Suppression of self-heating in nanoscale interfaces using h-BN based anisotropic heat diffuser

Jeon, Dasom; Lim, Jinho; Bae, Jun Seok; Kadirov, Arman; Choi, Yongsu; Lee, Seung–Hyun

doi:10.1016/j.apsusc.2020.148801

Cited by 8 publications

(3 citation statements)

References 39 publications

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“…[ 294 ] The combination of h ‐BN's large bandgap, inert chemical structures, and high thermal conductivity make h ‐BN an ideal substrate for future electronics. [ 13,21,26–30,36,77,295–302 ]…”

Section: Applicationsmentioning

confidence: 99%

“…[294] The combination of h-BN's large bandgap, inert chemical structures, and high thermal conductivity make h-BN an ideal substrate for future electronics. [13,21,[26][27][28][29][30]36,77,[295][296][297][298][299][300][301][302] Not only is h-BN of interest to the photonics community due its bandgap, but h-BN is also a naturally a hyperbolic material (the permittivity tensors along different crystallographic directions are opposite in sign) in the mid-IR, where these optical modes spectrally overlap with the molecular fingerprint region of the electromagnetic spectrum. [13,303,304] The ability to support hyperbolic phonon-polaritons (coupling of infrared photons with optical phonons [39,305] ) make it especially interesting for use in advanced optical signaling devices.…”

Section: Applicationsmentioning

confidence: 99%

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A Review of Scalable Hexagonal Boron Nitride (h‐BN) Synthesis for Present and Future Applications

2022

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Ga-N, In-P, etc. Crystalline BN has typically been perceived as a purely synthetic material, [1] however geological findings provide evidence of structures similar to BN in rocks. [2] BN exhibits several stable crystal forms (see Figure 1A), for example, i) sp 3 bonded cubic and wurtzite forms; and ii) sp 2 bonded hexagonal and rhombohedral forms. [3] The cubic BN (c-BN) form has "zincblende" type crystal structure consisting of overlapping fcc cubic lattices consisting of B and N atoms. The c-BN crystal structure is analogous to that of diamond. The wurtzite form of BN (w-BN) is also sp 3 bonded like c-BN, however the wurtzite form consists of a hexagonal lattice with each ring sitting in a boat configuration. The w-BN crystal structure is analogous to that of the rare lonsdaleite, a carbon allotrope formed from graphite under immense heat and pressure. [4] Hexagonal boron nitride (h-BN) is a layered hexagonal crystal (a = 2.505 Å and c = 6.653 Å) belonging to the P6 3 /mmc space group with a structure analogous to that of graphite. [11,12] Alternating B and N atoms are sp 2 bonded in-plane to form a hexagonal lattice and several such layers are stacked to form the bulk h-BN crystal (Figure 1B). [11,12] The BN sp 2 bonding results in strong in-plane σ bonds leading to high in-plane thermal conductivity, chemical stability and strength, while empty π orbitals make h-BN electrically insulating (bandgap ≈ 5.955 eV). [3,13] The in-plane BN bonds exhibit ionic behavior due to the stronger electronegativity of the N atoms and results in layer to layer interactions between h-BN layers leading to AA′ stacking configuration, that is, each N atom in one layer is directly above the B atoms of the next layer (Figure 1B). [14] In addition to AA′ stacking, AB stacking (Bernal stacking) has also been occasionally observed in thin h-BN films even though this is a higher energy configuration. [15,5] Finally, BN is also observed in rhombohedral form (r-BN). Each layer of r-BN is the same crystal structure as that of h-BN (Figure 1A), however r-BN follows an ABC stacking configuration whereby boron still sits atop nitrogen atoms, except layers are offset such that the 1 and 3 atoms (N and N for example) sit atop the 4 and 6 atoms (B and B in this example) of the ring below. [3] Hexagonal boron nitride (h-BN) is a layered inorganic synthetic crystal exhibiting high temperature stability and high thermal conductivity. As a ceramic material it has been widely used for thermal management, heat shielding, lubrication, and as a filler material for structural composites. Recent scientific advances in isolating atomically thin monolayers from layered van der Waals crystals to study their unique properties has propelled research interest in mono/few layered h-BN as a wide bandgap insulating support for nanoscale electronics, tunnel barriers, communications, neutron detectors, optics, sensing, novel separations, quantum emission from defects, among others. Realizing these futuristic applications hinges on scalable cost-effective high-qual...

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Section: Applicationsmentioning

confidence: 99%

Section: Applicationsmentioning

confidence: 99%

A Review of Scalable Hexagonal Boron Nitride (h‐BN) Synthesis for Present and Future Applications

2022

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“…While they exhibit some of the highest known conductivities along their in-plane directions, they often have relatively small cross-plane thermal conductivities. The high in-plane thermal conductivities make these materials excellent candidates for heat-spreading in nanoelectronics, , and the anisotropic thermal transport properties have found applications in thermoelectrics and thermal isolation of temperature-sensitive components. − The thermal conductivities of most bulk 2D crystals are well-known; however, at submicrometer length scales, the thermal conductivity of 2D materials can exhibit a strong thickness dependence. Once the thickness of a film is less than the average phonon mean free path, the thermal conductivity begins to decrease.…”

Section: Introductionmentioning

confidence: 99%

Thickness-Dependent Cross-Plane Thermal Conductivity Measurements of Exfoliated Hexagonal Boron Nitride

Jaffe

Smith

Watanabe

et al. 2023

ACS Appl. Mater. Interfaces

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Submicrometer-thick layers of hexagonal boron nitride (hBN) exhibit high in-plane thermal conductivity and useful optical properties, and serve as dielectric encapsulation layers with low electrostatic inhomogeneity for graphene devices. Despite the promising applications of hBN as a heat spreader, the thickness dependence of its cross-plane thermal conductivity is not known, and the cross-plane phonon mean free paths (MFPs) have not been measured. We measure the cross-plane thermal conductivity of hBN flakes exfoliated from bulk crystals. We find that submicrometer thick flakes exhibit thermal conductivities up to 8.1 ± 0.5 W m–1 K–1 at 295 K, which exceeds previously reported bulk values by more than 60%. Surprisingly, the average phonon mean free path is found to be several hundred nanometers at room temperature, a factor of 5 larger than previous predictions. When planar twist interfaces are introduced into the crystal by mechanically stacking multiple thin flakes, the cross-plane thermal conductivity of the stack is found to be a factor of 7 below that of individual flakes with similar total thickness, thus providing strong evidence that phonon scattering at twist boundaries limits the maximum phonon MFPs. These results have important implications for hBN integration in nanoelectronics and improve our understanding of thermal transport in two-dimensional materials.

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Reconstruction of interfacial thermal transport mediated by hotspot in silicon-based nano-transistors

Chen

Jiang

et al. 2023

International Journal of Heat and Mass Transfer

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Suppression of self-heating in nanoscale interfaces using h-BN based anisotropic heat diffuser

Cited by 8 publications

References 39 publications

A Review of Scalable Hexagonal Boron Nitride (h‐BN) Synthesis for Present and Future Applications

A Review of Scalable Hexagonal Boron Nitride (h‐BN) Synthesis for Present and Future Applications

Thickness-Dependent Cross-Plane Thermal Conductivity Measurements of Exfoliated Hexagonal Boron Nitride

Reconstruction of interfacial thermal transport mediated by hotspot in silicon-based nano-transistors

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