Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/48957
標題: Hydrogenated Microcrystalline Silicon Thin-Film Solar Cells Fabricated by VHF-PECVD
以超高頻電漿增強化學氣相沉積製作氫化微晶矽薄膜太陽電池
作者: 江雨龍
關鍵字: μc-Si:H;應用研究;材料科技, 光電工程;thin-film solar cell;VHF-PECVD;incubation layer;crystal volume ratio;crystal orientation;crystal structure;氫化微晶矽;薄膜太陽電池;超高頻電漿增強化學氣相沉積;孵育層;結晶比例;結晶方向;結晶型態
摘要: 
Hydrogenated amorphous silicon (a-Si:H)/hydrogenated microcrystalline silicon (μc-Si:H) (a-Si:H/μc-Si:H) tandem cell is a promising structure for improving the energy transfer efficiency of silicon thin-film solar cells. The device-quality of μc-Si:H bottom cell is the key issue for obtaining high performance of a-Si:H/μc-Si:H tandem cell. The crystal structure of μc-Si:H is generally controlled by the plasma chemistry in the gas-phase reaction of SiH4 gas diluted with high concentration of hydrogen. Altering the hydrogen dilution ratio can control the structure phase of the deposited film from single amorphous phase through amorphous and microcrystalline mixed phase to single microcrystalline phase. How to precisely control the incubation layer thickness, crystal volume ratio, crystal orientation, crystal structure and defect density are the key factors for obtaining device-quality μc-Si:H films. The reduction of deposition rate due to hydrogen dilution is also a serious limitation for mass production of μc-Si:H solar cells. How to increase the deposition rate is another important issue for fabricating μc-Si:H solar cell.In this proposal, we will use 40 MHz very-high-frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) to deposit μc-Si:H films. The ion density will increase and the ion energy will reduce in the plasma generated by this 40 MHz very-high-frequency radio wave source, which can increase the deposition rate and reduce the damage of the film due to high-energy ion bombardment. We will control the plasma chemistry by pulse-wave modulation plasma power, changing the hydrogen dilution ratio and chamber pressure to deposit a series of μc-Si:H films with various incubation layer thickness, crystal volume ratio, crystal orientation, crystal structure and defect density.The structure, optical and electrical properties of the μc-Si:H films will be measured and analyzed by x-ray diffraction meter (XRD), Raman spectrometer, transmission electron microscopy (TEM), spectral ellipsometer (SE) and current-voltage (I-V) parameter analyzer. These characteristics are used to find out the conditions and specifications for obtaining device-quality μc-Si:H films. The μc-Si:H films are used to the i-layers of the p-i-n solar cells. The influence of μc-Si:H i-layers on the performance of solar cells will investigate to find out the conditions for improving the energy transfer efficiency.It is expected that the fabricating conditions and specifications for high performance μc-Si:H solar cells can be well explored.

改善矽薄膜太陽電池轉換效率的主要發展方向,是製作氫化非晶矽(hydrogenatedamorphous silicon: a-Si:H)頂電池(top cell)結合氫化微晶矽(hydrogenated microcrystallinesilicon: c-Si:H)底電池(bottom cell)所構成的a-Si:H/c-Si:H 疊層太陽電池。而做為長波長光線吸收的c-Si:H 底電池是此項疊層太陽電池能否有效提升效率的關鍵。ㄧ般製作c-Si:H 薄膜是將矽烷(SiH4)以氫氣稀釋,經由電漿化學反應在沉積薄膜時控制薄膜內的結晶結構。變化氫氣稀釋比例,薄膜的結構可以由單一非晶相經由非晶及微晶混合相再變化至單一微晶相,因此製作c-Si:H 薄膜是一種如何控制結晶形成、結晶型態及結晶比例控制的技術。如何精確地控制c-Si:H 薄膜的孵育層厚度、結晶比例、結晶方向、結晶型態及缺陷密度是製作良好品質c-Si:H 薄膜的幾個重要關鍵,國際間相關的文獻研究,對於這些關鍵特性的要求,仍有很大的分歧。而由於大量氫氣的稀釋,使得沉積速率下降,對於生產效率有不利的影響。因此如何提升沉積速率也是製作c-Si:H 薄膜必須達成的目標。在本計劃中,我們將採用40 MHz超高頻電漿增強化學氣相沉積(VHF-PECVD)製作c-Si:H薄膜,使用超高頻電波可以在電漿內產生較高的離子密度及降低離子能量,使沉積速率提升及降低離子轟擊破壞。我們將以脈波調變電漿功率配合改變氫氣稀釋比及腔體壓力三種條件,製作ㄧ系列具有不同孵育層厚度、結晶比例、結晶方向、結晶型態及缺陷密度的氫化微晶矽薄膜,以明確地找出具有良好品質c-Si:H薄膜的特性要求條件。氫化微晶矽薄膜的結構、光學及電學特性將以X光繞射儀(XRD)、拉曼(Raman)光譜儀、電子穿透式顯微鏡(TEM)、橢圓偏光儀(SE)及電流-電壓特性測量儀進行測量。這些測量及分析將有效地釐清c-Si:H薄膜的各項特性。這些具有不同特性的氫化微晶矽薄膜將分別做為p-i-n薄膜太陽電池的i層光吸收層。藉由太陽電池各項光電性能測量與分析,詳細研究c-Si:H薄膜的各項特性對太陽電池轉換效率及穩定度之影響,並找出改善薄膜太陽電池性能的最適當結晶條件。預期本研究將對氫化微晶矽薄膜太陽電池性能之了解及改善性能有所貢獻。
URI: http://hdl.handle.net/11455/48957
其他識別: NSC98-2221-E005-091
Appears in Collections:電機工程學系所

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