摘要
以太阳电池级直拉单晶硅片为材料,利用瞬态微波反射光电导衰减仪研究了硅片分别经过单、双面扩散后Fe-B对与少子寿命τ、陷阱浓度及制备成电池的内量子效率(IQE)的相关性.对于单面扩散后的样品,Fe-B对浓度分布在较大程度上决定了少子寿命分布;对于双面扩散后的样品,Fe-B对浓度显著降低(在1.35×1011cm-3左右),已不及其他杂质和缺陷对少子寿命的影响.结合瞬态微波衰减信号和陷阱模型,对单、双面吸杂前后硅片的陷阱浓度进行数值计算,发现经过扩散吸杂后硅片的陷阱浓度显著减少.对经过单面扩散后的硅片进行取点分析,发现Fe-B对浓度与陷阱浓度的相关性较差,即Fe-B对不是影响陷阱浓度变化的主要因素.将分别经过单面和双面扩散的硅片制备成太阳电池,利用光生诱导电流测量了电池的IQE.分析发现,经过双面扩散制备的电池的IQE比经过单面扩散制备的电池的IQE高,且IQE分布较单面扩散制备的电池更均匀,说明Fe-B对的浓度分布显著影响IQE的分布.
Solar-grade p-type Czochralski silicon wafers are doped with phosphorus by single-face and double-face diffusions, and the influence of Fe-B pairs on the minority carrier lifetime,the trapping centers density and the internal quantum efficiency （IQE） of cells （fabricated from the wafers） is analyzed by measuring microwave-detected photo-conductance decay minority carrier lifetime. In the doped wafers with single-face diffusion,the minority carrier lifetime is determined mainly by the density distribution of Fe-B pairs. However,in the doped wafers with double-face diffusion,the minority carrier lifetime is less influenced by the concentration distribution of Fe-B pairs than by other impurities and defects. Numerical calculation based on the combination of the transient voltage signal and the trapping model indicates that the density of trapping centers is reduced by either of diffusion process. On the other hand,detailed analysis of selected specific spots in one wafer with single-face diffusion shows that Fe-B pairs are not the major factor influencing the density of trapping centers. The wafers with different diffusion processes are fabricated into c-Si solar cells and the IQE is measured by using a light beam induced current. The results show that the IQEs of cells with double-face diffusion are higher than those with single-face diffusion,which demonstrates the negative effect of Fe-B pairs on the IQE of solar cells.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2010年第6期4322-4329,共8页
Acta Physica Sinica
基金
国家自然科学基金(批准号:60876045)
上海市重点学科建设基金(批准号:S30105)
上海市科学技术委员会基础研究重点项目(批准号:09JC1405900)
上海大学研究生创新基金(批准号:SHUCX091012)资助的课题~~
关键词
少子寿命
陷阱浓度
内量子效率
Fe-B对
minority carrier lifetime
trapping density
internal quantum efficiency
Fe-B pairs
