Extraordinarily Strong Interlayer Interaction in 2D Layered PtS<sub>2</sub>

Zhao, Yuda; Qiao, Jingsi; Yu, Peng; Hu, Zhixin; Lin, Ziyuan; Lau, Shu Ping; Liu, Zheng; Ji, Wei; Chai, Yang

doi:10.1002/adma.201504572

Cited by 473 publications

(557 citation statements)

References 52 publications

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“…The incident light was polarized along the horizontal direction, which is parallel to the y-axis shown in Figure 4a. The Raman scattering intensity (I) of the observed Raman vibrational modes can be identified by: [40][41][42] i s These three peaks achieve their maximum intensities at 0° and 180°, while their minimum is at 90° (Figure 4d; Figure S4, SI).…”

Section: Resultsmentioning

confidence: 99%

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Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Zhou

et al. 2017

Adv Funct Materials

103

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As a layered p-type semiconductor with a wide bandgap of 2.7 eV, GeSe 2 can compensate for the rarity of p-type semiconductors, which are desired for the production of high-integration logic circuits with low power consumption. Herein, ultrathin 2D single crystals of β-GeSe 2 are produced using van der Waals epitaxy and halide assistance; each crystalline flake is ≈7 nm thick and shaped as a rhombus. The optical and electrical properties of the flakes are studied systematically, and the temperature-dependent Raman spectra of the flakes reveal that the intensity of the Raman peaks decrease with increasing temperature. Low-temperature electrical measurements suggest that the variable-range hopping model is best for describing the electrical transport at 20-180 K; meanwhile, optical-phonon-assisted hopping can account for the transport behavior at 180-460 K. Impressively, the angle-resolved polarized Raman measurements indicate strong in-plane anisotropy of the rhombic GeSe 2 flake under a parallel polarization configuration, which may result from the low symmetry of the monoclinic crystal structure of GeSe 2 . Furthermore, a photodetector based on a rhombic GeSe 2 flake is constructed and shown to exhibit a high responsivity of 2.5 A W −1 and a fast response of ≈0.2 s. flakes under a parallel polarization configuration. Additionally, a flake is used to produce a photodetector, which exhibits a high responsivity of 2.5 A W −1 and a fast response of ≈0.2 s.

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Section: Resultsmentioning

confidence: 99%

“…Since GeSe 2 belongs to the P2 1 /c space group, the Raman tensor R of the A g mode can be represented by: [40] Adv. In the back-scattering configuration, e i and e s are both in the yz plane.…”

Section: Resultsmentioning

confidence: 99%

Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Zhou

et al. 2017

Adv Funct Materials

103

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“…Van der Waals interactions were considered at the vdW-DF level 43,44 with the optB86b 45 exchange functional, which achieves accurate results in calculating structural properties of two dimensional materials 19,20,22,46,47 The authors declare no competing financial interests.…”

Section: Dft Calculationsmentioning

confidence: 99%

“…An exceptional interlayer coupling mechanism, namely covalent-like quasi-bonding, leads to strongly layer-dependent evolution of electronic and vibrational properties, e.g. electronic bandgap, in black phosphorus 6,18,19 and PtX2 (X=S or Se) [20][21][22] . Interlayer stacking order was predicted another degree of freedom to modify electronic structures of layered materials and recently demonstrated in twisted homo- 18,[23][24][25] and vdW hetero-bilayers [26][27][28] .…”

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confidence: 99%

Inversion Domain Boundary Induced Stacking and Bandstructure Diversity in Bilayer MoSe₂

et al. 2017

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Interlayer rotation and stacking were recently demonstrated as effective strategies for tuning physical properties of various two-dimensional materials. The latter strategy was mostly realized in heterostructures with continuously varied stacking orders, which obscure the revelation of the intrinsic role of a certain stacking order in its physical properties. Here, we introduce inversion-domain-boundaries into molecular-beam-epitaxy grown MoSe2 homobilayers, which induce uncommon fractional lattice translations to their surrounding domains, accounting for the observed diversity of large-area and uniform stacking sequences. Low-symmetry stacking orders were observed using scanning transmission electron microscopy and detailed geometries were identified by density functional theory. A linear relation was also revealed between interlayer distance and stacking energy. These stacking sequences yield various energy alignments between the valence states at the Γ and K points of the Brillouin zone, showing stacking-dependent bandgaps and valence band tail states in the measured scanning tunneling spectroscopy. These results may benefit the design of two-dimensional multilayers with manipulable stacking orders

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“…We study a 4 × 4 supercell of monolayer PtSe 2 with one gas molecule adsorbed, which eliminates intermolecular interaction. [1][2][3][4][5] TMDCs can have diverse electronic properties (metallic, [6] half-metallic, [7] semiconducting, [8] and superconducting [9] ), depending on the number of transition metal d electrons and the structural polytype. The structural relaxation is assumed to be converged when the Hellmann-Feynman forces have dropped below 0.005 eV Å −1 for all atoms.…”

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confidence: 99%

Superior Gas Sensing Properties of Monolayer PtSe₂

Sajjad

Montes

Singh

et al. 2016

Adv Materials Inter

127

107

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non-self-consistent calculation, respectively. We study a 4 × 4 supercell of monolayer PtSe 2 with one gas molecule adsorbed, which eliminates intermolecular interaction. Specifically, we employ the optimized in-plane lattice parameter of 3.72 Å and add a vacuum slab of 20 Å thickness in the out-of-plane direction for our slab model. The structural relaxation is assumed to be converged when the Hellmann-Feynman forces have dropped below 0.005 eV Å −1 for all atoms.Monolayer PtSe 2 consists of Pt atoms sandwiched between Se atoms such that a top view shows a hexagonal structure with Pt and Se atoms located at alternating corners and an additional Se atom in the center of each hexagon. To determine the favorable adsorption sites for gas molecules, we consider adsorption (1) on top of the center of a hexagon (H-site), (2) on top of a Se atom (Se-site), (3) on top of a Pt atom (Pt-site), and (4) on top of a PtSe bond (B-site). Initially the center of mass of the molecule is positioned at these sites and different orientations are assessed. For example, for NO the molecular axis can be oriented parallel to the monolayer or perpendicular with the N or O atom pointing to the monolayer. A quantitative assessment of the adsorption strength is possible by means of the adsorption energy E a = E(PtSe 2 + molecule) − E(PtSe 2 ) − E(molecule), where the individual terms represent the total energies of monolayer PtSe 2 with adsorbed gas molecule, pristine monolayer PtSe 2 , and an isolated gas molecule, respectively. Negative values of E a reflect exothermic adsorption.For each gas molecule and adsorption site the calculated adsorption energy and relaxed height of the molecule above the monolayer are given in Table 1. While adsorption energies can vary for different exchange correlation functionals, we are here only interested in relative adsorption energies to identify the most favorable geometry. For this reason our analysis is also not limited by the fact that discrepancies persist in the adsorption energies calculated with different methods to model the van der Waals interaction. [28][29][30] We note that the adsorption energies in Table 1 compare well to both MoS 2 and graphene, [15,21] 2D materials have huge potential in future nanodevices, particularly transition metal dichalcogenides (TMDCs), which therefore are studied extensively in recent years. [1][2][3][4][5] TMDCs can have diverse electronic properties (metallic, [6] half-metallic, [7] semiconducting, [8] and superconducting [9] ), depending on the number of transition metal d electrons and the structural polytype. [10] However, intrinsic limitations such as the relatively low carrier mobility in MoS 2[8] call for further research. Monolayer PtSe 2 can provide an enhanced mobility and thus is of great interest for electronic applications. [11] Sensing of toxic gases is a critical task, for example, in pollution monitoring. [12] 2D materials are ideal for such purposes because of their high surface-to-volume ratio and the often strong charge transfer to/from adsor...

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Extraordinarily Strong Interlayer Interaction in 2D Layered PtS₂

Cited by 473 publications

References 52 publications

Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Inversion Domain Boundary Induced Stacking and Bandstructure Diversity in Bilayer MoSe₂

Superior Gas Sensing Properties of Monolayer PtSe₂

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Extraordinarily Strong Interlayer Interaction in 2D Layered PtS2

Cited by 473 publications

References 52 publications

Ultrathin 2D GeSe2 Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Ultrathin 2D GeSe2 Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Inversion Domain Boundary Induced Stacking and Bandstructure Diversity in Bilayer MoSe2

Superior Gas Sensing Properties of Monolayer PtSe2

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Product

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Extraordinarily Strong Interlayer Interaction in 2D Layered PtS₂

Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Inversion Domain Boundary Induced Stacking and Bandstructure Diversity in Bilayer MoSe₂

Superior Gas Sensing Properties of Monolayer PtSe₂