Measurement of trap level near the electrode and dielectric thin film boundary by TSC and TL

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Fatigue and leak current of lead titanate and barium strontium titanate films for randam access memory devices were caused by metal ion defects, oxygen vacancy and trapped charge carriers. Objectives of these studies are clarified the relations these defects in the film and TSC peaks related to phase transitions and dielectric relaxation.Polarized barium strontium titanates released electric charges with phase transition from ferroelectric to ferrielectric phase. At phase transition temperature, another new TSC peak was observed except peaks related to phase transition. It was clarified that new peak was generated by relaxing trapped charges in the film.Furthermore, effect of heat treatment for lead titanate films, having relatively low resistivity and leaky property, was studied. Maximum polarization (Pm) of film was lowered and resistivity was increased from 1.2X10ィイD1-8ィエD1 to 3.0X10ィイD1-8ィエD1Ωcm slightly. P-E curves of film were asymmetry with applied electric field. TSC peaks were observed at 74 and 130℃, trap level is 0.45 and 0.52eV respectively for heated films. Otherwise no peak was observed for heated film. It seemed that TSC peaks highly depended on relaxation of electric charge. Leak current properties of films were improved by heating for decreasing the electric charge.