DX centers and persistent photoconductivity in CdTe-In films

In this work, we study the nature and behavior of the persistent photocondu ctivity (PPC) in CdTe-In films grown by cosputtering of CdTe-In-Cd targets, It was found that only when Ln atoms are substantially incorporated into C dTe films, the persistent photoconductivity is observed with a quenching te mperature of about 270 K, We have also investigated the trapping centers in the CdTe films by using the thermally stimulated conductivity technique. T wo localized deep levels were determined. One of them, with an activation e nergy of 0.42 eV, has been ascribed as a direct evidence of DX centers that are formed by Cd vacancies and In donors complexes, By formulating the PPC build-up and decay kinetics, we have associated the PPC effect in our film s to the photoionization of this deep level (DX like centers). Up to date, the existence of DX centers in CdTe-In polycrystalline films have not been previously reported. (C) 2000 Elsevier Science Ltd, All rights reserved.