Investigation of dielectric and electric behavior of MgTiO3 and Ba0.5Sr0.5TiO3 bilayer films by RF sputtering method

Abstract

The structural, microstructural, electrical, and dielectric properties of MgTiO3 (MTO)/ Ba0.5Sr0.5TiO3 (BST) bi-layer structures grown by reactive RF magnetron sputtering have been reported. The films exhibited polycrystalline nature and the stacking of BST on MTO (BST/MTO) exhibited better crystallinity than that of MTO stacking on BST(MTO/BST). The RMS roughness for BST/MTO and MTO/BST is found to be 1.82 nm and 49.2 nm, respectively. The dielectric constant (εr, ∼27.3) and loss tangent (tanδ, ∼10−2) at 100 kHz for BST/MTO are found to be intermediate to BST and MTO monolayer responses. The anomaly observed in dielectric response (εr, ∼323.2 and tanδ, ∼10−2) for MTO/BST can be attributed to the generation of charge carriers in the interfaces of individual layers. The relation between electrically active regions with the observed electrical response is studied by impedance spectroscopy. The leakage in MTO/BST (10−2 A/cm2 at 100 kV/cm) bilayer is higher than that of BST/MTO (10−4A/cm2 at 100 kV/cm) bilayer and Schottky emission along with Space-charge limited current contribute to the leakage current. Both MTO/BST and BST/MTO films exhibited tunable dielectric responses. These findings of this report provide prospective insight into the design of multilayer structured smart materials.11MTO and BST bilayer films