CHARACTERIZATION OF MGO LAYERS ON DIFFERENT ALUMINA AND GLASS SUBSTRATES BY GRAZING-INCIDENCE DIFFRACTOMETRY AND GRAZING-INCIDENCE X-RAY REFLECTOMETRY

Magnesium oxide thin films were deposited at an average evaporation ra te of 1.8 nm s(-1) onto different crystalline alumina substrates and a morphous float glass. The deposits were made in an electron-beam evapo rator at substrate temperatures between 25 degrees C and 190 degrees C under different oxygen partial pressures. Films of 0.1, 0.5 and 1 mu m thickness were deposited. These coatings were investigated by grazin g incidence diffractometry (GID) to vary the depth of penetration. For films 0.1 mu m thick the additional use of grazing incidence x-ray re flectometry (GIXR) was possible. The deposited films were polycrystall ine with different [100] textures depending on the substrate temperatu re. All the MgO thin-film reflexes measured were strongly broadened co mpared with the reflexes of a standard polycrystalline MgO material. T he crystal size and the microstrain of the MgO coatings were calculate d by profile analysis using the Fourier transformation method. It was demonstrated that the x-ray profiles of the MgO reflexes are influence d by the roughness of the substrate surface. Only small gradients were found in the particle sizes and microstrains within the deposited fil ms. The oxygen partial pressure did not significantly influence the fi lm properties measured by GID. The GIXR roughness and mass density mea surements agreed with the results of GID. Magnesium oxide films deposi ted at higher temperatures show a diminished crystallinity and less in terface roughness.