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Article Citation - WoS: 2Citation - Scopus: 2Structural, Electrical and Anisotropic Properties of Tl4se3< Chain Crystals(Pergamon-elsevier Science Ltd, 2009) Qasrawi, A. F.; Gasanly, N. M.The structure, the anisotropy effect on the current transport mechanism and the space charge limited current in Tl4Se3S chain crystals have been studied by means of X-ray diffraction, electrical conductivity measurements along and perpendicular to the crystal's c-axis and the current voltage characteristics. The temperature-dependent electrical conductivity analysis in the region of 150-400 K, revealed the domination of the thermionic emission of charge carriers over the chain boundaries above 210 and 270 K along and perpendicular to the c-axis, respectively. Below these temperatures, the variable range hopping is dominant. At a consistent temperature range, the thermionic emission analysis results in conductivity activation energies of 280 and 182 meV, along and perpendicular to the c-axis, respectively. Likewise, the hopping parameters are altered significantly by the conductivity anisotropy. The current-voltage characteristics revealed the existence of hole trapping state being located at 350 meV above the valence band of the crystal. (C) 2009 Elsevier Ltd. All rights reserved.Article Citation - WoS: 9Citation - Scopus: 9Thermally Stimulated Current Measurements in Undoped Ga3inse4< Single Crystals(Pergamon-elsevier Science Ltd, 2011) Isik, M.; Işık, Mehmet; Gasanly, N. M.; Işık, Mehmet; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics EngineeringThe trap levels in nominally undoped Ga3InSe4 crystals were investigated in the temperature range of 10-300 K using the thermally stimulated currents technique. The study of trap levels was accomplished by the measurements of current flowing along the c-axis of the crystal. During the experiments we utilized a constant heating rate of 0.8 K/s. Experimental evidence is found for one hole trapping center in the crystal with activation energy of 62 meV. The analysis of the experimental TSC curve gave reasonable results under the model that assumes slow retrapping. The capture cross-section of the trap was determined as 1.0 x 10(-25) cm(2) with concentration of 1.4 x 10(17) cm(-3). (C) 2011 Elsevier Ltd. All rights reserved.Article Citation - WoS: 7Citation - Scopus: 7Trapping Centers and Their Distribution in Tl2ga2< Layered Single Crystals(Pergamon-elsevier Science Ltd, 2009) Isik, M.; Gasanly, N. M.Thermally stimulated current (TSC) measurements with current flowing perpendicular to the layers were carried out on Tl2Ga2Se3S layered single crystals in the temperature range of 10-260K. The experimental data were analyzed by using different methods, such as curve fitting, initial rise and isothermal decay methods. The analysis revealed that there were three trapping centers with activation energies of 12, 76 and 177 meV. It was concluded that retrapping in these centers was negligible, which was confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping. The capture cross section and the concentration of the traps have been also determined. An exponential distribution of electron traps was revealed from the analysis of the TSC data obtained at different light illumination temperatures. This experimental technique provided values of 10 and 88 meV/decade for the traps distribution related to two different trapping centers. (C) 2009 Elsevier Ltd. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 7Temperature-Dependent Electrical Resistivity, Space-Charge Current and Photoconductivity of Ga0.75in0.25< Single Crystals(Elsevier Science Bv, 2013) Isik, M.; Gasanly, N. M.Dark electrical resistivity, space-charge-limited (SCL) current and photoconductivity measurements were carried out on Ga0.75In0.25Se single crystals. Analysis of the dark resistivity measurements revealed the presence of one level with activation energy of 0.10 eV. Current voltage characteristics showed that both ohmic and SCL characters exhibit in 180-300 K range. Analysis of the experimental data in the SCL region resulted with a trap level at 0.11 eV above the valence band. Photoconductivity measurements were performed at different light intensities in the temperature range of 150-300 K. Behavior of the recombination mechanism in the crystal was brought out as sublinear recombination from the dependence of photocurrent on illumination intensity. Moreover, obtained activation energies were compared with the results of other experimental techniques applied to Ga0.75In0.25Se crystals in literature. (C) 2013 Elsevier B.V. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 2Trapping Center Parameters in In6s7< Crystals(Elsevier Science Bv, 2011) Isik, M.; Gasanly, N. M.Thermally stimulated current measurements were carried out on In6S7 single crystals in the temperature range of 10-225 K with a constant heating rate of 0.8 K/s. The study of trapping centers was accomplished by the measurements of current flowing along the c-axis of crystals. The analysis of the glow curve according to various methods, such as curve fitting, initial rise and peak shape methods, gives results in good agreement with each other and revealed two trapping centers in In6S7 with activation energies of 157 and 290 meV. Their capture cross sections have been determined as 7.5 x 10(-23) and 7.1 x 10(-20) cm(2),respectively. The good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping has confirmed that retrapping is negligible in these centers. (C) 2011 Elsevier B.V. All rights reserved.Article Citation - WoS: 9Citation - Scopus: 9Transient and Steady State Photoelectronic Analysis in Tlinse2 Crystals(Pergamon-elsevier Science Ltd, 2011) Qasrawi, A. F.; Gasanly, N. M.The temperature and illumination effects on the transient and steady state photoconductivities of TlInSe2 crystals have been studied. Namely, two recombination centres located at 234 and at 94 meV and one trap center located at 173 meV were determined from the temperature-dependent steady state and transient photoconductivities, respectively. The illumination dependence of photoconductivity indicated the domination of sublinear and supralinear recombination mechanisms above and below 160 K, respectively. The change in the recombination mechanism is attributed to the exchange of roles between the linear recombination at the surface and trapping centres in the crystal, which become dominant as temperature decreases. The transient photoconductivity measurement allowed the determination of the capture coefficient of traps for holes as 3.11 x 10(-22) cm(-2). (C) 2011 Elsevier Ltd. All rights reserved.
