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Development of scalable quantum photonic technologies requires on-chip integration of photonic components. Recently, hexagonal boron nitride (hBN) has emerged as a promising platform, following reports of hyperbolic phonon-polaritons and optically stable, ultra-bright quantum emitters. However, exploitation of hBN in scalable, on-chip nanophotonic circuits and cavity quantum electrodynamics (QED) experiments requires robust techniques for the fabrication of high-quality optical resonators. In this letter, we design and engineer suspended photonic crystal cavities from hBN and demonstrate quality ( Q ) factors in excess of 2000. Subsequently, we show deterministic, iterative tuning of individual cavities by direct-write EBIE without significant degradation of the Q -factor. The demonstration of tunable cavities made from hBN is an unprecedented advance in nanophotonics based on van der Waals materials. Our results and hBN processing methods open up promising avenues for solid-state systems with applications in integrated quantum photonics, polaritonics and cavity QED experiments. Hexagonal boron nitride (hBN) is a layered van der Waals material showing promise for nanophotonics. Here, the authors design hBN photonic crystal cavities with quality factors exceeding 2000, and further demonstrate deterministic tuning of individual cavities by minimally-invasive electron beam induced etching.

Single-photon emitters serve as building blocks for many emerging concepts in quantum photonics. The recent identification of bright, tunable and stable emitters in hexagonal boron nitride (hBN) has opened the door to quantum platforms operating across the infrared to ultraviolet spectrum. Although it is widely acknowledged that defects are responsible for single-photon emitters in hBN, crucial details regarding their origin, electronic levels and orbital involvement remain unknown. Here we employ a combination of resonant inelastic X-ray scattering and photoluminescence spectroscopy in defective hBN, unveiling an elementary excitation at 285 meV that gives rise to a plethora of harmonics correlated with single-photon emitters. We discuss the importance of N π* anti-bonding orbitals in shaping the electronic states of the emitters. The discovery of elementary excitations in hBN provides fundamental insights into quantum emission in low-dimensional materials, paving the way for future investigations in other platforms. Combining resonant inelastic X-ray scattering and photoluminescence spectroscopy, an elementary excitation in hexagonal-boron-nitride-based single-photon emitters has been demonstrated, giving rise to multiple regular harmonics that can explain the wide frequency range of these emitters.

Hexagonal boron nitride (hBN) has become a cornerstone dielectric and encapsulation material for next‐generation 2D electronics. Its atomically flat surface, wide bandgap, chemical stability, low trap density, and high in‐plane thermal conductivity collectively enhance carrier mobility, suppress Coulomb and remote phonon scattering, and enable efficient heat dissipation across a range of 2D devices. Translating these properties into practical technologies demands wafer‐scale synthesis of hBN films with precise control over thickness, crystallographic orientation, and stacking sequence, along with integration schemes compatible with semiconductor manufacturing. This Review highlights recent advances in scalable vapor‐phase synthesis of hBN, emphasizing self‐limiting growth mechanisms and epitaxial strategies that yield single‐crystalline and stacking‐engineered films. We discuss transfer and direct‐integration methods for embedding hBN into 2D architectures and correlate synthesis parameters with device‐level metrics. Key challenges and future directions are outlined for establishing hBN as a manufacturable platform for high‐performance, wafer‐scale 2D electronics. This Review highlights recent breakthroughs in wafer‐scale hBN synthesis and its integration into next‐generation 2D electronics. We analyze growth kinetics, epitaxial strategies, and stacking‐sequence control while correlating material quality with device performance. Strategies to bridge the scale gap between material growth and device‐level application are proposed to enhance the reliability of hBN‐based electronic platforms.

2D hexagonal boron nitride (2D-hBN) is a lesser utilised material than other 2D counterparts in electrochemistry due to initial reports of it being non-conductive. As we will demonstrate in this review, this common misconception is being challenged, and researchers are starting to utilise 2D-hBN in the field of electrochemistry, particularly as the basis of electroanalytical sensing platforms. In this critical review, we overview the use of 2D-hBN as an electroanalytical sensing platform summarising recent developments and trends and highlight future developments of this interesting, often overlooked, 2D material.

Coupled two-dimensional electron-hole bilayers provide a unique platform to study strongly correlated Bose-Fermi mixtures in condensed matter. Electrons and holes in spatially separated layers can bind to form interlayer excitons, composite Bosons expected to support high-temperature exciton condensates. The interlayer excitons can also interact strongly with excess charge carriers when electron and hole densities are unequal. Here, we use optical spectroscopy to quantitatively probe the local thermodynamic properties of strongly correlated electron-hole fluids in MoSe 2 /hBN/WSe 2 heterostructures. We observe a discontinuity in the electron and hole chemical potentials at matched electron and hole densities, a definitive signature of an excitonic insulator ground state. The excitonic insulator is stable up to a Mott density of ~0.8 × 10 12 cm −2 and has a thermal ionization temperature of ~70 K. The density dependence of the electron, hole, and exciton chemical potentials reveals strong correlation effects across the phase diagram. Compared with a non-interacting uniform charge distribution, the correlation effects lead to significant attractive exciton-exciton and exciton-charge interactions in the electron-hole fluid. Our work highlights the unique quantum behavior that can emerge in strongly correlated electron-hole systems. Transition metal dichalcogenide bilayers offer a novel platform for studying correlated electron-hole fluids. Here the authors use optical spectroscopy to probe thermodynamic properties of coupled electron-hole states in MoSe 2 /hBN/WSe 2 heterostructures, providing evidence for an excitonic insulator ground state.

Two-dimensional (2D) hexagonal boron nitride (hBN) has garnered significant attention due to its exceptional thermal and chemical stability, excellent dielectric properties, and unique optical characteristics, making it widely used in deep ultraviolet (DUV) applications. However, the integration of hBN with plasmonic materials in the visible region (532 nm) has not been fully explored, particularly in terms of morphology regulation and size control of mono- and bimetallic nanoparticles (BMNPs) namely gold (Au), silver (Ag) and Au-Ag. A Schottky junction-based metal–semiconductor contact configuration is employed to achieve hot-carrier reflections on the metal side, enhancing the quantum efficiency of the photodetector. The fabricated metallic NPs/hBN photodetector demonstrates a responsivity of 1.33 A/W, a specific detectivity of 1.03 × 10 11 Jones, an ultra-low dark current of 7.00 µA and a high photo response ratio of 2.47. This improved performance is attributed to the visible light-modulated band-to-band excitation in hBN layer and internal photoemission resulting from the NPs/hBN junction. The device also exhibits a rapid response speed of less than 300 µs for all the devices. This approach of integrating 2D/metal opens possibilities for fabricating low-cost, high-performance, flexible photodetectors for a range of optoelectronic devices.

Hexagonal boron nitride (hBN) has emerged as a key two-dimensional material. Its importance is linked to that of graphene because it provides an ideal substrate for graphene with minimal lattice mismatch and maintains its high carrier mobility. Moreover, hBN has unique properties in the deep ultraviolet (DUV) and infrared (IR) wavelength bands owing to its indirect bandgap structure and hyperbolic phonon polaritons (HPPs). This review examines the physical properties and applications of hBN-based photonic devices that operate in these bands. A brief background on BN is provided, and the theoretical background of the intrinsic nature of the indirect bandgap structure and HPPs is discussed. Subsequently, the development of DUV-based light-emitting diodes and photodetectors based on hBN’s bandgap in the DUV wavelength band is reviewed. Thereafter, IR absorbers/emitters, hyperlenses, and surface-enhanced IR absorption microscopy applications using HPPs in the IR wavelength band are examined. Finally, future challenges related to hBN fabrication using chemical vapor deposition and techniques for transferring hBN to a substrate are discussed. Emerging techniques to control HPPs are also examined. This review is intended to assist researchers in both industry and academia in the design and development of unique hBN-based photonic devices operating in the DUV and IR wavelength regions.

Agricultural waste or agro-waste, including natural fibers and particles from various crop parts, is increasingly recognized as a significant contributor to environmental issues. However, from a circular economy perspective, these materials present an opportunity to be repurposed into new, eco-friendly products. The present study, specifically focuses on understanding the effect of different factors, such as the particulate loading and the size (coir and hBN − 1 to 5 wt%; Coir Powder size (100–200 μm) of the particles on composite’s corrosion rates and water absorption properties. These hybrid particulate composites (HPC) are fabricated using the hand layup process. The study uses a Box-Behnken Design (BBD-L15), a statistical experimental design tool that facilitates the effective investigation of many input parameters and their interactions, to comprehensively investigate these impacts. In addition, the study utilizes four metaheuristic algorithms—the Dragonfly Algorithm (DFO), the Salp Swarm Algorithm (SSA), Teaching Learning Optimization (TLO) and Particle Swarm Optimization (PSO)—alongside regression equations to predict the optimal characteristics of the composite material. To determine the best-performing algorithm, a comparison is made using Deng’s method. The findings indicate that the composite with a higher weight% of hBN particulates exhibits reduced water absorption and corrosion rates. A larger Deng’s Value often indicates better performance. Based on its higher Deng’s Value, the SSO algorithm outperforms other algorithms in minimizing both corrosion resistance (CR) and water absorption (WA). The Deng’s Value for SSO reached a maximum of 0.68, while the other algorithms show comparable but lower performance.

Two-dimensional (2D) supramolecular arrays provide a route to the spatial control of the chemical functionality of a surface, but their deposition is in almost all cases limited to a monolayer termination. Here we investigated the sequential deposition of one 2D array on another to form a supramolecular heterostructure and realize the growth—normal to the underlying substrate—of distinct ordered layers, each of which is stabilized by in-plane hydrogen bonding. For heterostructures formed by depositing terephthalic acid or trimesic acid on cyanuric acid/melamine, we have determined, using atomic force microscopy under ambient conditions, a clear epitaxial arrangement despite the intrinsically distinct symmetries and/or lattice constants of each layer. Structures calculated using classical molecular dynamics are in excellent agreement with the orientation, registry and dimensions of the epitaxial layers. Calculations confirm that van der Waals interactions provide the dominant contribution to the adsorption energy and registry of the layers. Supramolecular heterostructures have been formed by the sequential deposition of two molecular layers with different symmetries and lattice constants — one consisting of carboxylic acid, the other of cyanuric acid and melamine — on a hexagonal boron nitride substrate. Characterization by atomic force microscopy and molecular dynamics simulations shows epitaxial arrangements between the layers.

Enhancing the high-temperature tribological performance of protective claddings is crucial for demanding industrial applications. This study focuses on developing hexagonal boron nitride (hBN)-reinforced Ni-based composite claddings to improve wear resistance over a wide temperature range. Ni/WC/CeO2 cladding layers with varying hBN contents (0.25 wt% and 0.75 wt%) were fabricated on 45 steel substrates via vacuum cladding. Their microstructure, mechanical properties, and tribological behavior under thermal cycling (25–600 °C) were systematically evaluated. Results reveal that the in situ formation of a hard Cr2B phase, coupled with hBN addition, was key to achieving optimal overall properties. The composite with 0.25 wt% hBN (NWB25) demonstrated optimal overall properties, featuring the lowest porosity (0.1813%) and the highest H/E ratio (0.0405), leading to the best overall tribological performance. A distinct transition from mild to severe wear was observed during the 300 °C-2 stage, resulting from the fracture of a high-temperature tribo-oxidative layer. An hBN content of 0.25 wt% is identified as optimal for balancing solid lubrication and matrix cohesion, thereby achieving superior thermal cycling wear resistance. Higher hBN concentrations promote grain coarsening and increased porosity, which degrade performance.