Carbon depth profiling of superconducting YBCO thin films on nanometer scale

Ion beam analysis techniques have been used to probe for carbon contamination in high temperature superconductor thin films. These techniques provide a powerful tool to detect C with limit of detection close to 0.01 at.% and to measure carbon depth profiles on the nanometer scale with a depth resolution of 10 nm at the surface. In the present study, a series of YBa2Cu3O7−δ (YBCO) films have been formed on MgO substrates by a sol–gel method. Different film thicknesses and heat treatments were studied. Typical formation temperatures were 770–850 °C resulting in thicknesses from 50 to 600 nm. It was found that, depending on the sample preparation conditions, carbon was incorporated in the films at a concentration of 0.5–4.6 at.%. Carbon was homogeneously distributed throughout the films.