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Large Field of View Electron Ptychography

Cao, Shaohong (2017) Large Field of View Electron Ptychography. PhD thesis, University of Sheffield.

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Abstract

Electron ptychography can overcome the limits of the conventional electron microscopy in terms of both resolution and phase quantitative measurements. There are two ways to implement ptychography with electrons. One employs a focused probe and the other uses a large probe. The advantage of focused probe electron ptychography is allowing to analyse spectrum while collecting the data. The biggest advantage of large probe electron ptychography is much larger field of view with the same scanning positions. In this thesis, we investigate the applications of the large probe ptychography in three modes, which are a transmission electron microscope in the selected area diffraction mode (SAD ptychography), a scanning electron microscope in the transmission mode (SEM ptychography), and a scanning transmission electron microscope (STEM ptychography). The thesis includes the detailed experimental procedures to collect ptychographic data in the three modes, as well as the investigation and evaluation of the experimental parameters. It presents extensive experimental data and results, which includes the decomposition of a partially coherent electron source via the modal decomposition ptychography with the SAD ptychography, the improvement of the delocalization issue with the SEM ptychography, and the atomic resolution reconstruction with the STEM ptychography. The challenges of the implementation and the reconstruction of ptychography in the three modes are also discussed. The main achievement of the thesis is the modal decomposition of matter wave, which has never been done before.

Item Type: Thesis (PhD)
Keywords: electron ptychography, SAD, SEM, STEM
Academic Units: The University of Sheffield > Faculty of Engineering (Sheffield) > Electronic and Electrical Engineering (Sheffield)
Identification Number/EthosID: uk.bl.ethos.736529
Depositing User: Dr Shaohong Cao
Date Deposited: 14 Mar 2018 10:33
Last Modified: 12 Oct 2018 09:52
URI: http://etheses.whiterose.ac.uk/id/eprint/19405

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