Clarification of the relation between the grain structure of industrial grown mc-Si and the area fraction of electrical active defects by means of statistical grain structure evaluation
Clarification of the relation between the grain structure of industrial grown mc-Si and the area fraction of electrical active defects by means of statistical grain structure evaluation
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DOI：
10.1016/j.actamat.2015.12.049
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发表时间：
2016-03
期刊：
影响因子：
9.4
通讯作者：
T. Lehmann;C. Reimann;E. Meissner;J. Friedrich
中科院分区：
文献类型：
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作者：
T. Lehmann;C. Reimann;E. Meissner;J. Friedrich
本文对6种工业生产的常规多晶硅砖和6种不同厂家生产的高性能多晶硅砖的晶粒度、晶向和晶界类型分布进行了统计研究。研究发现，与常规MC-Si晶片相比，HP MC-Si晶片具有更均匀的初始晶粒度(变异系数CV)和取向分布，平均晶粒度(<；4 mm~2)更小，随机晶界长度百分比(>；60%)更高。尽管HP和传统MC-Si砖的初始颗粒结构完全不同，但顶部晶片的颗粒结构或多或少是相似的。结果表明，热压MC-Si砖的晶界能和表面能共同导致了晶界能量的最小化，从而驱动了晶界结构的发展。颗粒结构研究表明，尤其是砖的初始颗粒结构对电活性缺陷的面积分数和太阳电池的效率有显著的影响。热压MC-Si砖的电活性缺陷面积分数最低可达4%，最高太阳电池效率为18.8%，而常规MC-Si砖的电活性缺陷面积分数高达14%，最大太阳电池效率约为18.4%。
This paper presents results of a statistical investigation of the grain size-, grain orientation- and grain boundary type distribution of six industrially grown conventional multicrystalline (mc-Si) silicon bricks and six high performance (hp) mc-Si bricks of different producers. It was found that hp mc-Si wafers have a more uniform initial grain size (coefficient of variation CV < 2.5) and grain orientation (CV < 1.5) distribution, with a smaller mean grain size (<4 mm2) and a much higher length fraction of random grain boundaries (>60%) in comparison to the conventional mc-Si wafers. Despite the totally different initial grain structures between the hp and conventional mc-Si bricks the grain structure of the top wafers is more or less comparable. It was concluded that the grain structure development of the hp mc-Si bricks is driven by an energy minimization due to the surface energy as well as the grain boundary energy. The grain structure investigations show clearly that especially the initial grain structure of the bricks significantly influences the area fraction of electrical active defects as well as the solar cell efficiency. The hp mc-Si bricks show the lowest area fraction of electrical active defects up to 4% and the highest solar cell efficiency of 18.8%, whereas the conventional mc-Si bricks have an area fraction of electrical active defects up to 14% and a maximum solar cell efficiency of about 18.4%.