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Determination of trapping parameters in Tl4Ga3InSe8 single crystals by thermally stimulated luminescence

Thermo luminescence (IL) measurements were performed on Tl4Ga3InSe8 layered single crystals grown by Bridgman method in the temperature range of 10-200 K. After illuminating the sample with blue light at 10 K and heating at a rate of 1.0 K s(-1) in dark, TL curve exhibited peaks around 46 and 123 K. Thermal activation energies of the trap levels corresponding to the observed peaks were determined using curve fitting, initial rise and peak shape methods. Analyses have revealed the presence of two defect centers with activation energies of 7 and 41 meV. The consistency between the theoretical predictions for slow retrapping and experimental results showed that the retrapping process for the observed centers was negligible. Measurements at different heating rates and illumination temperatures were also carried out for the high-temperature peak. Distribution of traps has been established as a result of experiments. An increase of activation energy from 45 to 147 meV was revealed with the change of illumination temperature from 40 to 80 K. (C) 2014 Elsevier B.V. All rights reserved.