Extended decay times for the photoluminescence of Eu3+ ions in aluminum oxide films through interaction with localized states

The photoluminescence characteristics under continuous and pulsed excitation of Eu3+-doped aluminum oxide films deposited by the ultrasonic spray pyrolysis technique are reported. It was determined that localized states in the Al2O3 host are excited with 250 nm light and emit a broad band luminescent emission at 415 nm associated with a radiative recombination involving F centers. When Eu3+ ions are introduced in these films, a charge transfer mechanism to these ions from the localized states seems to occur predominantly. The Eu3+ related emission generated in this way results in an increase of the luminescence intensity and in an extended luminescence decay time compared to that obtained when the excitation is achieved through an inter-electronic energy level transition in this ion with 395 nm excitation light.

► An Al2O3 localized states – Eu3+ interaction takes place in Al2O3:EuCl3 films.
► Charge transfer from Al2O3 localized states to Eu3+ increases the red emission intensity.
► Charge transfer from Al2O3 localized states to Eu3+ extends the red emission decay time.