Pulsed-Laser Deposition of High-Temperature Superconducting Thin Films

Surface Structure and Particulate Generation in Pb0.97Nd0.02(Zr0.55Ti0.45)O3 Ablation Targets During Pulsed Laser Deposition

“…The ejection of the spherical top globules from the melt may be the mechanism for the generation of large particulates ( > 600 nm) on the growing PNZT film surface. 5 However, the generation mechanism for the smaller particulates ( < 200 nm) is probably different, as mentioned before.…”

“…The existence of the particulates impairs the properties of the thin-film structure, especially for optical applications. 5 Explosions of the molten target surface due to the superheating of the subsurface layer and a rapid expansion of gas pores buried below the target surface inside a ceramic polycrystalline target are considered to be the most important mechanisms responsible for particulate formation. 6,7 On the other hand, the formation of the laser-cone structure during a pulsed laser deposition process generates large-scale particulates on the growing thin-film surface.…”

“…6,7 On the other hand, the formation of the laser-cone structure during a pulsed laser deposition process generates large-scale particulates on the growing thin-film surface. 5,6 The formation of laser cones is related to compositional changes at the target surface leading to a surface segregation and formation of new compounds and phases in the surface layer which have higher melting-point temperatures as compared to that of the bulk target. These new structures are the reason for a shielding behavior which prevents the etching of the underlying layers of the target in the ablation process.…”

“…9 The off-axis laser deposition technique and mechanical velocity filters are probably the most effective methods introduced in order to minimize the number of particulates on the growing film surface. 5,10 However, in the case of the pulsed laser-ablation deposition, no method has yet been proposed which totally prevents the formation of particulates on the growing film surface and, at the same time, maintains the idea of deposition with a directed stream of high-velocity particles. In this work, we study the dependence of the surface morphology of deposited PNZT thin films on the laser-beam fluence and density of the ablation target.…”

Preparation of nanoparticles by excimer laser ablation of calcium iron complex oxide

“…Pulsed excimer laser ablation has been usually used for the preparation of thin films of complex oxide such as high Tc superconductors of YBCO. In this technique the film composition easily matches with that of the target, because the excimer laser ablation mechanism is based on both a photoinduced process and a thermal process (Venkatesan, 1994). In addition complex oxide films are deposited through atoms, molecules, and molecular ions formed by excimer laser irradiation.…”