DOPING SILVER INTO YBA2CU3O7-DELTA FILMS BY 800 KEV AG-TEMPERATURE AND ELEVATED-TEMPERATURES( IMPLANTATION AT ROOM)

Thin films (similar to 0.43 and similar to 0.95 mu m thick) of YBa2Cu3 O7-delta on (100) LaAlO3 substrates have been implanted with 800 keV A g+ to a dose of 5 x 10(14)/cm(2), at room temperature (i.e., the total range approximate to 0.4 mu m and the damage level approximate to 3.1 displacements per atom) and at elevated temperatures (450, 650, and 7 80 degrees C), followed by an in situ annealing schedule in flowing ox ygen ambient. We have found that the implantation at room temperature amorphizes the implanted layer. In such a case, the implanted layer ca nnot regrow to the superconducting phase if there is no crystal seed r emaining in the bottom of the film, whereas implantation at elevated t emperatures plus an in situ annealing schedule, including a step at 87 0 degrees C in flowing oxygen ambient, can maintain the crystal struct ure and superconductivity of the films. For the thicker film, we have found that after the implantation at 450 or 650 degrees C and the in s itu annealing, the total volume of the film has recovered to the super conducting 123 phase with a T-c = 89 K. (C) 1997 American Institute of Physics.