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Atomic electrostatic maps of 1D channels in 2D semiconductors using 4D scanning transmission electron microscopy.

ABSTRACT: Defects in materials give rise to fluctuations in electrostatic fields that reflect the local charge density, but imaging this with single atom sensitivity is challenging. However, if possible, this provides information about the energetics of adatom binding, localized conduction channels, molecular functionality and their relationship to individual bonds. Here, ultrastable electron-optics are combined with a high-speed 2D electron detector to map electrostatic fields around individual atoms in 2D monolayers using 4D scanning transmission electron microscopy. Simultaneous imaging of the electric field, phase, annular dark field and the total charge in 2D MoS₂ and WS₂ is demonstrated for pristine areas and regions with 1D wires. The in-gap states in sulphur line vacancies cause 1D electron-rich channels that are mapped experimentally and confirmed using density functional theory calculations. We show how electrostatic fields are sensitive in defective areas to changes of atomic bonding and structural determination beyond conventional imaging.

SUBMITTER: Fang S

PROVIDER: S-EPMC6408534 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Atomic electrostatic maps of 1D channels in 2D semiconductors using 4D scanning transmission electron microscopy.

Fang Shiang S Wen Yi Y Allen Christopher S CS Ophus Colin C Han Grace G D GGD Kirkland Angus I AI Kaxiras Efthimios E Warner Jamie H JH

Nature communications 20190308 1

Defects in materials give rise to fluctuations in electrostatic fields that reflect the local charge density, but imaging this with single atom sensitivity is challenging. However, if possible, this provides information about the energetics of adatom binding, localized conduction channels, molecular functionality and their relationship to individual bonds. Here, ultrastable electron-optics are combined with a high-speed 2D electron detector to map electrostatic fields around individual atoms in ...[more]

PMID: 30850616

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Project description:BackgroundThe collection and analysis of Atomic Force Microscopy force curves is a well-established procedure to obtain high-resolution information of non-topographic data from any kind of sample, including biological specimens. In particular, these analyses are commonly employed to study elasticity, stiffness or adhesion properties of the samples. Furthermore, the collection of several force curves over an extended area of the specimens allows reconstructing maps, called force volume maps, of the spatial distribution of the mechanical properties. Coupling these maps with the conventional high-resolution topographic reconstruction of the sample's surface, provides a deeper insight on the sample composition from the structural and nanomechanical point of view.ResultsIn this paper we present the open source software package FC_analysis that automatically analyses single force curves or entire force volume maps to yield the corresponding elasticity and deformability images. The principal characteristic of the FC_analysis is a large adaptability to the various experimental setups and to different analysis methodologies. For instance, the user can provide custom values for the detector sensitivity, scanner-z sensitivity, cantilever's elastic constant and map's acquisition modality and can choose between different analysis methodologies. Furthermore, the software allows the optimization of the fitting parameters and gives direct control on each step of the analysis procedure. Notably, to overcome a limitation common to many other analysis programs, FC_analysis can be applied to a rectangular portion of the image, allowing the analysis of inhomogeneous samples. Finally, the software allows reconstructing a Young's modulus map at different penetration depths, enabling the use of modern investigation tools such as the force tomography.ConclusionsThe FC_analysis software aims to become a useful tool for the analysis of force curves maps collected using custom or commercial Atomic Force Microscopes, and is especially useful in those cases for which the producer doesn't release a dedicated software.

Dataset Information

Atomic electrostatic maps of 1D channels in 2D semiconductors using 4D scanning transmission electron microscopy.

Publications

Atomic electrostatic maps of 1D channels in 2D semiconductors using 4D scanning transmission electron microscopy.

Similar Datasets

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