Nonswitching laver model for voltage shift phenomena in heteroepitaxial barium titanate thin films

We have introduced a nonswitching layer model to explain voltage shift phenomena of hysteresis loops in a heteroepitaxial barium titanate thin film capacitor. A nonswitching layer. which has irreversible spontaneous polarization, was assumed to be present between the ferroelectric layer and the bottom electrode layer. Calculation based on the model demonstrated that the presence of the nonswitching layer would cause an inherent voltage shift of the hysteresis loop from the origin along the voltage axis. If free charges accumulate at the interface between the ferroelectric layer and the nons itching layer to compensate the discontinuity of the polarization. the hysteresis loop would inversely move toward the opposite direction. A series of experimental results observed for a c-axis oriented barium titanate thin film seemed consistent with the model. It was suggested that the nonswitching layer may be formed in accordance with relaxation of lattice misfit stress in the early stage of the heteroepitaxial growth.