This award is made to Northwestern University in support of the collaborative research of Prof. R.P.H. Chang and Prof. Tobin Marks by the Advanced Materials Program in the Chemistry Division, The Solid-State Chemistry Program in the Division of Materials Science and the Physical Foundations of Enabling Technology Program in the Division of Electrical and Communication Systems. The focus of the research will be the growth of metal oxide superconductor/insulator thin film heterostructures using atomic layer epitaxy. Organometallic precursors will be designed and synthesized to provide contiguous self sealing pinhole-free films. Pulsed organometallic beam epitaxy will be used to fabricate cuprate superconducting oxide superlattices on insulator(SIS) or normal metal oxide(SNS) heterostructure junctions. under a variety of experimental conditions. Scanning electron microscopy, scanning tunneling microscopy, atomic force microscopy, ion scattering spectroscopy, x-ray diffraction and Auger spectroscopy will be used to characterize the films and interfaces. Collaborations with several companies to fabricate and characterize junction devices are in place. Multilayer high temperature superconductor-based heterostructure junction devices are of current interest for microwave circuitry. The precise control of superconducting thin film composition, morphology and epitaxy provided by this research will enhance the performance of such devices.