001     877846
005     20240610121213.0
020 _ _ |a 978-3-95806-476-8
024 7 _ |2 Handle
|a 2128/25339
024 7 _ |2 ISSN
|a 1866-1807
037 _ _ |a FZJ-2020-02470
041 _ _ |a English
100 1 _ |0 P:(DE-Juel1)165965
|a Zheng, Fengshan
|b 0
|e Corresponding author
|g male
|u fzj
245 _ _ |a High spatial resolution and three-dimensional measurement of charge density and electric field in nanoscale materials using off-axis electron holography
|f - 2020-07-23
260 _ _ |a Jülich
|b Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
|c 2020
300 _ _ |a XIX, 182 S.
336 7 _ |2 DataCite
|a Output Types/Dissertation
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|2 PUB:(DE-HGF)
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336 7 _ |2 ORCID
|a DISSERTATION
336 7 _ |2 BibTeX
|a PHDTHESIS
336 7 _ |0 2
|2 EndNote
|a Thesis
336 7 _ |0 PUB:(DE-HGF)11
|2 PUB:(DE-HGF)
|a Dissertation / PhD Thesis
|b phd
|m phd
|s 1595485554_4601
336 7 _ |2 DRIVER
|a doctoralThesis
490 0 _ |a Schriften des Forschungszentrums Jülich. Reihe Schlüsseltechnologien / Key Technologies
|v 221
502 _ _ |a RWTH Aachen, Diss., 2020
|b Dr.
|c RWTH Aachen
|d 2020
520 _ _ |a The ability to make local measurements of charge density in nanoscale materials and devices is essential for understanding many material properties. The charge density can then be used to infer the electric field or electrostatic potential within and around the specimen. This information is important for scientists working on subjects such as field electron emissionand atom probe tomography. Off-axis electron holography is a powerful technique that can be used to record the phase shift of a high-energy electron wave travelling through an electron-transparent specimenin a transmission electron microscope. Information about the charge density within the specimen can be retrieved from the measured phase with high spatial resolution. In this thesis, charge density and electric field measurements are performed, both in projection and in three dimensions, with a primary focus on samples that have a needle-shaped geometry. Three approaches are used: an analytical model-dependent approach, a model-independentapproach and an approach based on numerical model-based iterative reconstruction. The model-based iterative approach allows $\textit{a priori}$ information, such as the shape of the object and the influence of charges that are located outside the field of view, to be taken into account. More importantly, it also allows for the reconstruction of three-dimensional charge density distributions from incomplete tomographic tilt of phase images without the artefacts that would be present if conventional tomographic reconstruction algorithms were used. In this thesis, a W$_{5}$O$_{14}$ nanowire is investigated experimentally in the presence of anapplied electrical bias and the charge distribution along it is evaluated. A carbon fibre needle-shaped specimen is then studied, in order to demonstrate the capability of the modelbased iterative approach to measure the three-dimensional charge density, electric field and electrostatic potential both inside and around it. Finally, a systematic investigation of electron-beam-induced charging in a needle-shaped specimen with an insulating Al$_{2}$O$_{3}$ apex is presented, including the dependence of the results on electron dose rate, total dose, temperature, primary electron energy and the surface state of the sample. Great care is required with the acquisition and interpretation of the results, in particular because charging phenomena are sensitive to the electrical conductivity of the sample, the presence of contact potentials and the presence of (unknown) surface states.
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856 4 _ |u https://juser.fz-juelich.de/record/877846/files/Schluesseltech_221.pdf
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909 C O |o oai:juser.fz-juelich.de:877846
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910 1 _ |0 I:(DE-588b)5008462-8
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|a Forschungszentrum Jülich
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914 1 _ |y 2020
915 _ _ |0 StatID:(DE-HGF)0510
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|a Creative Commons Attribution CC BY 4.0
920 _ _ |l yes
920 1 _ |0 I:(DE-Juel1)ER-C-1-20170209
|k ER-C-1
|l Physik Nanoskaliger Systeme
|x 0
920 1 _ |0 I:(DE-Juel1)PGI-5-20110106
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981 _ _ |a I:(DE-Juel1)ER-C-1-20170209


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