Optical spectrum and excitons in bulk and monolayer MX<sub>2</sub>
 (M=Zr, Hf; X=S, Se)

Abdulsalam, Mahmud; Joubert, Daniel P.

doi:10.1002/pssb.201552584

Cited by 33 publications

(32 citation statements)

References 70 publications

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“…However, there exists the difference of approximate 0.44, 0.10, 0.08, and 0.01 eV for ZrS 2 , ZrSe 2 , HfS 2 , and HfSe 2 , respectively, when comparing the results with that of Ref. [28]. The difference could result from the different ground state structures of IVB-VIA TMDs or pseudopotentials used for the calculations.…”

Section: Electronic Propertiesmentioning

confidence: 86%

Elastic, electronic, and dielectric properties of bulk and monolayer ZrS₂, ZrSe₂, HfS₂, HfSe₂ from van der Waals density‐functional theory

Zhao

Guo

et al. 2017

Physica Status Solidi (b)

130

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The elastic, electronic, and dielectric properties of layered transition metal dichalcogenides MX2 (M = Zr and Hf; X = S, Se) have been investigated using density functional theory (DFT) with van der Waals correction. The elastic modulus indicate that the structures belong to brittle materials. The band gaps of these materials through Heyd–Scuseria–Ernzerhof hybrid functional are in reasonable agreement with the experimental data. Partial density of state analysis suggests that the metallic atoms play a dominant role in the conduction band and the chalcogenide atoms have the main effect on the valence band. The presence of peaks in the dielectric constant spectra mainly result from the transition between first, second, third valence bands and the first conduction bands and the direction is from Γ to M, M to K, and K to Γ of the high symmetry k‐points for bulk and monolayer structures, respectively. What is more, parallel band effect has been observed in monolayer structures, which suggests strong light‐matter interactions in these materials. This work promotes the property understanding of these materials and holds potential for the development of optoelectronic devices based on these layered materials.

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Section: Electronic Propertiesmentioning

confidence: 86%

Elastic, electronic, and dielectric properties of bulk and monolayer ZrS₂, ZrSe₂, HfS₂, HfSe₂ from van der Waals density‐functional theory

Zhao

Guo

et al. 2017

Physica Status Solidi (b)

130

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“…On the other hand, ZrX 2 (X = S, Se) are the group IVB TMDC materials that crystallized in one-layer trigonal (1T) structure of CdI 2 type [12]. These materials also have band gaps ranging from 1.1 to 2 eV [13,14]. The compounds usually possess high conductivity and contains defects and surface states in its layer structure.…”

Section: Introductionmentioning

confidence: 99%

Optical and Thermoelectric Properties of Surface-Oxidation Sensitive Layered Zirconium Dichalcogenides ZrS2−xSex (x = 0, 1, 2) Crystals Grown by Chemical Vapor Transport

Herninda

2020

Crystals

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In this work, structure, optical, and thermoelectric properties of layered ZrS2−xSex single crystals with selenium composition of x = 0, 1, and 2 were examined. Single crystals of zirconium dichalcogenides layer compounds were grown by chemical vapor transport method using I2 as the transport agent. X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM) results indicated that ZrS2−xSex (x = 0, 1, and 2) were crystalized in hexagonal CdI2 structure with one-layer trigonal (1T) stacking type. X-ray photoelectron and energy dispersive X-ray measurements revealed oxidation sensitive behavior of the chalcogenides series. Transmittance and optical absorption showed an indirect optical gap of about 1.78 eV, 1.32 eV, and 1.12 eV for the ZrS2−xSex with x = 0, 1, and 2, respectively. From the result of thermoelectric experiment, ZrSe2 owns the highest figure-of merit (ZT) of ~0.085 among the surface-oxidized ZrS2−xSex series layer crystals at 300 K. The ZT values of the ZrS2−xSex (x = 0, 1, and 2) series also reveal increase with the increase of Se content owing to the increase of carrier concentration and mobility in the highly Se-incorporated zirconium dichalcogenides with surface states.

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“…[1][2][3][4] Particularly, it was demonstrated that nanotubes produced from layered transition metal disulfides MoS 2 and WS 2 exhibit a stable, closed, hollow structure. [6,9,10] The theoretical modeling was carried out in references [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] for bulk Zr(Hf) sulfides and their monolayers. [4,7,8] The ZrS 2 and HfS 2 nanotubes have been synthesized since the early 2000s.…”

Section: Introductionmentioning

confidence: 99%

First‐Principles Calculations of Phonons and Thermodynamic Properties of Zr(Hf)S₂‐Based Nanotubes

2019

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Comparative hybrid density functional calculations on the structure, stability, and phonon frequencies of monolayers and single-walled nanotubes are performed for Zr(Hf)S 2 disulfides. The first-principles calculations of HfS 2 -based nanotubes are made for the first time. The symmetry analysis of infrared and Raman active vibrational modes in ZrS 2 and HfS 2 nanotubes is made using the induced representations of the isogonal point groups of line groups. It is shown that the number of infrared and Raman active modes is constant for NTs with the same chirality type. The correlation of the phonon modes of the nanotubes of relatively large diameters with those of monolayer is analyzed. The thermodynamic functions of monolayers and nanotubes with various chirality and diameters are calculated on the basis of the obtained phonon frequencies. It is established that the phonon contribution to the nanotube strain energy is small, but may be important for an accurate estimate of the stability of the nanotubes of small diameters. The calculated results show that the thermal contributions to Helmholtz free energy are positive; thereby they slightly reduce the stability of ZrS 2 and HfS 2 nanotubes at elevated temperatures.

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Optical spectrum and excitons in bulk and monolayer MX₂ (M=Zr, Hf; X=S, Se)

Cited by 33 publications

References 70 publications

Elastic, electronic, and dielectric properties of bulk and monolayer ZrS₂, ZrSe₂, HfS₂, HfSe₂ from van der Waals density‐functional theory

Elastic, electronic, and dielectric properties of bulk and monolayer ZrS₂, ZrSe₂, HfS₂, HfSe₂ from van der Waals density‐functional theory

Optical and Thermoelectric Properties of Surface-Oxidation Sensitive Layered Zirconium Dichalcogenides ZrS2−xSex (x = 0, 1, 2) Crystals Grown by Chemical Vapor Transport

First‐Principles Calculations of Phonons and Thermodynamic Properties of Zr(Hf)S₂‐Based Nanotubes

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Optical spectrum and excitons in bulk and monolayer MX2 (M=Zr, Hf; X=S, Se)

Cited by 33 publications

References 70 publications

Elastic, electronic, and dielectric properties of bulk and monolayer ZrS2, ZrSe2, HfS2, HfSe2 from van der Waals density‐functional theory

Elastic, electronic, and dielectric properties of bulk and monolayer ZrS2, ZrSe2, HfS2, HfSe2 from van der Waals density‐functional theory

Optical and Thermoelectric Properties of Surface-Oxidation Sensitive Layered Zirconium Dichalcogenides ZrS2−xSex (x = 0, 1, 2) Crystals Grown by Chemical Vapor Transport

First‐Principles Calculations of Phonons and Thermodynamic Properties of Zr(Hf)S2‐Based Nanotubes

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Optical spectrum and excitons in bulk and monolayer MX₂ (M=Zr, Hf; X=S, Se)

Elastic, electronic, and dielectric properties of bulk and monolayer ZrS₂, ZrSe₂, HfS₂, HfSe₂ from van der Waals density‐functional theory

Elastic, electronic, and dielectric properties of bulk and monolayer ZrS₂, ZrSe₂, HfS₂, HfSe₂ from van der Waals density‐functional theory

First‐Principles Calculations of Phonons and Thermodynamic Properties of Zr(Hf)S₂‐Based Nanotubes