GaAs纳米线晶格热导率温度和尺度效应及声子非弹性散射

Calculation of the temperature and scale effects for GaAs nanowires'' lattice thermal conductivity and phonon inelastic

中文关键词: 砷化镓纳米线  晶格热导率  态密度  热流自相关函数  声子非弹性散射

英文关键词: gallium arsenide nanowires  lattice thermal conductivity  vibration density of states  heat current autocorrelation function  phonon inelastic scattering

中文摘要:

      为了深入理解砷化镓(GaAs)纳米线的微观热输运机理,采用平衡分子动力学的方法模拟其晶格热导率。基于声子态密度的频域特性和热流自相关函数的时域特性,分别研究温度、尺寸对纳米线晶格热导率的影响规律。结果表明,纳米线的热导率有明显的温度与尺度效应。随温度升高,其晶格热导率先逐渐增大后减小,300K左右达到最大值1.6 W/(m·K)；晶格热导率随长度、直径的增大均先增加后趋于稳定。砷化镓纳米线晶格热导率的温度和尺度效应均可用声子非弹性散射解释。模拟的热导率比体材料的值小一个数量级,模拟结果可为改善半导体材料的热电性能提供指导。

英文摘要:

      In order to further understand the microscopic heat transport mechanism of gallium arsenide (GaAs) nanowires (NW), an equilibrium molecular dynamics (EMD) method is used to simulate the lattice thermal conductivity. Based on the frequency-domain characteristics of the phonon vibration density of states (VDOS) and the time-domain characteristics of the heat current autocorrelation function (HCACF), the influences of temperature and size on the thermal conductivity of NW are studied. The conclusion is that NW have obvious temperature effects and scale effects. The lattice thermal conductivity gradually increases and then decreases with the rise of temperature, reaching a maximum of 1.6 W/(m·K) around 300K. The lattice thermal conductivity increases and then tends to a constant value with the increase of GaAs nanowires’ length and diameter. The temperature and scale effects of NW lattice thermal conductivity can be explained by phonon inelastic scattering. The thermal conductivity by simulation is one order of magnitude lower than the bulk material value, and the simulation results provide guidance for improving the thermoelectric performance of semiconductor materials.