Quantitative chemical evaluation of dilute GaNAs using ADF STEM: Avoiding surface strain induced artifacts

Grieb, Tim; Müller, Knut; Fritz, R.; Grillo, Vincenzo; Schowalter, Marco; Volz, Kerstin; Rosenauer, A.

doi:10.1016/j.ultramic.2013.02.006

Cited by 28 publications

(15 citation statements)

References 22 publications

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“…S4). We note that these findings agree with previous reports in which low-angle unfiltered STEM served for qualitative analyses in thick specimen474849 whereas quantitative agreement was found in bright field STEM in thin specimens where the fraction of inelastic intensity is low50. Moreover, energy filtered diffraction patterns at elevated thicknesses agreed with simulations, too515253.…”

Section: Discussionsupporting

confidence: 92%

“…Our setup overcomes drastic limitations owing to the speed of slow-scan pixelated detectors that have as yet allowed for spatially resolved diffractometry on a STEM raster of 64 × 64 pixels54, which restricts the field of view to the scale of approximately one crystal unit cell in high-resolution STEM. Considering former semi-quantitative STEM studies that were aiming at the determination of two different chemical compositions47 and at eliminating contrast arising from surface strain fields49 using two different camera lengths, the present option of imaging at dedicated angle intervals is expected to improve the quantitative composition analysis in established semiconductor nanostructures significantly. Furthermore, recent studies55 employing variable-angle STEM by means of two camera lengths and a conventional annular detector have successfully demonstrated the detection mapping of dopant atoms in 3D as a proof of concept.…”

Section: Discussionmentioning

confidence: 99%

“…Simulation details3049 are summarised in brief here. The incident 300 kV STEM probe was simulated using a spherical aberration of C s = 1.2 mm for the probe-forming SuperTwin objective lens of the microscope at Scherzer defocus of −48 nm and Scherzer aperture corresponding to a convergence semi-angle of 9 mrad.…”

Section: Methodsmentioning

confidence: 99%

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Materials characterisation by angle-resolved scanning transmission electron microscopy

Müller‐Caspary

Oppermann

Grieb

et al. 2016

Sci Rep

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Solid-state properties such as strain or chemical composition often leave characteristic fingerprints in the angular dependence of electron scattering. Scanning transmission electron microscopy (STEM) is dedicated to probe scattered intensity with atomic resolution, but it drastically lacks angular resolution. Here we report both a setup to exploit the explicit angular dependence of scattered intensity and applications of angle-resolved STEM to semiconductor nanostructures. Our method is applied to measure nitrogen content and specimen thickness in a GaNxAs1−x layer independently at atomic resolution by evaluating two dedicated angular intervals. We demonstrate contrast formation due to strain and composition in a Si- based metal-oxide semiconductor field effect transistor (MOSFET) with GexSi1−x stressors as a function of the angles used for imaging. To shed light on the validity of current theoretical approaches this data is compared with theory, namely the Rutherford approach and contemporary multislice simulations. Inconsistency is found for the Rutherford model in the whole angular range of 16–255 mrad. Contrary, the multislice simulations are applicable for angles larger than 35 mrad whereas a significant mismatch is observed at lower angles. This limitation of established simulations is discussed particularly on the basis of inelastic scattering.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

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Materials characterisation by angle-resolved scanning transmission electron microscopy

Müller‐Caspary

Oppermann

Grieb

et al. 2016

Sci Rep

Self Cite

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“…This further indicates that static displacements are responsible for the observed phenomenon and that the signal is also sensitive to the extent of reduction. Notably, because these defects influence the signal in the HAADF image as well as the LAADF image, it is possible that quantitative analysis of the intensity could be performed if a proper model were derived as input for the multislice routine [46, 47]. …”

Section: Resultsmentioning

confidence: 99%

Oxidation-state sensitive imaging of cerium dioxide by atomic-resolution low-angle annular dark field scanning transmission electron microscopy

et al. 2016

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Low-angle annular dark field (LAADF) scanning transmission electron microscopy (STEM) imaging is presented as a method that is sensitive to the oxidation state of cerium ions in CeO2 nanoparticles. This relationship was validated through electron energy loss spectroscopy (EELS), in situ measurements, as well as multislice image simulations. Static displacements caused by the increased ionic radius of Ce3+ influence the electron channeling process and increase electron scattering to low angles while reducing scatter to high angles. This process manifests itself by reducing the high-angle annular dark field (HAADF) signal intensity while increasing the LAADF signal intensity in close proximity to Ce3+ ions. This technique can supplement STEM-EELS and in so doing, relax the experimental challenges associated with acquiring oxidation state information at high spatial resolutions.

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“…It is possible to study the intensities associated with atomic columns through statistical analysis [4], phenomenological procedures [5] or to compare with simulations [6]. But in the case of the analysis of nanostructures like QDs all of these methodologies are affected by the dependence of the HAADF intensities on the strain fields originating from the nanostructure that alter the intensities [7], making the precise quantification of HAADF images a complicated task. This paper presents an alternative method to quantify the chemical composition of low dimensional nanostructures based on the analysis of the atomic column positions present in High-Resolution HAADF images.…”

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confidence: 99%

Determination of Local Chemistry Composition of Low-Dimensional Semiconductor Nanostructures Through the use of High-Resolution HAADF images

et al. 2015

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Quantitative chemical evaluation of dilute GaNAs using ADF STEM: Avoiding surface strain induced artifacts

Cited by 28 publications

References 22 publications

Materials characterisation by angle-resolved scanning transmission electron microscopy

Materials characterisation by angle-resolved scanning transmission electron microscopy

Oxidation-state sensitive imaging of cerium dioxide by atomic-resolution low-angle annular dark field scanning transmission electron microscopy

Determination of Local Chemistry Composition of Low-Dimensional Semiconductor Nanostructures Through the use of High-Resolution HAADF images

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