含有倾斜界面硅/锗超晶格的导热性能

Thermal conductivity of Si/Ge superlattices containing tilted interface

采用非平衡分子动力学(NEMD)方法模拟含有倾斜界面的硅/锗(Si/Ge)超晶格在不同倾斜角、不同周期长度、不同样本长度和不同温度下的导热性能.模拟结果表明, Si/Ge超晶格的热导率随着界面倾斜角的增加而非单调变化.当周期长度为4—8原子层时,界面倾斜角为45°的热导率比其他界面倾斜角时热导率增大了一个数量级,且热导率随样本长度的增加而增加,随温度的增加而减小.然而当周期长度为20原子层时,由于声子局域化的存在,热导率对样本长度和温度的依赖性都较弱.

The non-equilibrium molecular dynamics(NEMD)method is used to study the thermal conductivities of Si/Ge superlattices with tilted interface under different period lengths,different sample lengths,and different temperatures.The simulation results are as follows.The thermal conductivity of Si/Ge superlattices varies nonmonotonically with the increase of interface angle:when the period length is 4–8 atomic layers,the thermal conductivity for the interface angle of 45°is one order of magnitude larger than those for other interface angles,and the thermal conductivity increases linearly with the sample length increasing and decreases with the temperature increasing.However,when the period length is 20 atomic layers,the thermal conductivity is weakly dependent on sample length and temperature due to the existence of phonon localization.