Layers dependent dielectric properties of two dimensional hexagonal boron nitridenanosheets

Wang, Liang; Pu, Yayun; Soh, Ai Kah; Shi, Yuping; Liu, Shuangyi

doi:10.1063/1.4973566

Cited by 19 publications

(16 citation statements)

References 43 publications

(35 reference statements)

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“…Meanwhile, partial band gap can be found in X → M, G → M, or G → X direction. Because it is nonplanar compared with planar honeycomb, the DOS of 2D titania nanosheets presents less 2D characters compared with h-BN; some steps indicating 2D features can also be found in the range of 0–100 cm –1 for o-ML and 160–318 cm –1 for p-ML, although they are far away from those for a strict 2D system. − …”

Section: Resultsmentioning

confidence: 99%

“…Figure a,c,e shows the optical dielectric functions of the three structures calculated on the basis of HSE06. The correction was done to subtract the vacuum effect according to the dielectric equation for complex layered materials. , Electronic screening properties are described by the complex dielectric function ε(ω) = ε r (ω) + iε i (ω), which depicts the electronic response to perturbation of the alternative electric field with frequency ω, and ε r and ε i represent screening ability of electrons and dielectric loss (photon absorption), respectively. For all sheets, the weakest screening ability is in z direction due to their size.…”

Section: Resultsmentioning

confidence: 99%

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Two-Dimensional Titania: Structures and Properties Predicted by First Principle Calculation

et al. 2018

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Material innovations, especially in classic semiconductor materials such as titania, are expected and more and more accelerated by ab initio design for their wide applications. For better realization in laboratory, feasible stability of structures in ambient temperature and pressure should be prior to the structure−property relationship study. However, there is discrepancy between experiments and ab initio calculations about how the freestanding two-dimensional TiO 2 exists. Herein, by the structural search method with the first principles evolution algorithm, the stable freestanding monolayers (MLs) were found to be composed by octahedral, hexahedral, or pentahedral Ti−O block (o-ML, h-ML, or p-ML) with nonplanar structure, where o-ML is right the lepidocrocite type found experimentally. Meanwhile, novel structure-dependent properties mainly due to quantum-confine effects were investigated and the abnormal optical absorption, better properties of insulation, and redox in photocatalysis were found for these titania sheets.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Two-Dimensional Titania: Structures and Properties Predicted by First Principle Calculation

et al. 2018

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“…Indeed, by performing a comparison with all data in literature, one can see a large spread of the dielectric constant values reported for hBN. We can divide the data into three groups: those with a dielectric constant of 2–4; ,− others, including our work, reporting a dielectric constant between 5 and 12; , and finally, one group reporting a dielectric constant of >200 . The data are summarized in Table S1.…”

Section: Resultsmentioning

confidence: 99%

All-2D Material Inkjet-Printed Capacitors: Toward Fully Printed Integrated Circuits

et al. 2018

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A well-defined insulating layer is of primary importance in the fabrication of passive (e.g. capacitors) and active (e.g. transistors) components in integrated circuits. One of the most widely known 2-Dimensional (2D) dielectric materials is hexagonal boron nitride (hBN).Solution-based techniques are cost-effective and allow simple methods to be used for device fabrication. In particular, inkjet printing is a low-cost, non-contact approach, which also allows for device design flexibility, produces no material wastage and offers compatibility with almost any surface of interest, including flexible substrates.In this work we use water-based and biocompatible graphene and hBN inks to fabricate all-2D material and inkjet-printed capacitors. We demonstrate an areal capacitance of 2.0 ± 0.3 nF cm -2 for a dielectric thickness of ~3 µm and negligible leakage currents, averaged across more than 100 devices. This gives rise to a derived dielectric constant of 6.1 ± 1.7. The inkjet printed hBN dielectric has a breakdown field of 1.9 ± 0.3 MV cm -1 . Fully printed capacitors with sub-µm hBN layer thicknesses have also been demonstrated. The capacitors are then exploited in two fully printed demonstrators: a resistor-capacitor (RC) low-pass filter and a graphene-based field effect transistor.

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“…The similarity in energy of the indirect and direct ILX transitions also explains the seemingly contradictory claims of K → K excitons ( 4 , 8 , 10 ) and K → Λ excitons ( 9 , 13 , 27 ) in the literature. Our measurements allow direct comparison between the K → K ILX dipole moments extracted from the absorption spectrum and the ILX PL, thus avoiding the experimental uncertainties encountered when measuring the absolute values of the PL dipole moment [e.g., arising from the hBN dielectric constant ( 28 , 29 )].…”

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confidence: 99%

Optical absorption of interlayer excitons in transition-metal dichalcogenide heterostructures

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Karni

Liu

et al. 2022

Science

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Interlayer excitons, electron-hole pairs bound across two monolayer van der Waals semiconductors, offer promising electrical tunability and localizability. Because such excitons display weak electron-hole overlap, most studies have examined only the lowest-energy excitons through photoluminescence. We directly measured the dielectric response of interlayer excitons, which we accessed using their static electric dipole moment. We thereby determined an intrinsic radiative lifetime of 0.40 nanoseconds for the lowest direct-gap interlayer exciton in a tungsten diselenide/molybdenum diselenide heterostructure. We found that differences in electric field and twist angle induced trends in exciton transition strengths and energies, which could be related to wave function overlap, moiré confinement, and atomic reconstruction. Through comparison with photoluminescence spectra, this study identifies a momentum-indirect emission mechanism. Characterization of the absorption is key for applications relying on light-matter interactions.

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Layers dependent dielectric properties of two dimensional hexagonal boron nitridenanosheets

Cited by 19 publications

References 43 publications

Two-Dimensional Titania: Structures and Properties Predicted by First Principle Calculation

Two-Dimensional Titania: Structures and Properties Predicted by First Principle Calculation

All-2D Material Inkjet-Printed Capacitors: Toward Fully Printed Integrated Circuits

Optical absorption of interlayer excitons in transition-metal dichalcogenide heterostructures

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