Title:  Impact of nanostructure on the thermal transport of silicon nanowire.
Reporter:   Yunshan Zhao
Time: 10:00 am, Wednesday, December 26, 2018
Place: Room 437, Xingjian Building

Abstract：We study the effect of nanostructure on the thermal transport of one-dimensional silicon nanowire, which is a versatile building block for nanoelectronic and thermoelectric devices. We firstly demonstrate that the thermal conductivity of single-crystalline silicon nanowires can be even lower than that of amorphous silicon by introducing nanoscale porosity, with values as low as 0.33 W/m-K at 300Kfor 43% porosity.This can be attributed to: (a) reduction of group velocity due to increased surface-to-volume ratio and (b) diffusive scattering at the pore boundaries. The second part of this work studies the impact of point defects on thermal transport in silicon nanowires. The creation of a well-controlled distribution of point-defects into silicon nanowires was demonstrated in this work. By using helium ion irradiation, we show that the thermal conductivity of an individual silicon nanowire can be tuned between the crystalline and amorphous limits.Moreover, the diffusive thermal transport in amorphous silicon with dimension ~30 nm and length-independent interface thermal conductance are demonstrated in this work as well.Our study aims to provide a better understanding of phonon transport at nanoscale.

简介：赵云山，现为新加坡国立大学电子系研究员，2017年博士毕业于新加坡国立大学，师从John T L Thong 教授和李保文教授，主要从事于低维尺度下热、热电性质的研究。发表多篇论文，其中影响因子大于10 的3篇，担任Journal of Heat Transfer、Nanotechnology、Chinese Physics等期刊的编委。曾在APS、ICMAT等国际会议上多次做口头报告。