Abstract
A non-equilibrium molecular dynamics simulation method is conducted to study the thermal conductivity (TC) of silicon nanowires (SiNWs) with different types of defects. The impacts of defect position, porosity, temperature, and length on the TC of SiNWs are analyzed. The numerical results indicate that SiNWs with surface defects have higher TC than SiNWs with inner defects, the TC of SiNWs gradually decreases with the increase of porosity and temperature, and the impact of temperature on the TC of SiNWs with defects is weaker than the impact on the TC of SiNWs with no defects. The TC of SiNWs increases as their length increases. SiNWs with no defects have the highest corresponding frequency of low-frequency peaks of phonon density of states; however, when SiNWs have inner defects, the lowest frequency is observed. Under the same porosity, the average phonon participation of SiNWs with surface defects is higher than that of SiNWs with inner defects.
Highlights
A one-dimensional material system is the smallest size structure that can be used for efficient electronic and optical transmission (Xia et al, 2003; Hsu et al, 2015) and has unique heat transfer properties (Wang et al, 2018)
The thermal conductivity (TC) is a physical parameter of the material which does not change with the size of the material
The TC of Silicon nanowire (SiNW) gradually decreases with the increase of porosity
Summary
A one-dimensional material system is the smallest size structure that can be used for efficient electronic and optical transmission (Xia et al, 2003; Hsu et al, 2015) and has unique heat transfer properties (Wang et al, 2018). Silicon nanowire (SiNW) is a typical one-dimensional material, and there are many mature methods to obtain this material, such as laser ablation, thermal evaporation, chemical vapor deposition, template method, solution method, and hydrothermal method (Yang et al, 2014). It has stable semiconductor characteristics of macroscopic silicon material and field emission (Frederick et al, 1999), thermal conductivity (TC) (Zhang and Zhang, 2013), visible photoluminescence (Feng et al, 2000), and quantum confinement effects (Kobayashi and Hiramoto, 2008) that are different from bulk silicon materials. The experimental measurement of the TC of a single SiNW at low temperature indicates that it is much lower than the bulk value (Li et al, 2003) and shows
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