Probing the Thermodynamic Stability and Phonon Transport inTwo-Dimensional Hexagonal Aluminum Nitride Monolayer
Probing the Thermodynamic Stability and Phonon Transport inTwo-Dimensional Hexagonal Aluminum Nitride Monolayer
复制标题
二维六方氮化铝单层热力学稳定性和声子输运的探讨
DOI：
10.1021/acs.jpcc.6b09706
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Shangchao Lin
中科院分区：
文献类型：
--
作者：
Lingling Zhao;Shang Xu;Mingchao Wang;Shangchao Lin
石墨烯的发现及其惊人的性能引起了人们对新型二维（2D）材料在微纳米器件中实际应用的极大兴趣。二维六方氮化铝单层膜（h-AlN）是一种III-V族宽带隙半导体材料，在光电子和能量转换等领域具有广阔的应用前景。不幸的是，它们的高温热力学稳定性和热输运性质还没有报道。在这里，我们调查这些属性，第一次，单层AlN使用平衡和非平衡分子动力学模拟。我们发现，由于Al-N共价键的存在，AlN在3500-4000 K之间具有很高的熔点。基于热输运动力学理论和量子修正，在量子修正的室温下，估算了h-AlN的本征面内热导率为264.1 W m-1 K-1，声子平均自由程为154 nm。声子输运性质的分析表明，声学模式与某些光学模式之间存在明显的频隙。此外，我们发现，低弹性刚度（声子群速度）和丢失的声子模式在这样的间隙归因于较低的热导率的h-AlN比其二维III-V族对应物，h-BN。我们的计算工作不仅表征了h-AlN在电子学实际应用中的热传输行为，而且还启发了其他二维III-V族材料作为更有效的高温热导体的最佳选择。
Discovery of graphene and its astonishing properties have drawn great interest in new two-dimensional (2D) materials for practical applications in micro- and nanodevices. 2D hexagonal aluminum nitride monolayer (h-AlN), a III–V group wide-bandgap semiconductor, has promising applications in optoelectronics and energy conversion. Unfortunately, their high temperature thermodynamic stability and thermal transport properties have not been reported. Here we investigate these properties, for the first time, of monolayerh-AlN using both equilibrium and nonequilibrium molecular dynamics simulations. We find thath-AlN has a very high melting point in the range of 3500–4000 K due to the strong Al–N covalent bonding. On the basis of the kinetic theory of thermal transport and quantum corrections, the intrinsic in-plane thermal conductivity of ∼264.1 W m–1K–1and phonon mean free path of ∼154 nm ofh-AlN are estimated at quantum-corrected room temperature. The analysis of phonon transport properties demonstrates that there is a notable frequency gap between acoustic and some optical modes. Moreover, we find that the low elastic stiffness (phonon group velocity) and missing phonon modes in such gap attribute to the lower thermal conductivity ofh-AlN than that of its 2D III–V group counterpart,h-BN. Our computational work not only characterizes the thermal transport behavior ofh-AlN for practical applications in electronics, but also inspires optimal selections of other 2D III–V group materials as more efficient high-temperature heat conductors.