Intensity effects in monitoring carrier lifetime measurements

The use of III-V compounds such as GaAs and AlGaAs in advanced solar cells has led to extensive use of transient photoluminescence technique to measure minority carrier lifetimes in these materials. A study of an intensity dependence of the observed carrier lifetime in AlGaAs samples in the low-intensity regime is described. It is shown that light intensities typically used for these measurements result in an effective lifetime that is a linear combination of the minority and majority carrier values. It is further shown that a series of measurements over a range of light intensities can be analyzed to yield the minority and majority carrier lifetimes and the equilibrium carrier concentration in the sample