电子辐照对直拉硅单晶电学参数的影响

Effects of Electron Irradiation on Electrical Parameter of Czochralski Silicon

对N型[111]晶向直拉硅样品进行电子辐照,然后在不同温度下进行常规热处理,对比研究了不同辐照剂量的样品少子寿命和电阻率随退火温度的变化。结果表明:直拉硅单晶样品经电子辐照后电阻率增加,少子寿命下降,辐照剂量越高电阻率增加的越多,少子寿命下降越明显。对辐照样品进行不同温度热处理发现热处理温度低于600℃,少子寿命基本处于稳定值,当退火温度达到650℃时,辐照样品的电阻率与少子寿命均恢复至辐照前的初始值,表明在该温度下辐照引入的缺陷基本消除,因此晶体的导电能力逐渐恢复。而经750℃热处理后,辐照样品的少子寿命和电阻率分别出现一个低谷,辐照剂量越高电阻率和少子寿命值在该温度下下降幅度越大,而且随着热处理时间的延长,辐照样品电阻率不断下降,通过间隙氧含量的测量也初步证明电阻率的下降与间隙氧原子的偏聚有关,该温度下电阻率的下降与辐照相关联。

The N-type [ 111 ] crystal electron irradiated Czochralski silicon （CZ-Si） samples were subjected to a thermal process at different temperatures. The variations of resistivity and minority-carrier lifetime with annealing times and irradiation doses were investi- gated. It was found that resistivity increased and minority-carrier lifetime decreased in electron-irradiated Czochralski silicon （Cz-Si）. The higher the irradiation dose were, the more the resistivity increased and minority-cartier lifetime decreased. The minority-carrier li- fetimes were in stable values below 600 ℃ annealing. The resistivity and minority-carrier lifetime recovered to values before electron ir- radiation at the annealing temperature of 650 ℃,which showed that defects were eliminated at this temperature as well as conductivity was recovered. The results showed that minority-carrier lifetime reached a low point annealing at 750 ℃ when the value of resistivity was lower than the real one. The resistivity decreased as a function of annealing time at 750 ℃ and it came down with the irradiation fluences. It was possible that irradiation defects were related to interstitial oxygen segregation.