Reactively sputter-deposited and coevaporated TeOx thin films for optical recording

The preparation of TeOx-based optical recording media by coevaporating TeO2 and Te and by reactive sputtering of Te is reported. The composition of the reactively sputter-deposited TeOx film is found to depend linearly on the O2 partial pressure used. Like the coevaporated films, these films are amorphous as deposited and are a mixture of Te and TeO2. Both oven and pulsed-laser annealing tend to induce substantial optical property changes in these films. The temperature at which this optical property change occurs during oven annealing was found to increase with increasing x value of the film. For the laser-annealed films, the optical reflectivity was found to increase slowly even after laser irradiation, not reaching a plateau value until several minutes later. The optical property changes are attributed to the amorphous-to-crystalline phase transformation and to the segregation of Te from the TeO2 matrix and the gradual growth of these segregated Te crystallites after annealing. The effects of the number of nuclei and defects in the films on the Te crystal growth after laser annealing are also reported.