Defect states responsible for leakage current in Ta2O5 films on Si due to Si contamination from the substrate

A defect state, defect B, was found in Ta2O5 after postdeposition annealing in O2 by a novel zero-bias thermally stimulated current spectroscopy technique. The activation energy ET was estimated to be about 0.3 eV. Evidence is given that defect B is a hole trap. We believe that defect B is an acceptor level in Ta2O5 due to Si substituting for Ta. The presence of Si contamination in Ta2O5 due to diffusion of Si from the Si substrate into Ta2O5 was confirmed by secondary-ion-mass spectrometry.