铝纳米薄膜热导率的实验研究

Experimental Study of Thermal Conductivity of Aluminum Nanofilms

金属纳米薄膜作为一种典型的纳米材料,已广泛应用于信息技术领域。研究表明,随着金属薄膜特征尺寸的减小,金属薄膜体现出与常规不同的热输运特性。本文采用飞秒激光泵浦-探测实验方法,结合抛物两步模型和修正的抛物两步模型,对铝纳米薄膜热导率进行研究。结果表明,考虑了声子热导率修正的抛物两步模型比抛物两步模型更能准确描述热反射信号。拟合得到铝膜热导率分别为98 W·m^(-1)·K^(-1)和94 W.m^(-1)·K^(-1),小于铝的体材料热导率,铝纳米薄膜热导率具有尺度效应,同时拟合得到声子热导率为2.8 W·m^(-1)·K^(-1),提出一种利用飞秒激光泵浦-探测测量声子热导率的方法。

As a typical kind of nanomaterial,the metallic nanofilm has been widely used in the field of information technology.It has been reported that the metallic nanofilm exhibits different thermal transport properties from the bulk ones when decreasing its characteristic size.In this paper,the thermal conductivity of aluminum nanofilm is measured by using the femtosecond laser pump-probe method.The fitted thermal conductivity of aluminum nanofilm by parabolic two-step(PTS) model and modified PTS model are 94 W·m^(-1)·K^(-1) and 98 W·m^(-1)·K^(-1),respectively,which is less than the corresponding bulk values,revealing the size effect on thermal transport.The fitted results also show that the modified PTS model describes thermoreflectance signals more accurately than the PTS model.In addition,a method which can extract the phonon thermal conductivity from transient thermoreflectance signals is proposed.And the phonon thermal conductivity of aluminum nanofilm fitted by the modified PTS model is 2.8 W·m^(-1)·K^(-1).