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Coupling of deterministically activated quantum emitters in hexagonal boron nitride to plasmonic surface lattice resonances
摘要： The cooperative phenomena stemming from the radiation field-mediated coupling between individual quantum emitters are presently attracting broad interest for applications related to on-chip photonic quantum memories and long-range entanglement. Common to these applications is the generation of electro-magnetic modes over macroscopic distances. Much research, however, is still needed before such systems can be deployed in the form of practical devices, starting with the investigation of alternate physical platforms. Quantum emitters in two-dimensional (2D) systems provide an intriguing route because these materials can be adapted to arbitrarily shaped substrates to form hybrid systems wherein emitters are near-field-coupled to suitable optical modes. Here, we report a scalable coupling method allowing color center ensembles in a van der Waals material (hexagonal boron nitride) to couple to a delocalized high-quality plasmonic surface lattice resonance. This type of architecture is promising for photonic applications, especially given the ability of the hexagonal boron nitride emitters to operate as single-photon sources at room temperature.
关键词： coupling,strain,delocalization,defect,quantum emission,photoluminescence,surface plasmons,hexagonal boron nitride,2D materials,surface lattice resonance
更新于2025-09-11 14:15:04
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Wafer-scale single-crystal hexagonal boron nitride film via self-collimated grain formation
摘要： Although polycrystalline hexagonal boron nitride (PC-hBN) has been realized, defects and grain boundaries still cause charge scatterings and trap sites, impeding high-performance electronics. Here, we report a method of synthesizing wafer-scale single-crystalline hBN (SC-hBN) monolayer films by chemical vapor deposition. The limited solubility of boron (B) and nitrogen (N) atoms in liquid gold promotes high diffusion of adatoms on the surface of liquid at high temperature to provoke the circular hBN grains. These further evolve into closely packed unimodal grains by means of self-collimation of B and N edges inherited by electrostatic interaction between grains, eventually forming an SC-hBN film on a wafer scale. This SC-hBN film also allows for the synthesis of wafer-scale graphene/hBN heterostructure and single-crystalline tungsten disulfide.
关键词： single-crystalline,hexagonal boron nitride,wafer-scale,tungsten disulfide,chemical vapor deposition,graphene/hBN heterostructure
更新于2025-09-10 09:29:36
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Angular Optical Transparency Induced by Photonic Topological Transition in Hexagonal Boron Nitride
摘要： The transmission property of hexagonal boron nitride at its four photonic topological transitions has been studied. An interesting result is revealed that the angular optical transparency can be achieved at wavelength 12.0494 μm. The numerical results indicate that the transparency window has an angular full width at half maximum of 4° with an optical transmission higher than 0.9 at normal incidence. Besides, corresponding to an angular full width at half maximum narrower than 20°, the wavelength span is about 230 nm. These features may make the hexagonal boron nitride holds promise for applications in private screens and optical detectors.
关键词： Hexagonal boron nitride,Photonic topological transition,Angular transparency
更新于2025-09-10 09:29:36
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Interface States in Bilayer Graphene Encapsulated by Hexagonal Boron Nitride
摘要： The threshold voltages at the onset of conduction for electron and hole branches can provide information on band gap values or the interface states in a gap. We measured conductivity of bilayer graphene encapsulated by hexagonal boron nitride as a function of back and top gates, where another bilayer graphene is used as a top gate. From the measured conductivity the transport gap values were extracted assuming zero interface trap states, and they are close to the theoretically expected gap values. From a little discrepancy an average density of interface states per energy within a band gap (Dit) is also estimated. The data clearly show that Dit decreases as a bilayer graphene band gap increases rather than being constant. Despite the decreasing trend of Dit, interestingly the total interface states within a gap increases linearly as a band gap increases. This is because of ~ 2 × 1010 cm-2 interface states localized at band edges even without a band gap, and other gap states are equally spread over the gap.
关键词： band gap,hexagonal boron nitride,bilayer graphene,transport gap,interface states
更新于2025-09-10 09:29:36
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Strength and toughness anisotropy in hexagonal boron nitride: An atomistic picture
摘要： Strength and toughness are two crucial mechanical properties of a solid that determine its ability to function reliably without undergoing failure in extreme conditions. While hexagonal boron nitride (hBN) is known to be elastically isotropic in the linear regime of mechanical deformation, its directional response to extreme mechanical loading remains less understood. Here, using a combination of density functional theory calculations and molecular dynamics simulations, we show that strength and crack nucleation toughness of pristine hBN are strongly anisotropic and chirality dependent. They vary nonlinearly with the chirality of the lattice under symmetry breaking deformation, and the anisotropic behavior is retained over a large temperature range with a decreasing trend at higher temperatures. An atomistic analysis reveals that bond deformation and associated distortion of electron density are nonuniform in the nonlinear regime of mechanical deformation, irrespective of the loading direction. This nonuniformity forms the physical basis for the observed anisotropy under static conditions, whereas reduction in nonuniformity and thermal softening reduce anisotropy at higher temperatures. The chirality-dependent anisotropic effects are well predicted by inverse cubic polynomials.
关键词： chirality,anisotropy,hexagonal boron nitride,molecular dynamics simulations,density functional theory,strength,toughness
更新于2025-09-10 09:29:36
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A universal method for large-yield and high-concentration exfoliation of two-dimensional hexagonal boron nitride nanosheets
摘要： Hexagonal boron nitride (hBN) is an ultra-wide bandgap insulating material, which possesses a graphite-like layered structure, and the two-dimensional (2D) hexagonal boron nitride nanosheets (hBNNS), exfoliated from the bulk hBN, have promising applications in electronic packaging and high-power devices, due to the high thermal conductivity, excellent thermal/chemical stability as well as the ultra-wide band gap. However, the exfoliation of hBNNS is still a challenge with respect to high cost, time consuming, and low yield. Herein, a facile hydrothermal exfoliation method was proposed for the first time to exfoliate the hBNNS in a large yield and high concentration. In the optimized hydrothermal conditions, the lithium ion (Li+) intercalation, isopropanol (IPA) solvent, and the strong stirring could give rise to a large exfoliation yield up to (cid:1)55% and a high concentration (cid:1)4.13 mg/mL. In addition, the exfoliated hBNNS could enhance the methyl orange (MO) photodegradation efficiency of TiO2 from 91% to 96.4 %. Most importantly, this hydrothermal exfoliation method could be a universal approach for the exfoliation of 2D materials.
关键词： Hydrothermal exfoliation,Nanosheets,2D materials,Hexagonal boron nitride,Solubility parameters theory,Universal approach
更新于2025-09-10 09:29:36
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Impacts of in-plane strain on commensurate graphene/hexagonal boron nitride superlattices
摘要： Due to atomically thin structure, graphene/hexagonal boron nitride (G/hBN) heterostructures are intensively sensitive to the external mechanical forces and deformations being applied to their lattice structure. In particular, strain can lead to the modification of the electronic properties of G/hBN. Furthermore, moiré structures driven by misalignment of graphene and hBN layers introduce new features to the electronic behavior of G/hBN. Utilizing ab initio calculation, we study the strain-induced modification of the electronic properties of diverse stacking faults of G/hBN when applying in-plane strain on both layers, simultaneously. We observe that the interplay of few percent magnitude in-plane strain and moiré pattern in the experimentally applicable systems leads to considerable valley drifts, band gap modulation and enhancement of the substrate-induced Fermi velocity renormalization. Furthermore, we find that regardless of the strain alignment, the zigzag direction becomes more efficient for electronic transport, when applying in-plane non-equibiaxial strains.
关键词： strain,graphene/hexagonal boron nitride,moiré pattern,electronic properties
更新于2025-09-10 09:29:36
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Probing the nanoscale origin of strain and doping in graphene-hBN heterostructures
摘要： We use confocal Raman microscopy and a recently proposed vector analysis scheme to investigate the nanoscale origin of strain and carrier concentration in exfoliated graphene-hexagonal boron nitride (hBN) heterostructures on silicon dioxide (SiO2). Two types of heterostructures are studied: graphene on SiO2 partially covered by hBN, and graphene fully encapsulated between two hBN flakes. We extend the vector analysis method to produce separated spatial maps of the strain and doping variation across the heterostructures. This allows us to visualise and directly quantify the much-speculated effect of the environment on carrier concentration in graphene. Moreover, we demonstrate that variations in strain and carrier concentration in graphene arise from nanoscale features of the heterostructures such as fractures, folds and bubbles trapped between layers. For bubbles in hBN-encapsulated graphene, hydrostatic strain is shown to be greatest at bubble centres, whereas the maximum carrier concentration is localised at bubble edges. Raman spectroscopy is shown to be a non-invasive tool for probing strain and doping in graphene, which could prove useful for engineering of two-dimensional devices.
关键词： hexagonal boron nitride,Raman,strain,van der Waals heterostructures,graphene,hBN,doping
更新于2025-09-09 09:28:46
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Recent progress in synthesis, properties and applications of hexagonal boron nitride based heterostructures
摘要： Featuring an absence of dangling bonds, large band gap, low dielectric constant, excellent chemical inertness, atomically thin hexagonal boron nitride (h-BN) is considered as an ideal candidate for the integration with graphene and other 2D materials. During the past years, great efforts have been devoted to the research area of h-BN based heterostructures from fundamental study to practical applications. In this review, we summarize the recent progress in the synthesis, novel properties and potential applications of h-BN based heterostructures, especially the synthesis technique. Firstly, various approaches for the preparation of both in-plane and vertical stacked h-BN based heterostructures are introduced in detail, including top-down strategies associated with exfoliation-transfer processes and bottom-up strategies such as chemical vapor deposition (CVD)-based growth. Secondly, we discuss some novel properties arise in these heterostructures. Then, several promising applications in electronic and optoelectronic devices based on these heterostructures are also reviewed. Finally, we discuss the main challenges and possible research directions in this field.
关键词： heterostructures,application,hexagonal boron nitride,property,synthesis
更新于2025-09-09 09:28:46
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Synthesis and photoluminescence properties of hexagonal BGaN alloys and quantum wells
摘要： Hexagonal boron nitride (h-BN) has emerged as an important extreme bandgap semiconductor as well as a two-dimensional material. Achieving the ability for tuning the optoelectronic properties through alloying and heterojunction will further expand the applications of h-BN. By utilizing h-BN epilayer as a template, the synthesis of BN-rich B1?xGaxN alloys and quantum wells crystalized in the hexagonal phase has been demonstrated for the first time by metal organic chemical vapor deposition. The incorporation of Ga tends to enhance the conductivity. A blue shift in the band-edge emission upon the formation of h-BN/BGaN/BN QW has been observed, indicating the feasibility for heterojunction formation.
关键词： hexagonal boron nitride,MOCVD,photoluminescence,BGaN alloys,quantum wells
更新于2025-09-09 09:28:46