Busse, Carsten
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Busse, Carsten
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Publication Access status: Metadata only , Dislocation-free two-dimensional concentric lateral heterostructures: MoS2–TaS2/Au(111)We prepared two-dimensional concentric lateral heterostructures of the monolayer transition metal dichalcogenides MoS 2 and TaS 2 by reactive molecular beam epitaxy on chemically inert and weakly interacting Au(111). The heterostructures are in a size regime where quantum confinement can be expected. Despite large lattice mismatch a seamless interconnection of the two materials has been achieved, confirming that the semiconducting core is fully enclosed by a metallic border around its circumference. The resulting strain is analyzed on the atomic scale using scanning tunneling microscopy, corroborated by calculations based on empirical potentials and compared to results from finite elements simulations.Source Type:Article2 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Phase engineering in tantalum sulfide monolayers on Au(111)We prepare monolayers of tantalum sulfide on Au(111) by evaporation of Ta in a reactive background of H 2 S. Under sulfur-rich conditions, monolayers of 2H-TaS 2 develop, whereas under sulfur-poor conditions TaS forms, a structure that can be derived from 2H-TaS 2 by removal of the bottom S layer. We analyze the alignment of the layers with respect to the substrate and the relation with the domains in the Au(111) herringbone reconstruction using scanning tunneling microscopy. With the help of density functional theory calculations we can determine the registry of the two phases with the substrate. We develop a growth process that allows preparation of uniquely oriented 2H-TaS 2 on Au(111). 2H-TaS 2 and TaS have a remarkably similar in-plane lattice structure and we observe the formation of lateral 2H-TaS 2 -TaS heterostructures with atomically well-defined and defect-free boundaries. We observe mirror twin boundaries within 2H-TaS 2 along the S- and Ta-edge.Source Type:Article6 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Probing the interplay of interactions, screening and strain in monolayer MoS2 via self-intercalationControlling many-body interactions in two-dimensional systems remains a formidable task from the perspective of both fundamental physics and application. Here, we explore remarkable electronic structure alterations of MoS2 monolayer islands on graphene on Ir(111) induced by non-invasive self-intercalation. This introduces significant differences in morphology and strain of MoS2 as a result of the modified interaction with the substrate. Consequently, considerable changes of the band gap and non-rigid electronic shifts of valleys are detected, which are a combined effect of the screening of the many-body interactions and strain in MoS2. Furthermore, theory shows that each substrate leaves a unique stamp on the electronic structure of two-dimensional material in terms of those two parameters, restricted by their correlation.Source Type:Article4 83 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Tin Halide Perovskite Epitaxial Films on Gold Surfaces: Atomic Structure and StabilityTin‐based halide perovskite solar cells can be efficient and environmentally friendly substitutions to lead‐based halide perovskite solar cells, but they have a drawback due to oxidation from Sn 2+ to Sn 4+ . Using vacuum deposition, epitaxially aligned CsSnBr 3 ultrathin films are prepared on Au(111) and Au(100) and characterized with scanning tunneling microscopy (STM), low‐energy electron diffraction (LEED), and X‐ray photoelectron spectroscopy (XPS). By co‐evaporation of the precursor molecules CsBr and SnBr 2 , few monolayers of perovskite are obtained. On Au(111), CsSnBr 3 grows in three differently oriented domains due to the hexagonal symmetry of the substrate. On Au(100), which has square symmetry, identical to CsSnBr 3 , but with about half the lattice constant of the perovskite, a (2×2) superstructure is observed. The perovskite is terminated with the (001) facet showing a square surface structure in agreement with density functional theory (DFT) calculations. Chemical analysis is performed in ultra‐high vacuum (UHV) conditions and no indication of a tin oxidation state higher than Sn 2+ is found in the films. However, after exposure to air, rapid and severe changes in the films are observed, highlighting the importance of preparing tin perovskites in a controlled environment to maintain their stability and avoid oxidation‐related issues.Source Type:Article3 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Transition from fractal-dendritic to compact islands for the 2D-ferroelectric SnSe on graphene/Ir(111)Epitaxial growth is a versatile method to prepare two-dimensional van der Waals ferroelectrics like group IV monochalcogenides which have potential for novel electronic devices and sensors. We systematically study SnSe monolayer islands grown by molecular beam epitaxy, especially the effect of annealing temperature on shape and morphology of the edges. Characterization of the samples by scanning tunneling microscopy reveals that the shape of the islands changes from fractal-dendritic after deposition at room temperature to a compact rhombic shape through annealing, but ripening processes are absent up to the desorption temperature. A two-step growth process leads to large, epitaxially aligned rhombic islands bounded by well-defined $\left\langle 110\right\rangle $ -edges (armchair-like), which we claim to be the equilibrium shape of the stoichiometric SnSe monolayer islands. The relaxation of the energetically favorable edges is detected in atomically resolved STM images. The experimental findings are supported by the results of our first-principles calculations, which provide insights into the energetics of the edges, their reconstructions, and yields the equilibrium shapes of the islands which are in good agreement with the experiment.Source Type:Article2
