STM/AFM investigations of β-MoTe2, α-MoTe2 and WTe2

Hla, Saw‐Wai; Marinković, V.; Prodan, A.; Muševič, Igor

doi:10.1016/0039-6028(95)01106-4

Cited by 39 publications

(22 citation statements)

References 9 publications

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“…The tendency of Δρ and its components to zero shows the proximity to the state of strong electron delocalization and signifies that the system approaches a "chemical catastrophe", 9 realized here in the transformation of 2-D semiconductor α-MoTe 2 to 1-D metal β-MoTe 2 . 11 The conclusion is supported by the topological analysis of the electron density distribution function of β-MoTe 2 ( Table 2) The same 1-D metal chains are found in the zigzag terminated nanoribbons of MoS 2 where S atoms at the side edge of ribbon are removed and the local axial symmetry of the edge Mo 4+ is ruptured. In this case the σ-overlapping of the polar lobes of the Mo(4d z 2 ) orbitals and formation of the 1-D 4+ ions is restored to its initial trigonal-prismatic coordination (in the arm-chair-terminated form nanoribbons of MoS 2 ), the electronic system of Mo(4d z 2 ) orbitals changes to the starting planar arrangement and σ-overlapping of the equatorial lobes of the Mo(4d z 2 ) orbitals.…”

Section: ■ Resultsmentioning

confidence: 81%

“…Here, we present a conclusive evidence that the electronic conductivity of twodimensional (2-D) semiconductors MoX 2 (X = S, 1−8 Se, Te) can be switched between "off" and "on" states either spontaneously or under the influence of an external stimulus. The conclusions are achieved with topological analysis of the function of electron density distribution 9,10 in nanolayered MoS 2 , MoSe 2 , and bistable MoTe 2 showing α−β transition 11 from the 2-D semiconductor to 1-D metal state. Similar transitions in one-dimensional (1-D) nanoribbons of MoS 2 can be caused by chemical modification of the edges from armchairterminated (semiconducting form) to the zigzag edges (metallic and ferromagnetic); 12 both forms are promising for nanoscale electronic devices.…”

Section: ■ Introductionmentioning

confidence: 98%

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Transition from 2-D Semiconductor to 1-D Metal State and Electron Density Distribution in Nanolayered MoX₂(X = S, Se, Te)

et al. 2012

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Molybdenum dichalcogenides MoX 2 (X = S, Se, Te) have been lately regarded as new and very promising compounds whith potential superiority over the physical limits of silicon to use in future electronic circuits in terms of miniaturization, electricity consumption, and mechanical flexibility. The purpose of the research is to study the transition from 2-D semiconductor to 1-D metal state in MoX 2 by the topological analysis of electron density distribution. It is shown that 2-D−1-D transition is accompanied by the rearrangement of Mo(4d)-electron density, the disruption of multicentered Mo−Mo interaction, loss of trigonal (C 3 ) symmetry, and formation of 1-D metal zigzag chains Mo−Mo−Mo along the selected axis of the structure. ■ INTRODUCTIONThe development of nano systems with switchable conductivity can potentially lead to the architecture of materials with controllable electronic properties. Here, we present a conclusive evidence that the electronic conductivity of twodimensional (2-D) semiconductors MoX 2 (X = S, 1−8 Se, Te) can be switched between "off" and "on" states either spontaneously or under the influence of an external stimulus. The conclusions are achieved with topological analysis of the function of electron density distribution 9,10 in nanolayered MoS 2 , MoSe 2 , and bistable MoTe 2 showing α−β transition 11 from the 2-D semiconductor to 1-D metal state. Similar transitions in one-dimensional (1-D) nanoribbons of MoS 2 can be caused by chemical modification of the edges from armchairterminated (semiconducting form) to the zigzag edges (metallic and ferromagnetic); 12 both forms are promising for nanoscale electronic devices. 13,14 However, the electronic mechanism of transition from semiconductor to metallic state in molybdenum dichalcogenides has not been studied yet. 15 ■ COMPUTATIONAL DETAILS AND THEORETICAL APPROACHThe density functional theory (DFT) was used to calculate the electron density distribution function of monolayers in molybdenum dichalcogenides MoX 2 (X = S, Se, Te). It should be mentioned that the properties of electron density distribution are most informative and sensitive parameters in relation to any changes of the symmetry properties of the electronic state of multielectron systems in strict accordance with the Hohenberg and Kohn theorem, demonstrating that the ground state properties of a many-electron system are uniquely determined by its electron density. 16 Topological analysis of the electron density distribution function ρ(r,R) (r and R are the coordinates of the electrons and the nuclei) is based on the quantum theory "atoms in molecules" (AIM). 9,10 According to the AIM method, the molecular and crystal structure and the interatomic interactions in the considered systems are completely determined by the set and types of critical points where the electron density gradient ∇ρ(r,R) vanishes. The second derivatives Δρ (r,R) calculated at the critical points form a real symmetric 3 × 3 matrix. It was established 9,10 that in the case of nondegenerate states of the matri...

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Section: ■ Resultsmentioning

confidence: 81%

Section: ■ Introductionmentioning

confidence: 98%

Transition from 2-D Semiconductor to 1-D Metal State and Electron Density Distribution in Nanolayered MoX₂(X = S, Se, Te)

et al. 2012

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“…Depending on the arrangement of X atoms, 27 the other stable phase which is popular in VI TMDs is the distorted 1T phase (1T 0 ). [28][29][30][31][32] The 1T 0 phase has semimetal characteristics. For example, bulk 1T 0 -MoTe 2 is a semimetal with much high carrier mobility of 4000 cm 2 V À1 s À1 .…”

Section: Introductionmentioning

confidence: 99%

Controlling phase transition for single-layer MTe₂ (M = Mo and W): modulation of the potential barrier under strain

Huang

Fan

Singh

et al. 2016

Phys. Chem. Chem. Phys.

116

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Using first-principles DFT calculations, the pathway and the energy barrier of phase transition between 2H and 1T' have been investigated for MoTe2 and WTe2 monolayers. The Phase transition is controlled by the simultaneous movement of metal atoms and Te atoms in their plane without the intermediate phase 1T. The energy barrier (less than 0.9 eV per formula cell) is not so high that the phase transition is dynamically possible. The relative stability of both 2H and 1T' phases and the energy barrier for phase transition can be modulated by the biaxial and uniaxial strain. The dynamic energy barrier is decreased by applying the strain. The phase transition between 2H and 1T' controlled by the strain can be used to modulate the electronic properties of MoTe2 and WTe2.

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“…For MoTe 2 a phase transition from the semiconducting 2H b -type ␣-MoTe 2 to a metallic polytype ␤-MoTe 2 , with a monoclinic structure having a distorted octahedral coordination is known. [1][2][3] The 2H b polytype, in the following assigned as MoTe 2 , is stable below Ϸ815°C.…”

Section: Introductionmentioning

confidence: 99%

Band structure ofMoS2,MoSe2,a

et al. 2001

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In this work the complete valence-band structure of the molybdenum dichalcogenides MoS 2 , MoSe 2 , and ␣-MoTe 2 is presented and discussed in comparison. The valence bands have been studied using both angleresolved photoelectron spectroscopy ͑ARPES͒ with synchrotron radiation, as well as ab initio band-structure calculations. The ARPES measurements have been carried out in the constant-final-state ͑CFS͒ mode. The results of the calculations show in general very good agreement with the experimentally determined valenceband structures allowing for a clear identification of the observed features. The dispersion of the valence bands as a function of the perpendicular component k ជ Ќ of the wave vector reveals a decreasing three-dimensional character from MoS 2 to ␣-MoTe 2 which is attributed to an increasing interlayer distance in the three compounds. The effect of this k ជ Ќ dispersion on the determination of the exact dispersion of the individual states as a function of k ជ ʈ is discussed. By performing ARPES in the CFS mode the k ជ ʈ component for off-normal emission spectra can be determined. The corresponding k ជ Ќ value is obtained from the symmetry of the spectra along the ⌫A, KH, and M L lines, respectively.

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STM/AFM investigations of β-MoTe2, α-MoTe2 and WTe2

Cited by 39 publications

References 9 publications

Transition from 2-D Semiconductor to 1-D Metal State and Electron Density Distribution in Nanolayered MoX₂(X = S, Se, Te)

Transition from 2-D Semiconductor to 1-D Metal State and Electron Density Distribution in Nanolayered MoX₂(X = S, Se, Te)

Controlling phase transition for single-layer MTe₂ (M = Mo and W): modulation of the potential barrier under strain

Band structure ofMoS2,MoSe2,a

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STM/AFM investigations of β-MoTe2, α-MoTe2 and WTe2

Cited by 39 publications

References 9 publications

Transition from 2-D Semiconductor to 1-D Metal State and Electron Density Distribution in Nanolayered MoX2(X = S, Se, Te)

Transition from 2-D Semiconductor to 1-D Metal State and Electron Density Distribution in Nanolayered MoX2(X = S, Se, Te)

Controlling phase transition for single-layer MTe2 (M = Mo and W): modulation of the potential barrier under strain

Band structure ofMoS2,MoSe2,a

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Product

Resources

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Transition from 2-D Semiconductor to 1-D Metal State and Electron Density Distribution in Nanolayered MoX₂(X = S, Se, Te)

Transition from 2-D Semiconductor to 1-D Metal State and Electron Density Distribution in Nanolayered MoX₂(X = S, Se, Te)

Controlling phase transition for single-layer MTe₂ (M = Mo and W): modulation of the potential barrier under strain