Thermal Transport Properties of Si Nanowire Covered with SiO₂ Layer: A Molecular Dynamics Study

Abstract

We demonstrate the impact of SiO2 layer on thermal conductivity of Si nanowire by nonequilibrium molecular dynamics simulation. Our results indicate that the presence of the oxide layer is influential to the significant decrease in the thermal conductivity. By analyzing the vibrational density of states, we show the reduction of the thermal conductivity stems from the attenuation of the low-frequency phonon modes. This work suggests that the disorders near the SiO2/Si surface is crucial to characterize the thermal properties of practical SiNW.

Localized Phonon Transport Study of GaN/SiO2Core/shell Nanowires under Thermal-Stress Coupling

“…In the phonon dispersion of GaN NW and its surface, new dispersionless phonon modes emerges at the original bandgap. 50,51 The cutoff frequency of phonons in bulk GaN is below 25 THz, while the cutoff frequencies of phonons in GaN NW and its surface are higher than those of bulk GaN. Additionally, the vibrational cutoff frequency of surface optical phonons surpasses the intrinsic frequency of GaN NW.…”

“…These new dispersive-free states and low group velocity phonon modes pose challenges in defining group velocity and phonon lifetime. 50 This intricate phonon behavior is interpreted as a result of localized phonon vibrations at the SiO 2 /GaN interface. It suggests that the presence of the interface triggers new phonon modes that are distinct in frequency and vibrational characteristics from phonons on the surface of GaN NW.…”