A charge-based deep level transient spectroscopy measurement system and characterization of a ZnO-based varistor and a Fe-doped SrTiO₃ dielectric

A charge-based deep level transient spectroscopy (Q-DLTS) method is applied to provide insights into the electronic behavior near grain boundaries and may provide new insights into mechanisms such as fatigue, degradation, dielectric aging, and dielectric breakdown. Here, we tested the Q-DLTS in both a ZnO varistor material and Fe-doped SrTiO₃ materials. Comparisons are made to other data on ZnO varistors, and we obtain very good agreement for the energy levels. The status of deep traps in Fe-doped SrTiO₃ dielectrics has been investigated where the relaxation was contrasted in a single crystal and polycrystalline ceramic materials. The relaxation is only observable in the polycrystalline materials, and was absent in single crystal Fe-doped crystals indicating that the deep traps originating from the Schottky barriers at the grain boundaries provide the DLTS signals. The energy associated with this grain boundary trap was found to be 1.26 eV.