Elastic constants of cubic and wurtzite boron nitrides

Nagakubo, Akira; Ogi, Hirotsugu; Sumiya, Hitoshi; Kusakabe, Koichi; Hirao, Masahiko

doi:10.1063/1.4811789

Cited by 56 publications

(45 citation statements)

References 65 publications

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“…36 Actually, larger-grain specimens include more wBNs, and apparent wBN dependence of C L could be seen. However, we found that the elastic constants of isotropic cBN and wBN are the same in the previous work, 37 insisting that wBN content dependence does not have to be considered. Then, we considered our specimens as composites, including softened pennyshaped inclusions of cBN, simulating grain boundaries, and Fig.…”

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confidence: 51%

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Elasticity and hardness of nano-polycrystalline boron nitrides: The apparent Hall-Petch effect

Nagakubo

Ogi

Sumiya

et al. 2014

Applied Physics Letters

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Nano-polycrystalline boron nitride (BN) is expected to replace diamond as a superhard and superstiff material. Although its hardening was reported, its elasticity remains unclear and the as-measured hardness could be significantly different from the true value due to the elastic recovery. In this study, we measured the longitudinal-wave elastic constant of nano-polycrystalline BNs using picosecond ultrasound spectroscopy and confirmed the elastic softening for small-grain BNs. We also measured Vickers and Knoop hardness for the same specimens and clarified the relationship between hardness and stiffness. The Vickers hardness significantly increased as the grain size decreased, while the Knoop hardness remained nearly unchanged. We attribute the apparent increase in Vickers hardness to the elastic recovery and propose a model to support this insight.

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confidence: 51%

“…37 The elastic stiffness tensor C C of the composite can be calculated by Eshelby's equivalent inclusion theory using Mori-Tanaka mean field modeling 38,39…”

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confidence: 99%

Elasticity and hardness of nano-polycrystalline boron nitrides: The apparent Hall-Petch effect

Nagakubo

Ogi

Sumiya

et al. 2014

Applied Physics Letters

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“…By adding boron as the lightest and smallest group III element to the currently used AlGaN system, another degree of freedom in band gap and lattice constant tailoring can be utilized. To lattice‐match AlBGaN QWs with an aluminium content of 50% to an AlN barrier, a boron incorporation below 6% would be sufficient . However, the solubility of boron in AlGaN is very low.…”

Section: Introductionmentioning

confidence: 99%

“…Considering state of the art UV‐LED devices, Al x Ga 1− x N quantum wells ( x = 0.4) and barriers ( x = 0.55) have a difference in aluminium composition of

Δ x = 15 %

. Lattice matching of both layers could be achieved by incorporating only small B amounts of about 2% in the quantum wells assuming the validity of Vegard's law and lattice constants of 0.3112, 0.3189, and 0.2549 nm for the binaries AlN, GaN, and wurtzite BN, respectively . Still, the low solubility, but also parasitic gas phase reactions and low surface mobility of boron, make it very challenging to grow high quality quaternary AlBGaN alloys with appropriate optoelectronic properties .…”

Section: Introductionmentioning

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Investigation of Boron Containing AlN and AlGaN Layers Grown by MOVPE

Rettig

Scholz

Steiger

et al. 2018

Physica Status Solidi (b)

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In this work we investigate the epitaxial growth of boron containing (Al,Ga)N layers and superlattices for applications in the active region of UV‐LEDs. For AlBN layers containing 5% of boron as quantified by secondary ion mass spectrometry, columnar growth has been observed. Transmission electron microscopy (TEM) studies revealed B‐lean, crystalline columns, separated by highly boron containing amorphous intermediate regions. However, in the first few nanometers of AlBN growth, no evidence of columnar growth can be found. Indeed, first layers of AlBGaN/AlN superlattice stacks do not show any sign of columnar growth. However, for increasing thickness, 3D‐like growth develops through formation of pyramidal structures. TEM‐based selective area electron diffraction analysis does not show evidence of lattice tilting, proving that the observed inclined facets are not a result of lattice twinning. Thin AlBGaN layers with different thickness containing 1% boron show similar photoluminescence (PL) spectra with slightly reduced intensity as compared to similar B‐free AlGaN layers. Although small grainy structures develop and increase in density for AlBGaN layers with a thickness of 10 nm and more, the PL intensity increases steadily with layer thickness, showing that these grains do not drastically deteriorate their luminescence properties.

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Recent Development of Boron Nitride towards Electronic Applications

Izyumskaya

Demchenko

Das

et al. 2017

Adv Elect Materials

113

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Boron nitride occurs in several polymorphs, among which cubic and hexagonal varieties have been extensively studied over many years and have found numerous practical applications. Although various forms of BN have been used as lubricant and abrasive material for many years, the unique electronic properties of BN have not been yet utilized. Due to their wide optical bandgaps (the widest among nitride semiconductors), cubic and hexagonal polymorphs of BN are promising candidates for optoelectronic devices operating in the deep‐ultraviolet range and for high‐power electronic devices for switching and radio‐frequency applications. The layered structure of hexagonal BN allows preparation of ultrathin nanosheets with very smooth surfaces and low defect density, which are proved to be useful as supporting substrates and gate dielectric layers in graphene‐based structures. The first device demonstrations are very encouraging. In this contribution, the recent progress in properties, fabrication technologies, and emerging applications of BN as a wide‐gap semiconductor material is reviewed.

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Elastic constants of cubic and wurtzite boron nitrides

Cited by 56 publications

References 65 publications

Elasticity and hardness of nano-polycrystalline boron nitrides: The apparent Hall-Petch effect

Elasticity and hardness of nano-polycrystalline boron nitrides: The apparent Hall-Petch effect

Investigation of Boron Containing AlN and AlGaN Layers Grown by MOVPE

Recent Development of Boron Nitride towards Electronic Applications

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