Percolation and microwave characteristics of CoFeB–SiO2 nano-granular films

Co40Fe40B20–SiO2 nano-granular films were synthesized by RF magnetron sputtering. Effects of SiO2 volume fraction on microstructure and electromagnetic characteristics were investigated. The transitional state relating transformation of electron transportation mechanism and percolation in granular films was also discussed. Results show that resistivity increases exponentially when volume fraction of SiO2 is near the percolation threshold, whereas microwave permeability keeps still large value. Thus, electromagnetic characteristics and microwave parameters of the granular film can be adjusted to satisfy the requirements of application as microwave absorber.