Abstract
Magnesium fluoride thin films were prepared by electron-beam evaporation and ion-assisted deposition (IAD). The effects of ion assistance and substrate temperature during deposition on the optical properties and microstructure were studied. The grain size, the crystallinity and the surface roughness of MgF2 films deposited without ion assistance all decreased with substrate temperature. MgF2 films deposited with IAD exhibited small grains, rough surfaces, fluorine deficiencies and large optical losses in the 200–500 nm wavelength range when bombarded with argon ions.