7PM1-C-4 バルクナノ構造化熱電材料における界面構造のフォノン輸送への影響(7PM1-C OS5 マイクロ・ナノと熱電変換)

抄録

In this study, we have performed molecular dynamics simulations based on the interatomic force constants obtained from first principles to evaluate phonon transport across the PbTe/PbS interface. Thermal boundary conductance was obtained by two different methods: (1) Landauer formula with the phonon transmission function calculated from equilibrium molecular dynamics (EMD) and (2) direct nonequilibrium molecular dynamics (NEMD). The thermal boundary conductance of an atomically smooth PbTe/PbS interface calculated by the two methods agrees well, indicating the validity of the phonon transmission function calculation. Furthermore, we have considered the thermal boundary conductance at the PbTe/PbS interfaces with step roughness to study the influence of the interface structure. It is found that the roughness decreases the thermal boundary conductance by 50 %. The calculated phonon transmission function indicates that the steps reduce the phonon transmission in the entire frequency regime without significant mode selectivity. The analysis also suggests that the inelastic phonon scattering at the interface contributes to at least 15 % of the entire thermal boundary conductance.