Deposition and patterning of Tl-Ca-Ba-Cu-O superconducting thin films

This paper reports on high temperature superconducting Tl-Ca-Ba-Cu-O which were sputter deposited from a single composite powder target on SrTiO3 and LaAlO3 substrates, in an rf magnetron sputtering system. The as-deposited thin films were sintered and annealed in an excess Tl partial pressure to obtain superconductivity. The superconducting films were characterized by scanning electron microscope (SEM), x-ray diffraction (XRD) and resistance vs temperature (R vs T) measurements. Fine line features as small as 25 μm were obtained in as-deposited thin films using standard photolithography and wet chemical etching in a weak acid. From the XRD and SEM results, the annealed thin films were found to be highly c-axis oriented, with smooth platelets of 2-10 μm in size. The R vs T measurements showed zero resistance at temperatures as high as 107 K on SrTiO3 and 103 K on LaAlO3