Practical aspects of diffractive imaging using an atomic-scale coherent electron probe

Chen, Zhen; Weyland, Matthew; Ercius, Peter; Ciston, Jim; Zheng, Changxi; Fuhrer, Michael S.; D’Alfonso, Adrian J.; Allen, L. J.; Findlay, Scott

doi:10.1016/j.ultramic.2016.06.009

Cited by 29 publications

(21 citation statements)

References 46 publications

(69 reference statements)

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“…Since then, 4D-STEM DPC has been applied to various materials science problems. Some atomic-resolution examples include imaging of SrTiO 3 by Müller et al (2014), imaging of GaN and graphene by Lazić et al (2016), and imaging of SrTiO 3 and MoS 2 by Chen et al (2016). Figure 7d shows a 4D-STEM DPC measurement of a multilayer BiFeO 3 /SrRuO 3 /DyScO 3 stack performed by Tate et al (2016).…”

Section: Differential Phase Contrastmentioning

confidence: 99%

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond

2019

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Scanning transmission electron microscopy (STEM) is widely used for imaging, diffraction, and spectroscopy of materials down to atomic resolution. Recent advances in detector technology and computational methods have enabled many experiments that record a full image of the STEM probe for many probe positions, either in diffraction space or real space. In this paper, we review the use of these four-dimensional STEM experiments for virtual diffraction imaging, phase, orientation and strain mapping, measurements of medium-range order, thickness and tilt of samples, and phase contrast imaging methods, including differential phase contrast, ptychography, and others.

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Section: Differential Phase Contrastmentioning

confidence: 99%

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond

2019

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“…In this technique, a fast pixelated detector is used to acquire a full convergent beam electron diffraction (CBED) pattern at each scan point. The resulting 4D ( x,y,k x ,k y ) data sets can later on be used to calculate synthetic images like bright field (BF), annular bright field (ABF), ADF or DPC . Even more interestingly, the 2D information available in the diffraction space allows to determine the shift of the center of mass (COM) which is directly correlated to the electric fields in present in the sample .…”

Section: Proving Charge Neutrality At the Gap–si Interface By 4dstemmentioning

confidence: 99%

Advanced Electron Microscopy for III/V on Silicon Integration

Beyer

Volz

2019

Adv Materials Inter

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The combination of III/V semiconductors with Si is very attractive, since it allows the fabrication of high efficient optoelectronic devices like solar cells, lasers or the integration of III/V transistors on Si substrates. However, the growth of polar III/V materials on nonpolar Si holds several challenges. The different valences of group III and group V atoms as well as Si possibly give rise to the formation of charged defects, i.e., antiphase boundaries, as well as to charge accumulation at the interface between the different materials. Accordingly, the interfaces present, i.e., the ones between antiphase and main phase and the one between III/V and Si, eventually limit any device's performance. Electron microscopy, in particular transmission electron microscopy, has proven to be a valuable tool to acquire quantitative information from III/V–Si heterostructures. Among this information are defect densities as well as the structure of the involved interfaces at spatial resolutions down to the atomic level. Moreover, information on charge distribution can be retrieved. In this review, the authors collocate the results gained for the model system GaP on Si utilizing various electron microscopy related techniques.

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confidence: 99%

“…In particular, the Electron Microscopy Pixel Array Detector (EMPAD) achieves a dynamic range of 1,000,000:1 within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity [4]. Sample drift distortions are minimized by the high frame rate, which enables capturing scattered electrons at each scanning position in STEM image [2][3][4][5]. While detector technologies are capable of single electron sensitivity while counting at > 1,000 fps, the number of pixels is fairly limited (128 x 128).In this presentation, we will demonstrate how a detector with a small number of pixels can be used to capture the entire electron scatter distribution at any camera length using scripting.…”

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confidence: 99%

Expanding the Dimensions of a High Dynamic Range Detector with a Limited Number of Pixels via Scripting

et al. 2019

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Hybrid 4D STEM detectors have recently enabled E/M field mapping [1], atomic resolution ptychography [2], strain mapping [1], and fully quantitative imaging [3]. In particular, the Electron Microscopy Pixel Array Detector (EMPAD) achieves a dynamic range of 1,000,000:1 within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity [4]. Sample drift distortions are minimized by the high frame rate, which enables capturing scattered electrons at each scanning position in STEM image [2][3][4][5]. While detector technologies are capable of single electron sensitivity while counting at > 1,000 fps, the number of pixels is fairly limited (128 x 128).In this presentation, we will demonstrate how a detector with a small number of pixels can be used to capture the entire electron scatter distribution at any camera length using scripting. We will discuss how we have built a custom python script to control the microscope to shift the diffraction pattern while the EMPAD acquires each dataset, Figure 1(a). We will also examine the challenges associated with reconstructing the datasets, including rotating the pattern shift axes and lens hysteresis. By including some overlap between the patterns, we will highlight our automated routine to accurately and precisely align the data post-acquisition. This process allows for the detection range to be limited only by the objective lens bore even with this small detector. As shown in Figure 1(b), a significant portion of reciprocal space is shown at high k-space sampling rate, with the final, assembled diffraction pattern retaining the fine details as in Figure 1(c).We will also discuss how to use the technique to capture only certain segments of reciprocal space to save time and storage. For example, to capture only high angle diffuse scattering, it is possible to acquire along an annulus of the diffracted intensity as in Figure 2(a). In this case, the diffraction pattern was shifted in a ring pattern to avoid the central beam. Finally, we will also discuss how this method can combine full 4D diffraction datasets to capture a larger diffraction pattern at each STEM image position. As shown in Figure 2(b)-(c), the CBED diffraction pattern was captured to beyond the FOLZ with good reciprocal space sampling using only a 128x128 pixel detector. The resulting patterns are each 32-bit 325x325 floating point pixels yielding a final image data size of 10011 gb. This enables simultaneous HAADF STEM and high precision strain mapping using the same dataset [6]. References:[1] H Ryll et al.

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Practical aspects of diffractive imaging using an atomic-scale coherent electron probe

Cited by 29 publications

References 46 publications

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond

Advanced Electron Microscopy for III/V on Silicon Integration

Expanding the Dimensions of a High Dynamic Range Detector with a Limited Number of Pixels via Scripting

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