Al2O3 and Cr3+-doped Al2O3 (0.3%, 1wt%) thin films have been grown on Si(100) substrates by pulsed laser deposition. The as-prepared films show cubic γ-Al2O3 structure. After vacuum annealing at 800°C for 1h, the crystallinity of the sample was improved. The annealed film presents the diffraction peaks of α-Al2O3 and γ- Al2O3. The SEM image reveals that crystal grains of the films have an average grain size of 250nm and a morphology of bar. The electron energy spectrum shows that element compositions of thin films are almost the same as the according targets. Compared with Al2O3 powder, the intensity of the luminescence peak at 386nm of Al2O3 thin films greatly enhances. This can be ascribed to an increase of oxygen vacancies in the thin films and the concentration of F2+ color centers caused by double-oxygen-vacancy absorbing electrons accordingly enhances. Compared with Al2O3 thin film, the intensity of the luminescence peak at 332 and 398nm of the annealed Al2O3 thin films greatly enhances, which can be ascribed to an increase of the concentration of color centers (F+, F). The blue shift from 386 to 381nm of emission peak of Al2O3 thin film after annealing was mainly attributed to release of the internal stress. The photoluminescence spectra of 1wt% Cr3+-doped Al2O3 thin film show two emission peaks at 694 and 646nm, which are caused by electron transition of Cr3+ ions from Ē to 4A2 and 4T2 to 4A2.
