硅熔体中碳化硅熔解与硅晶体中碳化硅生长

摘要

工业生产的太阳能电池用多晶硅锭内部常出现碳化硅夹杂,影响太阳能电池的转换效率,特别是严重威胁硅片的切割生产过程。本文研究了硅熔体中碳化硅熔解与硅晶体中碳化硅沉淀生长特性。在熔解实验中发现：即使在碳显著过饱和的情况下,碳化硅仍会熔解在1450℃的硅熔体中,同时熔体中易形核处发生新的碳化硅颗粒析出。在1350℃下进行了硅料中碳化硅沉淀的固相生长实验,结果表明晶体硅中碳化硅沉淀的高温固态生长十分缓慢。这一特性得到理论计算证实,它表明固相生长不可能是多晶硅锭中出现大颗粒碳化硅的原因。%Silicon carbide precipitates often occur in multi-crystalline solar grade silicon ingots.They are detrimental to both performance and wafering of solar cells.In present paper,the dissolution and growth of silicon carbide precipitates in silicon melt and crystals,respectively,were characterized.In the silicon carbide dissolution experiments,it is found that silicon carbide can dissolve in greatly carbon-supersaturated silicon melt at 1450℃,meanwhile,some new silicon carbide particles precipitate at easy sites of the system.Annealing at 1350℃ for up to 8 hours had not caused observable growth of SiC precipitates.Theoretical calculation confirms this feature.It is suggested that solid-phase growth cannot result in large silicon carbide particles,which appear in multi-crystalline silicon ingots.