Solidification control of multicrystal silicon ingot for solar battery

太阳能电池用多晶硅锭的凝固控制

基本信息

批准号：
14350401
负责人：
OGI Keisaku
金额：
$ 6.66万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14350401/
关键词：
Solar battery multicrystal silicon faceted growth twin boundary crystal growth undercooling photoelectric transformation diffusion length of carrier 発光電ファセット界面機能性材料ファセット

项目摘要

The mechanisms of columnar structure growth of the multicrystal silicon are investigated to the development of the photoelectric transformation efficiency and the productivity of solar battery cell fabricated by the unidirectional solidification technique.First of all, solar battery- grade high purity silicon crystals were solidified in small size crucibles (the inside diameter of 20 mm and the height of 100 mm) at the velocity of 0.075〜9.6 mm/s and a temperature gradient of 20K/cm by using the Bridgman type furnace. The undercoolings of nucleation and grain growth, the grain sizes and the crystal orientations of silicon multicrystal were investigated in related to the solidification conditions. The columnar structures are observed parallel to the heat flow direction in a velocity about 1 mm/min, and the larger size grains are obtained at the lower solidification speed. The crystal size becomes small with the increase of growth velocity and an equiaxed grain structure start forming abo … More ve a velocity around 1.8 mm/min.Twin boundaries, which have the crystal orientation relationship of sigma 3, grow parallel to the heat flow direction. Thus, the undercooling and driving force for crystal growth are estimated by the model based on two-dimensional nucleus growth regime. It was revealed that the undercooling of the <211> direction growth with twin boundary decreases to about 70 % of the case of <111> direction growth and reentrant corner of twin boundary gives an advantage to the faceted growth. Similar phenomena is obtained by the computer simulation based on the molecular dynamics theory. Therefore we conclude the kink site of the reentrant corner on twin boundary encourages the solidification velocity increasing and the development of grain size.The silicon crystal grows to the orientation between <211> to <101> along to the crucible bottom regardless on the form of the crucible shape and configuration at initial solidification stage. Similar phenomena are appeared even in the middle size specimen (the inside diameter of 80mm and the height of 20 mm) and also in the large size solar battery cell. Therefore, the grain size and grain orientation can be controlled by the covering the specimen bottom with the silicon crystal, which solidified toward the <211>〜<101> orientation due to the twin boundary at initial solidification stage, and then the growing upward at the relatively slow solidification velocity until final solidification stage. Less

研究了柱状硅的柱状结构生长的机制，研究了光电转化效率的发展以及由单向固化技术制造的太阳能电池的生产力。首先，太阳能电池级的高纯度高纯度硅晶体以小尺寸的crucibles固定（在20 mm和20 mmmmmet的内部直径的小尺寸）中固化使用Bridgman型炉子，0.075-9.6 mm/s和20k/cm的温度梯度。在与固化条件相关的情况下研究了成核和谷物生长，晶粒大小和硅晶体方向的底层冷却。在约1 mm/min的速度下平行观察到柱状结构与热流方向平行，并且在较低的固化速度下获得较大尺寸的晶粒。随着生长速度的增加，晶体尺寸变得很小，并且等效的晶粒结构开始形成ABO…更加速度约为1.8 mm/min。两次边界，它们具有Sigma 3的晶体取向关系，平行于热流动方向。这是根据二维核生长体制估算了晶体生长的过冷和驱动力。据揭示，<211>方向生长的过冷底座下降，约为<111>方向生长的情况的70％，而双边界的重新进入角落为相位的生长带来了优势。基于分子动力学理论的计算机模拟获得了类似的现象。因此，我们包括双边界上的重入角的扭结位点，促进了固化速度的增加和晶粒尺寸的发展。硅晶晶体在<211>到<101>之间的方向发展到坩埚底部，无论在初始凝固阶段的坩埚形状和构型形式如何。即使在中间尺寸标本（80mm的内径和20mm的高度）以及大型太阳能电池电池中，也出现了类似的现象。因此，晶粒尺寸和晶粒方向可以通过用硅晶体覆盖样品底部来控制，硅晶体朝向<211>〜<101>方向固化，这是由于初始固化阶段的双边界而导致的，然后在相对较慢的固体速度上向上生长，直到最终固化阶段。较少的