Origin of Bi3+–related luminescence in Gd3Ga5O12:Bi epitaxial films.

Photoluminescence characteristics of Gd 3 Ga 5 O 12 :Bi single crystalline films with different Bi contents grown by the liquid phase epitaxy are studied by the steady-state and time-resolved luminescence spectroscopy methods in the 4.2–500 K temperature range under excitation within the 3.8–6.0 eV. No ultraviolet emission, which could be ascribed to the radiative decay of the triplet excited state of Bi 3+ , is observed. Only visible emission is shown to arise from the Bi 3+ –related luminescence centers. Both the intense 2.54 eV emission and the weaker 2.46 eV emission of Gd 3 Ga 5 O 12 :Bi are shown to be of exciton origin. We suggest that they are due to the radiative decay of an exciton localized around a single Bi 3+ ion and a dimer {Bi 3+ –Bi 3+ } center, respectively. The characteristic parameters of the corresponding exciton states are determined. The photostimulated processes, resulting in the localized excitons formation under excitation in the Bi 3+ –related absorption bands, are discussed. Peculiarities of Gd 3+ –Bi 3+ energy transfer processes in Gd 3 Ga 5 O 12 :Bi are investigated. The possibility of application of Bi 3+ –doped gadolinium gallium garnets in scintillation detectors and light emitting diodes is considered. [ABSTRACT FROM AUTHOR]