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標題: High Efficiency Nanowire Array Silicon Thin Film Solar Cell(II)
作者: 裴靜偉
關鍵字: 應用研究
光電工程, 能源工程
摘要: This is a second year proposal. In this proposal, the main idea is to produce a nanowire structure that the light absorption direction is perpendicular to the photo-generated carrier transport direction. The short transport path could ensure the photo-generated carriers reach contact without signification recombination. Therefore, the efficiency is enhanced by nanorod structure.Among many type of solar cells, amorphous silicon (a-Si) thin film silicon solar cell is one of the promising cell to achieve low cost requirement. The a-Si solar cell is generally made in the p+ doped a-Si/intrinsic a-Si/n+ doped a-Si (p-i-n) form. The intrinsic layer is depleted at thermal equilibrium. Therefore, high electrical (~104 V/cm) field is presenting in the intrinsic layer. After light absorption, the internal electrical field forces the photo-generated carrier drift to the n and p contact contributes to photocurrent. The carrier's transport velocity is higher in the drift motion than in the diffusion motion as in the p-n junction solar cell. As a consequence, the absorption layer thickness in the a-Si p-i-n solar cell is smaller than the in the p-n junction solar cell. However, the material quality of a-Si is far beyond the crystalline Si that the thickness of the absorption layer is limited and is too thin to absorb most of the sun light. Thick i layer will reduce the electrical field and large amounts of the carriers might recombine in the a-Si film before they arrive at the contact because of the large amounts of traps in a-Si. This indicates there is a limitation for absorption layer thickness by compromise light absorption and photo-generated carrier transport. To overcome this limitation, the nanowire structure is an adequate method.To make a Si nanowire array, an one step nano-patterning method was invest in our last-year project. A dense Si nanowire array could be made accordingly. In this year's proposal, we will develop several passivation method to protect the surface of the nanowires that may be damaged during reactive etching process. Besides, analysis also takes on those nanowires by utilizing conductive AFM, Low temperature IV. The final goal is to fabricate a nanowire solar cell with 8% efficiency.
其他識別: NSC99-ET-E005-001-ET
Appears in Collections:電機工程學系所



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