Studies on strontium titanate/barium zirconate superlattices

Artificial superlattices of SrTiO3 and BaZrO3 were grown epitaxially with different periodicities on SrRuO3 coated (001) SrTiO3 substrates by pulsed excimer laser ablation. Superlattices were structurally characterized by X-Ray θ–2θθ–2θ diffraction data. Electrical characterization was done in metal–insulation–metal configuration. Capacitance–voltage measurements showed limited amount of tunability. The DC field induced tunability has been observed to be sensitive to the periodicity of the superlattices, hence the effective strain present in the layers. Hysteretic behaviour in capacitance–voltage (C–VC–V) and polarization versus electric field (P–EP–E) results from the superlattices also indicate the sensitivity of the interfaces. Interfacial strain is supposed to be the most probable cause for such a behaviour which is also manifested in the variation of dielectric constant with individual layer thicknesses.