LIGHT IMPURITIES IN HTC BISRCACUO SUPERCONDUCTOR FILMS

We have measured the H concentrations in Bi2Sr2Ca2Cu3O10-X films (80 n m thick) on MgO. For the detection of H, 2.5 MeV He elastic recoil det ection (ERD) was employed and the ERD cross section was calibrated wit h VH6. Samples of Bi-2223 films were prepared by the RF sputter deposi tion method and have a critical temperature (T-c) for superconductivit y of 70-90 K. Hydrogen contamination of 40-160 x 10(15)/cm(2) was foun d at the surface. It appears that in the him, the H concentration N-H is nearly constant and the ratio N-H/N-Bi ranges from 0.09 to 0.43, wh ere N-Bi is the Bi concentration. No appreciable H was detected at the interface between the film and MgO substrate. It is found that T-c is higher for lower N-H/N-Bi (C) 1998 Elsevier Science B.V.