Life Time and Defects

A first few curves showing the relation of the minority carrier life time and point defects
More to come in due time
Shown below is the life time as a function of the doping (or resistivity) for otherwise perfect crystal. This is the ultimate life time achievable - it can only get worse if crystal defects are added.
Life time versus dOping
Gold - an interstitial impurity atom in Si - is known to be a potent "life time killer" like many heavy metals. This is the reason why jewelry, watches, make-up (often containing heavy metals) are absolutely forbidden in clean rooms.
The curve below shows that minute amounts are sufficient to degrade the life time far below the level dictated by doping alone.
Life time with 

With frame With frame as PDF

go to 2.2.3 Life Time and Diffusion Length

go to 2.3.3 Shockley-Read-Hall Recombination

© H. Föll (Semiconductors - Script)