Role of cadmium-related defects on the structural and electrical properties of nanocrystalline CdTe:TiO2 sputtered films

CdTe:TiO2 nanocrystalline films with varying volume fraction of CdTe were prepared by rf magnetron sputtering from a composite TiO2:CdTe target. The structural and electrical properties of the films were analyzed as a function of their Cd concentration. It was found that thermally treated films were Cd-rich and were stress free and had lower resistivity values. Field dependent current measurements showed that nanocrystalline films upon thermal treatment in the range 250–300 °C exhibit an unusual current peak under certain conditions of field and temperature. The current peak was associated with the presence of Cd-related defects in the CdTe lattice. The threshold temperature for the formation of Cd-related defects shifted to lower values for Cd-deficient films.