Improvement of dielectric properties by inserting oxygen-rich initial layer in Pt/(Ba,Sr)TiO3/Pt structure

Abstract

Ba0.7Sr0.3TiO3 thin films with thicknesses ranging from 330 Angstrom to 2200 Angstrom were deposited on Pt/SiO2/Si substrates by RF-sputtering. To improve the dielectric constant of BST film, we inserted oxygen-rich layer at the initial stage of BST film deposition, the thickness of which was varied to 60 Angstrom. As the thickness of the initial oxygen-rich layer increased, the dielectric constant of 1100 Angstrom -thick BST films increased rapidly. Based on two assumptions, the thickness of the interfacial layer of the BST film without the oxygen-rich layer was estimated to be less than 70 Angstrom and its dielectric constant to be less than 110. And, it was found that the dielectric constant of the interfacial low dielectric layer increased to 415 when 60 Angstrom -thick initial oxygen-rich layer was inserted.