Enhancement in hardness and transmittance of ZnS via SiO2/Y2O3 multilayer

The cSiO2/bY2O3/aSiO2/ZnS/aSiO2/bY2O3/cSiO2 system was fabricated to enhance the hardness and improve the transmittance of Zinc sulfide. The data of each thickness was obtained by the simulation of Filmstar package. 150 nm SiO2 film was used to release the stress between ZnS and Y2O3 film as a buffer layer. Smooth SiO2 and crack-free Y2O3 films were successfully obtained. It was found that hardness of the multilayer system increased from 250 to 430 Kg/mm2 and transmittance increased from 63% to 83% at 3–5 μm.

► First experiment report on the cSiO2/bY2O3/aSiO2/ZnS/aSiO2/bY2O3/cSiO2 system.
► Crack-free Y2O3 was successfully deposited on ZnS with 150 nm SiO2 buffer layer.
► The hardness of ZnS increased from 250 to 430 Kg/mm2.
► Transmittance of ZnS increased from 63% to 83% at 3–5 μm.