臺灣博碩士論文加值系統

本實驗以定電流製程製備氧化亞銅薄膜，並選用多晶銀、多晶銅、單晶銅為基板，探討電鍍參數（溫度、鍍液pH值、電流密度）對氧化亞銅磊晶成長的影響。磊晶成長的分析，是以離位(ex-situ) 方法，於電鍍前以掃描式電子顯微鏡和電子背向散射繞射儀分析基板的結晶方位分布，再於電鍍後分析原位置上電鍍氧化亞銅薄膜的結晶方位分布，藉以探討在不同結晶方向的基板晶粒上氧化亞銅的成長行為。此外，以Ｘ光繞射儀確認薄膜的結晶相，以穿透式電子顯微鏡分析氧化亞銅鍍層的厚度與顯微組織。最後以反射光譜分析氧化亞銅鍍層的能隙值，以及利用光致螢光光譜分析磊晶的螢光發光特性。
實驗結果顯示，所有參數下電鍍所得的薄膜均為氧化亞銅。在pH值為9，溫度為25 oC時，鍍層係由粒徑細小的球狀顆粒團聚而成，但是在電流密度低至0.0125 mA/cm2時，電鍍的電流效率非常低，導致基板上僅有少量散佈的氧化亞銅顆粒存在。此外，鍍層與基板之間無特定方位關係。在pH值為9，溫度提高至60 oC時，鍍層係由粒徑較粗大且具有明顯晶癖面的八面體形狀顆粒覆蓋而成，在低電流密度下鍍層沉積不均勻。此外，在電流密度較高時，部分基板晶粒上有磊晶成長現象。在pH值為12，溫度為25 oC時，氧化亞銅有兩種形貌，其一是以八面體顆粒依照磊晶關係堆疊而成的薄膜，另一種則是相對平坦的磊晶薄膜。電流密度愈大，平坦的的磊晶薄膜比例愈高，而當電流密度太低時仍有電流效率偏低的問題。在pH值為12，溫度提高至60 oC時，氧化亞銅粒徑增加至300-2000 nm。當電流密度為0.2500 mA/cm2時，只有在(100)的基板晶粒上可以成長出平坦的氧化亞銅磊晶。當電流密度為0.0600或0.1250 mA/cm2時，大多數基板晶粒上均可成長平坦的氧化亞銅磊晶。因此高溫與高pH值較有利於氧化亞銅的磊晶成長。大多數磊晶成長的氧化亞銅與基板間的方位關係為cube-on-cube，但是在電流密度為0.060 mA/cm2或0.1250 mA/cm2時，部分電鍍試片的氧化亞銅與基板間存在兩種方位關係：cube-on-cube和rotate cube(<100>/45°)。
本研究同時於單晶銅(110) 基板沉積氧化亞銅、氧化亞銅以cube-on-cube的方位關係磊晶成長，rocking curve的半高寬為1.4o。電鍍氧化亞銅磊晶的能隙值為2.05 eV，室溫光致螢光光譜分析顯示（100）的磊晶會在1.97 eV處產生明顯的近能隙發光峰。

Cuprous oxide (Cu2O) films were prepared by galvanostatic condition to explore the effect of processing parameters (temperature and pH value of the electroyte and current density) on the epitaxial growth of on metallic substrates. Polycrystalline silver, copper and single crystal copper were used as the substrates. An ex-situ methos was used to analyze the orientation distribution of the substrate grains prior to and after electrodeposition for the same area by electron backscatter diffraction (EBSD). The surface morphology of the deposits was observed by scanning electron microscope, the composing phases of the deposits were identified by X-ray diffractometer, the thickness and microstructure of the deposits were observed by transmission electron microscope (TEM). In addition, optical reflective spectroscpoy and photoluminescence spectroscopy were used to analyze the energy band gap and luminescence characteristics of the deposits.
All the deposits were mainly composed of Cu2O no matter the processing parameters used. For the deposition carried out at pH=9 and 25 oC, the deposited films were composed of fine, spherical particles. The Cu2O particles deposited with no specific orientation relationship with the substrate grains. In addition, the cathode efficiency was extremely low at a low current density of 0.0125 mA/cm¬2. When the films were deposited at pH= 9 and 60 ° C, the films were composed of octahedral particles with coarser sizes. The coating was not uniformly distributed on the substrate at the lowest current density. Furthermore, about half of the Cu2O crystals could grow epitaxially on the substrate grains at higher current densities.
At a high pH of 12 and 25 oC, the films consisted of two morphologies. One is rough, regularly packed cuprous oxide crystals and the other is relatively flat epitaxial film. The larger the current density, the higher was the area fraction of the flat epitaxial film. At pH=12 and 60 °C, the size of the cuprous oxide crystals increased to 300-2000 nm. When the current density was increased to 0.2500 mA/cm2, Cu2O grew epitaxially only on the (100) substrate grains with very flat top surfaces. When the current density was decreased to 0.0600 - 0.1250 mA/cm2, most the substrate grains were covered by flat Cu2O epilayer. Accordingly, high growth temperature and high pH value of the electrolyte are beneficial for epiaxial growth of cuprous oxide. Most of the epilayers exhibit a cube-on-cube orientation relationship with the substrate grains, except that aportion of epilayers grown at the current density of 0.060 mA/cm2 or 0.1250 mA/cm2 follow a rotate-cube (<100> / 45 °) orientation relationship. In this study, cuprous oxide was also deposited on (110) single crystal copper substrate and epilayer with a full width at half maximum of the rocking curve of 1.4 ° was obtained. The energy gap of electroplated film is 2.05 eV. A strong near band emission at 1.97 eV was found in the photoluminescence spectrum of a (100) epilayer analyzed at room temperature.

論文審定書………………………………………………………………………….....i
致謝 …………………………………………………………………………………..ii
摘要 ………………………………………………………………………………….iii
Abstract………………………………………………………………………...…...…v
目錄 ……………………………………………………………………………...….vii
表目錄 ……………………………………………………………………...……...…x
圖目錄 ………………………………………………………………………….........xi
1.前言 1
2.基礎理論和文獻回顧 3
2.1氧化亞銅的基本特性及應用 3
2.2磊晶成核與成長 3
2.2.1同質成核 4
2.2.2異質成核 4
2.2.3異質磊晶成長 4
2.3氧化亞銅的薄膜成長 6
2.3.1氧化亞銅磊晶薄膜 6
2.4電鍍 7
2.4.1電鍍基本原理 7
2.5以電化學製程製備氧化亞銅薄膜與磊晶 8
2.5.1鍍液 8
2.5.2電壓 8
2.5.3 pH值 9
2.5.4 溫度與電流密度 10
2.5.5電鍍沉積的氧化亞銅多晶薄膜 11
2.5.6電鍍沉積的氧化亞銅磊晶薄膜 12
2.6晶體集合組織之分析 13
2.6.1尤拉角(Euler angle) 13
2.6.2反極圖(inverse pole figure) 14
3.研究方法和步驟 15
3.1基板前處理 15
3.2 電鍍製程 15
3.3　X光繞射分析 15
3.4掃描式電子顯微鏡、背向散射電子繞射與能量色散光譜分析 15
3.5光致螢光光譜(Photoluminescence，PL)分析 16
3.6薄膜光學特性 (N&K Analyzer) 分析 16
3.7原子力顯微鏡分析 16
4.實驗結果 17
4.1電解拋光後基板表面分析 17
4.2 X光繞射分析 17
4.3鍍層分析 18
4.3.1電鍍液pH9，溫度25 oC 18
4.3.2電鍍液pH9，溫度60 oC 21
4.3.3電鍍液pH12，溫度25oC 23
4.3.4電鍍液pH12，溫度60 oC 26
5.討論 32
5.1溫度與pH值對氧化亞銅粒徑和形狀的影響 32
5.2電鍍液pH與溫度對氧化亞銅成長方向的影響 33
5.3電流密度對於氧化亞銅鍍層影響 34
5.4基板對氧化亞銅鍍層影響 34
5.5 EBSD分析的訊號深度問題 35
5.6電鍍氧化亞銅鍍層的成長機構 36
6.結論 38
7.文獻參考 40

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