Chemical composition, microstructure and magnetic characteristics of yttrium iron garnet (YIG, Ce:YIG) thin films grown by rf magnetron sputter techniques

YIG thin films were grown by rf magnetron sputter techniques. We investigated the effect of post-deposition heat-treatment as well as various deposition parameters such as substrate materials, substrate temperature, sputter power, and sputter gas types on the crystallinity, chemical composition, microstructure and magnetic characteristics of the films. Post-deposition heat-treatment over 750°C was applied to crystallize as-prepared amorphous films, and a strong tendency of particular crystallographic planes lying parallel to substrate surface was observed for the heat-treated film on GGG substrate. The chemical composition of the film exhibited a wide range of chemical stoichiometry depending on the oxygen fraction of the sputter gas, and in particular the compositions of the YIG and Ce:YIG films deposited in sputter gas with an oxygen fraction of 20% were Y_2.88Fe_3.84O ₁₂ and Ce_0.24Y_1.10Fe_3.50O ₁₂, respectively. With raising the temperature of post-deposition heat-treatment from 900°C to 1100°C, the surface roughness of the film on GGG substrate increased, but coercive force as well as ferromagnetic resonance line width decreased