Bi0.5Sb1.5Te3+0.33 wt% aerogel與Cu0.02Bi2Te2.7Se0.3熱電薄膜與元件之熱電性質研究

Abstract

近幾年來，熱電材料蓬勃發展是許多物理、化學以及材料科學家的熱門研究的方向，然而此一跨領域的基礎研究工作處於萌芽的階段。熱電材料的益處在於可將熱機或是冷凍機之上所產生的廢熱轉化成電能。本研究利用鉍化碲(Bismuth Tellurium)在室溫附近具有一熱電優質係數(ZT)為1.0的熱電表現，其具有非常低的熱傳導率以及適當的載子傳輸性質，因此Bi-Te的合金系列成為大家研究的趨勢，成為另一項重大的焦點引發相當的關注。鉍化碲元素皆是地球殼中豐富的元素，且鉍化碲是對人無毒且對環境無害的化合物，相較於其他高性能熱電材料(一般由稀少元素/貴金屬組成)，具有非常大商業化的潛力。鉍化碲本身為非常穩定的多層層狀結構(Quintuple Layer)，表現出極低的熱傳導率以及良好的導電性。為了未來能製作出微小的熱電模組，本研究利用射頻磁控濺鍍系統(Radio-Frequency Magnetron Sputtering System)調控濺鍍參數的方式，得到最佳熱電性質之薄膜後，再使用半導體製程技術製作微結構的陣列熱電薄膜，利用光微影製程及金屬遮罩兩種分別不同的方式決定所需之電極和薄膜陣列之圖形。本論文使用磁控濺鍍設備，靶材n-type和p-type分別選用Cu0.02Bi2Te2.7Se0.3 和Bi0.5Sb1.5Te3+0.33 wt% Aerogel之熱電材料，經由實驗改變磁控濺鍍的工作壓力、RF power，再透過ZEM-3、EDS對薄膜的研究分析得到(最佳鍍膜參數) 最佳鍍膜品質參數(seebeck、電阻)。決定鍍膜參數後使用本研究開發的兩種方式製作微結構熱電元件，一使用光微影半導體製程，二使用金屬遮罩，針對兩種製程方式所得的n-type和p-type陣列熱電薄膜成長過程做比較與研究探討。

In recent years, physicists, chemists and material scientists at many major universities and research institutions throughout the world are attempting to create novel materials with high thermoelectric (TE) efficiency. It will be beneficial to harvest waste heat into electrical energy. Especially heating and cooling are other major applications for this class of new TE materials. At present the thermoelectric (TE) material bismuth telluride (Bi2Te3) baesd systems exhibit best figure of merit (ZT). Bismuth and tellurium are earth-abundant elements and Bi2Te3 is non-toxic to human beings and the environment. Therefore, it has great potential in commercial implements. Bismuth telluride is a quintuple layer-structured compound possessing ultralow thermal conductivity and moderate electrical conductivity. In this work, the TE thin film and device are fabricated and optimized by Radio-Frequency Magnetron Sputtering System (RFMSS) and the influence of the preparative parameters such as working pressure and working power of RF sputtering are investigated. In this study, we used the magnetron sputtering equipment and the thermoelectric materials n-type target and p-type target were Cu0.02Bi2Te2.7Se0.3 and Bi0.5Sb1.5Te3+0.33 wt% aerogel, respectively. In this study, the experimental changes the magnetron sputtering working pressure, RF power before the ZEM-3, EDS analysis the thin film thermoelectric properties to get the best thin film quality parameters (Seebeck coefficient, resistivity, power factor). After the thin film parameters were determined, the microstructural thermoelectric 442 pairs device were fabricated by the photolithography semiconductor process, and n-type and p-type arrays used by photolithography to define a pattern and deposit Au electrodes onto the substrate by thermal evaporation.