Recombination processes with the participation of localized electronic states of band tails in phosphate glasses

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Some regularities of thermally stimulated luminescence and exoelectron emission for phosphate glasses MeOP 2O 5 ( Me = Li, Ca, Sr, Ba, Zn, Be) after external excitation were investigated together with theoretical (MO LCAO cluster simulation) and experimental (ESR, optical absorption) studies of the electronic structure of charge localization centers. The centers involved in the relaxation processes in the bulk and in the surface layers of glasses were subdivided into two classes: (1) discrete levels of defects and (2) continual localized states of band tails. It was shown that the concentration and electronic structure of the latter specify the mechanisms of carrier transport to the luminescence and electron emission centers in glasses containing cation modifiers of different Ditzel ionic field intensity. Hole-induced mechanisms of thermally stimulated electronic processes at temperatures over 523 K have been found. The exoemission observed is due to the Auger recombination with the participation of both discrete and continual centers.