NANO-SCALE MODELING OF SOLID HEAT CONDUCTION FOR WIDE-GAP SEMICONDUCTOR DEVICES

宽禁带半导体，如碳化硅和氮化镓，具有很高的电子迁移率，是一种很有前途的材料。本项目的目标是从声子传播的角度对它们的热性质进行纳-微尺度的模拟，特别是热传递的模拟。结合大规模分子动力学模拟、基于统计力学和玻尔兹曼输运方程的各种声子分析技术，我们计划开发一种计算纳米结构固体热性质的模拟器。在这个项目中，我们做了以下研究：(1)开发了大规模高效的半导体材料及其界面分子动力学模拟程序。(2)提出了一种基于非平衡MD模拟的声子分析方法来估算声子弛豫时间，发现声子弛豫时间强烈依赖于声子频率。(3)利用该模拟器，我们研究了单晶和各种界面体系的热输运性质。本项目的主要成果将在2007年7月在温哥华举行的ASME-JSME热工程夏季热传递会议上公布，也将在其他地方发表。

Wide-gap semiconductors, such as SiC and GaN, are prospective materials for their high electronic mobility. This project has aimed at nano-micro scale modeling of their thermal properties, especially heat transfer from the viewpoint of phonon propagation. Combined with large-scale molecular dynamics simulations, various phonon analysis technique based on statistical mechanics and Boltzmann transport equations, we have planned to develop a simulator to calculate thermal properties of solids with nano-scale structures.In this project, we have done the following researches: (1) we developed alarge-scale efficient molecular dynamics (MD) simulation code for semiconducting materials and their interface. (2) we proposed a new technique of phonon analysis based on non-equilibrium MD simulations to estimate phonon relaxation time, with which technique we found that the relaxation time strongly depends on phonon frequency. (3) With this simulator, we investigated thermal transport properties of single crystals and various interfacial systems.The main outcome of this project will be reported at ASME-JSME Thermal Engineering Summer Heat Transfer Conference (Vancouver, July, 2007) and also be published elsewhere.