The influence on the internal stress and optical properties of Nb₂O₅ thin films with ion-beam energy was investigated. Nb₂O₅ thin films were deposited on unheated glass substrates by means of ion-beam sputtering with different ion-beam voltage, V _b. The refractive index, extinction coefficient, and surface roughness were found to depend on the ion-beam energy. The stresses in thin films were measured by the phase-shifting interferometry technique. The film stress was also found to be related to V _b, and a high compressive stress of -0.467 GPa was measured at V _b = 850 V. The Nb₂O₅–SiO₂ multilayer coatings had smaller average compressive stress as compared with single-layer Nb₂O₅ film.

Nitrogen-doped TiO₂ films were prepared by reactive ion-beam sputtering deposition (IBSD) in a mixed atmosphere of NH₃ and O₂ at a substrate temperature of 400 °C. X-ray photoelectron spectra revealed the presence of six ions, i.e., N³⁻, N²⁻, N¹⁻, N⁺, N²⁺, and N³⁺, respectively, in the films. The amorphous films had complex, randomly oriented chemical bonds. The Tauc–Lorentz model was employed to determine the bandgap energy of the amorphous films prepared using different NH₃/O₂ gas mixing ratios by ellipsometry. In addition, the optical constants of the films were measured. With the increase in the NH₃/O₂ gas mixture ratio to 3.0, the bandgap of N-doped TiO₂ narrowed to ~2.54 eV.

The optical properties and the surface morphologies of single-ion-beam sputtering (SIBS) and dual-ion-beam sputtering (DIBS) depositions of titanium oxide films are investigated and compared. In the DIBS process, the ion-assisted deposition by the voltage of a low ion beam ranged from 50 to 300 V at a 0% and 44% oxygen percentage. Cosputtering with materials of Si, SiO₂ (fused silica), and Al is also utilized in SIBS to improve amorphous-structure film. For the low-absorption and surface-roughness film, the optimum deposition condition of DIBS and postdeposition baking temperature for SIBS and DIBS are essential to the process.