Emission properties of ZnSe scintillation crystals co-doped by oxygen and aluminum

Photoluminescence properties of ZnSe scintillation crystals co-doped with oxygen and aluminum are studied together with conventional tellurium-doped ZnSe scintillators, for comparison, under continuous-wave and pulsed excitation in the temperature range from 8 to 300 K. A strong enhancement of the low-energy component in the deep-level-related emission is observed as the temperature approaches the room temperature. Fitting of the experimentally observed luminescence decay with calculations of the decay due to donor-acceptor pair recombination revealed that the increased density of recombination centers is responsible for the enhanced low-energy emission component in the co-doped crystals. The significant thermal enhancement of this spectral component is explained by carrier detrapping from the trapping centers abundant in the co-doped crystal due to a large concentration of aluminum impurities.