Nanosecond pulsed laser-induced segregation of Te in TeOx films

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Thin films of TeOx deposited by coevaporation of Te and TeO2 or by reactive sputtering of Te in the presence of Ar and O2 are amorphous as-deposited and are spatially homogeneous mixtures of Te and TeO2. Irradiation of these films by a nanosecond laser pulse leads to a substantial change in the optical properties (e.g., increase in the reflectivity) of the films. Electron spectroscopy for chemical analysis depth profiling, Rutherford backscattering, and x-ray diffraction techniques were used to analyze these films before and after laser irradiation. The results obtained indicated that the segregation of Te from TeO2 matrix is responsible for most of the observed optical property changes. The segregation of Te results in the formation of a nearly pure Te layer in the hottest region of the film without changing the overall film composition. A model based on melting of Te and TeO2 composites, followed by segregation and crystallization of Te is proposed to describe the nanosecond pulsed-laser irradiation of TeO2 thin films. The possible effects of Te segregation on the optical recording characteristics of TeO2 based media are also discussed. © 1986, American Vacuum Society. All right reserved.