Time-dependent phenomena in plasma-assisted chemical vapor deposition of rugate optical films.

The plasma-assisted chemical vapor deposition technique was used to produce thin-film structures with both sinusoidally and stepwise varying refractive-index profiles. The refractive index of the SiO(x)N(y) system used in the fabrication was found to be time dependent following a stepwise change in reactant gas flows or initiation of the plasma. This time dependence has been quantified using in situ ellipsometry and was found to have components with exponential and linear dependences.

Influence of ion assistance on the optical properties of MgF(2).

The optical properties of MgF(2) films prepared by evaporation and ion-assisted deposition have been determined from transmittance and near-normal incidence reflectance measurements and also from electron-energy loss spectroscopy (EELS). The results show that oxygen-ion assistance leads to higher extinction coefficients for wavelengths <180 nm. Transmission electron microscopy studies show that the crystal grain size of MgF(2) films is not strongly affected by oxygen or argon-ion bombardment.