Laser ablation induced surface modification of NdBa2Cu3O7-δ single crystal target in pulsed laser deposition

The surface modification of both morphology and composition of a single crystal NdBa2Cu3O7-delta (NBCO) target induced by laser ablation has been studied by scanning electron microscopy with x-ray energy dispersive spectroscopy. After a long period of laser ablation, the sintered target displays a cone-shaped columnar surface morphology. However, the single crystal target exhibits a continuous and smooth undulating morphology with ridges and grooves. This cone-free surface morphology is thought to inhibit the ejection of droplets from the target surface and thus lead to NBCO films with excellent surface morphology. After a large number of laser shots per site on the single crystal target, both the surface composition and deposition rate remain unchanged. Our experimental results prove that the observed results for the sintered target are in agreement with the erosion model, while the laser ablation induced surface modification for the single crystal target is dominated by the melt-resolidification process. (C) 1998 American Institute of Physics. [S0021-8979(98)06421-4].