本研究中，先以三源共蒸鍍法(Three source co-evaporation)並藉由化學組成控制成長近定比組成(near-stoichiometry)之CuGaSe2(簡稱CGSe)多晶薄膜。電阻率隨富銅(Cu-rich)到富鎵(Ga-rich)相區由3.7x10-1 -Ω‧cm 增至7.4x104 Ω‧cm，X-ray繞射分析結果確定薄膜為單一相。實驗中也發現薄膜表面殘存的Cu-Se導電相有助於促進CGSe與Mo金屬電極形成良好的歐姆接觸(Ohmic Contact)。
接著，在n型 Si (100)基板上成長Cu-rich CuGaSe2(p型CGSe)磊晶薄膜，XRD繞射分析結果顯示所製備出的CGSe薄膜其c軸是平行基板方向成長而形成方向性晶域結構(Orientation domain structure)，產生此晶域結構的原因為晶格不匹配程度所導致的。
由XRD分析結果亦可發現CGSe薄膜在(400)的繞射峰較為寬廣且為不對稱，我們推論可能是製程溫度(550℃)造成CGSe薄膜和Si在界面處有著一相互擴散(interdiffusion)的現象發生，經由歐傑縱深成分分析結果證實Si明顯地擴散進入富銅CGSe薄膜裡，Si取代Ga會造成n型摻雜而影響原為p型的CGSe轉為傾向n型，致使在製作p-CuGaSe2/n-Si異質結構太陽電池時不利於P-N接面的形成。因此，未來可採用低溫製程來製備CGSe薄膜以解決高溫製程所衍生的問題。

關鍵詞:分子束蒸鍍、方向性晶域結構、CuGaSe2磊晶、CuGaSe2/Si異質結構太陽電池

For the composition control and testing electric properties, polycrystalline CuGaSe2 (CGSe) films with near-stoichiometric compositions were deposited by
three-source co-evaporation on glass without the substrate rotation. XRD analysis veried that the film is single phase with the chalcopyrite structure. From Cu-rich to Ga-rich regions for the film grown on a glass substrate,the film resistivities varied from 3.7x10-1 Ω‧cm to 7.4x104 Ω‧cm. Further experiments on the formation of Ohmic contacts onto CGSe films indicated that the remaining Cu-Se phase on the surface of Cu-rich CGSe could improve the contact properties for the film attached with Mo metal electrodes.
Since the successful epitaxial growth should be demonstrated prior to device fabrication, Cu-rich CGSe(p-type CGSe) films were grown on (100) n-type Si wafers.XRD analysis reveal that the c-axis of tetragonal unit cell aligned parallel to the substrate surface to lower the strain energy and thus leaded to the formation of orientation domain structure. For the films grown at 550℃, the XRD peak of CGSe was broden and asymmetric indicating an interduffusion at the CGSe/Si interface. Auger depth profiling showed that a conderable amount of Si was diffused into CGSe. Considering in a Cu-rich CGSe that Si might incorporate into the lattice site of Ga and became as a donor, which could compensate the acceptor in p-type CGSe. This would seriously degrade the junction properties of p-CGSe/n-Si device structure. It is strongly suggested that a low-temperature process such as photo-assited MBE should be employed for the film growth.

Keywords:Molecular beam deposition,orientation domain structure,CuGaSe2 epitaxy, CuGaSe2/Si heterojunction solar cell

論文審定書 i
誌謝 ii
摘要 iii
Abstract iv
目錄 v
圖目錄 vi
表目錄 viii
第一章 導論 1
1.1 前言 1
1.2 太陽電池原理 2
1.3 矽基太陽電池 6
1.4 研究動機與目的 9
1.5 實驗流程規劃 12
第二章 文獻回顧 13
2.1 CuGaSe2(CGSe)之材料性質、相圖及薄膜成長 13
2.2 CuGaSe2(CGSe)薄膜反應機制 16
2.3 CuGaSe2(CGSe)本質點缺陷 17
第三章 實驗製程與分析儀器介紹 22
3.1 基板處理 22
3.2 分子束蒸鍍系統 23
3.3 分子束源瓶、溫控器及石英震盪晶片 24
3.4 平行濺鍍系統 25
3.5 分析儀器介紹 27
3.5.1 X-ray繞射分析儀(X-ray Diffraction) 27
3.5.2 四點探針(Four-Point Probe) 28
3.5.3 場發射型掃描式電子顯微鏡(Field-Emission SEM) 28
3.5.4 歐傑電子能譜儀(Auger Electron Spectroscopy) 29
3.5.5 模擬光源與I-V量測 29
第四章 實驗結果與討論 30
4.1 元件模擬計算結果 30
4.1.1 結晶矽(n型Si)搭配CuGaSe2(p型CGSe)太陽電池元件模擬 31
4.2 製備近定比組成之CuGaSe2薄膜 34
4.3 近定比組成的CuGaSe2薄膜與鉬(Mo)金屬電極之接觸特性 37
4.4 矽基板上製備Cu-rich CuGaSe2(p型CGSe)磊晶薄膜 39
第五章 結論 46
第六章 參考文獻 47

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