One of the main problems related to optical thin film materials used in high power laser environments is the catastrophic damage caused to them due to laser irradiation. While the influence of ion bombardment on the optical properties of oxide thin films is now a well understood subject, the morphology and crystalline behavior of these films under ion incidence is not so well studied. Hence, it is of great importance to investigate the effects of ion bombardment during growth on the microstructure and crystalline behavior of oxide materials. In this paper, the authors present the results of a detailed investigation of alumina, ceria, titania, and zirconia thin films prepared by ion-assisted deposition. It has been found that the crystalline behavior of the films is strongly material dependent. So that, while ceria crystallizes in situ independent of deposition parameters, all the other materials require thermal annealing for crystallization to occur. Both in zirconia as well as alumina, otherwise high temperature modifications; cubic zirconia and (alpha) -Alumina, have been synthesized at low temperatures. Some reasons for this behavior is discussed. The stress and grain sizes seem to be interrelated and also momentum dependent. The stress in particular was found to be dependent on the ion energy, current density, ion species and substrate temperature. Some theoretical models have been developed to explain the observed behavior.
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