Introduction

The minority carrier lifetime is strongly dependent of the injection (excess carrier concentration), which is extensively discussed in the book by REIN [1]. Figure 1 and 2 show several lifetime curves for different symmetry factors or different energy levels of the recombination center.

If nothing about the recombination center is known a priori, injection dependent measurements are not ambiguous and only in correlation with temperature or doping dependent measurement absolute information of the recombination center can be determined. However injection dependent lifetime measurements are very important and necessary to understand lifetime measurement results and make them comparable.

Aim

The aim is to measure injection dependent lifetime curves with a high precision and over a wide range of injection.

Solution

The MDPmap09 enables to measure the lifetime as well as the photoconductivity in a so far not possible wide range of injection. With MDPmap09 these measurements can be very accurately and easily done, since the photoconductivity and the lifetime can be measured with just one measurement. The injection can be varied with a varying laser intensity.
Figure 3 displays a comparison of the typical injection range of different known lifetime measuring methods. Because of its extraordinary sensitivity the MDPmap09 can measure over 7 decades of injection.

Result

With MDPmap09 the whole important injection range can be covered with just one method. Until now it was necessary to use several different methods, which often can not be compared to each other. With MDPmap09 an easy excess to the important injection dependent lifetime curves is now possible.

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