OPTICAL-PROPERTIES OF HAFNIA AND COEVAPORATED HAFNIA-MAGNESIUM FLUORIDE THIN-FILMS

Mixed films of HfO2 and MgF2 were prepared by the e-beam coevaporation of two source materials with or without the presence of ion assistanc e. Optical properties and hardness of mixed films were compared among various compositions that were achieved by controlling the deposition rate of MgF2. Results obtained from pure materials confirmed the densi fication of HfO2 and the increased absorption in MgF2 with a higher di scharge voltage. A refractive index of a composite film from 1.38 to 1 .91 was achievable with various HfO2:MgF2 deposition rate ratios. A lo w-index composite material with improved hardness may be substituted f or the soft MgF2. (C) 1996 Optical Society of America