Comparison of emitter saturation current densities determined by quasi-steady-state photoconductance measurements of effective carrier lifetimes at high and low injections
Methods for the determination of the emitter saturation current density J0e in high and low injection regime and the influence of different models for the Auger recombination on the evaluation are presented and compared. In this study symmetrical test structures with different emitter profiles on highly doped and lowly doped substrates have been investigated. The samples were analyzed by injection-dependent lifetime spectroscopy (IDLS) with the contactless measurement of the photoconductance. For highly injected substrates, the model for the Auger recombination of Kerr et al. can be used for a wider range of excess carrier densities resulting in a more conservative estimation than with the models of Schmidt et al., Glunz et al. and Sinton et al.. With the Auger parameterisation of Kerr et al. at low injections the same observations as in high injection regime have been made. A good agreement was found between the different methods showing that an accurate determination of J0e is possible for both low and high resistivity materials. The results for samples with different diffused phosphorus emitter profiles show that J0e decreases with increasing sheet resistance which is in good agreement with other emitter studies.