, Vol 150 Vol. 150, 87-184 (2008)..<br/>[2] J.C.H. Spence, High resolution electron microscopy, 4th Edition ed., Oxford University Press, Oxford, UK, 2013.<br/>[3] J.-M. Zuo, R. Yuan, Y.-T. Shao, H.-W. Hsiao, S. Pidaparthy, Y. Hu, Q. Yang, J. Zhang, Data-driven electron microscopy: electron diffraction imaging of materials structural properties, Microscopy, (2022) In print.<br/>[4] This work is funded by Intel and DOE BES.