Structural and dielectric studies of Co doped MgTiO3 thin films fabricated by RF magnetron sputtering

Abstract

We report the structural, dielectric and leakage current properties of Co doped MgTiO3 thin films deposited on platinized silicon (Pt/TiO2/SiO2/Si) substrates by RF magnetron sputtering. The role of oxygen mixing percentage (OMP) on the growth, morphology, electrical and dielectric properties of the thin films has been investigated. A preferred orientation of grains along (110) direction has been observed with increasing the OMP. Such evolution of the textured growth is explained on the basis of the orientation factor analysis followed the Lotgering model. (Mg1-xCox)TiO3 (x = 0.05) thin films exhibits a maximum relative dielectric permittivity of ɛr = 12.20 and low loss (tan δ ∼ 1.2 × 10−3) over a wide range of frequencies for 75% OMP. The role of electric field frequency (f) and OMP on the ac-conductivity of (Mg0.95Co0.05)TiO3 have been studied. A progressive increase in the activation energy (Ea) and relative permittivity ɛr values have been noticed up to 75% of OMP, beyond which the properties starts deteriorate. The I-V characteristics reveals that the leakage current density decreases from 9.93 × 10−9 to 1.14 × 10−9 A/cm2 for OMP 0% to 75%, respectively for an electric field strength of 250 kV/cm. Our experimental results reveal up to that OMP ≥ 50% the leakage current mechanism is driven by the ohmic conduction, below which it is dominated by the schottky emission.