Preparation of Thin Film Crystalline Si by Metal Induced Crystallization and Possibility Study for Solar Cell Application

本文研究主要目的是利用鋁誘發結晶之方式，將非晶矽薄膜結晶成多晶矽薄膜，並將之應用於太陽能電池元件。本論文分成三個主題，第一個部分為以鋁誘發金屬結晶的方式，將非晶矽薄膜退火誘發結晶成為多晶矽薄膜，並蝕刻薄膜表面之金屬薄膜，藉由 Raman、XRD 與霍爾量測等方式 分析、探討退火溫度與氧化層對多晶矽薄膜結晶特性之影響，並討論過程 中之擴散速度與成核速度的影響，並找出鋁誘發結晶過程中最理想的製作 條件。主題二為探討多晶薄膜之磊晶能力，將製作好的多晶矽薄膜當作晶 種層，在上方磊晶上 P 型與本質的矽薄膜，並使用拉曼分析其磊晶薄膜與非晶矽薄膜之結晶比例的差異，並研究矽薄膜之氫稀釋比與厚度對於磊晶過程中的影響，最後一部分以磊晶之結果製作兩種結構之太陽能電池，並以 I-V 量測探討此兩種結構間之效果差異，以及該多晶矽薄膜應用於太陽能電池元件的潛力與可行性。In this work, we investigate the influence of seed layer which is made by means of aluminum induced crystallization on effect of crystalline fraction, and the solar cell’s efficiency. The Si in the PIN solar cell on seed layer was expected to have higher crystalline fraction that will alleviate Stabler-Wronski effect in a thin film Si solar cell. The seed layer was made by aluminum induced crystallization. In the process of aluminum induced crystallization, an etching solution was used for removing aluminum from the surface of poly-crystalline silicon which annealed in furnace. Investigate to the influence of annealing temperature and oxidation duration on seed layer.In this part, using Hall measurements to determine the suitable conditions to make seed layer.The conditions were annealing temperature 450 ℃and oxidation duration 2 hours. Following, we deposite p-type and intrinsic silicon on the seed layer by PECVD. And intrinsic silicon obtained 25.69 % of the crystallization fraction enhancement.Design two structures of solar cell device to investigate the difference and discuss the potential and feasibility of the application to solar cell by I-V. The efficiency of Structure A solar cell on seed layer was 0.511 % and largest short circuit density was 5.856 mAcm-2.誌謝 ......................................................................................... i 摘要 ........................................................................................ ii Abstract..................................................................................... iii 目錄 .......................................................................................... iv 圖目錄 ........................................................................................ vii 表目錄 ............................................................................................ xi 第一章 緒論 ................................................................................................ 1 1.1 前言....................................................................................................... 1 1.2 太陽能電池的發展與種類................................................................... 3 1.2.1 晶片型太陽能電池................................................................... 4 1.2.2 薄膜型太陽能電池................................................................... 5 1.3 文獻回顧............................................................................................... 8 1.3.1 多晶矽太陽能電池發展............................................................ 8 1.3.2 多晶矽薄膜之製程技術.......................................................... 10 1.4 金屬誘發結晶形成機制.................................................................... 11 1.4.1 層交換 ( Layer exchange ) 反應 .......................................... 12 1.4.2 共晶 ( Eutectic ) 現象........................................................... 14 1.4.3 化合物( Compound )現象 ...................................................... 15 1.4.4 鋁誘發結晶特性..................................................................... 15 1.5 研究動機............................................................................................. 21 第二章 理論基礎 ...................................................................................... 22 2.1 太陽光光譜及太陽能電池光電轉換特性 ....................................... 22 2.1.1 太陽光光譜............................................................................. 22 2.1.2 太陽能電池工作原理............................................................. 24 2.2 拉曼光譜 ( Raman Spectra ) 分析.................................................... 28 第三章 實驗步驟與儀器介紹 .................................................................... 29 3.1 玻璃基板清洗..................................................................................... 29 3.2 製備鋁誘發結晶多晶矽薄膜............................................................. 30 3.2.1 鋁金屬層蒸鍍.......................................................................... 30 3.2.2 非晶矽沉積.............................................................................. 30 3.2.3 試片退火結晶.......................................................................... 31 3.3 鋁誘發結晶法於太陽能電池元件結構 A 製備................................ 32 3.4 鋁誘發結晶法於太陽能電池元件結構 B 製備................................ 37 3.5 製程設備............................................................................................ 40 3.5.1 電 漿 增 強 式 化 學 氣 相 沉 積 ( Plasma-enhanced chemical vapor deposition；PECVD ) 系統 - 沉積矽薄膜 ......................... 40 3.5.2 熱蒸鍍 (Thermal evaporation；TE ) 系統 - 蒸鍍金屬薄膜 ........................................................................................................... 41 3.5.3 射頻磁控濺鍍 ( Radio Frequency magnetron sputtering ) 系統 - 沉積氧化銦錫(Indium Tin Oxide,ITO) .................................. 42 3.5.4 高溫管型爐 ( Furnace ) 系統 - 試片退火.......................... 43 3.5.5 手套箱 ( glove box ) 系統 - 保存試片錯 誤 ! 尚 未 定 義 書籤。 3.6 量測設備............................................................................................. 44 3.6.1 電流-電壓特性曲線量測系統 - 量測電性.......................... 44 3.6.2 原子力顯微鏡(Atomic Force Microscope,AFM) - 分析試片表面................................................................................................... 44 3.6.3 拉曼螢光顯微鏡系統(Raman PL Microspectrometer) - 分析矽薄膜結晶率................................................................................... 45 3.6.4 X 光粉末繞射儀 (X-Ray Powder Diffractometer) - 分析薄膜結晶方向........................................................................................... 46 第四章 實驗結果與討論 ............................................................................ 47 4.1 鋁誘發結晶多晶矽薄膜..................................................................... 47 4.1.1 鋁金屬薄膜厚度調變............................................................. 47 4.1.2 試片氧化時間調變................................................................. 48 4.1.3 試片退火溫度調變.................................................................. 49 4.2 多晶矽薄膜磊晶................................................................................. 51 4.2.1 晶種層上磊晶 P 型非晶矽 .................................................... 51 4.2.2 晶種層上磊晶本質非晶矽 .................................................... 54 4.3 太陽能電池元件................................................................................. 61 4.3.1 不同結構之多晶矽薄膜製作太陽能電池元件 .................... 61 4.3.2 太陽能電池元件結構 A 量測................................................. 66 4.3.3 太陽能電池元件結構 B 量測................................................. 70 結論與未來展望 .......................................................................................... 77 參考文獻 ...................................................................................................... 7