Structure and growth of yttrium iron garnet thin films with enhanced magnetic properties by metalorganic chemical vapor deposition

Growth of undoped and CoyCe-doped yttrium iron garnet films by a low-pressure metalorganic chemical vapor deposition (MOCVD) process is described. As-deposited films require a 900 ±C oxygen anneal to crystallize into the cubic garnet phase. Inclusion of secondary nonmagnetic phases in the films is attributed to the local deviations in the YyFe oxide ratios. Crystallization behavior as established by x-ray diffraction studies shows that the garnet phase formation occurs by two mechanisms—by solid phase reaction of Y2O3 and a –Fe2O3 and by transformation of hex-YFeO3 solid solution with Fe2O3. Garnet film growth by chemical vapor deposition (CVD) occurs by precursor pyrolysis in the gas phase and by interaction with the substrate through a complex reaction sequence described through a model. Magnetic studies of undoped and CoyCedoped films show enhancement in perpendicular anisotropy and extremely high coercivity values of 170 kAym s­ 2125 Oed and saturation magnetization of 104 kAym s4pMs ­ 1306 Gsd due to CoyCe-doping which also promotes the garnet phase crystallization.