“…The image filtering procedure followed that used by Wu et al SnS 2 , as seen in the ADF–STEM image, appears to crystallize in the 1T polymorph. This arrangement is similar to that observed for 1T‐MoS 2 . On the other hand, the ADF–STEM image of SnS shows its orthorhombic arrangement, which can be clearly differentiated from the image of SnS 2 .…”
Tin sulfides can exist in a variety of phases and polytypes due to the different oxidation states of Sn. A subset of these phases and polytypes take the form of layered 2D structures that give rise to a wide host of electronic and optical properties. Hence, achieving control over the phase, polytype, and thickness of tin sulfides is necessary to utilize this wide range of properties exhibited by the compound. This study reports on phase-selective growth of both hexagonal tin (IV) sulfide SnS2 and orthorhombic tin (II) sulfide SnS crystals with diameters of over tens of microns on SiO2 substrates through atmospheric pressure vapor-phase method in a conventional horizontal quartz tube furnace with SnO2 and S powders as the source materials. Detailed characterization of each phase of tin sulfide crystals is performed using various microscopy and spectroscopy methods, and the results are corroborated by ab initio density functional theory calculations.
“…The image filtering procedure followed that used by Wu et al SnS 2 , as seen in the ADF–STEM image, appears to crystallize in the 1T polymorph. This arrangement is similar to that observed for 1T‐MoS 2 . On the other hand, the ADF–STEM image of SnS shows its orthorhombic arrangement, which can be clearly differentiated from the image of SnS 2 .…”
Tin sulfides can exist in a variety of phases and polytypes due to the different oxidation states of Sn. A subset of these phases and polytypes take the form of layered 2D structures that give rise to a wide host of electronic and optical properties. Hence, achieving control over the phase, polytype, and thickness of tin sulfides is necessary to utilize this wide range of properties exhibited by the compound. This study reports on phase-selective growth of both hexagonal tin (IV) sulfide SnS2 and orthorhombic tin (II) sulfide SnS crystals with diameters of over tens of microns on SiO2 substrates through atmospheric pressure vapor-phase method in a conventional horizontal quartz tube furnace with SnO2 and S powders as the source materials. Detailed characterization of each phase of tin sulfide crystals is performed using various microscopy and spectroscopy methods, and the results are corroborated by ab initio density functional theory calculations.
“…The plan-view HAADF-STEM images can be used to precisely measure the thickness of atomically-thin 2D materials as the image contrast has a direct correlation with the number of atoms in a given atomic column. 24,25 BAs has an AB stacking of layers where every other layer is half unit-cell shifted in the [100] direction from the layer before, as illustrated in Figure 2a. 14,25 When viewed from the [010] direction, the lateral atomic position of the alternating layers, that are half unit-cell shifted in the [100] direction, can be seen.…”
Section: Atomic Structure and Anisotropymentioning
Black arsenic (BAs) is a van der Waals layered material with a puckered honeycomb structure and has received increased interest due to its anisotropic properties and promising performance in devices. Here, crystalline structure, thickness-dependent dielectric responses, and ambient stability of BAs nanosheets are investigated using STEM imaging and spectroscopy. Atomic-resolution HAADF-STEM images directly visualize the three-dimensional structure and evaluates the degree of anisotropy. STEM-EELS is used to measure the dielectric response of BAs as a function of the number of layers. Finally, BAs degradation under different ambient environments is studied highlighting high sensitivity to moisture in the air.
“…Based on the image, the solution grown film shows step changes in its thickness. Figure 8c shows a high magnification image of the film where the atomic structure of MoS 2 can be observed along the [001] zone axis 31 . The lattice parameter of MoS 2 measured in the image is 3.2 A, which is in agreement with previous findings 32 .Figure 8ADF-STEM images of synthesized MoS 2 at various magnifications ( a ) Low magnification image showing a large synthesized and transferred continuous MoS 2 film.…”
It is of paramount importance to improve the control over large area growth of high quality molybdenum disulfide (MoS2) and other types of 2D dichalcogenides. Such atomically thin materials have great potential for use in electronics, and are thought to make possible the first real applications of spintronics. Here in, a facile and reproducible method of producing wafer scale atomically thin MoS2 layers has been developed using the incorporation of a chelating agent in a common organic solvent, dimethyl sulfoxide (DMSO). Previously, solution processing of a MoS2 precursor, ammonium tetrathiomolybdate ((NH4)2MoS4), and subsequent thermolysis was used to produce large area MoS2 layers. Our work here shows that the use of ethylenediaminetetraacetic acid (EDTA) in DMSO exerts superior control over wafer coverage and film thickness, and the results demonstrate that the chelating action and dispersing effect of EDTA is critical in growing uniform films. Raman spectroscopy, photoluminescence (PL), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and high-resolution scanning transmission electron microscopy (HR-STEM) indicate the formation of homogenous few layer MoS2 films at the wafer scale, resulting from the novel chelant-in-solution method.
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