High Performance Complex Oxide Thin Film Materials to Enable Switchable Film Bulk Acoustic Resonators (FBAR) for Low-Loss Radio Frequency Devices

The proposed project focuses on a new technology that has a built-in switch to turn the filter on and off, and thus is functionally equivalent to a high-selectivity filter and a low-loss switch, where the switch draws no DC power. Agile calls this new invention the Switchable Trimmable Acoustic Resonator (STAR). An array of such filters could implement a very compact and reconfigurable high-selectivity filter bank. Similar, BST-based STAR filters could be combined to make a low-loss and high-selectivity duplexer or TR switch. There are many other possibilities for frequency-agile components including filters with selectable and flexible bandwidths. Thus the proposed technology will have a profound impact on the front-end filtering problem in modern communications. This project will investigate the full potential and limits of this technology, and result in the first demonstration of voltage-controlled or tunable STAR devices. The technology is enabled by perovskite oxides, specifically BST and SrTiO3. The quality of the devices is highly sensitive to film quality and orientation. As is well-established in semiconductor devices, molecular beam epitaxy (MBE) offers the highest quality thin film materials and excellent control over film orientation and MBE-grown BST films will be a major focus of this program.