Optimization of La0.7Ba0.3MnO3-delta complex oxide laser ablation conditions by plume imaging and optical emission spectroscopy

The properties of thin films of complex oxides, such as La1-xDxMnO3- (D=Ba, Ca, Sr, etc.), produced by pulsed laser deposition depend critically on the experimental parameters in which laser ablation is carried out. Here, we report a comparative analysis of the pulsed laser ablation process of La0.7Ba0.3MnO3-, in oxygen background, in the ambient pressure range from 10-2 to 1 mbar, typically employed in pulsed laser deposition of manganites. The laser ablation plume was studied by using time-gated imaging and optical emission spectroscopy techniques. It was found that at a pressure of 10-2 mbar, the plume species arriving at the substrate are characterized by hyperthermal kinetic energy 10 eV, and high degree of excitation. On the contrary, at larger oxygen pressure 0.1-1 mbar, the velocity of plume species reaching the substrate, and their degree of excitation are much reduced by the confining effects of the background gas. These features explain why an appropriate choice of the experimental conditions in which the deposition process is carried out leads to better quality films, providing helpful indications to improve control over the growth process of both La1-xDxMnO3- and other perovskitic oxides.