Switchable high overtone resonances in BST film with MIM structure on sapphire substrate

Abstract

DC bias field dependent high overtone resonances are observed in a metal insulator metal (MIM) structure based on Ba0.5Sr0.5TiO3 (BST) thin films on a sapphire substrate. The microwave measurement shows the bias dependent nature of the device, wherein without any bias it acts like a MIM capacitor but upon biasing resonant peaks start appearing in its frequency spectra, which is typical of a response given by a high overtone bulk acoustic wave resonator (HBAR). Acoustic velocity of the sapphire substrate is calculated to be 11440 m/s and the HBAR exhibits a high quality factor of 4370 around 1.39 GHz.