Chemical Vapor Growth of Single-Crystal Magnetic Oxide Films

The chemical vapor deposition technique provides a means of growing single-crystal films of ferrite and garnet magnetic oxides on nonmagnetic substrates. The technique involves a chemical reaction at elevated temperatures between volatile metallic compounds and gaseous oxidizing agents on the substrate surface to form the solid film. It is possible to control the orientation of the magnetic vector with respect to the film, the film composition, and the surface condition of the film. The factors which affect the achievement of epitaxy and the crystal quality of the film include the structural similarity between the substrate crystal and the film, the chemical conditions of the reaction, the deposition temperature, the rate of crystal growth, and the relative expansion characteristics of the film and substrate. Epitaxial deposits of a variety of ferrites have been made on MgO, Al2O3, and MgAl2O3 single-crystal substrates in the deposition temperature range of 800° to 1100°C. Film thicknesses in the range 0.5 to 500 μ have been produced in (100), (110), and (111) orientations. The values obtained for saturation magnetization anisotropy constant and resonant linewidths are similar to bulk-crystal values of the same composition.