Optical properties and reactive sputtering conditions of AlN and AlSiN thin films for magneto-optical applications

The dependence of the refractive index and film thickness of AlN and AlSiN thin films on the reactive sputtering conditions (N-2 partial pressure, total pressure, and rf sputtering power) have been studied in detail and analyzed in terms of the mechanism of reactive sputtering and the target poisoning phenomenon. On the basis of the results, the sputtering conditions of AlN and AlSiN films have been optimized for magneto-optical applications. The AlN and AlSiN films after optimization of the sputtering conditions had very high transmissivity and refractive index, and were suitable for magneto-optical Kerr effect enhancement. A marked enhancement of the magneto-optical Kerr effect for a TbFeCo film coated with AlN and AlSiN films was observed. The improvement of the signal-to-noise ratio obtained with the AlSiN film was greater than the AlN film.