Diao Jiankuai, Srivastava Deepak, Menon Madhu
University Affiliated Research Center, University of California, Santa Cruz and NASA Ames Center for Nanotechnology, Moffett Field, California 94035, USA.
J Chem Phys. 2008 Apr 28;128(16):164708. doi: 10.1063/1.2905211.
Using molecular dynamics simulations with Tersoff reactive many-body potential for Si-Si, Si-C, and C-C interactions, we have calculated the thermal conductance at the interfaces between carbon nanotube (CNT) and silicon at different applied pressures. The interfaces are formed by axially compressing and indenting capped or uncapped CNTs against 2 x 1 reconstructed Si surfaces. The results show an increase in the interfacial thermal conductance with applied pressure for interfaces with both capped and uncapped CNTs. At low applied pressure, the thermal conductance at interface with uncapped CNTs is found to be much higher than that at interface with capped CNTs. Our results demonstrate that the contact area or the number of bonds formed between the CNT and Si substrate is key to the interfacial thermal conductance, which can be increased by either applying pressure or by opening the CNT caps that usually form in the synthesis process. The temperature and size dependences of interfacial thermal conductance are also simulated. These findings have important technological implications for the application of vertically aligned CNTs as thermal interface materials.
利用针对硅 - 硅、硅 - 碳和碳 - 碳相互作用的Tersoff反应性多体势进行分子动力学模拟，我们计算了在不同外加压力下碳纳米管（CNT）与硅之间界面处的热导率。这些界面是通过将有帽或无帽的碳纳米管轴向压缩并压入2×1重构的硅表面而形成的。结果表明，对于有帽和无帽碳纳米管的界面，界面热导率均随外加压力的增加而增大。在低外加压力下，发现无帽碳纳米管界面处的热导率远高于有帽碳纳米管界面处的热导率。我们的结果表明，碳纳米管与硅衬底之间形成的接触面积或键的数量是界面热导率的关键因素，可通过施加压力或打开通常在合成过程中形成的碳纳米管帽来提高热导率。还模拟了界面热导率的温度和尺寸依赖性。这些发现对于垂直排列的碳纳米管作为热界面材料的应用具有重要的技术意义。
