Tunneling recombination luminescence under excitation of PbWO4:Mo crystals in the defect-related absorption region |
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Authors: | P. Fabeni,T. Kä rner,M. Nikl,S. Zazubovich |
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Affiliation: | a Institute of Applied Physics “N.Carrara”(IFAC) of CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Firenze), Italy b Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia c Institute of Physics AS CR, Cukrovarnicka 10, 162 53 Prague, Czech Republic |
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Abstract: | Time-resolved emission and excitation spectra and luminescence decay kinetics were studied at 150-300 K for the green emission of PbWO4:Mo crystals. It was found that the slow (μs-ms) decay component observed under excitation in the defect-related absorption region (around 3.8-3.9 eV) arises from the G(II) emission which appears at the tunneling recombination of optically created electron and hole centers. The study of the emission decay kinetics at different temperatures and excitation intensities allowed concluding that both the monomolecular and the bimolecular tunneling recombination process can be stimulated in the mentioned energy range. The monomolecular process takes place in the isolated spatially correlated pairs of electron and hole centers produced without release of electrons into the conduction band. The bimolecular process takes place in the pairs of randomly distributed centers created at the trapping of free electrons from the conduction band. The formation of electron centers under irradiation in the defect-related absorption region was investigated by the electron spin resonance (ESR) and thermally stimulated luminescence (TSL) methods. The possibility of various photo-thermally stimulated defects creation processes, which take place with and without release of free electrons into the conduction band, was confirmed. |
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Keywords: | 78.55.Hx 78.47.+p 78.60.Kn 71.55.Ht 78.40.Ha 76.30.Da |
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