Tuning the Bandgap of Exfoliated InSe Nanosheets by Quantum Confinement

Mudd, Garry W.; Svatek, Simon A.; Ren, Tianhang; Patanè, A.; Makarovsky, O.; Eaves, L.; Beton, Peter H.; Kovalyuk, Z. D.; Lashkarev, G. V.; Kudrynskyi, Z. R.; Дмитриев, А. И.

doi:10.1002/adma.201302616

Cited by 539 publications

(581 citation statements)

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“…23 Very recently, samples of few-layer hexagonal InSe have been produced and their optical properties have been studied. 24,25 Indium sulfide (InS) and indium telluride (InTe) exhibit orthorhombic and tetragonal structures, respectively, but this does not exclude the possibility of growing metastable hexagonal structures (structural changes induced by annealing have been reported in transmission electron microscopy of indium chalcogenide thin films 26 ). We have investigated whether monolayers of the hexagonal phase are stable in any of these three materials.…”

Section: Introductionmentioning

confidence: 99%

Electrons and phonons in single layers of hexagonal indium chalcogenides fromab initiocalculations

2014

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We use density functional theory to calculate the electronic band structures, cohesive energies, phonon dispersions, and optical absorption spectra of two-dimensional In2X2 crystals, where X is S, Se, or Te. We identify two crystalline phases (α and β) of monolayers of hexagonal In2X2, and show that they are characterized by different sets of Raman-active phonon modes. We find that these materials are indirect-band-gap semiconductors with a sombrero-shaped dispersion of holes near the valence-band edge. The latter feature results in a Lifshitz transition (a change in the Fermi-surface topology of hole-doped In2X2) at hole concentrations nS = 6.86×10 13 cm −2 , nSe = 6.20×10 13 cm −2 , and nTe = 2.86 × 10 13 cm −2 for X=S, Se, and Te, respectively, for α-In2X2 and nS = 8.32 × 10 13 cm −2 , nSe = 6.00 × 10 13 cm −2 , and nTe = 8.14 × 10 13 cm −2 for β-In2X2.

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Section: Introductionmentioning

confidence: 99%

Electrons and phonons in single layers of hexagonal indium chalcogenides fromab initiocalculations

2014

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“…Because of this merit, Few layered 2DLMCs such as transition metal dichalcogenides (TMDs) (MoS 2 ,26, 27, 28 WS 2 ,29, 30, 31, 32, 33, 34, 35, 36 TiS 3 ,37 etc.) and group III–VI nanomaterials (InSe,38, 39, 40, 41, 42 GaSe,43, 44, 45, 46, 47, 48 etc.) have been extensively investigated in many fields including photodetectors,49, 50, 51, 52, 53, 54, 55, 56, 57, 58 gas sensors,59, 60 field effect transistors (FETs),38, 61, 62, 63, 64, 65 and flexible devices 66, 67, 68…”

Section: Introductionmentioning

confidence: 99%

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

et al. 2016

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As an important component of 2D layered materials (2DLMs), the 2D group IV metal chalcogenides (GIVMCs) have drawn much attention recently due to their earth‐abundant, low‐cost, and environmentally friendly characteristics, thus catering well to the sustainable electronics and optoelectronics applications. In this instructive review, the booming research advancements of 2D GIVMCs in the last few years have been presented. First, the unique crystal and electronic structures are introduced, suggesting novel physical properties. Then the various methods adopted for synthesis of 2D GIVMCs are summarized such as mechanical exfoliation, solvothermal method, and vapor deposition. Furthermore, the review focuses on the applications in field effect transistors and photodetectors based on 2D GIVMCs, and extends to flexible devices. Additionally, the 2D GIVMCs based ternary alloys and heterostructures have also been presented, as well as the applications in electronics and optoelectronics. Finally, the conclusion and outlook have also been presented in the end of the review.

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“…As the latter tends to underestimate the electronic bandgap, we This is the post-peer reviewed version of the following article: J. Quereda et al "Strong quantum confinement effect in the optical properties of ultrathin α-In2Se3". [27,28] The evolution of the optical bandgap with the flake thickness can be modeled using a square quantum well potential of infinite height: [29,30] This unusually high bandgap change, induced by quantum confinement, is among the highest observed in two-dimensional semiconductors [32,33] , comparable with the one observed in atomically thin black phosphorus. Therefore, the bandgap of atomically thin In 2 Se 3 crystals can be tuned to cover a wide region of the near ultraviolet spectrum.…”

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“…Advanced [27,28] The evolution of the optical bandgap with the flake thickness can be modeled using a square quantum well potential of infinite height: [29,30] , is reduced. However, compared with the experimental data, the theoretical curve seems to be displaced in the horizontal axis towards lower values of thickness.…”

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Strong Quantum Confinement Effect in the Optical Properties of Ultrathin α‐In₂Se₃

Quereda

Biele

Rubio‐Bollinger

et al. 2016

Advanced Optical Materials

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This is the post-peer reviewed version of the following article: J. Quereda et al. "Strong quantum confinement effect in the optical properties of ultrathin α-In2Se3".Advanced The isolation of atomically thin semiconductors has attracted the interest of the nanoscientists as these materials can complement graphene in those applications where its lack of an electronic band gap hinders its use. [1][2][3][4][5] In fact, two dimensional semiconductors have been recently employed in the fabrication of field effect transistors, [6,7] photodetectors [8][9][10][11][12][13][14] and solar cells. [15][16][17][18][19] Inherent to their reduced out-of-plane dimension, atomically thin semiconductors present a marked thickness-dependent band structure due to the quantum confinement of the charge carriers. For instance, the band gap in Mo-and W-based transition metal dichalcogenides increases from its bulk value (~1.3 eV, indirect gap) up to 1.9 eV (direct gap) in the single-layer limit. [20,21] More recently, black phosphorus has also shown a pronounced thickness-dependent band gap ranging from ~0.3 eV (direct gap) for bulk to ~1.75 eV (direct gap) for single-layer black phosphorus. [22] This thickness-dependent band gap can be very advantageous for applications as photodetectors as one can select the sensing photon energy window by simply selecting the right material thickness for the photodetector device. Up to now, however, there is a broad spectral window from 2.0 eV to 3.0 eV uncovered by 2D materials that could be very relevant for applications requiring 'solar blind' This is the post-peer reviewed version of the following article: J. Quereda et al. "Strong quantum confinement effect in the optical properties of ultrathin α-In2Se3". In this work we demonstrate a very strong quantum confinement effect in the optical properties of atomically thin α-In 2 Se 3 crystals. We observe a marked thickness-dependent shift in the optical absorption spectra acquired on mechanically exfoliated Figure S1). In order to study the optical absorption of the In 2 Se 3 crystals we used a home-made hyperspectral imaging setup, described in detail elsewhere.[25] The hyperspectral imaging is carried out by sweeping the excitation wavelength in steps and acquiring transmission mode images of the In 2 Se 3 crystals for each wavelength.The collected data is then arranged in a three-dimensional matrix, being the first two matrix According to Tauc et al. [26] , near the absorption edge the absorption coefficient of a direct-gap semiconductors iswhere A is a material-dependent constant and E g opt is the optical energy gap of the material.Equation (2) can be rewritten asThis is the post-peer reviewed version of the following article: J. Quereda et al. "Strong quantum confinement effect in the optical properties of ultrathin α-In2Se3".Advanced The usual method for determining the value of E g opt involves representing (αℏω) 2 versus the photon energy, ℏω, and fitting the absorption band edge to a linear function. According to Equation (3), the int...

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Tuning the Bandgap of Exfoliated InSe Nanosheets by Quantum Confinement

Cited by 539 publications

References 35 publications

Electrons and phonons in single layers of hexagonal indium chalcogenides fromab initiocalculations

Electrons and phonons in single layers of hexagonal indium chalcogenides fromab initiocalculations

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

Strong Quantum Confinement Effect in the Optical Properties of Ultrathin α‐In₂Se₃

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Tuning the Bandgap of Exfoliated InSe Nanosheets by Quantum Confinement

Cited by 539 publications

References 35 publications

Electrons and phonons in single layers of hexagonal indium chalcogenides fromab initiocalculations

Electrons and phonons in single layers of hexagonal indium chalcogenides fromab initiocalculations

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

Strong Quantum Confinement Effect in the Optical Properties of Ultrathin α‐In2Se3

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Strong Quantum Confinement Effect in the Optical Properties of Ultrathin α‐In₂Se₃