铸造单晶硅性能和应用分析

PROPERTIES AND APPLICATION ANALYSIS OF CASTING MONOCRYSTALLINE SILICON

以G6型多晶硅定向凝固铸锭炉生长的铸造单晶硅为研究对象,对其性能特点及应用进行分析。铸造单晶硅中含有位错、亚晶粒、多晶晶粒、间隙态元素和硬质点等缺陷。在铸造单晶硅制备过程中,因长晶界面不平及杂质存在的原因,硅锭生长时存在较大的应力,致使硅原子排列出现错排,从而导致位错、亚晶粒和多晶晶粒的产生,其中多晶晶粒的晶向主要有(331)等;在硅锭的中上部易产生位错,并随着晶体生长大量增殖。铸造单晶硅中的间隙态元素Fe和O的分布规律和铸造多晶硅相似;硬质点的主要成分是氮化硅和碳化硅。缺陷密度较低的铸造单晶片制作成钝化发射极背面接触(PERC)太阳电池,其光电转换效率达21.7%,较直拉单晶硅PERC太阳电池低0.4%。

The performance characteristics and application of casting monocrystalline silicon produced by G6 type polysilicon directional solidification furnace were analyzed.The results show that the casting monocrystalline silicon contains dislocations,subgrains,polycrystalline grains,interstitial elements and hard points.During the production process of casting monocrystalline silicon,the dislocation,sub-grains and polycrystalline grains were generated by the misalignment of the silicon atoms which caused by the large stress from the uneven crystal growth interface and impurities,the main orientation of these polycrystalline grains was(331)etc,and the dislocation was easy to form in the middle and upper part of silicon ingots and proliferate with the crystal growth of the crystal.The distribution of interstitial elements Fe and O in casting monocrystalline silicon was similar to that of cast polysilicon.The main components of the hard points were silicon nitride and silicon carbide.At last,the conversion efficiency of PERC cell produced by casting monocrystalline silicon wafer with low defect density was 21.7%,0.4%lower than that of the czochralski silicon which under the same cell process.