Effect of SF6 flow ratio on microstructure and properties of MgF2 thin films prepared by magnetron sputtering

[Display omitted] •Broadband antireflection MgF2 thin films are deposited with magnetron sputtering.•F: Mg ratio varies between 1.85 to 2.13 with the increase of SF6 flow ratio.•F: Mg ratio is 2.13 when the SF6 flow ratio is 7%, closest to the stoichiometric ratio.•MgF2 film increases the transmittance of the glass substrate from 93.2% to 94.24%.•MgF2 film increases GaAs solar cell photoelectric conversion efficiency 2.1%. In order to suppress F- deficiency of MgF2 film prepared with magnetron sputtering, the effects of SF6: Ar gas flow ratio on the structure and properties of the film were investigated. F: Mg ratio increased rapidly first then decreased with the increase of SF6 flow ratio, got 2.13 at 7%, closest to the stoichiometric ratio 2:1; while the film's refractive index first decreased and then increased, got a minimum at 550 nm 1.409 at 7%. MgF2 film increased the glass substrate transmittance within 300–1100 nm to 94.24% from 93.2%, and improved photoelectric conversion efficiency of GaAs solar cell by 2.1%.