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Article Defect Characterization of Ga4se3< Layered Single Crystals by Thermoluminescence(indian Acad Sciences, 2016) Isik, M.; Delice, S.; Gasanly, N.Trapping centres in undoped Ga4Se3S single crystals grown by Bridgman method were characterized for the first time by thermoluminescence (TL) measurements carried out in the low-temperature range of 15-300 K. After illuminating the sample with blue light (similar to 470 nm) at 15 K, TL glow curve exhibited one peak around 74 K when measured with a heating rate of 0.4 K/s. The results of the various analysis methods were in good agreement about the presence of one trapping centre with an activation energy of 27 meV. Analysis of curve fitting method indicated that mixed order of kinetics dominates the trapping process. Heating rate dependence and distribution of the traps associated with the observed TL peak were also studied. The shift of peak maximum temperature from 74 to 113 K with increasing rate from 0.4 to 1.2 K/s was revealed. Distribution of traps was investigated using an experimental technique based on cleaning the centres giving emission at lower temperatures. Activation energies of the levels were observed to be increasing from 27 to 40 meV by rising the stopping temperature from 15 to 36 K.Article Citation - WoS: 4Citation - Scopus: 4Crystal Data and Indirect Optical Transitions in Tl2ingase4< Crystals(Pergamon-elsevier Science Ltd, 2008) Qasrawi, A. F.; Gasanly, N. M.The room temperature crystal data and the optical properties of the Bridgman method grown Tl2InGaSe4 crystals are reported and discussed. The X-ray diffraction technique has revealed that Tl2InGaSe4 is a single phase crystal of monoclinic structure. The unit cell lattice parameters, which were recalculated from the X-ray data, are found to be a = 0.77244 nm, b = 0.64945 nm, c = 0.92205 nm and beta = 95.03 degrees. The temperature dependence of the optical band gap of Tl2InGaSe4 single crystal in the temperature region of 290-500 K has also been investigated. The absorption coefficient was calculated from the transmittance and reflectance data in the incident photon energy range of 1.60-2.10 eV. The absorption edge is observed to shift toward lower energy values as temperature increases. The fundamental absorption edge corresponds to indirect allowed transition energy gap of 1.86 eV that exhibited a temperature coefficient gamma = -3.53 x 10(-4) eV/K. (C) 2007 Elsevier Ltd. All rights reserved.Article Citation - WoS: 28Citation - Scopus: 10Electrical Conductivity and Hall Mobility in P-Type Tlgase2 Crystals(Pergamon-elsevier Science Ltd, 2004) Qasrawi, AF; Qasrawı, Atef Fayez Hasan; Gasanly, NM; Qasrawı, Atef Fayez Hasan; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics EngineeringSystematic dark electrical conductivity and Hall mobility measurements have been carried out in the temperature range of 200-350 K on p-type TlGaSe2 crystals. The analysis of the temperature-dependent electrical conductivity and carrier concentration reveals the extrinsic type of conduction with an acceptor impurity level located at 0.33 eV, and donor and acceptor concentrations of 9.0 x 10(15) and 1.3 x 10(16) cm(-3), respectively. A hole and electron effective masses of 0.520m(0) and 0.325m(0), respectively, with a donor to acceptor compensating ratio of 0.69 are also being identified. The Hall mobility is found to be limited by the hole-phonon short-range interactions scattering with a hole-phonon coupling constant of 0.17. (C) 2004 Elsevier Ltd. All rights reserved.
