定向凝固法生长多晶硅中位错密度降低的研究进展

Research Progress of Dislocation Density Reduction in Multicrystalline Silicon Grown by Directional Solidification Method

位错可以通过缩短少数载流子寿命而严重限制多晶硅太阳电池的转换效率,随着对高转换效率的追求,研究多晶硅位错的重要性也随之增加。在介绍现有半导体晶体CRSS和HAS位错模型的基础上,归纳了定向凝固法生长多晶硅中应力、晶界、杂质、过冷度对位错形成的影响机制与缺陷腐蚀和原位检测等多种位错表征方法。重点阐述了控制固液界面形貌、籽晶、掺杂、硅锭制备工艺、硅片退火等技术对减少与抑制多晶硅位错的影响。最后,针对位错模型、位错表征以及多晶硅生长过程中位错的抑制和生长后位错密度降低技术进行了展望。

Dislocations can seriously limit the conversion efficiency of multicrystalline silicon solar cells by shortening the minority carrier lifetime.With the pursuit of high conversion efficiency, the importance of studying multicrystalline silicon dislocations increases.Based on the introduction of the exis-ting CRSS and HAS dislocation models of semiconductor crystal, influence mechanisms of stress, grain boundary, impurities and undercooling on the formation of dislocation in multicrystalline silicon grown by directional solidification, and the dislocation characterization methods such as defect corrosion and in-situ detection are summarized.The effects of controlling solid-liquid interface morphology, seed crystal, doping, silicon ingot preparation process and silicon wafer annealing on the reduction and suppression of dislocation in polycrystalline silicon are emphatically described.Finally, the dislocation model, dis-location characterization, and the technologies of dislocation suppression during multicrystalline silicon growth and dislocation density reduction after growth are prospected.