Influence of heavy magnesium codoping on emission decay in Ce-doped multicomponent garnet scintillators

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 11; no. 35; pp. 127 - 1215
• Main Authors: Nargelas, Saulius, Solovjovas, Arnoldas, Talochka, Yauheni, Podlipskas, ydr nas, Kucera, Miroslav, Lucenicova, Zuzana, Tamulaitis, Gintautas
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 14.09.2023
• Subjects: Cathodoluminescence; Cerium; Decay; Emission analysis; Epitaxial layers; Garnets; Low temperature; Luminescence; Magnesium; Photoluminescence; Radiative recombination; Scintillation counters; Spectroscopy; Spectrum analysis; Thin films; X ray imagery
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d3tc02247a

This study is aimed at the acceleration of luminescence decay in Ce-doped garnet-type scintillators by heavy aliovalent codoping. Time-resolved photoluminescence spectroscopy over a wide temperature range of LuGAGG:Ce epitaxial layers with up to 6000 ppm of codoping magnesium, and a transient absorption technique probing the population of the emitting Ce centers and energies of optical transitions at Ce 3+ ions in the layers, enabled the interpretation of luminescence decay. Heavy Mg-codoping facilitated the luminescence decay acceleration due to the coexistence of two types of emission centers: regular ions of Ce 3+ ; and Ce ions with magnesium in the immediate vicinity, i.e. , Ce 3+ + Mg 2+ centers. In the latter centers, the activation energy for thermal quenching is 0.2 eV, instead of 0.48 eV in regular Ce 3+ centers; and a new channel of temperature-independent nonradiative recombination occurs, pushing the low-temperature luminescence decay time from 50 ns - due to radiative recombination at regular Ce 3+ centers - down to 10.5 ns. The magnesium content does not change the properties of the emission centers but increases the contribution of the Mg-related centers. Time-resolved cathodoluminescence spectroscopy of the layers evidences a broad applicability of the suggested model for heavy aliovalently codoped Ce-doped garnets beyond the LuGAGG:Ce thin films prospective for X-ray imaging. Heavy Mg-codoping substantially increases the emission decay rate of Ce-doped garnet-type scintillators by introducing Mg-Ce centers with a lower barrier for thermal quenching and a channel for temperature-independent nonradiative recombination.