施主型杂质对单晶硅中少子衰减过程的影响

Influence of the Donor Impurity on the Decay Process of Minority Carriers in Monocrystalline Silicon

单晶硅材料内少子的衰减过程可以反映出其内部杂质和缺陷的信息。针对施主型杂质是单晶硅内多数杂质呈现的基本形态,首先在小注入条件下分析了p型单晶硅内少子衰减的基本机制,然后根据施主型杂质密度、俘获截面和能级距导带底之间距离等参数的不同,重点讨论了存在施主型电子陷阱和复合中心时,太阳电池用p型单晶硅内少子衰减的基本规律。研究表明:存在施主型电子陷阱或复合中心时,p型单晶硅的少子衰减过程具有恒定的少子寿命,且杂质的密度N_T和俘获截面σ_n之积(N_T×σ_n)存在最小的影响阈值,N_T×σ_n值大于阈值的杂质和缺陷对少子衰减过程才具有重要的影响。

The decay process of minority carriers can reflect the information of defects and impurities in crystalline silicon materials. Because most of impurities in crystalline silicon take on a form of donor impurities,the basic mechanisms for the decay process of minority carriers in p type crystalline silicon was discussed under the low injection condition. And then based on the different parameters of donor electron traps and recombination centers,i. e. impurity density,the capture cross section and the energy difference between the impurity band and the bottom of conduction band, the rules for the decay process of minority carriers in the p type crystalline silicon used in solar cell were discussed in detail.The results show that with donor electron traps and recombination centers,the decay process of minority carriers in p type crystalline silicon has a constant lifetime of minority carriers. The product（ N_T× σ_n）of impurity density（ N_T） and cross section（ σ_n） have a minimum threshold value and only if larger than the threshold value,defects or impurities can have an important influence on the decay process of minority carrier.