Analysis of the NdBa₂Cu₃O_x thin film growth mechanism by time of flight mass spectrometry of the laser plume

Abstract

Time of flight (TOF) spectroscopic measurements are used to diagnose the laser-generated plume of ceramic NdBa₂Cu₃O_x targets. We have been able to directly correlate the laser-deposited films’ properties such as superconductivity, crystallinity, and orientation with plasma properties. Study of the TOF spectra shows that at laser fluences greater than 3 J/cm² the plume become Nd-rich, and this leads to a low T_c in the deposited film. We have also shown the effect of target density on the energy of the plume species, and through energy considerations we have explained the observed change in the crystalline orientation of films from c- to a-orientation with increasing the target density. Finally, we have examined the oxidation mechanism of NdBa₂Cu₃O_x thin films, and have shown that highly energetic atomic oxygens have a prevailing role in oxidizing our laser-deposited thin films.