Influence of Mg‐to‐Ce Concentration Ratio on Cathodoluminescence in LuAG and LuGAGG Single‐Crystalline Films

Abstract

The cathodoluminescence (CL) characterizations of Lu3Al5O12:Ce,Mg (LuAG:Ce,Mg) and of multicomponent (Lu0.25Gd0.74)3(Ga2.48Al2.52)O12:Ce,Mg (LuGAGG:Ce,Mg) single‐crystalline garnet films are supported by the optical absorption spectroscopy. Using this approach, the influence of the Mg‐to‐Ce concentration ratio on the CL spectra and the CL decay is analyzed. The crucial role of stable Ce4+ centers in CL is shown in Mg‐rich film studies. Although the CL intensity is somewhat reduced, drastic improvements in timing performance are demonstrated, including the CL decay time as low as 4.2 ns and the afterglow as low as 0.015% at 500 ns after the e‐beam excitation cutoff. These results predetermine the utilization of the LuAG:Ce,Mg and LuGAGG:Ce,Mg single‐crystalline films in e‐beam detection systems, where especially fast scintillator response is crucial.

Composite Detectors Based on Single-Crystalline Films and Single Crystals of Garnet Compounds

“…Strong modification of the scintillation decay kinetics of SCF doped with Ce 3+ LuAG and mixed grenades is observed due to co-doping with M 2+ (M = Mg 2+ , Ca 2+ ) and formation of partial cerium ions in the Ce 4+ charge state [ 70 , 71 , 72 , 73 , 74 ]. In this way, the scintillation decay kinetics of the doubly doped garnet compounds of Ce 4+ -M 2+ garnet are strongly accelerated.…”

“…The absorption spectra of Gd 3 Al 5−x Ga x O 12 :Ce/GAGG2.5:Ce (x = 1.16–2.615) composite scintillators show the presence of an additional broadband peak at about 255 nm ( Figure 15 ). This band is related to the O 2+ Ce 4+ charge transfer transitions (CTT) (see [ 70 , 71 , 72 , 73 , 74 ] for details). The formation of Ce 4+ states in these SCFs, especially in the samples with the highest Ga content, is due to the inclusion of the impurity associated with the Pb 2+ flux ( Table 2 ).…”

“…A negative influence of Pb 2+ on the LY of epitaxially grown films was observed in many scintillators [ 3 , 22 , 27 , 28 , 29 , 62 , 63 , 64 ]. Such influence can be attributed to the creation of Pb 2+ -Ce 4+ pairs due to charge and volume compensation at relatively large concentration of lead ions in SCF samples and subsequent reduction in Ce 3+ concertation ions in garnet hosts (see [ 70 , 71 , 72 , 73 ] for details).…”

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

“…Such a change of absorption spectrum in LYSO:-Ce,Mg is attributed to transforming Ce 3+ ions into Ce 4+ ions by introduction of divalent Mg 2+ ions 9 and is observed in many codoped garnets including LuAG:Ce,Mg 20 and LuGAGG:-Ce,Mg. 21 This transformation is accompanied by increasingly broad UV absorption band, probably related to absorption at certain Mg-related centers. Sample S6 with 6000 ppm of magnesium exhibits extremely weak Ce 3+ -related absorption and emission, probably due to the substantial deterioration of the matrix structure as the Mg content is high, and serves as a reference of the limit of Mg-codoping capability.…”

Ho3+ codoping of GGAG:Ce: a detailed analysis of acceleration of scintillation response and scintillation efficiency loss

“…26 In the study of scintillation characteristics special attention was paid to stabilization of Ce 4+ by stable divalent dopants as Mg 2+ or Ca 2+ which creates new fast radiative recombination pathway at Cerium centers and accelerates noticeably the scintillation response. [27][28][29][30] Other codopants were studied for this purpose as well. 31 Dependence of the bandgap value on the host composition was also studied 32,33 and garnet compounds luminescence and scintillation characteristics were reviewed in ref.…”