臺灣博碩士論文加值系統

氧化亞銅為一直接能隙(2.0eV)的半導體材料，具有在可見光區內高吸收係數、低製造成本、無毒性且在地球上含量豐富之優點。其光電特性使其可應用於光敏元件及氣體感測器，亦適用於具經濟效益的薄膜太陽能電池。本研究利用反應濺鍍方式在低溫於玻璃基板沉積單相之氧化亞銅薄膜，並藉由製程參數之控制改變氧化亞銅薄膜之光電特性。研究中首先藉由基板溫度及氧氣分壓之改變，探討其對於氧化亞銅薄膜的型態、結晶結構及光電特性的影響，此外，亦藉由氮摻雜製程提升氧化亞銅薄膜之載子濃度，以提升其應用。
研究結果顯示，在反應濺鍍製程中若固定基板溫度為250℃，氬氣流量為7.5 sccm，濺鍍功率為200瓦時，藉由氧氣流量之變化，可沉積出單相氧化亞銅、單相氧化銅或其兩相混合之薄膜。將工作氣體中之氧氣原子百分比控制於 35 ~ 42 at%範圍時，可生成單相之氧化亞銅薄膜；其中，若氧氣原子百分比控制於 35 ~ 40 at%時，薄膜呈n型半導體特性；而氧氣原子百分比控制於 40at%以上，薄膜之電學性質則呈P型半導體特性。
研究成果亦顯示，除了氧氣流量會改變氧化亞銅薄膜之電性外，濺鍍過程中之基板溫度對於氧化亞銅薄膜電性亦會產生影響。X光繞射分析結果證明，當基板溫度變化時，氧化亞銅薄膜之(111)和(200)平面之繞射峰強度亦隨之消長，當溫度增加時， I(111) / I(200) 繞射峰強度比值隨之減小，顯示基板溫度升高時，薄膜之優選方位將由(111)平面逐漸轉變為(200)平面。薄膜之霍爾量測結果亦指出，當氧化亞銅薄膜的優選方位從(111)改變至(200)時，其電學性質將從n型半導體轉變為p型半導體。
在薄膜的電性方面，以反應濺鍍所製作之氧化亞銅薄膜其載子濃度約為1012/cm3，本研究藉由製程中通入氮氣參予反應濺鍍之方式掺雜氮原子以提升薄膜之載子濃度。研究結果顯示，控制氮氣分壓為5.0×10-3 mbar ，濺鍍功率提升至500瓦時，可成功於氧化亞銅薄膜摻雜入氮原子，使其載子濃度提升至1018/cm3，符合光電元件半導體材料所需之載子濃度為1016~1019/cm3之需求。

Cuprous oxide (Cu2O), a semiconductor material with a direct band gap of about 2.0 eV, has several advantages such as a relatively high absorption coefficient in the region of visible light, low-cost production, nontoxicity, and abundance of available materials, which make it applicable to photo-sensitive devices or gas sensors. It is also a candidate material for the fabrication of cost effective thin film solar cells. In this study, single-phase Cu2O films were successfully grown at relatively low temperature on glass substrates by reactive magnetron sputtering. The characteristics of these Cu2O films can be modulated by means of changes of the process parameter such as the substrate temperature or oxygen partial pressure. The effects of the substrate temperature and oxygen partial pressure on the chemical, opto-electronic, and structural properties of these films were investigated. A nitrogen doping process was used to raise the carrier concentration of the Cu2O films to increase their potential for commercial application.
The results indicate that a film of single phase of Cu2O or CuO, or mixing phases of both Cu2O and CuO can be manipulated via controlling the oxygen flowing rate in the reactive sputtering process with the substrate temperature of 250℃, the argon flow rate of 7.5 sccm, and the dc power of 200W. Single phase Cu2O thin films can be deposited when the oxygen atomic percent in the working atmosphere was controlled at 35 ~ 42 at%, in which the carrier type belongs to n-type when the oxygen atomic percent was at 35 ~ 40 at% and the carrier type belongs to p-type when the oxygen atomic percent was at 42 at%.
The results also indicate that, in addition to the oxygen flow rate, the substrate temperature can also affect the electric properties of the Cu2O thin films. XRD analysis reveals that the ratio of peak intensity, I(111)/I(200) , decreased when the substrate temperature increased, which suggests that the preferred plane of the Cu2O film would transit from (111) to (200) when the substrate temperature rose. Hall-effect measurements also indicates that when the preferred plane of Cu2O film changed from (111) to (200), the carrier type switched from n-type to p-type.
The carrier concentration of our Cu2O film was around 1012/cm3, which is a little bit lower for practical utility. A nitrogen element doping process by blending nitrogen into the working atmosphere of the reactive sputtering was used to raise the carrier concentration of our Cu2O films. The result shows that by controlling the nitrogen partial pressure at 5.0 × 10-3 mbar and the dc power at 500 W, we can successfully doped nitrogen atoms into the Cu2O films and increased the carrier concentration up to 1018/cm3 which fills the requirement of semiconductor material for photoelectric devices, say, 1016～1019/cm3.

誌謝 ii
摘要 iii
ABSTRACT v
目錄 vii
表目錄 x
圖目錄 xi
1. 緒論 1
1.1 前言 1
1.2 研究動機與目的 1
2. 理論基礎與文獻回顧 3
2.1 太陽能電池發展之背景 3
2.2氧化亞銅薄膜 4
2.2.1 氧化亞銅薄膜特性 4
2.2.2 氧化亞銅相關文獻回顧 5
2.3 反應性直流磁控濺鍍原理 6
2.3.1 直流磁控濺鍍原理 6
2.3.2 反應性濺鍍 7
2.4 反應式濺鍍法製備氧化亞銅相關文獻回顧 9
3. 研究方法與儀器設備 11
3.1 研究方法 11
3.1.1 研究流程圖 11
3.1.2 研究方法 12
3.1.2.1 基板清洗 12
3.1.2.2 濺鍍薄膜程序 13
3.1.2.3 反應濺鍍參數設定 14
3.2 研究基材與設備 14
3.2.1 研究基材 14
3.2.2 研究設備 16
3.2.2.1 反應式直流磁控濺鍍系統 16
3.3 薄膜性質分析 17
3.3.1 薄膜成份分析 17
3.3.1.1 低銳角X光繞射分析儀 17
3.3.2 薄膜厚度量測與成長速率 18
3.3.2.1 表面粗度儀(α-step) 18
3.3.3 薄膜表面型態觀察 18
3.3.3.1 掃描式電子顯微鏡 18
3.3.3.2 原子力顯微鏡 19
3.3.4 薄膜電性量測 20
3.3.4.1 四點探針量測儀 20
3.3.4.2 霍爾量測(Hall- Effect Measurement System) 21
3.3.5 薄膜光性量測 21
4. 結果與討論 23
4.1 氧氣流率對濺鍍薄膜之影響 23
4.1.1 氧氣流率對薄膜微結構之影響 23
4.1.2 氧氣流率對薄膜濺鍍沉積速率之影響 28
4.1.3 氧氣流率對薄膜表面形貌之影響 30
4.1.4 氧氣流率對薄膜電學性質之影響 34
4.1.5 氧氣流率對薄膜光學性質之影響 37
4.2基板加熱溫度對薄膜之影響 38
4.2.1 基板加熱溫度對薄膜微結構之影響 38
4.2.2 基板加熱溫度對薄膜濺鍍沉積速率之影響 40
4.2.3 基板加熱溫度對薄膜表面形貌之影響 41
4.2.4 基板加熱溫度對薄膜電學性質之影響 46
4.2.5 基材加熱溫度對薄膜光學性質之影響 48
4.3 氮氣(N2)掺雜對氧化亞銅薄膜之影響 49
4.3.1 濺鍍功率對氮氣(N2)掺雜之氧化亞銅薄膜微結構之影響 50
4.3.2 濺鍍功率對氮氣(N2)掺雜氧化亞銅薄膜濺鍍沉積速率之影響 52
4.3.3 氮氣(N2)掺雜濺鍍功率對電學性質之影響 52
5. 結論 56
6. 未來展望 57
參考文獻 58
自傳 63

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