THERMALLY STIMULATED CURRENTS IN CDTE POLYCRYSTALLINE FILMS

Investigations of trapping centers have been carried out in CdTe polyc rystalline films by using the thermally stimulated conductivity (TSC) technique. The measurements were performed in the temperature range fr om 80 to 300 K. The TSC spectra showed three peaks related to three tr apping levels with energy activations of 0.18, 0.29, and 0.32 eV, resp ectively, The two first trapping levels correspond to known acceptor c enters in bulk CdTe previously reported. It is suggested that the leve l at 0.32 eV is due to grain boundary defects characteristic of the po lycrystalline films. The main parameters of these trapping centers hav e been determined by using known theoretical relations. The temperatur e dependence of the dark resistivity indicates that the impurity condu ction does not make an important contribution to the TSC spectra of th e films. From these measurements an activation energy of 0.49 eV for t he conductivity of the films was found. (C) 1995 American Institute of Physics.