Carbon concentration and particle precipitation during directional solidification of multicrystalline silicon for solar cells
Carbon concentration and particle precipitation during directional solidification of multicrystalline silicon for solar cells
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DOI：
10.1016/j.jcrysgro.2007.11.165
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发表时间：
2008-04-01
影响因子：
1.8
通讯作者：
Kakimoto, Koichi
中科院分区：
文献类型：
--
作者：
Liu, Lijun;Nakano, Satoshi;Kakimoto, Koichi
碳和碳化硅（SiC）沉淀物的含量和均匀性对多晶硅太阳能电池的效率有重要影响。基于Si-C相图建立了熔融硅中SiC颗粒析出的动力学模型。结合瞬态传热全局模型，对太阳能电池用多晶硅定向凝固过程中碳偏析和颗粒形成的特性进行了计算。研究了硅原料中杂质含量和凝固工艺条件对凝固硅锭中替位碳和SiC析出相分布的影响。结果表明，当硅原料中碳浓度超过1.26 × 10 ~（17）atoms/cm ~ 3时，随着碳浓度的增加，凝固铸锭中析出的SiC颗粒的含量在数量和空间上都显著增加。通过优化工艺条件可以控制SiC析出相的分布。SiC沉淀物在快速冷却过程中凝固的锭中聚集在中心上部区域，而在缓慢冷却过程中聚集在外围上部区域。(C)2007 Elsevier B. V.保留所有权利。
The content and uniformity of carbon and silicon carbide (SiC) precipitates have an important impact on the efficiency of solar cells made of multicrystalline silicon. We established a dynamic model of SiC particle precipitation in molten silicon based on the Si-C phase diagram. Coupling with a transient global model of heat transfer, computations were carried out to clarify the characteristics of carbon segregation and particle formation in a directional solidification process for producing multicrystalline silicon for solar cells. The effects of impurity level in silicon feedstock and solidification process conditions on the distributions of substitutional carbon and SiC precipitates in solidified silicon ingots were investigated. It was shown that the content of SiC particles precipitated in solidified ingots increases markedly in magnitude as well as in space with increase in carbon concentration in silicon feedstock when it exceeds 1.26 x 10(17) atoms/cm(3). The distribution of SiC precipitates can be controlled by optimizing the process conditions. SiC precipitates are clustered at the center-upper region in an ingot solidified in a fast-cooling process but at the periphery-upper region for a slow-cooling process. (C) 2007 Elsevier B.V. All rights reserved.