Bi/Te多層複合濺鍍薄膜製程與熱電性質之研究

Fabrication and thermoelectric characterization of sputtered Bi/Te multilayer thin films

佘東和(Tong-Her She)

指導教授 ： 廖建能

國立清華大學/工學院/材料科學工程學系/碩士(2006年)

https://doi.org/10.6843/NTHU.2006.00485

摘要

本論文利用磁控濺鍍製程，在已長有二氧化矽薄膜之矽基材上製備Bi/Te多層複合薄膜，後續利用退火處理促使Bi/Te複合薄膜反應成Bi-Te化合物薄膜。本研究探討薄膜Bi與Te相對比例對其熱電性質之影響。實驗結果發現，Bi/Te多層複合薄膜結構改善了Bi、Te相互擴散行為，並縮短了反應時間。更由不同退火時間下Bi、Te交互擴散係數 之變化來佐證Bi2Te3生成將減緩Bi/Te間擴散行為之推論。在反應初期隨退火時間之改變，由於量子尺寸效應引發傳輸特性出現震盪行為，Seebeck係數最高值可達-345 μV/K，比Bi2Te3塊材理論值(-240 μV/K)還高。本實驗採用改變Bi/Te之鍍膜時間比之方式來控制薄膜之Te原子百分比；長時間退火後，隨薄膜之Te原子百分比變化，Seebeck係數出現了正負轉換之情形，最高值分別為+211(μV/K)、-201.3(μV/K)。並以3ω法量得Bi/Te複合薄膜垂直膜面方向之熱傳導係數約為0.62 (W/m-K)。

關鍵字

熱電 ； 多層 ； Bi2Te3

並列摘要

In this study, the Bi/Te multilayer thin films were deposited on SiO2/Si substrate by magnetron sputter deposition method, and transformed into Bi-Te compound by thermal treatment. Effect of relative Bi/Te composite on the thermoelectric properties of annealed Bi/Te multilayer thin films was investigated. It has been observed that the interdiffusion between Bi and Te was improved and the reaction time was shortened by using the Bi/Te multilayer structure. According to the variation of interdiffusivity with annealing time, it is speculated that the formation of Bi2Te3 may retard the interdiffusion between Bi and Te. During short annealing time, the oscillatory behavior of transport properties was attributed to quantum size effects. The Bi/Te multilayer thin films shows a maximum Seebeck coefficient of -345μV/K, that is much higher than that of bulk Bi2Te3 (-240 μV/K). We can control Te at.% of thin films by changing the sputtering time ratio of Bi to Te. After long time annealing, Seebeck coefficient changes from positive to negative at a composition around 60 at.% Te. The maximum values of positive and negative were found to be +211μV/K and -201.3μV/K, respectively. Moreover, the cross-plane thermal conductivity of the Bi/Te multilayer thin films was measured to be 0.62W/m-K by the 3ω method.

並列關鍵字

thermoelectric ； multilayer ； Bi2Te3

參考文獻

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