Broad range injection-dependent minority carrier lifetime from photoluminescence

Broad range injection-dependent carrier lifetime measurements in crystalline silicon are most relevant for both defect level spectroscopy, and for the investigation of recombination properties of novel solar cell technologies. The approach presented in this paper combines a determination of the effective carrier lifetime via time-dependent (quasi-steady-state) photoluminescence with a steady-state photoluminescence lifetime scan over a broad range of excess carrier densities. Thereby, the power of a virtually artifact-free time-domain approach is combined with the high sensitivity of steady-state photoluminescence at extremely low injection conditions. Time-dependent fluctuations of dark photocurrent measurements are identified as the essential source of uncertainty under such low injection. A measurement design which eliminates this source of uncertainty is presented and tested. Lifetime measurements at excess carrier densities as low as 108 cm−3 are shown in detail.