How kinks can tune the thermal conductivity of silicon nanoribbons
How kinks can tune the thermal conductivity of silicon nanoribbons lead image
The power to tweak a nanostructure’s thermal conductivity is crucial for thermoelectric energy conversion, thermal management of nanoelectronic devices and other applications.
Researchers recently realized that kinks in silicon nanoribbons can be used as a new degree of freedom to tune their thermal conductivity. Through combined experimental and numerical studies, Li et al. investigated the mechanisms behind kinks’ effect.
They found that kink boundaries cause the backscattering of phonons. Comparing kinked nanoribbons along different crystalline directions, the authors discovered that they can take advantage of phonon focusing — the directional transport of phonons — to suppress phonon transport and decrease thermal conductivity.
“Energy consumption and its related environmental impacts are critical concerns of today’s world,” said author Deyu Li. “Tuning heat transfer process with this new transport mechanism is certainly highly desirable.”
The authors’ work could help establish new design rules for nanostructures, allowing researchers to tune their thermal conductivity for different applications, such as improving the energy conversion efficiency of thermoelectric devices and enhancing thermal insulation materials.
In their experiments, the authors fabricated silicon nanoribbons with kinks of various sizes and measured their thermal conductivity. They found that as the kink period length decreases, the thermal conductivity first decreases and then steeply increases. Their work also describes the conditions for minimum thermal conductivity in kinked silicon nanoribbons.
Next, the authors will seek the maximum level of thermal conductivity regulation and explore its implications in designing superior thermoelectric energy conversion devices and thermal insulation materials.
Source: “Kink as a new degree of freedom to tune the thermal conductivity of Si nanoribbons,” by Lin Yang, Qian Zhang, Zhiyong Wei, Zhiguang Cui, Yang Zhao, Terry T. Xu, Juekuan Yang, and Deyu Li, Journal of Applied Physics (2019). The article can be accessed at https://doi.org/10.1063/1.5119727 .
