高阻区熔硅单晶的径向少子寿命变化

Radial Variation of Minority Carrier Lifetime in FZ-Si with Higher Resistivity

在氩气气氛及真空环境下生长的高阻区熔硅单晶的径向少子寿命分布情况进行了检测。检测结果表明,在氩气气氛下生长的各种规格的高阻单晶,其少子寿命一般都在1 000μs以上,且径向变化大部分在10%以内,当生长工艺参数改变时,单晶少子寿命的径向分布规律虽然会有所不同,但对少子寿命径向均匀性的影响却几乎可以忽略。而在真空环境、不同工艺参数下生长的单晶,其少子寿命的径向分布及均匀性的变化则十分的明显,还会经常看到中心少子寿命400~500μs、边缘区域少子寿命高于1 000μs的单晶。本文在单晶生长试验的基础上,通过对产生这种现象的原因进行分析,确定了采用适当地降低晶体生长速率、提高加热功率的方法,可以使高阻真空区熔硅单晶中心区域的少子寿命的提高,并使其径向分布变均匀。

The radial distribution of minority carrier lifetime in higher resistivity FZ-Si was investigated,and the tested specimens in this experimentation were grown in vacuum and argon circumstance respectively.The testing results indicate that the minority carrier lifetime of all kinds of single crystals grown in argon circumstance is hardly lower than 1 000 μs,and the radial uniformity of minority carrier lifetime is mostly less than 10%.The radial uniformity of minority carrier lifetime is hardly influenced by the technical parameters changing although the radial distributing of minority carrier lifetime is different for different specimens.On the contrary,for the FZ-Si single crystals grown in vacuum,the radial distribution and uniformity is influenced in evidence by the technical parameters changing.For these specimens,lots of tested results of minority carrier lifetime are 400-500 μs in centers,and beyond 1 000 μs on edges.This phenomenon is analyzed and it＇s confirmed that the minority carrier lifetime in center increased by reducing the crystal growth rate and by increasing the heating power properly.