Concentration-dependent visible photoluminescence of In2O3:Er3+ under 532 nm excitation

In2O3 thin films were doped with Er3+ at different concentrations (0.5-2%) by sol-gel method and annealed at 1000 °C. The In2O3:Er3+ films were characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, photoluminescence (PL) and ellipsometry. The films are polycrystalline with a cubic structure related to In2O3. The trivalent state of Erbium in the In2O3 crystal is confirmed by photo electron spectroscopy. Doped films were excited under selective Er3+ excitation at 532 nm; the visible Er3+-related emission is observed in the photoluminescence spectra and the major emissions occur in the green region with strongest lines at 548 and 567 nm. They are mainly produced by the Stark split 2H11/2 and 4S3/2 transitions to 4I15/2 ground state and highest emission is observed on In2O3:1% Er3+.