Remarkable Reduction of Thermal Conductivity in Silicon Nanotubes

We propose to reduce the thermal conductivity of silicon nanowires (SiNWs) by\nintroducing small hole at the centre, i.e. construct silicon nanotube (SiNT)\nstructures. Our numerical results demonstrate that a very small hole (only 1%\nreduction in cross section area) can induce a 35% reduction in room temperature\nthermal conductivity. Moreover, with the same cross section area, thermal\nconductivity of SiNT is only about 33% of that of SiNW at room temperature. The\nspatial distribution of vibrational energy reveals that localization modes are\nconcentrated on the inner and outer surfaces of SiNTs. The enhanced\nsurface-to-volume ratio in SiNTs reduces the percentage of delocalized modes,\nwhich is believed to be responsible for the reduction of thermal conductivity.\nOur study suggests SiNT is a promising thermoelectric material with low thermal\nconductivity.\n