Band gap measurements of monolayer h-BN and insights into carbon-related point defects

Román, Ricardo Javier Peña; Costa, F. J. R.; Zobelli, Alberto; Elias, Christine; Valvin, Pierre; Cassabois, Guillaume; Gil, Bernard; Summerfield, Alex; Cheng, T.S.; Mellor, Christopher J.; Beton, Peter H.; Новиков, С. В.; Zagonel, Luiz Fernando

doi:10.1088/2053-1583/ac0d9c

Cited by 42 publications

(41 citation statements)

References 122 publications

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“…[ 45,55 ] This trend illustrates that the screening depends only on the adjacent graphene layers as previously reported for other vdW heterostructures. [ 56 ] Our predictions also agree well with the E g = 6.8 ± 0.2 eV recently measured with STM for monolayer hBN, [ 33 ] and the variation of the bandgap among different stacking configurations is small, less than 0.1 eV.…”

Section: Resultssupporting

confidence: 89%

“…[ 48–50 ] Recently, the emissions with higher peak energies (above 5.96 eV) were attributed to the carrier transition and recombination processes in monolayer hBN with a direct bandgap. [ 32,33,51 ] However, there is a large difference between the experimentally measured emission (6–6.15 eV) [ 32,33 ] and the theoretically predicted bandgap (8 eV) for a monolayer hBN. [ 34–36 ] To explain the 6.12 eV emission resonance from a monolayer hBN/HOPG heterostructure, we use first‐principles calculations based on density functional theory (DFT) and many‐body perturbation theory.…”

Section: Resultsmentioning

confidence: 99%

“…The unique optical properties of monolayer hBN result from the extraordinary strong light-matter interaction. [33][34][35][43][44][45][46] Therefore, we characterize our hBN/HOPG samples further by using temperature-variable PL spectroscopy, as schematically shown in Figure 3a. The measured, time-integrated PL spectrum at 12 K (blue curve) and the reflectance spectrum at 300 K (red curve) are presented in Figure 3b for the monolayer hBN sample of Figure 1g.…”

Section: Deep-uv Emission Of Epitaxial Monolayer Hbnmentioning

confidence: 99%

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Scalable Synthesis of Monolayer Hexagonal Boron Nitride on Graphene with Giant Bandgap Renormalization

et al. 2022

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as fundamental building blocks of such 2D devices. Specifically, vertically stacked hBN/ graphene (hBN/G) van der Waals (vdW) heterostructures have been successfully employed to produce emergent properties, such as quantum Hall effect, [8] Hofstadter butterfly spectrum, [9] and plasmon and phonon polaritons. [10] Complementary to the vertical hBN/G vdW heterostructure, the in-plane version forms a covalent hBN/G heterostructure with equally attractive properties, such as transitions between semiconducting, half-metallic, and metallic phases, spin polarization magnetism, and exotic electronic states, [11][12][13][14][15] or even the possibility to reconstruct electronic interfaces similar to those observed in oxide heterostructures. [16,17] The scope of these fascinating properties could be radically expanded by demonstrating epitaxially grown monolayer hBN on graphene with superior structural, electrical, and optical properties, as well as precise control of both the hBN/G out-ofplane and in-plane monolayer interfaces.Recently, intensive efforts have been devoted to the epitaxial growth of hBN on metals, [18][19][20] sapphire, [21] and graphene substrates [22] by using sputtering, [23] chemical vapor deposition (CVD), [24] metal-organic chemical vapor deposition (MOCVD), [25] and molecular beam epitaxy (MBE). [26] Due to the Monolayer hexagonal boron nitride (hBN) has been widely considered a fundamental building block for 2D heterostructures and devices. However, the controlled and scalable synthesis of hBN and its 2D heterostructures has remained a daunting challenge. Here, an hBN/graphene (hBN/G) interface-mediated growth process for the controlled synthesis of high-quality monolayer hBN is proposed and further demonstrated. It is discovered that the in-plane hBN/G interface can be precisely controlled, enabling the scalable epitaxy of unidirectional monolayer hBN on graphene, which exhibits a uniform moiré superlattice consistent with single-domain hBN, aligned to the underlying graphene lattice. Furthermore, it is identified that the deep-ultraviolet emission at 6.12 eV stems from the 1s-exciton state of monolayer hBN with a giant renormalized direct bandgap on graphene. This work provides a viable path for the controlled synthesis of ultraclean, wafer-scale, atomically ordered 2D quantum materials, as well as the fabrication of 2D quantum electronic and optoelectronic devices.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Deep-uv Emission Of Epitaxial Monolayer Hbnmentioning

confidence: 99%

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Scalable Synthesis of Monolayer Hexagonal Boron Nitride on Graphene with Giant Bandgap Renormalization

et al. 2022

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“…The photoluminescence of the BN monolayer emits at 6.085 eV at low temperature, which was recently confirmed by the direct measurement of the density of states of a single monolayer of h-BN epitaxially grown on HOPG. This was achieved by performing low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) [153]. According to group theory, the D 3h point group authorizes piezoelectric behavior, which was observed experimentally [154].…”

Section: Linear Optical Properties Of the Bn Monolayermentioning

confidence: 99%

Polytypes of sp2-Bonded Boron Nitride

et al. 2022

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The sp2-bonded layered compound boron nitride (BN) exists in more than a handful of different polytypes (i.e., different layer stacking sequences) with similar formation energies, which makes obtaining a pure monotype of single crystals extremely tricky. The co-existence of polytypes in a similar crystal leads to the formation of many interfaces and structural defects having a deleterious influence on the internal quantum efficiency of the light emission and on charge carrier mobility. However, despite this, lasing operation was reported at 215 nm, which has shifted interest in sp2- bonded BN from basic science laboratories to optoelectronic and electrical device applications. Here, we describe some of the known physical properties of a variety of BN polytypes and their performances for deep ultraviolet emission in the specific case of second harmonic generation of light.

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“…Recently, experiments performed on h-BN/Graphite using scanning tunneling microscopy/spectroscopy (STM/STS) suggested an energy gap of 6.8 ± 0.2 eV. 38 The optical energy gap calculations of monolayer h-BN are determined by the exciton energy and a range of energy gap values from 5.30 -6.30eV have been calculated. 36 h-BN is also successfully synthesized using a variety of other techniques such as atomic layer deposition, 39 chemical vapour deposition 40 ,molecular beam epitaxy 30,41 and layer-by-layer sputtering process.…”

Section: Introductionmentioning

confidence: 99%

Room temperature deep UV photoluminescence from low dimensional hexagonal boron nitride prepared using a facile synthesis

Sunny¹,

Balapure²,

Ganesan³

et al. 2022

Preprint

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Evaluation of the defect levels in low-dimensional materials is an important aspect of quantum science. In this article, we report a facile synthesis method of hexagonal boron nitride (h-BN) and evaluate the defects and their light emission characteristics.The thermal annealing procedure is optimized to obtain clean h-BN. The UV-Vis spectroscopy shows the optical energy gap of 5.28 eV which is comparable to the reported energy gap for exfoliated, clean h-BN samples. The optimized synthesis route of h-BN 1 has generated two kinds of defects which are characterised using room temperature photoluminescence measurements. The defects emit light at 4.18 eV (in deep ultraviolet region) and 3.44 eV (ultraviolet), respectively. The defect emitting deep ultraviolet (DUV) has oscillatory dependency on the excitation energy, while that emitting 3.44 eV light (ZPL3.44 eV) has a phonon bands with mean energy level separation of 125 meV measured at room temperature. This agrees very well with the Franck-Condon-like structure having regularly spaced energy levels, which are typical indications of single defect levels in the low dimensional h-BN.

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Band gap measurements of monolayer h-BN and insights into carbon-related point defects

Cited by 42 publications

References 122 publications

Scalable Synthesis of Monolayer Hexagonal Boron Nitride on Graphene with Giant Bandgap Renormalization

Scalable Synthesis of Monolayer Hexagonal Boron Nitride on Graphene with Giant Bandgap Renormalization

Polytypes of sp2-Bonded Boron Nitride

Room temperature deep UV photoluminescence from low dimensional hexagonal boron nitride prepared using a facile synthesis

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