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Article Citation - WoS: 4Citation - Scopus: 5Thermoluminescence Properties of Tl2ga2< Layered Single Crystals(Amer inst Physics, 2013) Delice, S.; Isik, M.; Bulur, E.; Gasanly, N. M.The trap center(s) in Tl2Ga2S3Se single crystals has been investigated from thermoluminescence (TL) measurements in the temperature range of 10-300 K. Curve fitting, initial rise, and peak shape methods were applied to observed TL glow curve to evaluate the activation energy, capture cross section, and attempt-to-escape frequency of the trap center. One trapping center has been revealed with activation energy of 16 meV. Moreover, the characteristics of trap distribution have been studied using an experimental technique based on different illumination temperature. An increase of activation energy from 16 to 58 meV was revealed for the applied illumination temperature range of 10-25K. (C) 2013 AIP Publishing LLC.Article Citation - WoS: 3Citation - Scopus: 4Hall Mobility and Photoconductivity in Tlgases Crystals(Amer inst Physics, 2013) Qasrawi, A. F.; Gasanly, N. M.In this work, the fundamental properties of the TlGaSeS single crystals are investigated by means of temperature dependent electrical resistivity and Hall mobility. The crystal photo-responsibility as function of illumination intensity and temperature is also tested in the temperature range of 350-160 K. The study allowed the determination of acceptor centers as 230 and 450 meV below and above 260 K, and recombination centers as 181, 363, and 10 meV at low, moderate, and high temperatures, respectively. While the temperature-dependent Hall mobility behaved abnormally, the photoconductivity analysis reflected an illumination intensity dependent recombination center. Namely, the recombination center increased from 10 to 90 meV as the light intensity increased from 27.9 to 76.7 mW cm(-2), respectively. That strange behavior was attributed to the temporary shift in Fermi level caused by photoexcitation. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4775577]Article Citation - WoS: 19Citation - Scopus: 19Temperature-Dependent Band Gap Characteristics of Bi12sio20< Single Crystals(Amer inst Physics, 2019) Isik, M.; Delice, S.; Gasanly, N. M.; Darvishov, N. H.; Bagiev, V. E.Bi12SiO20 single crystals have attracted interest due to their remarkable photorefractive characteristics. Since bandgap and refractive index are related theoretically to each other, it takes much attention to investigate temperature dependency of bandgap energy to understand the behavior of photorefractive crystals. The present study aims at investigating structural and optical characteristics of photorefractive Bi12SiO20 single crystals grown by the Czochralski method. The structural characterization methods indicated that atomic composition ratios of constituent elements were well-matched with the chemical compound Bi12SiO20, and grown crystals have a cubic crystalline structure. Optical properties of crystals were investigated by room temperature Raman spectroscopy and temperature-dependent transmission measurements between 10 and 300 K. The analyses of transmittance spectra by absorption coefficient and derivative spectrophotometry techniques resulted in energy bandgaps decreasing from 2.61 to 2.48 eV and 2.64 to 2.53 eV as temperature was increased from 10 to 300 K. The Varshni model was applied to analyze temperature-bandgap energy dependency.Article Citation - WoS: 5Citation - Scopus: 4Dielectric Functions and Interband Critical Points of Anisotropic Chain Structured Tlse Single Crystals(Amer inst Physics, 2012) Isik, M.; Gasanly, N. M.Spectroscopic ellipsometry measurements were carried out on TlSe single crystals for orientations of electric field, parallel (E parallel to c), and perpendicular (E perpendicular to c) to optic axis c. The experiments were performed in the 1.2-6.2 eV spectral range at room temperature. The real and imaginary parts of the pseudodielectric function as well as pseudorefractive index and pseudoextinction coefficient were calculated from the analysis of ellipsometric data under the light of ambient-substrate optical model. The energies of interband transitions (critical points) have been found from the analysis on second derivative spectra of the pseudodielectric function. The analysis revealed four and five interband transition structures for E parallel to c and E perpendicular to c configurations, respectively. The obtained critical point energies were assigned tentatively to interband transitions using the available electronic energy band structure given in literature. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4761963]
