Study of electronic excitation relaxation at cerium ions in Gd3Al2Ga3O12 matrix using multipulse transient absorption technique

A method for investigation of excitation relaxation—the multipulse transient absorption technique—has been applied for studying carrier relaxation and recombination processes of excited Ce3+ ions in Ce-doped and Mg-codoped gadolinium aluminum gallium garnet (Gd3Al2Ga3O12, GAGG) single crystals with...

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Bibliographic Details
Published in:Journal of applied physics 2020-09, Vol.128 (10)
Main Authors: Nargelas, S., Korjik, M., Vengris, M., Tamulaitis, G.
Format: Article
Language:English
Subjects:
Absorption spectra
Aluminum
Applied physics
Banded structure
Carrier recombination
Cerium
Electron transitions
Electrons
Excitation
Gadolinium
Gallium
Ion recombination
Relaxation time
Single crystals
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Summary:A method for investigation of excitation relaxation—the multipulse transient absorption technique—has been applied for studying carrier relaxation and recombination processes of excited Ce3+ ions in Ce-doped and Mg-codoped gadolinium aluminum gallium garnet (Gd3Al2Ga3O12, GAGG) single crystals with different codoping levels. The method enabled deeper insight into the complex dynamics of electron transitions between higher excited levels and the emitting state of Ce3+, which are difficult to observe in conventional pump–probe experiments because of overlapping absorption bands arising from different structural units. Fitting the experimental results to calculations based on the rate equations for the population levels of Ce3+ ions and traps enabled us to estimate the relaxation times from these levels. In particular, it was shown that the electron relaxation time between doublet eg and triplet t2g components of the split level 5d of Ce3+ is faster than 300 fs. Substantial influence of electron trapping is demonstrated, and the potential fluctuations due to intrinsic composition fluctuations in multicomponent GAGG crystals are shown to be the predominant origin of the traps.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0015141