為了達到一個低成本高效率的太陽能電池，全矽堆疊式太陽能電池具有很大的潛力，藉由不同能隙的矽奈米晶體薄膜(例如: Si/SiO2矽奈米晶體薄膜)堆疊於單晶矽太陽能電池可減少熱損耗的發生，以提高整體之效率。Si/SiO2矽奈米晶體薄膜導性深受SiO2阻障層的影響，為了提升該矽奈米晶體薄膜導電性，我們在阻障層中加入一些缺陷，去創造額外的路徑以提供載子傳輸。我們利用拉曼光譜去分析該缺陷對結晶以及矽奈米晶體尺寸的影響，並利用X光繞射分析去對尺寸做進一步的驗證，接著使用光激發光譜去探討阻障層對於缺陷態的變化，最後再藉由電性的量測探討該矽奈米晶體薄膜傳輸機制。

In order to achieve low cost and high efficiency solar cells, all silicon tandem solar cells made of Si nanocrystal (Si NC) thin films with different bandgaps (such as Si/SiO2 Si NC thin films) stacking on crystalline Si solar cells are proposed. The solar cells can greatly reduce thermalization loss. However, Si/SiO2 Si NC thin films exhibit low conductivity because of poor conductivity of SiO2 barrier layers. In this thesis, we created additional transportation paths by increasing the defects of barrier layers. We studied effects of the defects on the crystallization and dimension of Si NC thin films by Raman spectra and XRD. In addition, we analyzed the influences of the defects on optical properties of Si NC thin films by PL spectra. Finally, we discussed a possible carrier transportation mechanism from electrical results.

Chapter 1 Introduction 1
1.1 Background 1
1.2 Solar Cells 2
1.3 Silicon based tandem solar cells 5
1.3.1 Power Loss Paths 5
1.3.2 Quantum Confine Effect 7
1.3.3 Tandem solar cells using Si NC thin films 8
1.4 Paper Review 10
1.5 Motivation 13

Chapter 2 Fabrication of Si Nanocrystal Thin Film 14
2.1 Substrate Clean 14
2.2 Precusor Thin Film Deposition 15
2.3 Formation of Si NC Thin Films 17
2.4 Remove Thermal Oxide after Annealing Process 18
2.5 Metal Deposition 18

Chapter 3 Characterization of Si NC Thin Films 19
3.1 Analysis of Si NC thin films by High Resolution Confocal-Raman Microscope 19
3.1.1 Fundamental of Confocal Raman Microscope 19
3.1.2 Experimental Results and Discussions 21
3.2 Analysis of Si NC thin films by X-Ray Diffraction 25
3.2.1 Fundamental of XRD Analysis 25
3.2.2 Experimental Results and Discussions 26
3.3 Analysis of Si NC thin films by PL spectroscopy 28
3.3.1 Fundamental of PL spectroscopy 28
3.3.2 Experimental Results and Discussions 28

Chapter 4 Electrical Properties of Si NC Thin Films 33
4.1 Experimental Results and Discussions 33
4.2 Carrier Transport Mechanism of Si NC Thin Films 37 4.3 Temperature Dependence I-V Curves of Si NC Thin Films 40

Chapter 5 Conclusion and Future Work 43
5.1 Conclusion 43
5.2 Future Work 44

Reference 45

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