Influence of Disorder in Scintillating Solid Solutions on Thermalization and Recombination of Electronic Excitations

Abstract

The spatial distribution of components of substitutional solid solution is nonuniform. This disorder influences optical properties, migration, localization, and recombination of secondary electrons and holes created by high‐energy excitation. The scintillation properties in such systems are studied in terms of fluctuations of the bottom of the conduction band due to the disorder of the substitutional solid solution AxB1 − xC. The simulation of the spatial distribution of the components is performed for different affinities of the components. If the creation of AA (BB) pairs is preferable (high AA affinity), the fluctuations of the bottom of the conduction band can result even in the creation of clusters enriched by AC or BC components. The scattering of hot electrons by the fluctuations of the spatial structure of solid solution at the thermalization stage is discussed. The role of clustering of solid solution in the restriction of migration and recombination of thermalized carriers is analyzed using the model of the geminate recombination of electron–hole pairs. The change of properties of some scintillators (YAG‐LuAG, CeF3‐LaF3, etc.) with concentrations of components is explained on the basis of the considered models.