Some effects on the properties of electron-beam evaporated thin films produced by ion bombardment of the growing film are reported. Substantial increases in the packing densities of SiO2 , TiO2 , and ZrO2 films have been produced as measured by the reduction in the adsorption of moisture when the films are exposed to a humid atmosphere. In a ZrO2-SiO2 multilayer interference filter, changes in the wavelength of the peak transmittance on exposure to the atmosphere have been reduced from 8 nm for films deposited without ion bombardment to <1 nm for ion-beam-assisted films.

Mixed thin films of TiO2 and SiO2 were produced by coevaporation from separate electron-beam sources and simultaneous bombardment of the growing film with oxygen ions. The optical properties of the films were determined during growth by in situ ellipsometry and the surface composition of the deposited films studied by in situ ion scattering spectroscopy, ex situ x-ray photoelectron spectroscopy, and energy filtered electron diffraction. The correlation between the optical and surface characterization is presented. There is evidence of local variations in the relative concentrations of TiO2 and SiO2. The position of the Si 2p binding energy depends on the TiO2 content in the film, indicating the possible formation of an intimate mixture.

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Inert and reactive gas ion beams have been used in the preparation of high-quality optical thin films for use as dielectric coatings on optical components, solar selective absorbers, and protective films on Ag and Al mirrors. Films are deposited by electron-beam evaporation and simultaneous irradiation of the growing film at the substrate or by ion-beam sputtering with and without ion assistance. Substantial improvement in the film packing density has been achieved, the refractive indices increased, and water penetration through the films was suppressed. TiN has been deposited by Ti evaporation and nitrogen irradiation for use as an element in a high-temperature solar selective absorber. Amorphous hydrogenated silicon (a-Si:H) has also been produced by Si evaporation and hydrogen irradiation or by mixed ion-beam sputtering. Significant changes in the crystal structure of PbS have also been achieved by ion irradiation. Dielectric films of ZrO2, SiO2, and Al2O3 have been deposited by ion-assisted deposition and ZrO2 has been used as a highly successful protective coating on Al and Ag mirrors. The optical properties of the films have been studied and the film composition checked by x-ray diffraction, nuclear reaction analysis (NRA), Rutherford backscattering (RBS), x-ray photoelectron spectroscopy (XPS), and ion scattering spectroscopy (ISS).