Transition-Metal Chalcogenides With Layer Structures and Features of the Filling of Their Brillouin Zones

Kalikhman, V. L.; Umanskii, Ya.S.

doi:10.1070/pu1973v015n06abeh005061

Cited by 48 publications

(15 citation statements)

References 62 publications

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“…4) for 773 K by Moh et al 78 shows a complete ternary solid solution, (W,Mo)S 2 , whereby tungsten and molybdenum interchangeably occupy the trigonally coordinated site and the sulfur remains in the pyramidal locations. 36 At 773 K, MoS 2 is more stable, so the tie lines between the MoS 2 -WS 2 solid solution and the Mo-W solid solution include a tie line between a very MoS 2 -rich solution and tungsten-rich solution, as shown in Fig. 4.…”

Section: Group 5: V Nb and Tamentioning

confidence: 99%

“…36,37 The 3R-MoS 2 structure is metastable, and will transform to 2H-MoS 2 upon annealing at 873 K for around 3 weeks. 38 Most experimental research has been performed on 2H-MoS 2 bulk samples before work began on 2D samples, so unless otherwise noted, all literature summarized below was performed on bulk samples of the 2H-MoS 2 polymorph.…”

Section: Molybdenum Disulfide Crystallographymentioning

confidence: 99%

“…36 In the bulk, MoS 2 has two common polymorphs: 2H-MoS 2 and 3R-MoS 2 , the difference between them being the stacking order of S-Mo-S sheets. In both structures, Mo has trigonal-prismatic coordination.…”

Section: Molybdenum Disulfide Crystallographymentioning

confidence: 99%

See 2 more Smart Citations

Transition Metal–MoS2 Reactions: Review and Thermodynamic Predictions

Domask

Gurunathan

Mohney

2015

Journal of Elec Materi

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Molybdenum disulfide is a layered transition-metal dichalcogenide semiconductor that is attracting renewed attention for its potential use in future nanoscale electronics, optoelectronics, catalysis, tribology, and other fields. In all of these cases, the interaction between MoS 2 and various transition metals is very important. In this work we survey the thermodynamics of the metal-Mo-S systems and the anticipated reaction products from transition metals and MoS 2 . We examined over 200 references on the reactions between transitions metals (M) and MoS 2 , compiled thermodynamic data, and used the thermodynamic data to predict M-Mo-S ternary phase diagrams for systems without experimentally determined diagrams. Where possible, experimental literature on the interactions between metals and MoS 2 was used to corroborate our predicted diagrams and stable reaction products. Both the previously reported and newly predicted M-Mo-S phase diagrams fall into three categories. In the first category, the metal is in thermodynamic equilibrium with MoS 2 . In another, there is a driving force for the metal to reduce MoS 2 , with tie lines to sulfides of the contact metal dominating the phase diagram. In a final category, there is a very stable solid solution or ternary phase that dominates the phase diagram. Better understanding of the phase equilibria in the M-Mo-S systems will aid research on the use of MoS 2 in a variety of fields.

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Section: Group 5: V Nb and Tamentioning

confidence: 99%

Section: Molybdenum Disulfide Crystallographymentioning

confidence: 99%

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Transition Metal–MoS2 Reactions: Review and Thermodynamic Predictions

Domask

Gurunathan

Mohney

2015

Journal of Elec Materi

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“…2a-d, respectively, and clearly display the six-fold crystal symmetry. At an electron energy of 48eV, the mean free path of the low-energy electrons is ~5.2Å, [20] which is comparable to the thickness of a single covalently bound Se-W-Se unit of monolayer WSe 2 (~7Å).[4] [21] With increasing WSe 2 thickness, the LEED spots become sharper due, in part, to decreased scattering from the substrate. [22] This assertion is supported by the monotonically decreasing full-width-at-half-maximum (FWHM) of the (00) diffraction spot, plotted for different electron energies in Fig.…”

mentioning

confidence: 99%

“…[4] [21] With increasing WSe 2 thickness, the LEED spots become sharper due, in part, to decreased scattering from the substrate. [22] This assertion is supported by the monotonically decreasing full-width-at-half-maximum (FWHM) of the (00) diffraction spot, plotted for different electron energies in Fig.…”

mentioning

confidence: 99%

Layer-dependent electronic structure of an atomically heavy two-dimensional dichalcogenide

et al. 2015

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We report angle-resolved photoemission spectroscopic measurements of the evolution of the thickness-dependent electronic band structure of the heavy-atom two-dimensional layered, dichalcogenide, tungsten-diselenide (WSe 2 ). Our data, taken on mechanically exfoliated WSe 2 singlecrystals, provide direct evidence for shifting of the valence-band maximum from Γ (multilayer WSe 2 ), to K , (single-layer WSe 2 ). Further, our measurements also set a lower bound on the energy of the direct band-gap and provide direct measurement of the hole effective mass.Single layers of two-dimensional metal dichalcogenides (TMDCs) such as MoS 2 , have emerged as a new class of non-centrosymmetric direct-bandgap materials with potential photonic and spintronic applications.[ [4] . In addition, ML WSe 2 has been demonstrated to be the first TMDC material possessing ambipolar, i.e., both p-type and n-type conducting behavior, [4][12] thus making it possible to design additional electronic functionality, such as p-n junctions or complementary logic circuits.Despite these intriguing characteristics, measurements of ML WSe 2 have generally been limited to probing of optical and transport properties. [4][5] [6] In this paper, we report thickness-dependent measurements of the surface and electronic structure of exfoliated WSe 2, using low-energy electron microscopy (LEEM), diffraction (LEED), and micrometer-scale angle-resolved photoemission spectroscopy (µ-ARPES) of samples supported on a native-oxide terminated silicon substrate. Our experimental results provide direct evidence for a predicted valence-band maximum (VBM) symmetrypoint change, which leads to an indirect-to-direct bandgap transition. Because TMDCs have a large carrier effective mass and reduced screening in two dimensions, electron-hole interactions are much stronger than in conventional semiconductors. [13][14] [15] Our results allow us to obtain a direct measurement of the hole effective mass. Finally, our measurements allow us to directly infer a lower bound on the energy of the direct band gap. 2Our measurements were performed using the spectroscopic photoemission and low-energy electron microscope (SPE-LEEM) system at the National Synchrotron Light Source (NSLS) beamline U5UA.[16] [17] The spectrometer energy resolution of this instrument was set to 100 meV at 33 eV incident photon energy with a beam spot size of 1 μm in diameter. The momentum resolution is ~0.02 Å -1. Exfoliated WSe 2 samples were transferred to a native-oxide covered Si substrate; prior to measurements, these samples were annealed at 350 o C for ~12 hours under UHV conditions. The layer number of the sample is determined by Raman and photoluminescence spectroscopy.[18] [19] Additional experimental details can be found in the Supplemental Materials section.Sample quality and crystal orientation were examined using both LEEM and µ-LEED (Fig. 1). Diffraction patterns (at a primary electron energy of 48eV) of exfoliated WSe 2 flakes of 1-3ML and bulk are shown in Fig. 2a-d, respectively, and cl...

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Future Aspects of MOCVD Technology for Epitaxial Growth of Semiconductors

Detchprohm

Ryou

et al. 2019

Metalorganic Vapor Phase Epitaxy (MOVPE)

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Transition-Metal Chalcogenides With Layer Structures and Features of the Filling of Their Brillouin Zones

Cited by 48 publications

References 62 publications

Transition Metal–MoS2 Reactions: Review and Thermodynamic Predictions

Transition Metal–MoS2 Reactions: Review and Thermodynamic Predictions

Layer-dependent electronic structure of an atomically heavy two-dimensional dichalcogenide

Future Aspects of MOCVD Technology for Epitaxial Growth of Semiconductors

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