Effect of Argon ion irradiation on grain orientation in platinum thin films

Platinum thin films were prepared on Mo/Si(100) substrate by Argon ion beam assisted deposition. X-ray diffraction analysis showed that the crystal orientation in Pt film was influenced by the incidence angle of the Ar+ beam. The films exhibited preferred (111) orientation without concurrent ion beam bombardment. The films, which were deposited with simultaneous bombardment by a 500 eV Ar+ beam along normal direction, showed mixed (111) and (200) orientation. Tilting the Ar+ beam off the normal direction of the film surface, the film exhibited highly preferred (111) orientation, even at the tilting angle of 45°. The results suggested that the surface free energy of (111) plane is much lower than that of other lattice planes and dominates during the film growing.