Improvement of the Production Yield of Spherical Si by Optimization of the Seeding Technique in the Dropping Method
Improvement of the Production Yield of Spherical Si by Optimization of the Seeding Technique in the Dropping Method
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DOI：
10.1143/jjap.46.5695
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发表时间：
2007-09
影响因子：
1.5
通讯作者：
Zhengxin Liu;K. Asai;A. Masuda;T. Nagai;Y. Akashi;M. Murozono;M. Kondo
中科院分区：
文献类型：
--
作者：
Zhengxin Liu;K. Asai;A. Masuda;T. Nagai;Y. Akashi;M. Murozono;M. Kondo
通过滴下法形成直径分布为约1.0mm的球形Si，其可用于球形太阳能电池。为了控制熔融硅液滴的凝固发生在浅过冷度，籽晶技术的发展。在本文中，我们描述了种子技术的优化，重点是高产量和高少数载流子寿命。首次引入了有效的种子供应系统。结果发现，晶种与Si粉导致杂质，如铁，进入Si球，和结晶度变差，随着产量的增加。SiO、SiO2、Si3N4和氮化硼粉末被示出具有与Si粉末相同的晶种效应。其中，SiO2是最好的候选者。用SiO2粉作晶种不会增加Fe和O杂质的浓度，也不会降低结晶度。系统地研究了SiO_2粉体的粒度和密度对产率的影响。在高SiO2粉末密度下实现了近70%的最佳产率。
Spherical Si with a diameter distribution of approximately 1.0 mm, which is applicable to spherical solar cells, was formed by the dropping method. To control the solidification of the molten Si droplet to occur at shallow undercooling, a seeding technique was developed. In this paper, we describe the optimization of the seeding technique with emphases on high production yield and high minority carrier lifetime. An effective seeding supply system was first introduced. It was found that the seeding with Si powder causes impurities, such as Fe, into Si spheres, and the crystallinity becomes poor with increasing yield. SiO, SiO2, Si3N4, and boron nitride powders were shown to have the same seeding effect as Si powder. Among these, SiO2 was the best candidate. The seeding with SiO2 powder did not increase the concentration of Fe and O impurities and did not decrease the crystallinity. The dependences of the yield on the size and the density of SiO2 powder were systemically investigated. The best yield of nearly 70% was realized at a high SiO2 powder density.