硅锗超晶格结构热导率的分子动力学模拟

Molecular dynamics simulation on the thermal conductivity of Si/Ge superlattice system

采用Stillinger-Webber势能函数描述硅锗超晶格结构原子间的相互作用,建立硅锗超晶格结构的热传导系统,利用非平衡分子动力学模拟方法计算了不同周期数、不同厚度、不同温度下的Si/Ge超晶格结构热导率.模拟结果表明:超晶格结构热导率随着周期长度和周期数的增加而逐渐增大.受界面热阻效应的影响,靠近高温热墙处导热层的温度跳跃最为明显.当温度在200～600 K变化时,热导率随着温度的升高而增大,并且明显小于相应的合金材料热导率.

The interaction of atoms in the Si/Ge superlattice is described by using Stillinger-Weber potentials yield intermolecular energy and the heat transport system for Si/Ge superlattice is built up.The dependences of Si/Ge superlattice thermal conductivity on period length,number of periods and temperature are investigated by non-equilibrium molecular dynamics（NEMD） simulation.The results of calculations show that the thermal conductivities increase with an increase in period length and the number of periods.Because of the effects of thermal boundary resistance offered by interfaces,the temperature drop across the interface closest to the hot reservoir is the highest.In addition,the thermal conductivities also increase with the increasing of temperature within the range from 200 K to 600 K.Compared with that of the corresponding SiGe alloy,the thermal conductivities of Si/Ge superlattice are much smaller.