EVOLUTION OF THE IMPLANTED O-18 CONCENTRATION DISTRIBUTION IN A YBA2CU3O7-DELTA FILM DURING RAPID THERMAL ANNEALING

To understand the behaviour of oxygen migration in YBa2Cu3O7-delta (YB CO) films during rapid thermal annealing (RTA), a c-axis oriented YBCO film (800-900 nm) was implanted, at room temperature, with 200 keV O- 18(+) to a dose of 5 x 10(16) O-18(+)/cm(2). After implantation sample s were annealed, at various temperatures between 450 and 870 degrees C for 2 min or 870 degrees C for 20 s, in a RTA annealer, in a flowing natural oxygen ambient. O-18 concentration versus depth profiles were obtained with an Atomika 6500 SIMS instrument, using a 10 keV Cs+ prim ary beam, It is found that the implanted O-18 plays a very sensitive r ole in monitoring the migration of oxygen within the film during RTA. There is clear evidence that RTA at 450 degrees C for 2 min results in an obvious re-distribution of as-implanted O-18 but only very small a mount of oxygen isotopic exchange between the gas ambient and the impl anted O-18. In this case, the retained dose is found to be similar to 95.6% Q(0) (where Q(0) is the retained dose after implantation); where as RTA at 870 degrees C for 20 s results in a sufficient oxygen exchan ge between the gas ambient and the implanted O-18, with the retained d ose being smaller than 1% Q(0). Practical RTA conditions for annealing of irradiated YBCO films are discussed.