本實驗利用濺鍍的方式將目前室溫下性質最好的熱電材料Bi0.5Sb1.5Te3濺鍍在長有二氧化矽的基板上，藉由控制基板溫度的高低得到不同晶粒尺寸的Bi0.5Sb1.5Te3薄膜。利用3ω法量測不同晶粒尺寸以及經過退火之後的Bi0.5Sb1.5Te3薄膜的熱傳導係數(κ)，並利用Wiedemann-Franz law分離出載子熱傳導係數(κe)與晶格熱傳導係數(κL)。由於未退火的Bi0.5Sb1.5Te3薄膜有很高的電阻率，使熱傳導係數幾乎全由晶格熱傳導係數所貢獻，且晶格熱傳導係數隨著晶粒尺寸變大而提升。退火後，由於電阻率大幅下降，使載子熱傳導係數大幅上升。由於晶粒尺寸在退火前後沒有很大的差異，所以推測晶格熱傳導係數的上升來自退火後晶粒內部缺陷數量的減少。

Bi0.5Sb1.5Te3 thin films are deposited on silicon dioxide substrates by RF sputtering. By changing the substrate temperature, we acquire Bi0.5Sb1.5Te3 thin films with different grain size. The thermal conductivity of Bi0.5Sb1.5Te3 thin films is measured using the 3ω method, and the lattice thermal conductivity and the electrical thermal conductivity are separated using the Wiedemann-Franz law. The lattice thermal conductivity dominates because of the high resistivity of the Bi0.5Sb1.5Te3 thin films, and it increases with greater grain size. After annealing, the electrical thermal conductivity substantially increases because of the decreasing of the resistivity, and we conjecture that the increasing of the lattice thermal conductivity results from the decreasing of the defects number in grains due to the same grain size before and after annealing.

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