Ag-doped YBa2Cu3O7-x Thin Films for Improved Power Handling and Better Intermodulation Products in Microwave Devices

In response to the Air Force SBIR solicitation AF96-159, "High Temperature Superconducting Thin Films" for developing advanced thin film processes to enable fabrication of HTS devices for electronic, microwave and opto-electronic applications, Conductus, Inc. is please to propose the following program. This proposal seeks funding to support development of material alternatives to YBa2Cu3O7-x (YBCO) which may have more favorable properties for high temperature superconducting microwave devices, namely--lower loss, higher power handling, and lower intermodulation products. To achieve these improvements it is necessary to improve both the intragranular and intergranular properties of YBCO. We will investigate Ag doped YBa2Cu3O7-x to address improvements in intergranular properties. Research of others has indicated that the grain-to-grain coupling is improved by the presence of Ag at the grain boundaries. A process for the thin film growth of this material will be developed using pulsed laser ablation and various material characterization techniques. The microwave properties (Rs, , power handling) of promising Ag-doped YBCO films will be characterized using dielectric cavity and microstrip resonator techniques. To characterize the intermodulation characteristics of Ag-doped YBCO, an eight-pole bandpass filter in the 900 Mhz cellular communications band will be fabricated from a double-sided Ag-doped YBCO film on a 2" substrate. The performance of this device will be compared to a similar device made from undoped YBCO. If Ag-doped YBCO shows improved performance, it will be immediately integrated into our production of films for our wireless product group.