The thermal transport properties of single-crystalline nanowires covered with amorphous shell: A molecular dynamics study

The thermal transport properties of single-crystalline nanowires (carbon nanowires (CNWs) and silicon nanowires (SiNWs)) covered with amorphous silicon shell are investigated by non-equilibrium molecular dynamics (NEMD). The thermal conductivity of SiNWs covered with amorphous silicon shell (Si/a-Si core-shell NWs) is obviously lower than that of single-crystalline SiNWs and it keeps approximately constant when the temperature exceeds a definite value for the diffusion properties of amorphous shell. It is quite different from that of single-crystalline SiNWs whose thermal conductivity decreases significantly for relatively higher temperature. Compared to single-crystalline SiNWs, Si/a-Si core-shell NWs express stronger non-propagation, diffusion thermal transport properties. The thermal transport properties of CNWs covered with amorphous silicon shell (C/a-Si core-shell NWs) are essentially similar to that of Si/a-Si core-shell NWs. It expresses stronger non-propagation, diffusion thermal transport properties and its thermal conductivity increases very little with the growth of length. However, its diffusion characteristics are weaker than that of Si/a-Si core-shell NWs. Generally speaking, the amorphous shell and amorphous/crystalline interface play a negative role to the thermal conductivities and an enhance role to the diffusion characteristics of single-crystalline nanowires, however, their degree of effect on different single-crystalline nanomaterials is different.