In situ growth and properties of epitaxial TlBa/sub 2/CaCu/sub 2/O/sub 7/ and TlBa/sub 2/(Ca/sub 1-x/Y/sub x/)Cu/sub 2/O/sub 7/ thin films

Epitaxial TlBa/sub 2/CaCu/sub 2/O/sub 7/ thin films have been grown on single-crystal LaAlO/sub 3/, NdGaO/sub 3/, and CeO/sub 2/ buffered sapphire substrates by in situ off-axis magnetron sputtering in the presence of Tl/sub 2/O vapor. Phase formation in this system has been investigated for substrate temperatures from 490 degrees C to 600 degrees C and deposition pressures from 50 mTorr to 300 mTorr. The effect of Tl/sub 2/O evaporation rate has also been studied. X-ray diffraction shows that films deposited under optimum conditions are highly epitaxial with the c-axis perpendicular to the substrate surface and