臺灣博碩士論文加值系統

由於氫化微晶矽薄膜(hydrogenated microcrystalline silicon, μc-Si:H)之沉積速率遠小於氫化非晶矽薄膜(hydrogenated amorphous silicon, a-Si:H)，但氫化微晶矽薄膜在太陽能電池中又占有重要的角色。因此，研究以較快的製程獲得氫化微晶矽薄膜的方法，且所以如何讓薄膜具有適當的結晶率、氫含量、矽氫鍵結結構以及更大的吸收係數是此研究的主要方向。
本實驗使用玻璃與矽晶圓作為沉積矽薄膜之基板，調變以電漿增強型化學氣相沈積系統(plasma-enhanced chemical vapor deposition, PECVD)沉積矽薄膜時之射頻(radio frequency, RF)功率(power)，並以表面輪廓儀(profilometer)、場發射掃描式電子顯微鏡(field emission scanning electron microscopy, FESEM)、拉曼光譜(Raman Spectroscopy)、高解析X光繞射儀(high resolution X-ray diffraction, HRXRD)、紫外可見光光譜(UV-Vis Spectroscopy)、以及傅氏轉換紅外線光譜儀(fourier transform infrared spectroscopy, FTIR)探討薄膜退火前後特性之變化。
研究結果顯示，薄膜退火前沉積之射頻功率在100 W以下時，其結晶率、晶粒尺寸會隨著功率上升而分別增加至70 %與15 nm；但沉積功率在125 W以上，其結晶率與晶粒尺寸則會隨之下降。退火後，其結晶率與晶粒尺寸會隨著沉積功率上升，分別從82 %與16 nm開始下降。能隙大小的變化也與結晶率相應，結晶率越高，其能隙大小就越小。由結晶率與能隙大小的結果顯示，在退火處理後，我們將能控制矽薄膜之能隙分布在更寬廣的範圍中。
最後，比較單層與雙層矽薄膜之吸收度的結果顯示，堆疊雙層或多層不同成長條件之非晶矽薄膜，後將其退火處理，能將原本較小的光吸收範圍延伸。未來如將其應用在薄膜太陽能電池之吸收層中，將能以更短的製程時間獲得更高效率之太陽能電池。

The deposition rate of μc-Si:H is smaller than a-Si:H, but μc-Si:H is an important material in solar cell. Therefore, how to obtain μc-Si:H faster and optimized the crystalline fraction, hydrogen content, Si-H bonding and absorption coefficient of the films should be investigated.
In this thesis, PECVD was used to deposit silicon thin film by different RF power on glass and n-type silicon wafer. And we will investigate the influence of furnace annealing on silicon thin film by profilometer, SEM, Raman spectroscopy, HRXRD, UV-Vis spectroscopy, and FTIR.
The results show that the crystalline fraction and grain size of the samples before annealing increased from 0 % and 0 nm to 70 % and 15 nm when the RF power applied between 20 W to 100 W. But the crystalline fraction and grain size of the samples decreased when the RF power applied between 125 W to 250 W. After annealing, the crystalline fraction and grain size of the samples decreased from 82 % and 16 nm to amorphous state. The bandgap of the samples changes with the crystalline fraction. The effects of crystalline fraction on the bandgap were investigated. The bandgap of the samples decreased when the crystalline fraction increased. The distribution of the bandgap after annealing is larger than which before annealing. Therefore, we can control larger region of the bandgap by annealing.
Finally, the absorbance of the bilayer film is higher than the monolayer film after annealing. The result shows that annealing the multilayer of the silicon thin film can expand the light absorption region.
By obtaining a graded bandgap absorber layer in one-step annealing process, which can make the process of high efficiency solar cells shorter and easier.

中文摘要 I
Abstract III
致謝 V
目錄 VII
圖目錄 IX
表目錄 XI
第一章 緒論 1
1.1 研究背景與動機 1
1.2 研究目的 4
第二章 文獻回顧 5
2.1 太陽能電池的發展 5
2.2 氫化非晶矽、多晶矽薄膜之簡介 8
2.2.1 氫化非晶矽薄膜 8
2.2.2 微晶矽薄膜 9
2.3 非晶、多晶矽薄膜形成技術 10
2.3.1 化學氣相沉積法 11
2.3.2 固相結晶法 11
2.4 各種矽基太陽能電池簡介 13
2.4.1 單晶矽太陽能電池 13
2.4.2 多晶矽太陽能電池 14
2.4.3 氫化非晶矽太陽能電池 14
2.4.4 堆疊結構之太陽能電池 14
2.5 電漿增強型化學氣相沉積 16
2.6 拉曼光譜量測之基本原理 20
2.7 高解析X光繞射儀之基本原理 23
2.8 Tauc plot之基本原理 24
2.9 傅氏轉換紅外線光譜儀之基本原理 25
第三章 實驗儀器和研究方法 29
3.1 成長氫化非晶矽薄膜流程 30
3.1.1 以電漿增強型化學氣相沉積沉積氫化非晶矽薄膜 30
3.1.2 氫化非晶矽薄膜的製程條件 33
3.2 高溫爐退火 33
3.3 薄膜特性量測 34
3.3.1 表面輪廓儀膜厚量測 34
3.3.2 場發射掃描式電子顯微鏡 35
3.3.3 拉曼光譜量測 36
3.3.4 高解析X光繞射儀 36
3.3.5 紫外可見光光譜儀 36
3.3.6 傅氏轉換紅外線光譜儀 37
第四章 實驗結果與討論 38
4.1 矽薄膜之沉積速率 38
4.2 矽薄膜退火前後結晶率之變化 39
4.3 矽薄膜退火前後晶粒尺寸之變化 49
4.4 矽薄膜退火前後光能隙之變化 51
4.5 雙層矽薄膜結構對光吸收度變化的影響 54
第五章 結論 57
參考文獻 59

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