DFT-Assisted Investigation of the Electric Field and Charge Density Distribution of Pristine and Defective 2D WSe$_2$ by Differential Phase Contrast Imaging
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arXiv
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2023
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| author | Groll, Maja Bürger, Julius Caltzidis, Ioannis Jöns, Klaus D. Schmidt, Wolf Gero Gerstmann, Uwe Lindner, Jörg K. N. |
| author_facet | Groll, Maja Bürger, Julius Caltzidis, Ioannis Jöns, Klaus D. Schmidt, Wolf Gero Gerstmann, Uwe Lindner, Jörg K. N. |
| contents | Most properties of solid materials are defined by their internal electric field and charge density distributions which so far are difficult to measure with high spatial resolution. Especially for 2D materials, the atomic electric fields influence the optoelectronic properties. In this study, the atomic-scale electric field and charge density distribution of WSe$_2$ bi- and trilayers are revealed by using an emerging microscopy technique, differential phase contrast (DPC) imaging in the scanning transmission electron microscope (STEM). For pristine material, a higher positive charge density located at the selenium atomic columns compared to the tungsten atomic columns is obtained and tentatively explained by a coherent scattering effect. Furthermore, the change in the electric field distribution induced by a missing selenium atomic column is investigated. A characteristic electric field distribution in the vicinity of the defect with locally reduced magnitudes compared to the pristine lattice is observed. This effect is accompanied by a considerable inward relaxation of the surrounding lattice, which according to first principles DFT calculation is fully compatible with a missing column of Se atoms. This shows that DPC imaging, as an electric field sensitive technique, provides additional and remarkable information to the otherwise only structural analysis obtained with conventional STEM imaging. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2304_01068 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | DFT-Assisted Investigation of the Electric Field and Charge Density Distribution of Pristine and Defective 2D WSe$_2$ by Differential Phase Contrast Imaging Groll, Maja Bürger, Julius Caltzidis, Ioannis Jöns, Klaus D. Schmidt, Wolf Gero Gerstmann, Uwe Lindner, Jörg K. N. Materials Science Most properties of solid materials are defined by their internal electric field and charge density distributions which so far are difficult to measure with high spatial resolution. Especially for 2D materials, the atomic electric fields influence the optoelectronic properties. In this study, the atomic-scale electric field and charge density distribution of WSe$_2$ bi- and trilayers are revealed by using an emerging microscopy technique, differential phase contrast (DPC) imaging in the scanning transmission electron microscope (STEM). For pristine material, a higher positive charge density located at the selenium atomic columns compared to the tungsten atomic columns is obtained and tentatively explained by a coherent scattering effect. Furthermore, the change in the electric field distribution induced by a missing selenium atomic column is investigated. A characteristic electric field distribution in the vicinity of the defect with locally reduced magnitudes compared to the pristine lattice is observed. This effect is accompanied by a considerable inward relaxation of the surrounding lattice, which according to first principles DFT calculation is fully compatible with a missing column of Se atoms. This shows that DPC imaging, as an electric field sensitive technique, provides additional and remarkable information to the otherwise only structural analysis obtained with conventional STEM imaging. |
| title | DFT-Assisted Investigation of the Electric Field and Charge Density Distribution of Pristine and Defective 2D WSe$_2$ by Differential Phase Contrast Imaging |
| topic | Materials Science |
| url | https://arxiv.org/abs/2304.01068 |