In situ growth of epitaxial TlBa2CaCu2O7 thin films

Epitaxial TlBa2CaCu2O7 thin films have been grown on single‐crystal LaAlO3 and NdGaO3 substrates by in situ off‐axis magnetron sputtering in the presence of Tl2O vapor. X‐ray diffraction shows that the films are highly epitaxial with the c axis perpendicular to the substrate surface and [100] TlBa2CaCu2O7 aligned with pseudo‐cubic [100] NdGaO3 and LaAlO3. The full width at half maximum of the rocking curve for the best films is 0.2°. X‐ray diffraction finite size effects show that the film surface is smooth to within several unit cells (∼40 A). The films are superconducting as deposited with a Tc (onset) of about 80 K and a Tc (R=0) of about 8 K. In situ oxygen treatment of the films at 675 °C has produced films with a Tc(R=0) as high as 40 K. Ex situ annealing in O2 and Tl2O vapor at 800 °C has produced films with a Tc(R=0) as high as 97 K while still retaining a very smooth surface.

[1]  W. L. Holstein,et al.  Tl2Ba2CaCu2O8 films with very low microwave surface resistance up to 95 K , 1992 .

[2]  E. V. Pechen,et al.  In situ preparation of high‐Tc TlBaCaCuO thin films by a combination of laser ablation and thermal evaporation , 1992 .

[3]  Ivan K. Schuller,et al.  High Tc thin films with roughness smaller than one unit cell , 1992 .

[4]  J. Preston,et al.  Growth of (Pb0.75Cu0.25)Sr2(Y1−yCay)Cu2O7 thin films by laser ablation , 1991 .

[5]  A. Kortan,et al.  Processing of a TlBa2Ca2Cu3Oy superconducting film by liquid‐gas solidification , 1991 .

[6]  T. Marks,et al.  Phase‐selective route to high Tc superconducting Tl2Ba2Can−1CunO2n+4 films: Combined metalorganic chemical vapor deposition using an improved barium precursor and stoichiometry‐controlled thallium vapor diffusion , 1991 .

[7]  David S. Ginley,et al.  Morphology control and high critical currents in superconducting thin films in the Tl-Ca-Ba-Cu-O system , 1989 .

[8]  A W Sleight,et al.  Bulk Superconductivity up to 122 K in the Tl-Pb-Sr-Ca-Cu-O System , 1988, Science.

[9]  T. C. Huang,et al.  Superconducting Tl‐Ca‐Ba‐Cu‐O thin films with zero resistance at temperatures of up to 120 K , 1988 .

[10]  A. Hermann,et al.  Superconductivity in the rare-earth-free Tl–Ba–Cu–O system above liquid-nitrogen temperature , 1988, Nature.

[11]  H. Adachi,et al.  In Situ Preparation of Pb-Based Superconducting Thin Films at Low Temperature and Low Oxidizing Atmosphere , 1991 .