臺灣博碩士論文加值系統

摘要
半導體異質奈米結構在光電、能源、生醫與環保等領域皆展現極為優異的材料特性，本研究所採用震盪與鍛燒兩步驟製程以製備功能性奈米碳點，具備製程快速、簡單、光敏感度高、耐光、耐酸鹼等優點外，其產率更是高達48.6%，遠超越傳統鍛燒製程之產率[9-11]。奈米碳點是由碳氧雙鍵、碳氧鍵、羥基等官能基修飾表面的石墨晶體結構，其平均粒徑約5.68 nm、能隙約3.45 eV且其螢光特性優越並具備高光敏感性，藉由滴塗法製程奈米碳點/矽奈米線展現出超親水 (接觸角<4o)，並證明材料與染劑之間的接觸面積非常大，利於提升光觸媒材料的光降解效率，並由其特殊的能帶結構使奈米碳點/矽奈米線於可見光 (580 nm)與紫外光 (420 nm)在沒有添加其他化學藥劑的情況下具備優越寬頻的光觸媒效果：在580 nm光源照射下120分鐘降解率52.4%，420 nm光源照射下120分鐘降解率46.9%。奈米碳點薄膜/矽基板光偵測器亦是由滴塗法將奈米碳點均勻沉積於矽基板上後進行鍛燒處理製程，可精準控制薄膜厚度於30~95 nm之間，其穿透率高達95%，並於XRD分析中驗證其(100)石墨晶體結構的特徵峰，顯示奈米碳點薄膜是由官能基表面修飾的奈米石墨晶體堆積而成，同時具備厚度可控制與高光穿透性的薄膜。本研究並針對薄膜與不同摻雜的矽基板異質接面造成的電性與載子濃度變化進行探討，設計出奈米碳點薄膜/矽基板異質結構的異質接面。以不同厚度奈米碳薄膜光偵測結果確認光偵測器的最佳條件為40 nm的奈米碳點薄膜並且同時確認奈米碳點薄膜具備主動層的可能性，其最佳條件於580 nm的光源下其光電流增益可高達2.86 mA。證實奈米碳點應用於奈米碳點/ 矽材料的複合結構的可靠性。
關鍵字:半導體、異質結構、奈米碳點、矽奈米線、光觸媒、光偵測器

Abstract
The semiconductor heterostructures exhibited extremely excellent properties such as photovoltaics, energy materials, biomedicine, and environmental protection etc. In this study, a fast and simple two-step process of sonication and post-thermal was used to prepare functional Carbon-Nanodots. With the advantages of high photo-sensitivity, photo-resistance, and high yield 48.6 %, it was far exceeding the traditional thermal process [9-11]. Carbon-Nanodot were composed of graphitic crystal structures which was modified with functional groups such as Carbonyl group, Hydroxy group, etc. The average particle size of Carbon-Nanodot was about 5.68 nm, and the energy gap was about 3.45 eV ,and it possessed superior fluorescent characteristics and sensitivity. Heterostructure of Carbon-Nanodot/silicon nanowire which was prepared by drop-coating method provided super hydrophilic property (with contact angle < 4o), and demonstrated that contact area between dye solution and photocatalyst were large, it was beneficial to enhance the photodegradation efficiency of photocatalyst. Due the its special energy band structure Carbon-Nanodot/silicon nanowires provided excellent broadband photocatalyst effect in visible light (580 nm) and ultraviolet light (420 nm) without adding other chemical agents : The photodegradation rate was 52.4% in 120 minutes at 580 nm light source and 46.9 % in 120 minutes at 420 nm light source. Carbon-Nanodot film /silicon wafer heterostructure photodetector also fabricated by drop-coating method and post-thermal method. Which could accurately control the thickness of the Carbon-Nanodot thin film between 30 to 95 nm. It also showed that high transmittance (95%) on glass substate. The crystal structure of graphite (100) was also discussed with XRD analysis, it demonstrated that Carbon-Nanodot possessed high-crystalline carbon structures and function groups. In addition, the electrical properties and differences of carrier concetration caused by the heterostructure between Carbon-Nanodot and different doped silicon wafer was discussed in this research. The Carbon-Nanodot heterostructure photodetector was designed by its band structure. The photodetection test showed the optimal condition of Carbon-Nanodot film was 40 nm, and also confirmed that Carbon-Nanodot film had the possibility of active layer. The optimal condition caused that the photocurrent gain can be 2.86 mA under the 580 nm light source. The reliability of the heterostructure of Carbon-Nanodot /silicon materials was confirmed.

Keyword: Semiconductor, heterostructure, Carbon-Nanodot, silicon-nanowire, photo catalyst, photo-detector

目次
摘要 i
Abstract iii
目次 v
表目次 vii
圖目次 viii
第一章 簡介 1
1.1前言 1
1.2 研究目的 3
第二章 基礎理論 4
2.1 奈米碳點的基礎介紹: 4
2.2 奈米碳點的結構與螢光特性 5
2.3 奈米碳點的上轉換螢光特性 9
2.4 滴塗法 11
第三章 實驗方法與步驟 12
3.1 量測儀器 12
3.1.1 光致螢光(Photoluminescence, PL)光譜 12
3.1.2 紫外光可見光分光光譜(Ultraviolet-visible spectroscopy, UV-vis) 12
3.1.3 傅立葉轉換紅外光(Fourier-transform infrared spectroscopy, FTIR)光譜 12
3.1.4 接觸角(Contact angle)量測儀器 13
3.1.5 四點探針 13
3.1.6 電特性量測儀器 (I-V Curve) 13
3.1.7 X光繞射(X-ray diffraction)光譜 14
3.1.8 光化學反應儀器 14
3.1.9 掃描式電子顯微鏡 (Scanning electron microscope ,SEM) 14
3.1.10 穿透式電子顯微鏡 (Transmission electron microscope ,TEM) 14
3.1.11霍爾效應(Hall effect)量測儀器 15
3.1.12金屬半導體金屬電極設計(金半金電極) 15
3.2 奈米碳點製程 16
3.2.1 奈米碳點製程及原理 16
第四章 結果與討論 18
4.1奈米碳點基礎分析 18
4.1.1 產率與分析 18
4.2 奈米碳點/矽奈米線複合結構光觸媒材料 25
4.2.1濕式製程的奈米碳點/矽奈米線複合結構 25
4.2.2光觸媒特性分析 25
4.2.3 奈米碳點/矽奈米線複合結構光降解原理 27
4.2.4 奈米碳點/矽奈米線複合結構光降解應用 29
4.3奈米碳點薄膜/矽異質接面光偵測 31
4.3.1 奈米碳點薄膜製程 31
4.3.2 奈米碳點薄膜/矽異質接面分析 31
4.3.3 奈米碳點薄膜/矽異質接面光偵測原理 39
4.3.4 奈米碳點薄膜/矽異質接面光偵測應用 41
第五章 結論 46
參考文獻 47
一、中文參考文獻 47
二、英文參考文獻 48


表目次
表4.1不同溫度鍛燒製程奈米碳點與鹽酸震盪鍛燒奈米碳點產率比較表 18
表4.2奈米碳點薄膜於不同電組率與不同型摻雜的矽基板上的表面電阻比較 37
表4.3圖4.20 (a)與(b)的奈米碳點載子濃度數值與厚度對照比較 38
表4.4不同光源波長下奈米碳點薄膜/矽光偵測器的光電流增幅比較 43
表4.5奈米碳點薄膜/矽光偵測器於580 nm光源下的光電流增益比較 44


圖目次
圖2.1奈米碳點的主要的製程方式: Top-down與Bottom-up 5
圖2.2 (a)石墨烯材料可以依切割方向而有不同電性、磁性以及光學特性，可以分為Armchair-edge與Zigzag-edge型態 (b)為Armchair-edge (c)為Zigzag-edge 7
圖2.3為Zigzag-edge的奈米碳點其三重基態σ1π1的示意圖，以及各能態的能量差距，以利分析奈米碳點的螢光模型 7
圖2.4奈米碳點的光電子以π-π*方式躍遷並釋放能量於sp2能態或是缺陷態，而其能量將以藍色螢光或是長波長螢光與熱的方式釋放的示意圖 8
圖2.5奈米碳點的980 nm 的上轉換螢光光譜 9
圖2.6奈米碳點的600~800 nm光源上轉換螢光光譜 10
圖2.7奈米碳點的上轉換螢光機制 (a)為粒徑較小的奈米碳點螢光機制 (b)為粒徑較大的奈米碳點螢光機制 (c)粒徑較大的奈米碳點上轉換螢光機制 (d)粒徑較小的奈米碳點上轉換螢光機制 10
圖3.1 (a)金半金指叉電極示意圖 (b)金半金電極光偵測器原理示意圖 16
圖3.2奈米碳點製程原理示意圖 17
圖4.1鍛燒製程與鹽酸震盪鍛燒奈米碳點產率比較 18
圖4.2 SEM表面形貌與粒徑分析: (a)2 M鹽酸處理的奈米碳點 (b)2 M鹽酸震盪處理的奈米碳點 (c)2 M鹽酸震盪鍛燒處理的奈米碳點 (d)10 M高濃度鹽酸處理的奈米碳點 (e)10 M高濃度鹽酸震盪處理的奈米碳點 (f)10 M高濃度鹽酸震盪鍛燒處理的奈米碳點 19
圖4.3 鹽酸震盪鍛燒處理之奈米碳點 (a)TEM (b)SEM圖 (c)-(d) HR-TEM 20
圖4.4不同濃度鹽酸處理的震盪鍛燒奈米碳點: (a)螢光光譜、(b)吸收光譜 21
圖4.5奈米碳點FTIR圖譜 21
圖4.6 (a)為奈米碳點水溶液情況下在365 nm光源下的螢光光譜 (b)為固體奈米碳點薄膜製作在玻璃基板上的365 nm光源下的螢光光譜 23
圖4.7 (a)為奈米碳點螢光機制 (b)為其螢光機制能帶結構圖 24
圖4.8 複合結構光觸媒材料: (a)為奈米碳點/矽奈米線複合結構光觸媒 (b)為金奈米顆粒/矽奈米線複合結構光觸媒 (c)為銀奈米顆粒/矽奈米線複合結構光觸媒的SEM圖 26
圖4.9 接觸角分析圖: (a)為矽奈米線 (b)為奈米碳點/矽奈米線複合結構光觸媒、(c)為金奈米顆粒/矽奈米線複合結構光觸媒 (c)為銀奈米顆粒/矽奈米線複合結構光觸媒 27
圖4.10 奈米碳點/矽奈米線複合結構光觸媒原理示意圖 28
圖4.11 (a)光觸媒實驗裝置示意圖 (b)為不同濃度鹽酸處理震盪鍛燒奈米碳點粉末的光觸媒實驗結果 30
圖4.12 (a)為580 nm光源下的亞甲基藍、矽奈米線、奈米銀顆粒/矽奈米線複合結構、奈米金顆粒/矽奈米線複合結構、奈米碳點/矽奈米線複合結構的光觸媒實驗結果。(b)為420 nm光源下的亞甲基藍、矽奈米線、奈米銀顆粒/矽奈米線複合結構、奈米金顆粒/矽奈米線複合結構、奈米碳點/矽奈米線複合結構的光觸媒實驗結果 30
圖4.13 奈米碳點薄膜製程示意圖 31
圖4.14 滴數與厚度關係SEM圖: (a)-(f)分別為3、5、7、10、12、14滴配置之奈米碳點溶液形成薄膜於矽基板上 32
圖4.15 奈米碳點溶液滴數與奈米碳點薄膜厚度之關係圖 33
圖4.16 (a)為奈米碳點薄膜/矽基板的XRD分析圖譜 (b)為30 nm、50 nm、64 nm奈米碳點薄膜於玻璃基板上的穿透率圖譜 33
圖4.17不同厚度下奈米碳點薄膜於N型矽基板(電阻率1~10 Ω/cm)的四點探針電阻值比較圖 35
圖4.18不同厚度下奈米碳點薄膜於P型矽基板(電阻率1~10 Ω/cm)的四點探針電阻值比較圖 36
圖4.19 將N與P型矽基板於不同厚度奈米碳點薄膜下電阻值進行疊圖的比較圖 36
圖4.20 不同摻雜矽基板與不同厚度奈米碳點薄膜載子濃度比較: (a)為50、65、95 nm的奈米碳點薄膜於N型矽基板上的載子濃度比較 (b)為30、40、65、95 nm的奈米碳點薄膜於P型矽基板上的載子濃度比較 37
圖4.21 (a)為奈米碳點薄膜製作於N型矽基板(電阻率1~10 Ω/cm)上之載子型態示意圖 (b)為奈米碳點薄膜製作於P型矽基板(電阻率1~10 Ω/cm)上之載子型態示意圖 39
圖4.22 奈米碳點薄膜/矽異質接面光偵測原理示意圖 40
圖4.23 (a)不同光源波長下厚度64 nm奈米碳點薄膜/矽光偵測器的光電流增幅比較與光偵測元件示意圖 (b)光源波長與奈米碳點薄膜/矽光偵測器光電流增幅比較關係圖 43
圖4.24 (a)為不同厚度的奈米碳點薄膜/矽光偵測器於580 nm光源下的光電流增益比較圖 (b)為不同厚度的奈米碳點薄膜/ 矽光偵測器奈米碳點的表面電阻 (c)為40 nm奈米碳點薄膜/矽光偵測器於各種不同波長下的光電流增益數值關係圖 45

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