Success in growth of quasi-monocrystalline silicon ingot for solar cell applications - Overcoming a problem of multi-crystallization by grain boundary engineering -


The research group led by Prof. Ichiro Yonenaga and his colleague Dr. Kentaro Kutsukake of Institute for Materials Research (IMR), Tohoku University (Japan), has invented a novel growth method for crystalline silicons for solar cell applications and realized a quasi-monocrystalline silicon, so called mono-like Si, ingot without multi-crystallization. While approximately 50% of substrate for solar cells is currently based on multicrystalline silicon, mono-like Si is promising as a material capable of additionally increasing the conversion efficiency of the solar cells, of which research and development has accelerate worldwide. However, mono-like Si faces a problem of "multi-crystallization" that is an increase in occupying portion of several grains nucleated at crucible side walls with different orientation from that of the seed, in the growth process of a quasi-mono crystal from silicon melt. In order to solve this problem, we have devised a method suppressing such enlargement of the grains by utilizing functions of grain boundaries artificially induced by specific composed seed.

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