YBa2Cu3Ox Crossover Structures Using CeO2 Film as Insulating Layer

We have fabricated YBa2Cu3O x (YBaCuO) crossover structures using CeO2 films as insulating layers, varying the area from 10×50 to 50×50 µm2. The fabrication process of the crossover structure was performed ex situ, by combining the deposition of YBaCuO and CeO2 films with the microfabrication of YBaCuO bridges and contact holes in the CeO2 layer using a liquid-nitrogen-cooled dry etching method. Even though we used ex situ processes, the bottom YBaCuO bridges had a transition temperature T c of 87 K and a critical current density J c of 1.0×105 A/cm2 at 77 K. Typical crossover resistivity was more than 2.0×108 Ω·cm below 80 K even for 50×50 µm2 structures. This indicates that CeO2 is a promising material for insulating layers in high-T c superconducting devices.