THE TRANSITION FROM 2D-NUCLEATION TO SPIRAL GROWTH IN PULSED-LASER DEPOSITED YBA2CU3O7-DELTA FILMS

Using scanning probe microscopy we observe a growth mode transition in pulsed laser deposited (PLD) YBa2Cu3O7-delta films. By increasing the background oxygen pressure the generally observed 2D-nucleation and g rowth mode transforms into a spiral growth mode. Keeping the oxygen pr essure at increased levels and reducing the target-substrate distance, the growth spirals disappear and 2D-nucleation and growth becomes the dominant growth mode again. We attribute the growth mode transition t o a change in surface diffusivity of similar to 2 orders of magnitude. Our experiments confirm that in PLD surface kinetics is strongly link ed to plume dynamics. (C) 1998 Elsevier Science B.V. All rights reserv ed.