Structural and optical properties of yttrium oxide thin films for planar waveguiding applications

摘要

Thin films of Yttrium Oxide, Y2O3 were deposited by reactive sputtering and reactive evaporation to determine their suitability as a host for a rare earth doped planar waveguide upconversion laser. The optical properties, structure and crystalline phase of the films were found to be dependent on the deposition method and process parameters. X-ray diffraction (XRD) analysis on the 'as-deposited' thin films revealed that the films vary from amorphous to highly crystalline with a strong peak along the 222 plane of Y2O3. The samples with the polycrystalline structure had a stoichometry close to bulk cubic Y2O3. SEM imaging revealed a regular column structure confirming their crystalline nature. The thin film layers which allowed guiding in both the visible and infra-red region had lower refractive indices, higher oxygen content and had a more amorphous structure. Higher oxygen pressures during the deposition leads to a more amorphous layer.