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Article Citation - WoS: 1Citation - Scopus: 1Photovoltaic Effect and Space Charge Limited Current Analysis in Tlgate2 Crystals(Polish Acad Sciences inst Physics, 2012) Qasrawi, A. F.; Yaseen, T. R.; Eghbariy, B.; Gasanly, N. M.Anisotropic space charge limited current density analysis and photovoltaic effect in TlGaTe2 single crystals has been investigated. It is shown that, above 330 K, the crystal exhibits intrinsic and extrinsic type of conductivity along (c-axis) and perpendicular (a-axis) to the crystal's axis, respectively. The current density (J) is found to be space charge limited. It is proportional to the square and three halves power of voltage (V) along the a- and c-axis, respectively. Along the a-axis and at sufficiently low electric field values, the activation energy of the current density is found to depend on the one half power of electric field. At high electric fields, the activation energy is field invariant. This behavior is found to be due to the Pool Frenkel effect and due to a trap set located at 0.26 eV, respectively. Along the c-axis the crystal is observed to operate under the Child Langmuir space charge limited regime. TlGaTe2 crystals are found to exhibit photovoltaic properties. The open circuit photovoltage is recorded as a function of illumination intensity at room temperature.Article Citation - WoS: 6Citation - Scopus: 6Low-Temperature Thermo Luminescence Studies on Tlins2 Layered Single Crystals(Polish Acad Sciences inst Physics, 2014) Isik, M.; Delice, S.; Gasanly, N. M.Thermoluminescence characteristics of TlInS2 layered single crystals grown by the Bridgman method were investigated in the low temperature range of 10-300 K. The illuminated sample with blue light (approximate to 470 nm) at 10 K was heated at constant heating rate. Curve fitting, initial rise and various heating rate methods were used to determine the activation energy of the trap levels. All applied methods showed good consistency about the presence of five trapping centers located at 14, 19, 350, 420, and 520 meV. Behavior of the TL curve for various heating rates was investigated. Traps distribution has also been studied. The activation energies of the distributed trapping centers were found to be increasing from 14 to 46 meV.Article Citation - WoS: 15Citation - Scopus: 15Deep Traps Distribution in Tlins2 Layered Crystals(Polish Acad Sciences inst Physics, 2009) Isik, M.; Gasanly, N. M.; Ozkan, H.The trap centers and distributions in TlInS2 were studied in the temperature range of 100-300 K by using thermally stimulated currents technique. Experimental evidence was found for the presence of three trapping centers with activation energies 400, 570, and 650 meV. Their capture cross-sections were determined as 6.3 x 10(-16), 2.7 x 10(-12), and 1.8 x 10(-11) cm(2), respectively. It was concluded that in these centers retrapping is negligible as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping. An exponential distribution of hole traps was revealed from the analysis of the thermally stimulated current data obtained at different light excitation temperatures. This experimental technique provided a value of 800 meV/decade for the trap distribution.Article Compositional Dependence of Optical Modes Frequencies in T1gax< Layered Mixed Crystals (0 ≤ x ≤ 1)(Polish Acad Sciences inst Physics, 2014) Isik, M.; Gasanly, N. M.; Korkmaz, F.The infrared transmittance and Raman scattering spectra in TlGaxIn1-xS2 (0 <= x <= 1) layered mixed crystals grown by the Bridgman method were studied in the frequency ranges of 400-2000 and 250-400 cm(-1), respectively. The bands observed at room temperature in IR transmittance spectra of TlGaxIn1-xS2 were interpreted in terms of multiphonon absorption processes. The dependences of the frequencies of IR- and Raman-active modes on the composition of TlGaxIn1-xS2 mixed crystals were also established. The structural characterization of the mixed crystals was investigated by means of X-ray diffraction measurements and compositional dependence of lattice parameters was revealed.Article Driving Electric Field Effects on the Space Charge Limited Photocurrent of In6s7<(Natl inst Optoelectronics, 2013) Qasrawi, A. F.; Al-Balshi, Madleen A.; Gasanly, N. M.; Department of Electrical & Electronics EngineeringA new type of photovoltaic materials, which are designed on the base of In6S7 single crystals using silver and gold metals to construct Ag/In6S7/Au point contacted photocells, are reported and discussed. The influence of the driving electric field on the performance of the device was tested. The current density-electric field dependence curve reflected a space charge limited photocurrent effect being dominant in the field region of 1.0-4.3 V/cm. In addition, the In6S7 photocell short circuit and loaded current dependencies on the excitation intensity were measured. The short circuit current was observed to exhibit exponential trap distribution effect and supralinear recombination at low and high illumination intensities, respectively. The device displays a current density of 0.5 mA/cm(2) for excitation intensity of 76 klux. When loaded, it displayed a stable power dissipation curve. Such behavior reflects the novelty of these types of cells for future application.Article Analysis of Thermoluminescence Glow Peaks in Β-Irradiated Tlgases Crystals(Polish Acad Sciences inst Physics, 2016) Isik, M.; Yildirim, T.; Gasanly, N. M.Thermoluminescence properties of TlGaSeS layered single crystals were investigated in the temperature range of 280-720 K. Thermoluminescence glow curve exhibited three peaks with maximum temperatures of approximate to 370, 437, and 490 K. Curve fitting, initial rise and peak shape methods were used to determine the activation energies of the trapping centers. All applied methods resulted with energies around 0.82, 0.91, and 0.99 eV. Dose dependence of the thermoluminescence intensity was also examined for the doses in the range of 0.7-457.6 Gy. Peak maximum intensity of the observed peak around 370 K showed an increase up to a certain dose and then a decrease at higher doses. This non-monotonic dose dependence was discussed under the light of a reported model in which different kinds of competition between radiative and nonradiative recombination centers during excitation or heating stages of the thermoluminescence process are explained.
