High thermal conductivity driven by the unusual phonon relaxation time platform in 2D monolayer boron arsenide

At a Glance

Metadata	Details
Publication Date	2020-01-01
Journal	RSC Advances
Authors	Yanxiao Hu, Dengfeng Li, Yan Yin, Shichang Li, Hangbo Zhou
Institutions	Chongqing University of Posts and Telecommunications, Institute of High Performance Computing
Citations	24
Analysis	Full AI Review Included

Technical Documentation & Analysis: High Thermal Conductivity in 2D Boron Arsenide

Source Paper: High thermal conductivity driven by the unusual phonon relaxation time platform in 2D monolayer boron arsenide (RSC Adv., 2020, 10, 25305)

Executive Summary

This research highlights the potential of monolayer honeycomb Boron Arsenide (h-BAs) as a high-performance material for thermal management in miniaturized electronic devices. While h-BAs demonstrates exceptional thermal properties for a 2D semiconductor, 6CCVD provides superior, scalable, and proven Single Crystal Diamond (SCD) solutions for engineers requiring the highest possible thermal dissipation.

Core Achievement: First-principles calculations revealed that monolayer h-BAs possesses an ultra-high thermal conductivity (κ) of 181 W m⁻¹ K⁻¹ at 300 K.
Unique Mechanism: Unlike graphene and h-BN, where out-of-plane (ZA) phonons dominate, the high κ in h-BAs is primarily driven by in-plane acoustic (IA) phonons (76% contribution).
Relaxation Platform: The high IA contribution stems from a unique, frequency-independent ‘platform’ region in the phonon relaxation time, caused by the suppression of the ZA + ZA → IA scattering channel.
Comparative Performance: The κ of h-BAs (181 W m⁻¹ K⁻¹) is significantly higher than similar 2D materials like h-GaN (16 W m⁻¹ K⁻¹) and MoS₂ (87.6 W m⁻¹ K⁻¹).
6CCVD Value Proposition: For high-power density applications requiring extreme thermal management, 6CCVD’s SCD material offers intrinsic thermal conductivity exceeding 2000 W m⁻¹ K⁻¹, providing an order of magnitude improvement over the simulated h-BAs performance.

Technical Specifications

The following hard data points were extracted from the analysis of monolayer h-BAs thermal transport properties:

Parameter	Value	Unit	Context
Thermal Conductivity (κ)	181	W m⁻¹ K⁻¹	Iterative BTE solution for h-BAs at 300 K
RTA Thermal Conductivity	~130	W m⁻¹ K⁻¹	Relaxation Time Approximation (72% of iterative)
Dominant Phonon Mode Contribution	76	%	In-plane Acoustic (IA) modes (TA and LA)
Out-of-Plane Mode Contribution	23	%	Out-of-plane Acoustic (ZA) modes
Maximum IA Relaxation Time	10²	ps	Observed in the frequency-independent ‘platform’ region
Maximum ZA Frequency	1.81	THz	Flat ZA branch, indicating weak out-of-plane bonding
LO-TO Frequency Splitting	0.31	THz	At the Brillouin Zone center (Γ point)
Lattice Constant	3.39	Å	Optimized structure of monolayer h-BAs
Born Effective Charge (Z*(B)_xx)	1.744	e	In-plane charge transfer
Dielectric Constant (ε_xx)	4.678	-	Static dielectric constant

Key Methodologies

The thermal transport properties of monolayer h-BAs were determined using advanced computational techniques based on Density Functional Theory (DFT) and the Boltzmann Transport Equation (BTE).

First-Principles Calculation (DFT): Performed using the Vienna Ab initio Simulation Package (VASP) with the Generalized Gradient Approximation (GGA) functional of Perdew-Burke-Ernzerhof (PBE).
Structural Relaxation: Structure fully relaxed until interatomic force was less than 10^-5 eV Å^-1, utilizing a cutoff energy of 550 eV.
BTE Solution: The phonon BTE was solved using the ShengBTE code to calculate the thermal conductivity tensor element (κ_αβ).
Force Constant Calculation: Both 2nd and 3rd Order Anharmonic Force Constants (IFCs) were calculated via the finite displacement method.
Supercell and k-mesh: 7 x 7 x 1 supercells and a 3 x 3 x 1 k-mesh were used to ensure the convergence of IFCs.
Scattering Calculation: Phonon-phonon scattering was calculated using a dense 101 x 101 x 1 q-mesh, considering interactions up to the 7th nearest neighbors (cutoff distance of 0.68 nm).
Electrostatic Correction: Born effective charges and dielectric constants were calculated via Density Functional Perturbation Theory (DFPT) to correct the dynamical matrix for long-range electrostatic interactions.

6CCVD Solutions & Capabilities

The research confirms the critical need for materials with ultra-high thermal conductivity to manage heat in high-power density and miniaturized electronic systems. While 2D h-BAs is a promising theoretical candidate, 6CCVD offers commercially available, scalable, and superior MPCVD diamond materials that meet and exceed the thermal performance requirements cited in this study.

Applicable Materials for Extreme Thermal Management

To replicate or extend research into extreme thermal management, 6CCVD recommends the following materials, which offer intrinsic thermal conductivity far surpassing the 181 W m⁻¹ K⁻¹ achieved by h-BAs:

6CCVD Material	Key Specifications	Application Relevance to Paper
Electronic Grade SCD	κ > 2000 W m⁻¹ K⁻¹; Low Nitrogen Content (< 1 ppm)	Ideal heat spreaders for high-power density devices (e.g., GaN/SiC integration).
Optical Grade SCD	κ > 1800 W m⁻¹ K⁻¹; Ra < 1 nm polishing	Substrates for epitaxial growth of 2D materials (like h-BAs) or high-quality optical windows requiring zero thermal lensing.
Polycrystalline Diamond (PCD)	κ up to 1800 W m⁻¹ K⁻¹; Plates up to 125 mm diameter	Large-area thermal management and robust heat sinks for industrial applications.
Boron-Doped Diamond (BDD)	Tunable conductivity (metallic to semiconducting)	Electrochemical applications or integration where electrical conductivity is required alongside high thermal stability.

Customization Potential for Advanced Research

The study relies on precise material characteristics (e.g., planar structure, specific bonding properties). 6CCVD provides the necessary engineering precision to support the next generation of thermal transport research:

Custom Dimensions: We offer SCD and PCD plates/wafers in custom sizes, including PCD wafers up to 125 mm in diameter, suitable for scaling up device integration studies.
Thickness Control: SCD and PCD layers are available from 0.1 µm up to 500 µm, allowing researchers to precisely control the material dimension for studying quantum confinement effects and thermal boundary resistance.
Ultra-Smooth Polishing: Our internal polishing capability achieves surface roughness (Ra) of < 1 nm for SCD and < 5 nm for inch-size PCD, critical for minimizing interface scattering losses when integrating 2D materials like h-BAs.
Advanced Metalization: We offer custom metalization services (including Au, Pt, Pd, Ti, W, and Cu) directly on the diamond surface, essential for creating electrical contacts or bonding layers required in device fabrication.

Engineering Support

6CCVD’s in-house team of PhD-level material scientists specializes in optimizing MPCVD diamond properties for extreme environments. We offer comprehensive engineering support for projects focused on High-Power Thermal Management and Low-Dimensional Thermal Transport. Our expertise ensures optimal material selection, precise doping control, and surface preparation necessary to achieve maximum performance in applications requiring superior thermal dissipation.

Call to Action: For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

The cubic boron arsenide (BAs) crystal has received extensive research attention because of its ultra-high thermal conductivity comparable to that of diamond.

Tech Support

Original Source

DOI: https://doi.org/10.1039/d0ra04737f