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	Author	Müller-Caspary, K.; Krause, F.F.; Winkler, F.; Béché, A.; Verbeeck, J.; Van Aert, S.; Rosenauer, A.
	Title	Comparison of first moment STEM with conventional differential phase contrast and the dependence on electron dose			Type	A1 Journal article
	Year	2019	Publication	Ultramicroscopy	Abbreviated Journal	Ultramicroscopy
	Volume	203	Issue	203	Pages	95-104
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	This study addresses the comparison of scanning transmission electron microscopy (STEM) measurements of momentum transfers using the first moment approach and the established method that uses segmented annular detectors. Using an ultrafast pixelated detector to acquire four-dimensional, momentum-resolved STEM signals, both the first moment calculation and the calculation of the differential phase contrast (DPC) signals are done for the same experimental data. In particular, we investigate the ability to correct the segment-based signal to yield a suitable approximation of the first moment for cases beyond the weak phase object approximation. It is found that the measurement of momentum transfers using segmented detectors can approach the first moment measurement as close as 0.13 h/nm in terms of a root mean square (rms) difference in 10 nm thick SrTiO3 for a detector with 16 segments. This amounts to 35% of the rms of the momentum transfers. In addition, we present a statistical analysis of the precision of first moment STEM as a function of dose. For typical experimental settings with recent hardware such as a Medipix3 Merlin camera attached to a probe-corrected STEM, we find that the precision of the measurement of momentum transfers stagnates above certain doses. This means that other instabilities such as specimen drift or scan noise have to be taken into account seriously for measurements that target, e.g., the detection of bonding effects in the charge density.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000465021000013	Publication Date	2018-12-30
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0304-3991	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.843	Times cited	25	Open Access	OpenAccess
	Notes	; The direct electron detector (Medipix3 Merlin) was funded by the Hercules fund from the Flemish Government. K. Muller-Caspary acknowledges funding from the Initiative and Network Fund of the Helmholtz Association within the framework of the Helmholtz Young Investigator Group moreSTEM (VH-NG-1317) at Forschungszentrum Julich, Germany. F. F. Krause acknowledges funding from the Central Research Development Fund of the University of Bremen, Germany. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 770887). The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) and the Research Fund of the University of Antwerp. ;			Approved	Most recent IF: 2.843
	Call Number	UA @ admin @ c:irua:160213			Serial	5242
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	Author	Grieb, T.; Krause, F.F.; Schowalter, M.; Zillmann, D.; Sellin, R.; Müller-Caspary, K.; Mahr, C.; Mehrtens, T.; Bimberg, D.; Rosenauer, A.
	Title	Strain analysis from nano-beam electron diffraction : influence of specimen tilt and beam convergence			Type	A1 Journal article
	Year	2018	Publication	Ultramicroscopy	Abbreviated Journal	Ultramicroscopy
	Volume	190	Issue	190	Pages	45-57
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Strain analyses from experimental series of nano-beam electron diffraction (NBED) patterns in scanning transmission electron microscopy are performed for different specimen tilts. Simulations of NBED series are presented for which strain analysis gives results that are in accordance with experiment. This consequently allows to study the relation between measured strain and actual underlying strain. A two-tilt method which can be seen as lowest-order electron beam precession is suggested and experimentally implemented. Strain determination from NBED series with increasing beam convergence is performed in combination with the experimental realization of a probe-forming aperture with a cross inside. It is shown that using standard evaluation techniques, the influence of beam convergence on spatial resolution is lower than the influence of sharp rings around the diffraction disc which occur at interfaces and which are caused by the tails of the intensity distribution of the electron probe. (C) 2018 Elsevier B.V. All rights reserved.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Amsterdam	Editor
	Language		Wos	000432868800006	Publication Date	2018-04-12
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0304-3991	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.843	Times cited	1	Open Access	OpenAccess
	Notes	; This work was supported by the German Research Foundation (DFG) under Contracts RO2057/11-1 and RO2057/12-1. ;			Approved	Most recent IF: 2.843
	Call Number	UA @ lucian @ c:irua:151454			Serial	5041
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	Author	Mahr, C.; Müller-Caspary, K.; Graf, M.; Lackmann, A.; Grieb, T.; Schowalter, M.; Krause, F.F.; Mehrtens, T.; Wittstock, A.; Weissmueller, J.; Rosenauer, A.
	Title	Measurement of local crystal lattice strain variations in dealloyed nanoporous gold			Type	A1 Journal article
	Year	2018	Publication	Materials research letters	Abbreviated Journal	Mater Res Lett
	Volume	6	Issue	1	Pages	84-92
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Reversible macroscopic length changes in nanoporous structures can be achieved by applying electric potentials or by exposing them to different gases or liquids. Thus, these materials are interesting candidates for applications as sensors or actuators. Macroscopic length changes originate from microscopic changes of crystal lattice parameters. In this report, we show spatially resolved measurements of crystal lattice strain in dealloyed nanoporous gold. The results confirm theory by indicating a compression of the lattice along the axis of cylindrically shaped ligaments and an expansion in radial direction. Furthermore, we show that curved npAu surfaces show inward relaxation of the surface layer. [GRAPHICS] .
	Address
	Corporate Author				Thesis
	Publisher	Taylor & Francis	Place of Publication	Abingdon	Editor
	Language		Wos	000428141500013	Publication Date	2017-11-03
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2166-3831	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	4.773	Times cited	4	Open Access	Not_Open_Access
	Notes	; This work has been supported by the Deutsche Forschungsgemeinschaft (DFG) under contracts no. RO2057/12-1 (SP 6), WI4497/1-1 (SP 2) and WE1424/17-1 (SP 3) within the research unit FOR2213 (www.nagocat.de). K.M.-C acknowledges support by the DFG under contract no. MU3660/1-1 and T.G. under contract no. RO2057/ 11-1. ;			Approved	Most recent IF: 4.773
	Call Number	UA @ lucian @ c:irua:150921			Serial	4973
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	Author	Grieb, T.; Tewes, M.; Schowalter, M.; Müller-Caspary, K.; Krause, F.F.; Mehrtens, T.; Hartmann, J.-M.; Rosenauer, A.
	Title	Quantitative HAADF STEM of SiGe in presence of amorphous surface layers from FIB preparation			Type	A1 Journal article
	Year	2018	Publication	Ultramicroscopy	Abbreviated Journal	Ultramicroscopy
	Volume	184	Issue	B	Pages	29-36
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	<script type='text/javascript'>document.write(unpmarked('The chemical composition of four Si1-xGex layers grown on silicon was determined from quantitative scanning transmission electron microscopy (STEM). The chemical analysis was performed by a comparison of the high-angle annular dark field (HAADF) intensity with multislice simulations. It could be shown that amorphous surface layers originating from the preparation process by focused-ion beam (FIB) at 30 kV have a strong influence on the quantification: the local specimen thickness is overestimated by approximately a factor of two, and the germanium concentration is substantially underestimated. By means of simulations, the effect of amorphous surface layers on the HAADF intensity of crystalline silicon and germanium is investigated. Based on these simulations, a method is developed to analyze the experimental HAADF-STEM images by taking the influence of the amorphous layers into account which is done by a reduction of the intensities by multiplication with a constant factor. This suggested modified HAADF analysis gives germanium concentrations which are in agreement with the nominal values. The same TEM lamella was treated with low-voltage ion milling which removed the amorphous surface layers completely. The results from subsequent quantitative HAADF analyses are in agreement with the nominal concentrations which validates the applicability of the used frozen-lattice based multislice simulations to describe the HAADF scattering of Si1-xGex in STEM. (C) 2017 Elsevier B.V. All rights reserved.'));
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Amsterdam	Editor
	Language		Wos	000417779800004	Publication Date	2017-10-14
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0304-3991	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.843	Times cited	7	Open Access	Not_Open_Access
	Notes	; This work was supported by the German Research Foundation (DFG) under Contract No. RO2057/11-1. ;			Approved	Most recent IF: 2.843
	Call Number	UA @ lucian @ c:irua:148500			Serial	4893
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	Author	Gauquelin, N.; van den Bos, K.H.W.; Béché, A.; Krause, F.F.; Lobato, I.; Lazar, S.; Rosenauer, A.; Van Aert, S.; Verbeeck, J.
	Title	Determining oxygen relaxations at an interface: A comparative study between transmission electron microscopy techniques			Type	A1 Journal article
	Year	2017	Publication	Ultramicroscopy	Abbreviated Journal	Ultramicroscopy
	Volume	181	Issue	181	Pages	178-190
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Nowadays, aberration corrected transmission electron microscopy (TEM) is a popular method to characterise nanomaterials at the atomic scale. Here, atomically resolved images of nanomaterials are acquired, where the contrast depends on the illumination, imaging and detector conditions of the microscope. Visualization of light elements is possible when using low angle annular dark field (LAADF) STEM, annular bright field (ABF) STEM, integrated differential phase contrast (iDPC) STEM, negative spherical aberration imaging (NCSI) and imaging STEM (ISTEM). In this work, images of a NdGaO3-La0.67Sr0.33MnO3 (NGO-LSMO) interface are quantitatively evaluated by using statistical parameter estimation theory. For imaging light elements, all techniques are providing reliable results, while the techniques based on interference contrast, NCSI and ISTEM, are less robust in terms of accuracy for extracting heavy column locations. In term of precision, sample drift and scan distortions mainly limits the STEM based techniques as compared to NCSI. Post processing techniques can, however, partially compensate for this. In order to provide an outlook to the future, simulated images of NGO, in which the unavoidable presence of Poisson noise is taken into account, are used to determine the ultimate precision. In this future counting noise limited scenario, NCSI and ISTEM imaging will provide more precise values as compared to the other techniques, which can be related to the mechanisms behind the image recording.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000411170800022	Publication Date	2017-06-03
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0304-3991	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.843	Times cited	34	Open Access	OpenAccess
	Notes	The authors acknowledge financial support from Flanders (FWO, Belgium) through project fundings (G.0044.13N, G.0374.13N, G.0368.15N, G.0369.15N), and by a Ph.D. grant to K.H.W.v.d.B. The Qu-Ant-EM microscope used for this study was partly funded by the Hercules fund from the Flemish Government. A.B. and N.G. acknowledge the EUROTAPES project (FP7-NMP.2011.2.2-1 Grant no.280432) which partly funded this study. N.G., A.B. and J.V. acknowledge funding from the European Research Council under the 7th Framework Program (FP7), ERC Starting Grant 278510 VORTEX. The research leading to these results has received funding from the Deutsche Forschungsgemeinschaft under Contract No. RO 2057/4-2 and the European Union Seventh Framework Programme under Grant Agreement 312483 – ESTEEM2. We thank Prof. G. Koster from the University of Twente for kindly providing us with the LSMO-NGO test sample.			Approved	Most recent IF: 2.843
	Call Number	EMAT @ emat @ c:irua:144435UA @ admin @ c:irua:144435			Serial	4620
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	Author	Grieb, T.; Krause, F.F.; Mahr, C.; Zillmann, D.; Müller-Caspary, K.; Schowalter, M.; Rosenauer, A.
	Title	Optimization of NBED simulations for disc-detection measurements			Type	A1 Journal article
	Year	2017	Publication	Ultramicroscopy	Abbreviated Journal	Ultramicroscopy
	Volume	181	Issue		Pages	50-60
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Nano-beam electron diffraction (NBED) is a method which can be applied to measure lattice strain and polarisation fields in strained layer heterostructures and transistors. To investigate precision, accuracy and spatial resolution of such measurements in dependence of properties of the specimen as well as electron optical parameters, simulations of NBED patterns are required which allow to predict the result of common disc-detection algorithms. In this paper we demonstrate by focusing on the detection of the central disc in crystalline silicon that such simulations require to take several experimental characteristics into account in order to obtain results which are comparable to those from experimental NBED patterns. These experimental characteristics are the background intensity, the presence of Poisson noise caused by electron statistics and blurring caused by inelastic scattering and by the transfer quality of the microscope camera. By means of these optimized simulations, different effects of specimen properties on disc detection – such as strain, surface morphology and compositional changes on the nanometer scale – are investigated and discussed in the context of misinterpretation in experimental NBED evaluations. It is shown that changes in surface morphology and chemical composition lead to measured shifts of the central disc in the NBED pattern of tens to hundreds of grad. These shifts are of the same order of magnitude or even larger than shifts that could be caused by an electric polarisation field in the range of MV/cm. (C) 2017 Elsevier B.V. All rights reserved.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Amsterdam	Editor
	Language		Wos	000411170800006	Publication Date	2017-05-03
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0304-3991	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.843	Times cited	6	Open Access	Not_Open_Access
	Notes	; This work was supported by the German Research Foundation (DFG) under Contract No. R02057/11-1, R02057/4-2 and MU3660/1-1. ;			Approved	Most recent IF: 2.843
	Call Number	UA @ lucian @ c:irua:146725			Serial	4792
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	Author	Alania, M.; De Backer, A.; Lobato, I.; Krause, F.F.; Van Dyck, D.; Rosenauer, A.; Van Aert, S.
	Title	How precise can atoms of a nanocluster be located in 3D using a tilt series of scanning transmission electron microscopy images?			Type	A1 Journal article
	Year	2017	Publication	Ultramicroscopy	Abbreviated Journal	Ultramicroscopy
	Volume	181	Issue	181	Pages	134-143
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
	Abstract	In this paper, we investigate how precise atoms of a small nanocluster can ultimately be located in three dimensions (3D) from a tilt series of images acquired using annular dark field (ADF) scanning transmission electron microscopy (STEM). Therefore, we derive an expression for the statistical precision with which the 3D atomic position coordinates can be estimated in a quantitative analysis. Evaluating this statistical precision as a function of the microscope settings also allows us to derive the optimal experimental design. In this manner, the optimal angular tilt range, required electron dose, optimal detector angles, and number of projection images can be determined.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000411170800016	Publication Date	2016-12-15
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0304-3991	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.843	Times cited	3	Open Access	OpenAccess
	Notes	The authors acknowledge financial support from the European Union under the Seventh Framework Program under a contract for an Integrated Infrastructure Initiative. Reference No. 312483-ESTEEM2. The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through project fundings (G.0374.13N, G.0369.15N, G.0368.15N, and WO.010.16N) and a post-doctoral grant to A. De Backer, and from the DFG under contract No. RO-2057/4-2.			Approved	Most recent IF: 2.843
	Call Number	EMAT @ emat @ c:irua:144432			Serial	4618
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	Author	van den Bos, K.H.W.; Krause, F.F.; Béché, A.; Verbeeck, J.; Rosenauer, A.; Van Aert, S.
	Title	Locating light and heavy atomic column positions with picometer precision using ISTEM			Type	A1 Journal article
	Year	2016	Publication	Ultramicroscopy	Abbreviated Journal	Ultramicroscopy
	Volume	172	Issue	172	Pages	75-81
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Recently, imaging scanning transmission electron microscopy (ISTEM) has been proposed as a promising new technique combining the advantages of conventional TEM (CTEM) and STEM [1]. The ability to visualize light and heavy elements together makes it a particularly interesting new, spatially incoherent imaging mode. Here, we evaluate this technique in term of precision with which atomic column locations can be measured. By using statistical parameter estimation theory, we will show that these locations can be accurately measured with a precision in the picometer range. Furthermore, a quantitative comparison is made with HAADF STEM imaging to investigate the advantages of ISTEM.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000390600200009	Publication Date	2016-10-09
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0304-3991	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.843	Times cited	8	Open Access
	Notes	The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through project fundings (G.0374.13N, G.0368.15N, G.0369.15N), and by a Ph.D. grant to K.H.W. van den Bos. The research leading to these results has received funding from the Deutsche Forschungsgemeinschaft under Contract No. RO 2057/4-2 and the European Union Seventh Framework Programme under Grant Agreement 312483 – ESTEEM2. We thank Prof. G. Koster from the University of Twente for kindly providing us with the PbTiO3 test sample.			Approved	Most recent IF: 2.843
	Call Number	EMAT @ emat @ c:irua:136109UA @ admin @ c:irua:136109			Serial	4288
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	Author	Muller-Caspary, K.; Krause, F.F.; Grieb, T.; Loffler, S.; Schowalter, M.; Béché, A.; Galioit, V.; Marquardt, D.; Zweck, J.; Schattschneider, P.; Verbeeck, J.; Rosenauer, A.
	Title	Measurement of atomic electric fields and charge densities from average momentum transfers using scanning transmission electron microscopy			Type	A1 Journal article
	Year	2016	Publication	Ultramicroscopy	Abbreviated Journal	Ultramicroscopy
	Volume	178	Issue	178	Pages	62-80
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	This study sheds light on the prerequisites, possibilities, limitations and interpretation of high-resolution differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM). We draw particular attention to the well-established DPC technique based on segmented annular detectors and its relation to recent developments based on pixelated detectors. These employ the expectation value of the momentum transfer as a reliable measure of the angular deflection of the STEM beam induced by an electric field in the specimen. The influence of scattering and propagation of electrons within the specimen is initially discussed separately and then treated in terms of a two-state channeling theory. A detailed simulation study of GaN is presented as a function of specimen thickness and bonding. It is found that bonding effects are rather detectable implicitly, e.g., by characteristics of the momentum flux in areas between the atoms than by directly mapping electric fields and charge densities. For strontium titanate, experimental charge densities are compared with simulations and discussed with respect to experimental artifacts such as scan noise. Finally, we consider practical issues such as figures of merit for spatial and momentum resolution, minimum electron dose, and the mapping of larger-scale, built-in electric fields by virtue of data averaged over a crystal unit cell. We find that the latter is possible for crystals with an inversion center. Concerning the optimal detector design, this study indicates that a sampling of 5mrad per pixel is sufficient in typical applications, corresponding to approximately 10x10 available pixels.
	Address	Institut fur Festkr perphysik, Universitat Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Wos	000403862900009	Publication Date	2016-05-12
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0304-3991	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.843	Times cited	93	Open Access
	Notes	K.M.-C. acknowledges support from the Deutsche Forschungsgemeinschaft (DFG) under contract MU3660/1-1. This work was further supported by the DFG under contract RO2057/4-2 and O2057/11-1. J.V. and A.B. acknowledge funding from the European Research Council (ERC) under the 7th Framework Program (FP7), and ERC Starting Grant No. 278510-VORTEX. Experimental results are obtained on the Qu-Ant-EM microscope partly funded by the Hercules fund from the Flemish government. J.V. also acknowledges funding through a GOA project “Solarpaint” of the University of Antwerp. SL and PS acknowledge financial support by the Austrian Science Fund (FWF) under grants No. I543-N20 and J3732-N27. ECASJO_;			Approved	Most recent IF: 2.843
	Call Number	c:irua:134125UA @ admin @ c:irua:134125			Serial	4098
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	Author	Krause, F.F.; Ahl, J.P.; Tytko, D.; Choi, P.P.; Egoavil, R.; Schowalter, M.; Mehrtens, T.; Müller-Caspary, K.; Verbeeck, J.; Raabe, D.; Hertkorn, J.; Engl, K.; Rosenauer, A.
	Title	Homogeneity and composition of AlInGaN : a multiprobe nanostructure study			Type	A1 Journal article
	Year	2015	Publication	Ultramicroscopy	Abbreviated Journal	Ultramicroscopy
	Volume	156	Issue	156	Pages	29-36
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	The electronic properties of quaternary AlInGaN devices significantly depend on the homogeneity of the alloy. The identification of compositional fluctuations or verification of random-alloy distribution is hence of grave importance. Here, a comprehensive multiprobe study of composition and compositional homogeneity is presented, investigating AlInGaN layers with indium concentrations ranging from 0 to 17 at% and aluminium concentrations between 0 and 39 at% employing high-angle annular dark field scanning electron microscopy (HAADF STEM), energy dispersive X-ray spectroscopy (EDX) and atom probe tomography (APT). EDX mappings reveal distributions of local concentrations which are in good agreement with random alloy atomic distributions. This was hence investigated with HAADF STEM by comparison with theoretical random alloy expectations using statistical tests. To validate the performance of these tests, HAADF STEM image simulations were carried out for the case of a random-alloy distribution of atoms and for the case of In-rich clusters with nanometer dimensions. The investigated samples, which were grown by metal-organic vapor phase epitaxy (MOVPE), were thereby found to be homogeneous on this nanometer scale. Analysis of reconstructions obtained from APT measurements yielded matching results. Though HAADF STEM only allows for the reduction of possible combinations of indium and aluminium concentrations to the proximity of isolines in the two-dimensional composition space. The observed ranges of composition are in good agreement with the EDX and APT results within the respective precisions.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Amsterdam	Editor
	Language		Wos	000361001800006	Publication Date	2015-04-26
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0304-3991;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.843	Times cited	11	Open Access
	Notes	312483 Esteem2; esteem2_ta			Approved	Most recent IF: 2.843; 2015 IF: 2.436
	Call Number	c:irua:126965 c:irua:126965UA @ admin @ c:irua:126965			Serial	1485
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	Author	Mueller, K.; Krause, F.F.; Béché, A.; Schowalter, M.; Galioit, V.; Loeffler, S.; Verbeeck, J.; Zweck, J.; Schattschneider, P.; Rosenauer, A.
	Title	Atomic electric fields revealed by a quantum mechanical approach to electron picodiffraction			Type	A1 Journal article
	Year	2014	Publication	Nature communications	Abbreviated Journal	Nat Commun
	Volume	5	Issue		Pages	5653
	Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
	Abstract	By focusing electrons on probes with a diameter of 50 pm, aberration-corrected scanning transmission electron microscopy (STEM) is currently crossing the border to probing subatomic details. A major challenge is the measurement of atomic electric fields using differential phase contrast (DPC) microscopy, traditionally exploiting the concept of a field- induced shift of diffraction patterns. Here we present a simplified quantum theoretical interpretation of DPC. This enables us to calculate the momentum transferred to the STEM probe from diffracted intensities recorded on a pixel array instead of conventional segmented bright- field detectors. The methodical development yielding atomic electric field, charge and electron density is performed using simulations for binary GaN as an ideal model system. We then present a detailed experimental study of SrTiO3 yielding atomic electric fields, validated by comprehensive simulations. With this interpretation and upgraded instrumentation, STEM is capable of quantifying atomic electric fields and high-contrast imaging of light atoms.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000347227700003	Publication Date	2014-12-15
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2041-1723;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	12.124	Times cited	197	Open Access
	Notes	246791 COUNTATOMS; 278510 VORTEX; Hercules; 312483 ESTEEM2; esteem2ta; ECASJO;			Approved	Most recent IF: 12.124; 2014 IF: 11.470
	Call Number	UA @ lucian @ c:irua:122835UA @ admin @ c:irua:122835			Serial	166
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