[21p-C102-1~17] 9.4 Thermoelectric conversion

[21p-C102-5] Decreasing thermal conductivity of epitaxial BaSi₂ film/Si by introducing point defect

〇Takafumi Ishibe¹, Suguru Yachi², Yudai Yamashita², Takuma Sato^2,3, Takashi Suemasu², Yoshiaki Nakamura¹ (1.Grad. School of Eng. Sci., 2.Univ. of Tsukuba, 3.Hiroshima Univ.)

Keywords:Thermoelectric material, Silicide, Thermal conductivity

BaSi₂ is a primising candidate of thermoelectric materials because it has complex crystal structure leading to low phonon group velocity, namely low thermal conductivity. We have developed epitaxial BaSi₂ films/Si substrates. Surprisingly, this film exhibited ultralow thermal conductivity of less than 1 Wm^-1K^-1. However, the detailed physics of ultralow thermal conducitivity is not elucidated. In this study, we experimentally and theoretically reveal the physical mechanism of ultralow thermal conducitivity by separately discussing phonon group velocity and relaxation rate.