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

宽间隙半导体，如SiC和GaN，因其高电子迁移率而成为有前景的材料。本项目旨在从声子传播的角度对其热特性，特别是传热进行纳米尺度的建模。结合大尺度分子动力学模拟、基于统计力学和玻尔兹曼输运方程的各种声子分析技术，我们计划开发一个模拟纳米结构固体热性能的模拟器。本课题主要做了以下工作：(1)开发了半导体材料及其界面的大规模高效分子动力学（MD）模拟代码。(2)提出了一种基于非平衡态MD模拟的声子分析方法来估计声子弛豫时间，该方法发现弛豫时间与声子频率密切相关。(3)利用该模拟器研究了单晶和不同界面体系的热输运性质。该项目的主要成果将在ASME-JSME热工程夏季传热会议（温哥华，2007年7月）上报告，并在其他地方发表。

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.