| Résumé: | The in situ process-laser ablation in combination with thermal evaporation of Tl2O-has turned out to be a preparation method for single-phase and epitaxial TlBa2Ca2Cu3O9 (1223) thin films with T-c values up to 109 K. It was found by several groups that a partial substitution of T1 by Bi simplifies the phase development of the 1223 compound in the usual two-step process. We have investigated the influence of the Bi doping on the in situ growth. Xray measurements show that the films consisted mainly of the 1223 compound. In 300-nm thin films there was no evidence of a Bi amount in the crystal structure, but thinner films (80 nm) show a small amount of Bi. We concluded that Bi doping supports the phase develop ment of the 1223 compound only in an early stage of the film growth. The Bi-doped films have higher T-c values up to 114 K, higher j(c) values up to 6 x 10(5) A/cm(2) (77 K, 0 T), and lower surface resistances of 56 m Omega (77 K, 87 GHz) than the undoped films.
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