Angular distribution of atoms emitted from a SrZrO3 target by laser ablation under different laser fluences and oxygen pressures

Angular distributions of atoms emitted by laser ablation of perovskite-type oxide SrZrO3 have been investigated using electron probe microanalysis with wavelength-dispersive spectroscopy and charge-coupled device photography with an interference filter. Each constituent element has been analyzed as a two-modal distribution composed of a broad cosm θ distribution and a narrow cosn θ distribution. The exponent n characterizes the component of laser ablation while the exponent m characterizes that of thermal evaporation, where a larger n or m means a narrower angular distribution. In vacuum, O (n=6) showed a broader distribution than those of Sr (n=16) and Zr (n=17), and Sr+ exhibited a spatial distribution similar to that of Sr. As the laser fluence was increased from 1.1 to 4.4 J/cm2, the angular distribution of Sr became narrower. In the laser fluence range of 1.1-4.4 J/cm2, broadening of the angular distribution of Sr was observed only at the fluence of 1.1 J/cm2 under the oxygen pressure of 10 Pa. Monte Carlo simulations were performed to estimate approximately the energy of emitted atoms, focusing on the broadening of the angular distribution under the oxygen pressure of 10 Pa. The energies of emitted atoms were estimated to be 1-20 eV for the laser fluence of 1.1 J/cm2, and more than 100 eV for 2.2 and 4.4 J/cm2.