Effect of MgO Dopant on the Microstructure and Dielectric Properties of rf-Sputtered Ba0.5Sr0.5TiO3 Thin Films

Abstract

MgO-doped (BST) thin films were synthesized by radio-frequency (rf) magnetron sputtering at substrate temperature using single-phase targets with different MgO contents ranging from . Microstructure, surface morphology, dielectric constant, and leakage current of the MgO-doped BST films were characterized to understand the influence of the MgO dopant on film properties. Polycrystalline and single-phase solid solution films with a dense microstructure were obtained in all deposition conditions. The electrical and dielectric properties of the BST-containing capacitors are both found to be improved significantly by doping MgO in the BST films. The leakage current density of the MgO-doped BST capacitors is nearly two orders of magnitude lower and the dielectric constant is about 45% times higher than that of the undoped BST capacitors. It is speculated that the increase in the dielectric constant is due to the formation of electric dipole complex resulting in an increase in the residual stress, whereas the improvement in the leakage properties is attributed to the oxygen vacancies by MgO doping, resulting in a reduced electron concentration in the materials.