EFFECTS OF SILICON-NITRIDE CHEMICAL-COMPOSITION ON MAGNETOOPTICAL PROPERTIES OF NONSTOICHIOMETRIC SILICON-NITRIDE TBFECO LAYERS

The effects of various silidon nitride chemical compositions on the ma gneto-optical properties of non-stoichiometric silicon nitride/TbFeCo layers have been investigated. With increasing pressure of the sputter ing gas, stoichiometric Si3N4 changes to silicon oxynitride SiON, and with decreasing in the N-2/Ar ratio of the sputtering gas, it changes to nitrogen-defective silicon nitride (SiNx). The refractive index of films decreases with increasing oxygen concentration, and it increases with decreasing nitrogen concentration. Measured values for Kerr rota tion angle and reflectivity of the SiNx/TbFeCo/SiNx layers mere found to correspond quite well to those derived theoretically. Increase of t he oxygen concentration of the SION layer results in oxidation at the interface, which in turn results in an observable decrease in the Kerr rotation angle of SiON/TbFeCo bilayers. A SiNx/TbFeCo layer has been found to be just as effective as a Si3N4/TbFeCo layer for use in magne to-optical disks.