Ferrite/TBa2Cu3O7-x Thin Film Structure by Metalorganic Chemical Vapor Deposition for Low Loss Microwave Devices

Microstrip-geometry phase shifters have had limited use at microwave frequencies because of high insertion loss resulting from resistance in the metal conductors. With the use of YBCO meanderline circuits in a glue contact with a magnetized ferrite substrate nonreciprocal differential phase shift in excess of 1000 degree/dB has recently been demonstrated by a group at MIT Lincoln Labs. Such a contact method is unacceptable for production quality control and for survival in a deployed environment. Based on our extensive experiences in growth of high-quality YBCO thin films and recent successes with thick nickel ferrite film growth, NZAT propose to demonstrate the feasibility of MOCVD processing for fabrication of ferrite/YBCO thin film structure phase shifters. Development of an effective buffer layer between ferrite and superconducting layer will be part of the effort to realize this multilayer device. It is projected that optimization of the meander line ferrite phase shifter could result in figure-of-merit values that approach 10000 degree/dB, which is more than an order of magnitude higher than those produced by a waveguide ferrite phase shifter. Production of the superconducting phase shifter by a cost effective process satisfies the phased array need for low cost, low weight, small size and low power consumption. Such a capability would be useful for the integration of ferrites with semiconductors in a planar technology mnd for the fabrication of other technically important complex oxides.