Outstanding performance of Si-bilayer graphene using first-principle computation: Significant effects of Si atoms configuration

Abdullah, Nzar Rauf

doi:10.1016/j.physb.2021.413273

Cited by 18 publications

(6 citation statements)

References 46 publications

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“…where S notes the Seebeck coefficient, σ is the electrical conductance, k is the thermal conductance, and T is the temperature. In order to obtain a high ZT , one has to have high values of S and σ, and a low value of k [51]. The S (a), σ (b), and k (c) as functions of energy are plotted in Fig.…”

Section: Resultsmentioning

confidence: 99%

Modulation of electronic and thermal proprieties of TaMoS$_2$ by controlling the repulsive interaction between Ta dopant atoms

Abdullah,

Rashid

et al. 2021

Preprint

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We theoretically study the electronic and the thermal characteristics of Tantalum, Ta, doped Molybdenum disulfide, MoS 2 , using density functional theory. It has been shown that the MoS 2 monolayer is not a good material for thermoelectric devices due to its relatively large band gap. We find that a Ta doped MoS 2 forming a TaMoS 2 monolayer can be useful for thermoelectric devices. The particular attention of this work is paid to the interaction effect between the Ta atoms in the MoS 2 structure. We find that the interaction type is repulsive. It introduces an asymmetry in the density of states, DOS, reducing the band gap. In the presence of a strong repulsive interaction of Ta-Ta atoms, new states in the DOS around the Fermi energy are found leading to a reduction of the band gap. Consequently, a high Seebeck coefficient and figure of merit are seen over a wide range of energy around the Fermi energy. In contrast, a small reduction of the band gap and a vanishing degeneracy of the valence and the conduction bands are observed for the case of a weak Ta-Ta repulsive interaction leading to less promising thermoelectric properties.

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Section: Resultsmentioning

confidence: 99%

Modulation of electronic and thermal proprieties of TaMoS$_2$ by controlling the repulsive interaction between Ta dopant atoms

Abdullah,

Rashid

et al. 2021

Preprint

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“…A two-dimensional metallic nitride monolayer, h-BN monolayer, consists of of 2 × 2 supercell with equal number of B and N atoms. In the calculations we select cutoffs for the calculation of the charge densities and the kinetic energy of the plane-waves at 1.088 × 10 4 eV [32], and 1088.5 eV, respectively. The BN monolayer is considered fully relaxed when all the forces on the atoms are less than 10 −5 eV/ Å in the 18 × 18 × 1 Monkhorst-Pack grid.…”

Section: Methodsmentioning

confidence: 99%

Enhanced ultraviolet absorption in BN monolayers caused by tunable buckling

Abdullah¹,

Abdullah²,

Tang³

et al. 2022

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The optical properties of a hexagonal Boron Nitride (BN) monolayer across the UV spectrum are studied by tuning its planar buckling. The strong σ-σ bond through sp 2 hybridization of a flat BN monolayer can be changed to a stronger σ-π bond through sp 3 hybridization by increasing the planar buckling. This gives rise to the s-and p-orbital contributions to form a density of states around the Fermi energy, and these states dislocate to a lower energy in the presence of an increased planar buckling. Consequently, the wide band gap of a flat BN monolayer is reduced to a smaller band gap in a buckled BN monolayer enhancing its optical activity in the Deep-UV region. The optical properties such as the dielectric function, the reflectivity, the absorption, and the optical conductivity spectra are investigated. It is shown that the absorption rate can be enhanced by (12-15)% for intermediate values of planar buckling in the Deep-UV region, and (15-20)% at higher values of planar buckling in the near-UV region. Furthermore, the optical conductivity is enhanced by increased planar buckling in both the visible and the Deep-UV regions depending on the direction of the polarization of the incoming light. Our results may be useful for optoelectronic BN monolayer devices in the UV range including UV spectroscopy, deep-UV communications, and UV photodetectors.

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“…The atomic positions are considered relaxed when the forces are smaller than 0.001 eV/ Å. To decrease the strain caused by the substituents, the lattice parameters are very carefully optimized [25]. In addition, the partial occupancies in the electronic ground-state, and the density of state, DOS, calculations are treated by using Gaussian smearing, and the Tetrahedron methodology [26,27,28], respectively.…”

Section: Computational Detailsmentioning

confidence: 99%

Enhanced electronic and optical responses of Nitrogen- or Boron-doped BeO monolayer: First principle computation

Abdullah,

Rashid

et al. 2021

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In this work, the electronic and optical properties of a Nitrogen (N) or a Boron (B) doped BeO monolayer are investigated in the framework of density functional theory. It is known that the band gap of a BeO monolayer is large leading to poor material for optoelectronic devices in a wide range of energy. Using substitutional N or B dopant atoms, we find that the band gap can be tuned and the optical properties can be improved. In the N(B)-doped BeO monolayer, the Fermi energy slightly crosses the valence(conduction) band forming a degenerate semiconductor structure. The N or B atoms thus generate new states around the Fermi energy increasing the optical conductivity in the visible light region. Furthermore, the influences of dopant atoms on the electronic structure, the stability, the dispersion energy, the density of states, and optical properties such as the plasmon frequency, the excitation spectra, the dielectric functions, the static dielectric constant, and the electron energy loss function are discussed for different directions of polarizations for the incoming electric field.

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Outstanding performance of Si-bilayer graphene using first-principle computation: Significant effects of Si atoms configuration

Cited by 18 publications

References 46 publications

Modulation of electronic and thermal proprieties of TaMoS$_2$ by controlling the repulsive interaction between Ta dopant atoms

Modulation of electronic and thermal proprieties of TaMoS$_2$ by controlling the repulsive interaction between Ta dopant atoms

Enhanced ultraviolet absorption in BN monolayers caused by tunable buckling

Enhanced electronic and optical responses of Nitrogen- or Boron-doped BeO monolayer: First principle computation

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