Department of Mechanical and Aerospace Engineering, University of Virginia , Charlottesville, Virginia 22904, United States.
Institute for Nanoscale and Quantum Scientific and Technological Advanced Research, University of Virginia , Charlottesville, Virginia 22904, United States.
ACS Nano. 2016 May 24;10(5):5431-9. doi: 10.1021/acsnano.6b01674. Epub 2016 Apr 21.
Heterostructures that are assembled by interfacing two-dimensional (2D) materials offer a unique platform for the emerging devices with unprecedented functions. The attractive functions in heterostructures that are usually absent and beyond the single layer 2D materials are largely affected by the inherent lattice mismatch between layers. Using nonequilibrium molecular dynamics simulations, we show that the phonon thermal transport in the graphene-MoS2 bilayer heterostructure is reduced by the lattice mismatch, and the reduction can be mitigated well by an external tension, weakening the effect of inherent mismatch-induced strain on thermal conductivity. Mechanical analysis in each layered component indicates that the external tension will alleviate the lattice mismatch-induced deformation. The phonon spectra are also softened by the applied tension with a significant shift of frequency from high to low modes. A universal theory is proposed to quantitatively predict the role of the lattice mismatch in thermal conductivity of various bilayer heterostructures and shows good agreement with simulations.
由二维（2D）材料界面组装而成的异质结构为具有前所未有功能的新兴设备提供了独特的平台。异质结构中通常不存在且超出单层 2D 材料的吸引力功能在很大程度上受到层间固有晶格失配的影响。通过非平衡分子动力学模拟，我们表明，晶格失配对石墨烯- MoS2 双层异质结构中的声子热传输有降低作用，而外部张力可以很好地缓解这种降低作用，从而减弱固有失配诱导应变对热导率的影响。对各层组件的力学分析表明，外部张力将减轻晶格失配引起的变形。施加的张力也使声谱软化，频率从高到低模式有明显的移动。提出了一个通用理论来定量预测晶格失配对各种双层异质结构热导率的作用，与模拟结果吻合较好。
