Thickness-dependent (001) orientation and surface morphology of rapid-annealed FePt thin films on a glass substrate

Thickness-dependent (001) orientation and surface morphology of rapid-annealed FePt thin films were investigated. For the rapid annealed FePt films with different thicknesses (5-60 nm), the ordering parameters were obtained to be higher than 0.9. As film thickness (t) was increased from 5 to 20 nm, the Lotgering orientation factor (LOF) increased from 0.75 to 0.99 (nearly perfect 00l texture), and then decreased to 0.85 for films with t = 60 nm. Surface morphology observation indicates an evolution from a continuous to island-like structure with decreasing t. Due to high temperature annealing, the surface atomic diffusion and substrate-film interfacial diffusion results in the de-wetting of film structure, when t is thin. This morphological change leads to the stress-relaxation of the preformed tensile stress induced by the impingement of grain growth, which further causes a decrease of LOF.