Dependence of the interfacial capacitance on measurement regime used for investigation of thin film ferroelectric capacitors

Thin film parallel-plate capacitor structures with Ba0.5Sr0.5TiO3 as the dielectric layer were fabricated using pulsed-laser deposition. The thickness of the dielectric was varied between 7.5 nm and 1.4 μm. Low-field measurements of the dielectric constant showed the system to possess a nonzero interfacial capacitance. Since there is considerable debate about the origin of interfacial capacitance, further functional analysis was performed: zero-field dielectric susceptibility information was extracted using Landau–Ginzburg–Devonshire fitting of saturated polarization loops. This analysis revealed that the zero-field dielectric susceptibility extracted from P–E loops does not possess a finite interfacial component. The origin of interfacial capacitance therefore disappears (albeit temporarily) after a significant field has been applied and then removed during the P–E loop measurement cycle.