同位素掺杂硅纳米线的超低热导率
Ultralow Thermal Conductivity of Isotope-Doped Silicon Nanowires
摘要：
采用分子动力学（MD）模拟方法研究了硅纳米线的热导率.研究发现，在室温下，同位素缺陷可以使硅纳米线的热导率呈指数下降。当掺杂50%的同位素原子时，热导率达到最小值，约为纯28Si NW的27%。同位素超晶格结构的硅纳米线的热导率明显依赖于超晶格的周期。在1.09 nm的临界周期处，热导率仅为纯Si NW值的25%。当超晶格周期小于这个临界长度时，观察到热导率的异常增强。用声子谱理论解释了超晶格结构硅纳米线的超低热导率。
英文摘要：
The thermal conductivity of silicon nanowires (SiNWs) is investigated by molecular dynamics (MD) simulation. It is found that the thermal conductivity of SiNWs can be reduced exponentially by isotopic defects at room temperature. The thermal conductivity reaches the minimum, which is about 27% of that of pure 28Si NW, when doped with fifty percent isotope atoms. The thermal conductivity of isotopic-superlattice structured SiNWs depends clearly on the period of superlattice. At a critical period of 1.09 nm, the thermal conductivity is only 25% of the value of pure Si NW. An anomalous enhancement of thermal conductivity is observed when the superlattice period is smaller than this critical length. The ultra-low thermal conductivity of superlattice structured SiNWs is explained with phonon spectrum theory.
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