Fabrication and patterning of Tl-Ca-Ba-Cu-O superconducting thin films on LaAlO3 substrates

This paper reports on high critical transition temperature (high Tc) superconducting thin films of Tl-Ca-Ba-Cu-O (TlCaBaCuO) that were fabricated on LaAlO3 substrates in an rf magnetron sputtering system. As-deposited thin films were sintered and annealed in a thallium rich ambient to obtain superconductivity with a zero resistance critical temperature (Tc) at 103 K. X-ray diffraction (XRD) results showed that the thin films were highly c-axis oriented with both Tl2Ca2Ba2Cu3Ox (2223) and Tl2Ca1Ba2Cu2Ox (2122) phases present. A wet chemical etching process was used for patterning the as-deposited TlCaBaCuO thin films. Linewidths as small as 25 μm were patterned using standard photolithography and wet chemical etching techniques. A ring resonator designed for a center frequency of 30 GHz has been fabricated