Injection dependent measurements

The minority carrier lifetime is strongly dependent on the injection (excess carrier concentration). From the shape and height of the lifetime curve information about the dominant recombination center as well as trapping center can be deduced.

With MDPmap it is possible to measure not only injection dependent lifetime curves but also photoconductivity curves over a very wide range of injection.

 

In the MDPmap and MDPingot up to 4 different lasers can be integrated and hence it is possible to measure not only injection dependent lifetime curves but also photoconductivity curves over a very wide range of injection. Figure 1 displays a comparison of the typical injection range of different known lifetime measuring methods. Because of its extraordinary sensitivity the MDPmap and MDPingot are able to measure over seven decades of injection. Due to bias light and reflection measurements a very good accuracy could be improved profoundly.

Bulklifetime versus injection for a varying symmetry factor and energy level
Fig. 1: Comparison of typical injection ranges of different measuring methods

Fig. 2: injection dependent lifetime measurements on 2 different spots on a SiNx passivated mc-Si wafer

With MDPmap the whole important injection range can be covered with just one method as demonstrated in figure 2 for 2 different spots on a SiNx passivated mc-Si wafer. Until now it was necessary to use several different methods, which often cannot be compared to each other. With MDP an easy excess to the important injection dependent lifetime curves is possible.


For further information please read:

[1] S. Rein, Lifetime Spectroscopy - A Method of Defect Characterization in Silicon for Photovoltaic Applications, Vol. 85 (Springer, Berlin Heidelberg, 2005)