Banerjee Anibrata, Das Bikram Kumar, Chattopadhyay Kalyan Kumar
School of Materials Science and Nanotechnology, Jadavpur University, Kolkata 700032, India.
Department of Physics, Jadavpur University, Kolkata 700032, India.
Phys Chem Chem Phys. 2022 Jul 6;24(26):16065-16074. doi: 10.1039/d2cp01513g.
Using rigorous calculations within the framework of phonon Boltzmann transport theory, we have carried out a detailed investigation to probe the effects of uniform bi-axial strain and finite size on the lattice thermal conductivity () of monolayer AlN. We show that implementation of bi-axial tensile strain can shoot up the value of of monolayer AlN by a large amount unlike in the case of analogous 2D materials. The value of for monolayer AlN is calculated to be 306.5 W m K at room temperature (300 K). The value of can be raised by one order of magnitude to up to 1500.9 W m K at 300 K by applying a bi-axial strain of about 5%. A similar trend persists when the finite size effect is incorporated in the calculation. As the sample size is varied from 10 nm to 10 000 nm along with increasing tensile strain, a huge variation of (from 20.7 W m K to 558.9 W m K) is observed. Our study reveals that the major part of the lattice thermal conductivity of monolayer AlN comes from the contribution of the flexural acoustic (ZA) phonon modes. The anomalous trend of drastic increment in the value of with tensile strain is found to be a direct effect of interaction between nitrogen lone-pair electrons and bonding electrons in the ionic lattice which results in the reduction of phonon anharmonicity with increasing tensile strain. Our study provides a detailed analysis of the strain modulated and size-tuned thermal transport properties of monolayer AlN revealing that it is an impactful 2D material to be used in thermal management devices.
我们在声子玻尔兹曼输运理论框架内进行了严格计算，对均匀双轴应变和有限尺寸对单层AlN晶格热导率（κ）的影响进行了详细研究。我们发现，与类似的二维材料不同，施加双轴拉伸应变可大幅提高单层AlN的κ值。计算得出，单层AlN在室温（300K）下的κ值为306.5W·m⁻¹·K⁻¹。在300K时，通过施加约5%的双轴应变，κ值可提高一个数量级，达到1500.9W·m⁻¹·K⁻¹。在计算中纳入有限尺寸效应时，也会出现类似趋势。随着样品尺寸从10nm变化到10000nm，同时拉伸应变增加，可观察到κ值有巨大变化（从20.7W·m⁻¹·K⁻¹到558.9W·m⁻¹·K⁻¹）。我们的研究表明，单层AlN晶格热导率的主要部分来自弯曲声学（ZA）声子模式的贡献。发现κ值随拉伸应变急剧增加的异常趋势是离子晶格中氮孤对电子与成键电子相互作用的直接结果，这导致随着拉伸应变增加，声子非谐性降低。我们的研究对单层AlN的应变调制和尺寸调谐热输运性质进行了详细分析，表明它是一种可用于热管理器件的重要二维材料。
