Unpatterned Ferroelectric Thin Film Measurements for Optimization of Perovskite Oxide Thin Film Based Microwave Devices

摘要

The Army's Future Force (FF) antennas require increased bandwidth for multimission communications; increased antenna gain for robust communications and range extension; increased mobility for high data rate on-the-move (OTM) communications; and undetectable antenna visual signatures for low probably of mission detection and increased tunbility. Electronic scanning antennas (ESA's) are the key components for such advanced communication systems. ESA's provide rapid scanning capability, which enables modes such as multiple target tracking, track while scan, and sensor fusion operation. One of the major challenges, which must be overcome before such advanced ESA systems can be realized, is the development of affordable, low loss, high tunability, low power, lightweight, and high performance microwave frequency phase shifters. The enabling technology for such phase shifters is centered, on the development of single-phase nanometer-scale constituent perovskite oxide thin films with enhanced dielectric, insulating, and microstructural properties. The Army Research Laboratory (ARE) has successfully designed, fabricated, characterized, and optimized, novel pure and acceptor doped Ba_(0.6)Sr_(0.4)TiO_3 (BST) based thin films on MgO substrates with excellent microwave material properties. Pure and 1-mol percent Mg doped BST thin films were fabricated by the metalorganic solution deposition (MOSD) technique and the film's dielectric properties were characterized at microwave frequency via a tuned coupled-split dielectric resonator technique developed at NIST. Using this measurement technique, for first time ever, has allowed the true "singular" dielectric loss (tan S) and permittivity (epsilon_r) of the BST-based films to be assessed and optimized without the influence of device design (radiative losses) and electrode metallization (conductor losses).