太阳电池用直拉硅单晶中氧沉淀的研究

STUDY ON OXYGEN PRECIPITATION IN THE CZOCHRALSKI SILICON (CZ-Si) FOR SOLAR CELLS

主要通过单步退火与二步退火的方法 ,借助于红外光谱仪、扫描电镜等研究了太阳电池用直拉硅单晶中氧沉淀性质 ,发现太阳电池用直拉硅单晶氧沉淀的过程不同于微电子用直拉硅单晶 ,尽管碳浓度很高 ,经过单步退火处理没有氧沉淀生成。这被认为由于晶体生长速度快等原因 ,太阳能用硅单晶的原生氧沉淀很少 ,氧沉淀缺乏原始核心的缘故。而经过 75 0℃预退火 ,生成氧沉淀核心 ,太阳能用硅单晶中也有大量的氧沉淀产生。研究表明 ,如果太阳电池工艺中硅片仅经 80 0～ 110 0℃的单步热处理 ,太阳能用直拉硅单晶中的氧可能对太阳电池的效率没有影响。

By means of one-step annealing and two-step annealing,the properties of oxygen precipitation in CZ-Si for solar cells(S-CZ Si) were investigated.The results show that the oxygen precipitation in S-CZ Si is different from that in CZ-Si for microelectronics(M-CZ Si).It is found that no oxygen precipitation occurs in S-CZ Si after one-step annealing because of the scarcity of as-grown oxygen precipitates,though the carbon concentration is high.While after two-step annealing,oxygen precipitation occurs because the nuclei of oxygen precipitates have formed during the first-step annealing at 750℃.The study shows that the oxygen in M-CZ Si perhaps has no effect on the efficiency of the solar cells if the silicon is only treated by one-step annealing of 800℃～1100℃.