Influence of buffer layers within YBa/sub 2/Cu/sub 3/O/sub 7-x/ coplanar waveguide structure

A YBa/sub 2/Cu/sub 3/O/sub 7-x/ coplanar waveguide structure is investigated theoretically via a partial wave synthesis. The high-T/sub c/ superconductor material is described by the two-fluid model and the London theory. A very thin buffer layer of about 100 nm thickness is positioned between the substrate and the superconducting film. The material combinations considered for buffer layer/substrate are: zirconium oxide/sapphire, strontium titanate/sapphire, zirconium oxide/silicon, and lanthanum aluminate/silicon. The influence of these buffer layers on effective permittivity and attenuation is examined over a wide range of structure widths whereby the attenuation is subdivided into superconductor losses, losses in the buffer layer, and substrate losses.<
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