PERSISTENT PHOTOCONDUCTIVITY AND DX CENTERS

Persistent photoconductivity is commonly attributed to the existence of DX centers within the semiconductor layer under investigation. Based on this assumption, we develop a model that clearly predicts a linear-increase regime for the dependence of the sheet density of the persisting carriers upon cumulative photon dose, before saturation. The discrepancy between this expected linearity and the experimental findings of several authors, as well as those deriving from the wide variety of our samples, renders implausible the speculation that DX centers are an inevitable prerequisite for the observation of the persistent-photoconductivity effect and renews consideration of the possible validity of an alternative model of macroscopic potential barriers inducing the persistent photoconductivity.