Persistent Photoconductivity in Polycrystalline Cu(In,Ga)Se2 Thin Films: Experiment Versus Theoretical Predictions

The persistent increase of conductivity after illumination in CuInGaSe₂ thin films was investigated as a function of the temperature and light intensity at its creation. Experimentally observed dependences were compared with the results of calculations based on the Lany-Zunger (L-Z) model relating the phenomenon to configurational changes of VSe-VCu divacancy. The calculations showed that the description of all results within this model would require, in some cases, unrealistic values of cross section for electron capture by the center in donor configuration. We concluded that the model does not fully account for the observed phenomena, and that additional mechanisms, in particular to explain the temperature effect, are required.