Dielectric properties of Ba0.5Sr0.5TiO3/SiN bilayered thin films grown on Pt-coated sapphire substrates

The Ba0.5Sr0.5TiO3(BST)/SiN bilayered thin films with a SiN layer serving as a buffer layer between the top electrode and the BST layer have been prepared onto Pt-coated c-plane sapphire substrates. The dielectric measurements show that the loss tangent has been significantly lowered. The dielectric properties of the BST/SiN bilayered thin films are strongly dependent on the SiN thickness. The BST/SiN bilayered thin films at a SiN/BST thickness ratio of 0.2 give the largest figure of merit of 50.1. The thickness effect was discussed as well with a series connection model of multilayered capacitors, and the favorable simulation was obtained.