Ion-beam direct-structuring of high-temperature superconductors

Abstract

A novel method allows for a direct modification of the electric properties of high-temperature superconductors (HTS) and for patterning of devices into thin films of HTS. A low-divergence beam of light ions is directed at a thin film of HTS through a mask placed at some distance from the surface of the material. It converts the illuminated areas of the film from superconducting to semiconducting and even insulating in a single process. Computer simulations of the ion-target interactions and experimental investigations on 100-nm thick films of YBa 2Cu 3O 7 by X-ray diffraction, electrical resistivity and Hall effect measurements after cumulative irradiation are reported. A central result is that 75 keV He + ions can penetrate through thin films of HTS without implantation effects, create point defects without destruction of the main building blocks of the crystal structure and convert a HTS to an insulating material with technically feasible ion doses of a few 10 15 cm −2.