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Article Citation - WoS: 1Citation - Scopus: 1Analysis of Glow Curve of Gas0.5se0.5< Single Crystals(Elsevier Science Bv, 2015) Isik, Mehmet; Delice, Serdar; Gasanly, NizamiCharacterization of shallow trapping centers in GaS0.5Se0.5 crystals grown by a Bridgman method was carried out in the present work using thermoluminescence (TL) measurements performed in the low temperature range of 10-300 K. The activation energies of the trapping centers were obtained under the light of results of various analysis methods. The presence of three trapping centers located at 6, 30 and 72 meV was revealed. The analysis of the experimental glow curve gave reasonable results under the model that assumes slow retrapping which states the order of kinetics as b=1. Heating rate dependence of the observed TL peaks was studied for the rates between 0.4 and 1.0 K/s. Distribution of the traps was also investigated using an experimental technique based on the thermal cleaning of centers giving emission at lower temperatures. The distributed levels with activation energies increasing from 6 to 136 meV were revealed by increasing the stopping temperature from 10 to 52 K. (C) 2015 Elsevier B.V. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 9Temperature-Dependent Optical Properties of Tio2 Nanoparticles: a Study of Band Gap Evolution(Springer, 2023) Isik, Mehmet; Delice, Serdar; Gasanly, NizamiIn this study, we present the first comprehensive investigation of the temperature-dependent band gap energy of anatase TiO2 nanoparticles, utilizing transmission measurements in the range of 10-300 K. X-ray diffraction pattern exhibited nine peaks related to tetragonal crystal structure. Scanning electron microscope image showed that the nanoparticles with the dimensions of 25-50 nm were found as micrometer sized agglomerated. When the spectrum obtained as a result of the transmission measurements was analyzed, it was seen that the band gap energy decreased from 3.29(5) to 3.26(6) eV as the temperature was increased from 10 to 300 K. Temperature-band gap dependence was analyzed using Varshni and O'Donnell-Chen optical models and optical parameters of the TiO2 nanoparticles like absolute zero band gap energy, rate of change of band gap with temperature and average phonon energy were reported.
