Luminescence of Cr3+ ions associated with surpassing the green-emissive defect centers in β-Ga2O3

Photoluminescence of undoped and Cr3+-doped β-Ga2O3 was investigated. The transparent, undoped β-Ga2O3 film was successfully prepared by thermal conversion from GaOOH. The film exhibited predominant green luminescence in response to ultraviolet light excitation at 250 nm. This luminescence behavior, which was proposed to result from the oxygen defect centers, was used in examining excitation and emission mechanisms for Cr3+ ions doped in β-Ga2O3. It was found that red luminescence of Cr3+ surpasses green luminescence of the host lattice, as evidenced by the dependence of the spectral structure on the Cr3+ concentration. The excitation of Cr3+ was then suggested to be caused by the energy transfer from Ga3+O6 octahedra present in the monoclinic β-Ga2O3 lattice.