Characterization methods dedicated to nanometer-thick hBN layers

Schue, Léonard; Stenger, Ingrid; Fossard, F.; Loiseau, Annick; Barjon, Julien

doi:10.1088/2053-1583/4/1/015028

Cited by 64 publications

(91 citation statements)

References 80 publications

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“…(The value of Eg on quartz was found by us to be Eg ≈ 6.2 eV.) [5], energetically located inside the gap, and is termed, in bulk hBN, the D−series (D from diffuse) [31]. In addition to this, those authors identified two sharp peaks (S−series) in the region λ ∈ [210, 200] nm.…”

Section: Photoluminescence Of Hbn On Graphitementioning

confidence: 93%

Optical absorption of single-layer hexagonal boron nitride in the ultraviolet

Henriques

Ventura

Fernandes

et al. 2019

J. Phys.: Condens. Matter

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In this paper we theoretically describe the absorption of hexagonal boron nitride (hBN) single layer. We develop the necessary formalism and present an efficient method for solving the Wannier equation for excitons. We give predictions for the absorption of hBN on quartz and on graphite. We compare our predictions with recently published results [Elias et al., Nat. Comm. 10, 2639] for a monolayer of hBN on graphite. The spontaneous radiative lifetime of excitons in hBN is also computed. We argue that the optical properties of hBN in the ultraviolet are very useful for the study of peptides and other biomolecules.

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Section: Photoluminescence Of Hbn On Graphitementioning

confidence: 93%

Optical absorption of single-layer hexagonal boron nitride in the ultraviolet

Henriques

Ventura

Fernandes

et al. 2019

J. Phys.: Condens. Matter

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“…The radiative recombination of free excitons dominates the CL spectra of both 10 BN and 11 BN exfoliated crystals with a maximum at 215 nm. The intensity of luminescence signals related to structural defects (227 nm) and deep defects (broadbands near 300 nm) remains much weaker than exciton signal (17.8 and 3.6 times lower for 10 BN and 11 BN), which indicates that the quality of APHT BN crystals is close to HPHT ones [41]. The control of the boron isotopes results in a slight energy shift for the series of narrow lines due to various phonon modes, including longitudinal and transverse optical (LO, TO) and longitudinal and transverse acoustic (LA, TA) phonons, which assist the indirect exciton recombination in BN, as seen in Fig.…”

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confidence: 90%

“…1(b) we can clearly distinguish the in-plane E 2g Raman mode of the two isotopes positioned at 1391.0 cm −1 and 1355.2 cm −1 for 10 BN and 11 BN respectively. The width of this peak is commonly used as a measure for the crystallinity of BN [41]. In the highest quality HPHT grown BN crystals with the natural distribution of boron the lowest width observed is 7.3 cm −1 [41], mainly broadened by isotopic disorder.…”

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confidence: 99%

“…This narrow width of the E 2g mode indicates a high isotope purity and a high crystal quality. For the characterization of high quality hBN crystals, information gained from Raman spectroscopy is limited and needs to be completed by luminescence experiments [41]. To this end, we record cathodoluminescence (CL) spectra at low temperature (T = 10 K) with an acceleration voltage of 5 kV and correct them for the spectral response of the detection system [42], see Fig.…”

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confidence: 99%

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Excellent electronic transport in heterostructures of graphene and monoisotopic boron-nitride grown at atmospheric pressure

Sonntag

Plaud

et al. 2020

2D Mater.

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Hexagonal boron nitride (BN), one of the very few layered insulators, plays a crucial role in 2D materials research. In particular, BN grown with a high pressure technique has proven to be an excellent substrate material for graphene and related 2D materials, but at the same time very hard to replace. Here we report on a method of growth at atmospheric pressure as a true alternative for producing BN for high quality graphene/BN heterostructures. The process is not only more scalable, but also allows to grow isotopically purified BN crystals. We employ Raman spectroscopy, cathodoluminescence, and electronic transport measurements to show the high-quality of such monoisotopic BN and its potential for graphene-based heterostructures. The excellent electronic performance of our heterostructures is demonstrated by well developed fractional quantum Hall states, ballistic transport over distances around 10 µm at low temperatures and electron-phonon scattering limited transport at room temperature.

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“…h-BN films thickness was determined from their optical contrast (OC) using the cross-correlated calibration procedure with Atomic Force Microscopy measurements as detailed in [2,6]. This procedure insures a thickness uncertainty within ± 0.2L in the range of 1-20L range [6]. The…”

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confidence: 99%

Low frequency Raman spectroscopy of few-atomic-layer thick hBN crystals

Stenger¹,

Schue²,

Boukhicha³

et al. 2017

2D Mater.

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Hexagonal boron nitride (hBN) has recently gained a strong interest as a strategic component in engineering van der Waals heterostructures built with two dimensional crystals such as graphene. This work reports micro-Raman measurements on hBN flakes made of a few atomic layers, prepared by mechanical exfoliation. The temperature dependence of the Raman scattering in hBN is investigated first such as to define appropriate measurements conditions suitable for thin layers avoiding undesirable heating induced effects. We further focus on the low frequency Raman mode corresponding to the rigid shearing oscillation between adjacent layers, found to be equal to 52.5 cm -1 in bulk hBN. For hBN sheets with thicknesses below typically 4 nm, the frequency of this mode presents discrete values, which are found to decrease down to 46.0(5) cm -1 for a three-layer hBN, in good agreement with the linear-chain model. This makes Raman spectroscopy a relevant tool to quantitatively determine the number of layers in ultra thin hBN sheets, below 8L.Hexagonal boron nitride (h-BN) is a 2D insulator with a wide bandgap (>6eV) and an atomic structure very similar to that of graphene where boron and nitrogen atoms alternate at the

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Characterization methods dedicated to nanometer-thick hBN layers

Cited by 64 publications

References 80 publications

Optical absorption of single-layer hexagonal boron nitride in the ultraviolet

Optical absorption of single-layer hexagonal boron nitride in the ultraviolet

Excellent electronic transport in heterostructures of graphene and monoisotopic boron-nitride grown at atmospheric pressure

Low frequency Raman spectroscopy of few-atomic-layer thick hBN crystals

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