Berlin 2024 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 7: 2D Materials and their Heterostructures III
DS 7.4: Vortrag
Mittwoch, 20. März 2024, 10:15–10:30, A 053
Direct visualization of stacking-selective self-intercalation in epitaxial Nb1+xSe2 films — Hongguang Wang1, •Jiawei Zhang1, Chen Shen2, Chao Yang1, Kathrin Küster1, Ulrich Starke1, Hongbin Zhang2, Dennis Huang1, Peter A. van Aken1, and Hidenori Takagi1 — 1Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany — 2Department of Materials and Earth Sciences, Technical University of Darmstadt, 64289 Darmstadt, Germany
Two-dimensional (2D) van der Waals (vdW) materials are particularly intriguing due to the rich tuning possibilities offered by stacking 2D layers or introducing intercalants into the vdW gaps. However, current knowledge of the interplay between stacking polytypes and intercalation is limited by macroscopically averaged probes. Here, using atomic-resolution electron energy-loss spectroscopy in a scanning transmission electron microscope, we directly visualize a stacking-selective self-intercalation phenomenon in the transition-metal dichalcogenide (TMDC) material Nb1+xSe2: In epitaxial Nb1+xSe2 films with both the parent 180∘ stacking and additional 0∘-stacked phases, the excess Nb atoms are predominantly found between the 180∘-stacked layers. The 0∘-stacked layers arise as a means of staggering the intercalants, i.e., to increase their interlayer separation, rather than to accommodate the intercalants themselves, as has been previously suggested. Our results not only provide an updated microscopic understanding of Nb1+xSe2, but also prospects for engineering the functionality of TMDCs via stacking-selective self-intercalation.
Keywords: transition metal dichalcogenide; intercalation; stacking polytypes; scanning transmission electron microscope; thin-film epitaxy