Models of electrode-dielectric interfaces in ferroelectric thin-film devices

We discuss electrode-dielectric interfaces in ferroelectric thin films and thin films that have high dielectric constants. We consider the charge on the electrodes in several cases, and focus on the effects that arise from this charge being distributed over a finite length (i.e. the Thomas-Fermi screening length). The effects differ for high kappa dielectrics, where a fraction of the applied potential now falls across the electrodes and not the film, and materials with a ferroelectric polarization where the screening of the field in the electrodes sets a scale for the depolarization field. The effects of space charge can be easily incorporated. We also discuss the manner in which high concentrations of oxygen vacancies near the interface arise via a combined grain-boundary and bulk diffusion process, and the effect this charge has on the characteristics of the interface (for example, the Schottky barrier height). [DOI: 10.1143/JJAP.41.6848]