Comparison of Y-Ba-Cu-O Films Irradiated With Helium and Neon Ions for the Fabricationof Josephson Devices

We have irradiated high-quality YBa 2 Cu 3 O 7-δ thin films with 90-keV helium and 175-keV neon ions to compare how ions of different mass affect electrical transport and reduce superconducting transition temperature. We measure the temperature dependence of the resistivity for films irradiated with different fluence and compare the results with Monte Carlo ion implantation simulations. We observe a smaller increase in resistivity for films irradiated with neon than those irradiated with helium for an equivalent reduction in transition temperature. We attribute this observation to nonuniform damage throughout the thickness of the film when irradiated with neon, as opposed to a more uniform damage profile in the case of helium irradiation.