High frequency microwave characteristics of amorphous FeCoNiB–SiO2 thin films

A series of FeCoNiB–SiO2 thin films were synthesized by RF magnetron sputtering. Effects of the Ni addition to FeCoB–SiO2 system and the sputter pressure on microstructure and electromagnetic characteristics were investigated. It is found that appropriate increment of Ni content and suitable low argon pressure is of advantage to the high-frequency characteristics. High permeability and high magnetic loss in the GHz frequency range are achieved in the optimum process parameters. Both μ′ and μ″ are larger than 85 until 2.0 GHz and larger than 400 at 2.1 GHz, and the resistivity reaches 682 μΩ cm. These results show that the presented films possess potential in designing microwave absorbers or synthesizing EMI shielding materials.