Emitter saturation current densities determined by self-consistent calibration: Impact of laterally non-uniform lifetime distribution on calibration accuracy

The impact of laterally non-uniform carrier lifetime on the determination of the emitter saturation current(J_oe) from photoconductance-based measurements, based on the self-consistent method proposed by Trupke and Bardos, is investigated using a model assuming two adjacent regions with considerably difference J_oe. It is shown that the method can result in an underestimation of the mean J_oe if the distribution of the J _oe across the sensed area is not uniform. From simulation it is verified that the error can be eliminated through independent measurement of the sample optical properties. The self-consistent calibration mechanism is also studied by the model. Experimental measurements confirm the model predictions.