Improvement of optical ZrO/sub 2/ deposited film's properties

Vacuum-evaporated ZrO/sub 2/ films which are widely used for optical multilayer coatings have a disadvantage regarding to the application to multilayer antireflection coatings. This disadvantage is due to optical inhomogeneity of the films whose refractive index decreases with increasing thickness. For the improvement of their optical properties, the effects of TiO/sub 2/ and Y/sub 2/O/sub 3/ additions to evaporants of ZrO/sub 2/ on optical homogeneities and the crystal structures of the deposited films were investigated by electron-beam evaporations. The deposited films of TiO/sub 2/ additions were optically almost homogeneous and the film's structure was amorphous. The ones of Y/sub 2/O/sub 3/ additions showed fairly lowered optical inhomogeneities and stabilized cubic crystal structures. The most favorable ZrO/sub 2/ films for multilayer coatings were obtained by suitable additions of both TiO/sub 2/ and Y/sub 2/O/sub 3/, which had good optical homogeneities, adequate and variable refractive indices, enhanced harnesses and reliable reproducibilities of properties.