Quantitative analysis of the persistent photoconductivity effect in Cu(In,Ga)Se2

The magnitude of the persistent photoconductivity effect (PPC) in two sets of Cu(In,Ga)Se2 samples, differing in the amount of cadmium and sodium, was measured. Using equations describing the magnitude of PPC, metastable defect and shallow acceptor densities were calculated. The method of the analysis of PPC in the presence of a deep acceptor level was presented. Based on obtained results, we drew conclusions about reasons of decreased PPC in Cu(In,Ga)Se2 without sodium as well as the role of (VSe-VCu) complexes in establishing the carrier concentration in Cu(In,Ga)Se2 with and without sodium.