Superconducting Tl-Ba-Ca-Cu-O films by sputtering

Superconducting Tl-Ba-Ca-Cu-O thin films 0.2-1.0 ?m thick have been prepared on MgO(100) and SrTiO3(100) substrates by dc diode sputtering using a single oxide target. Films containing primarily the Tl2Ba2Ca1Cu2O8 phase were obtained with a T c (R=0) at 102 K and a transport J c of 104 A/cm2 at 90 K. For the nearly pure phase Tl2Ba2Ca2Cu3O1 0films, the T c 's (R=0) are higher at 116 K and the transport J c 's at 100 K are of 105 A/cm2. Both types of films show a strong preferred orientation with the c axis perpendicular to the film plane. The rocking curve of the Tl2Ba2Ca2Cu3O1 0films is 0.32° wide and the typical grain size is over 10 ?m.