Two-dimensional heterostructures offer a new route to manipulate phonons at the nanoscale. By performing non-equilibrium molecular dynamics simulations we address the thermal transport properties of structurally asymmetric graphene/hBN nanoribbon heterojunctions deposited on several substrates: graphite, Si(100), SiC(0001), and SiO2. Our results show a reduction of the interface thermal resistance in coplanar G/hBN heterojunctions upon substrate deposition which is mainly related to the increment on the power spectrum overlap. This effect is more pronounced for deposition on Si(100) and SiO2 substrates, independently of the planar stacking order of the materials. Moreover, it has been found that the thermal rectification factor increases as a function of the degree of structural asymmetry for hBN-G nanoribbons, reaching values up to ∼24%, while it displays a minimum (∈[0.7,2.4]) for G-hBN nanoribbons. More importantly, these properties can also be tuned by varying the substrate temperature, e.g., thermal rectification of symmetric hBN-G nanoribbon is enhanced from 8.8% to 79% by reducing the temperature of Si(100) substrate. Our investigation yields new insights into the physical mechanisms governing heat transport in G/hBN heterojunctions, and thus opens potential new routes to the design of phononic devices.

中文翻译：

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通过衬底工程增强不对称石墨烯/hBN纳米带异质结的热传输性能

二维异质结构提供了一种在纳米尺度上操纵声子的新途径。通过执行非平衡分子动力学模拟，我们解决了沉积在几种基材上的结构不对称石墨烯/hBN 纳米带异质结的热传输特性：石墨、Si(100)、SiC(0001) 和 SiO2。我们的结果表明，衬底沉积时共面 G/hBN 异质结的界面热阻降低，这主要与功率谱重叠的增加有关。这种效应对于在 Si(100) 和 SiO2 衬底上的沉积更为明显，与材料的平面堆叠顺序无关。此外，已经发现热整流因子随着 hBN-G 纳米带结构不对称程度的增加而增加，达到 24%，而它显示了 G-hBN 纳米带的最小值 (∈[0.7,2.4])。更重要的是，这些特性也可以通过改变衬底温度来调整，例如，通过降低 Si(100) 衬底的温度，对称 hBN-G 纳米带的热整流从 8.8% 提高到 79%。我们的研究为 G/hBN 异质结中控制热传输的物理机制提供了新的见解，从而为声子器件的设计开辟了潜在的新途径。