SUPERCONDUCTIVITY AND STRUCTURE OF ION IRRADIATED LASRCUO THIN-FILMS

Superconducting LaSrCuO thin films yielding zero resistance values above 20 K have been deposited by sputtering from single compound targets. The films have been irradiated at low temperature (5 K, 77 K) with 300 keV protons and He+ ions. The irradiation induced Tc-depression are strongly dependent on the initial material quality and for best films comparable to results obtained for YBaCuO films. Appreciable annealing effects of Tc and resistivity in the films are observed above 110 K up to room temperature indicating oxygen displacements as a major defect structure influencing Tc X-ray diffraction measurements revealed a lattice expansion coinciding with the main Tc depression range. The total destruction of superconductivity is accompanied by a metal to semiconductor transition. At high damage levels (>0.1 dpa) the resistivity of the films increases strongly due to amorphization of the structure. © 1990.