IN-SITU GROWTH OF SUPERCONDUCTING YBA2CU3O7-DELTA THIN-FILMS AT LOW-OXYGEN PARTIAL PRESSURES

In-situ superconducting c-axis oriented YBa2Cu3O7-delta (YBCO) thin fi lms have been grown at T-sub = 775 degrees C on SrTiO3(100) and MgO(10 0) by r.f.-magnetron sputtering at an oxygen partial pressure, which n ot only lies below the st: stability line but is more than an order of magnitude lower than its empirically suggested limit. The effect of v ariation in partial pressure of oxygen (P-O2) on the film characterist ics is analyzed by employing a.c.-magnetic susceptibility, resistance- temperature variation, Rutherford backscattering, atomic force microsc opy (AFM), scanning electron microscspy and X-ray diffraction techniqu es. The oxygen deficiency, delta, is calculated employing a number of techniques. The higher c-axis lattice parameters of the films are supp ortive of antisite disorder in the cations. The AFM investigations hav e established that Stranski-Krastanov-type growth mechanism is operati ve in the present case. The variation in critical current density(J(c) (mag)(T)) with temperature is reported for the first time in the low p ressure sputtered films exhibiting a J(c)(mag)(43 K) of approximate to 4.6 x 10(6) A cm(-2). (C) 1997 Elsevier Science S.A.