An <i>ab initio</i> study of the electronic structure of indium and gallium chalcogenide bilayers

Ayadi, T.; Debbichi, Lamjed; Saïd, M.; Lebègue, Sébastien

doi:10.1063/1.4997233

Cited by 29 publications

(18 citation statements)

References 43 publications

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“…From this value of η 0 and Eq. 12, we estimate that E B = 15 meV/Å 2 for InSe, within the range of values of E B reported for other vdW crystals [80].…”

Section: A Elastic Properties Of Inse and Hbnsupporting

confidence: 85%

Coherent acoustic phonons in van der Waals nanolayers and heterostructures

et al. 2018

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Terahertz (THz) and sub-THz coherent acoustic phonons have been successfully used as probes of various quantum systems. Since their wavelength is in the nanometer range, they can probe nanostructures buried below a surface with nanometer resolution and enable control of electrical and optical properties on a picosecond time scale. However, coherent acoustic phonons have not yet been widely used to study van der Waals (vdW) two-dimensional (2D) materials and heterostructures. This class of 2D systems features strong covalent bonding of atoms in the layer planes and weak van der Waals attraction between the layers. The dynamical properties of the interface between the layers or between a layer and its supporting substrate are often omitted as they are difficult to probe. On the other hand, these play a crucial role in interpreting experiments and/or designing new device structures. Here, we use picosecond ultrasonic techniques to investigate phonon transport in vdW InSe nanolayers and InSe/hBN heterostructures. Coherent acoustic phonons are generated and detected in these 2D systems and allow us to probe elastic parameters of different layers and their interfaces. In particular, our study of the elastic properties of the interface between vdW layers reveals a strong coupling over a wide range of frequencies up to 0.1 THz, offering prospects for high-frequency electronics and technologies that require control over the charge and phonon transport across an interface. In contrast, we reveal a weak coupling between the InSe nanolayers and sapphire substrates, relevant in thermoelectrics and sensing applications, which can require quasi-suspended layers.

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“…From this value of η 0 and Eq. 12, we estimate that E B = 15 meV/Å 2 for InSe, within the range of values of E B reported for other vdW crystals [80].…”

Section: A Elastic Properties Of Inse and Hbnsupporting

confidence: 85%

Coherent acoustic phonons in van der Waals nanolayers and heterostructures

et al. 2018

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“…Single-layer group-III monochalcogenides in hexagonal structure 16,[30][31][32][33] gathered attention also for their in-triguing thermoelectric properties. Interestingly, theoretical and experimental results demonstrate that they present so-called Mexican-hat shape dispersion at their valence band maximum (VBM), and consequently gives rise to Van-Hove singularity 34 in the density of states (DOS) near VBM [35][36][37][38] .…”

Section: Introductionmentioning

confidence: 99%

Structural, vibrational, and electronic properties of single-layer hexagonal crystals of group IV and V elements

et al. 2018

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Using first-principles density functional theory calculations, we investigate a family of stable two-dimensional crystals with chemical formula A2B2, where A and B belong to groups IV and V, respectively (A = C, Si, Ge, Sn, Pb; B = N, P, As, Sb, Bi). Two structural symmetries of hexagonal lattices P6m2 and P3m1 are shown to be dynamically stable, named as α-and βphases correspondingly. Both phases have similar cohesive energies, and the α-phase is found to be energetically favorable for structures except CP, CAs, CSb and CBi, for which the β-phase is favored. The effects of spin-orbit coupling and Hartree-Fock corrections to exchange-correlation are included to elucidate the electronic structures. All structures are semiconductors except CBi and PbN, which have metallic character. SiBi, GeBi and SnBi have direct band gaps, whereas the remaining semiconductor structures have indirect band gaps. All structures have quartic dispersion in their valence bands, some of which make the valence band maximum and resemble a Mexican hat shape. SnAs and PbAs have purely quartic valence band edges, i.e. E∼−αk 4 , a property reported for the first time. The predicted materials are candidates for a variety of applications. Owing to their wide band gaps, CP, SiN, SiP, SiAs, GeN, GeP can find their applications in optoelectronics. The relative band positions qualify a number of the structures as suitable for water splitting, where CN and SiAs are favorable at all pH values. Structures with quartic band edges are expected to be efficient for thermoelectric applications.PACS numbers: 31.15. A-,71.20.-b,63.22.-m

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“…These experiments have identified two main photoluminescence lines, interpreted 30 as a lower energy transition between bands dominated by s and p z orbitals (A-line) and hot luminescence, involving holes in a deeper valence band based on p x and p y orbitals (B-line). The band structure analysis of mono-and few-layer InSe [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] has revealed that the conduction and valence band edges near the Γ-point are non-degenerate, being dominated by s and p z orbitals of both metal and chalcogen atoms. Combined with the opposite z → −z (mirror reflection) symmetry of conduction and valence bands, this determines that the transition across the principal band gap has a dominantly electric dipole-like character, coupled to out-of-plane polarized photons.…”

Section: Introductionmentioning

confidence: 99%

Spin-orbit coupling, optical transitions, and spin pumping in monolayer and few-layer InSe

2017

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We show that spin-orbit coupling (SOC) in InSe enables the optical transition across the principal band gap to couple with in-plane polarized light. This transition, enabled by px,y ↔ pz hybridization due to intra-atomic SOC in both In and Se, can be viewed as a transition between two dominantly s-and pz-orbital based bands, accompanied by an electron spin-flip. Having parametrized k · p theory using first principles density functional theory we estimate the absorption for σ ± circularly polarized photons in the monolayer as ∼ 1.5%, which saturates to ∼ 0.3% in thicker films (3 − 5 layers). Circularly polarized light can be used to selectively excite electrons into spin-polarized states in the conduction band, which permits optical pumping of the spin polarization of In nuclei through the hyperfine interaction.

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An ab initio study of the electronic structure of indium and gallium chalcogenide bilayers

Cited by 29 publications

References 43 publications

Coherent acoustic phonons in van der Waals nanolayers and heterostructures

Coherent acoustic phonons in van der Waals nanolayers and heterostructures

Structural, vibrational, and electronic properties of single-layer hexagonal crystals of group IV and V elements

Spin-orbit coupling, optical transitions, and spin pumping in monolayer and few-layer InSe

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