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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: 9Citation - Scopus: 10Spectroscopic Ellipsometry Investigation of Optical Properties of Β-ga2s3< Single Crystals(Elsevier Science Bv, 2018) Isik, M.; Gasanly, N. M.; Gasanova, L.Ga2S3 single crystals were studied by x-ray diffraction (XRD), energy dispersive spectroscopy and spectroscopic ellipsometry measurements. XRD pattern of the sample is well-matched with reported hexagonal structure of beta-Ga2S3 . The spectra of real and imaginary parts of complex dielectric function (epsilon = epsilon(1) + epsilon(2)) and refractive index (N = n + ik) were plotted in the 1.2-6.2 eV range according to results of ellipsometric data. The e 2 -spectrum and analyses of absorption coefficient pointed out that studied sample has band gap energy of 2.48 eV which is consistent with that of beta-Ga(2)S(3)2. Critical point energies of beta-Ga2S3 were also reported in the present study.Article Citation - WoS: 24Citation - Scopus: 22Spectroscopic Ellipsometry Study of Above-Band Gap Optical Constants of Layered Structured Tlgase2, Tlgas2 and Tlins2 Single Crystals(Elsevier Science Bv, 2012) Isik, M.; Gasanly, N. M.; Turan, R.Spectroscopic ellipsometry measurements on TlGaSe2, TlGaS2 and TlInS2 layered crystals were carried out on the layer-plane (0 0 1) surfaces, which are perpendicular to the optic axis c*, 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 found as a result of analysis of ellipsometric data. The structures of critical points in the above-band gap energy range have been characterized from the second derivative spectra of the pseudodielectric function. The analysis revealed four, five and three interband transition structures with critical point energies 2.75, 3.13, 3.72 and 4.45 eV (TlGaSe2), 3.03, 3.24, 3.53, 4.20 and 4.83eV (TlGaS2), and 3.50, 3.85 and 4.50 eV (TlInS2). For TlGaSe2 crystals, the determined critical point energies were assigned tentatively to interband transitions using the available electronic energy band structure. (c) 2012 Elsevier B.V. All rights reserved.Article Citation - Scopus: 1Infrared and Raman Scattering Spectra of Layered Structured Ga3inse4< Crystals(Elsevier Science Bv, 2013) Isik, M.; Gasanly, N. M.; Korkmaz, F.The infrared reflectivity and transmittance and Raman scattering in Ga3InSe4 layered crystals were investigated in the frequency ranges of 100-400, 400-4000 and 25-500 cm(-1). The refractive and absorption indices, the frequencies of transverse and longitudinal optical modes, high- and low-frequency dielectric constants were obtained from the analysis of the IR reflectivity spectra. The bands observed in IR transmittance spectra were interpreted in terms of two-phonon absorption processes. (C) 2012 Elsevier B.V. All rights reserved.Article Citation - WoS: 7Citation - Scopus: 9Thermoluminescence Study in Cu3ga5< Single Crystals: Application of Heating Rate and tm< Methods(Elsevier Science Bv, 2018) Isik, M.; Gasanly, N. M.; Gasanova, L. G.; Mahammadov, A. Z.Cu3Ga5S9 semiconducting single crystals were investigated using thermoluminescence (TL) measurements in 10-300 K temperature region. In the TL glow curve, one peak starting to appear at the instant temperature is increased from 10 K and another peak, which is broader than a general individual TL peak, were observed. The broad peak around 66 K was investigated using T-m-T-stop experimental method to understand whether or not this peak is composed of more than one individual peaks or continuously distributed traps. Curve fitting, initial rise and peak shape methods were used for acceptable TL curves to be analyzed. TL curves in T-m-T-stop method indicated that observed peaks are due to the existence of quasi-continuous distribution of traps. Structural characterizations of Cu3Ga5S9 single crystals were studied using x-ray diffraction and energy dispersive spectroscopy measurements. The crystal structure, lattice parameters and atomic composition of the elements were reported in the present paper.Article Citation - WoS: 2Citation - Scopus: 2Properties of Tl4se3< Single Crystals and Characterization of Ag/Tl4< Schottky Barrier Diodes(Elsevier Science Bv, 2010) Qasrawi, A. F.; Gasanly, N. M.The main physical properties of Tl4Se3S single crystals were investigated for the first time. Particularly, the crystal data, Debye temperature, dark electrical resistivity and Hall effect in addition to the temperature dependent current-voltage characteristics and photosensitivity of the Ag/Tl4Se3S Schottky barrier diode were studied. The X-ray diffraction patterns have revealed that the crystal exhibited a single phase of tetragonal structure belonging to the D-4h(18) - 14mcm space group. A Debye temperature of 100 K was calculated using the results of the X-ray diffraction analysis. The dark electrical resistivity and Hall-effect measurements indicated that the samples exhibits p-type conduction with an electrical resistivity, carrier concentration and Hall mobility of 6.20 x 10(3) Omega cm, 1.16 x 10(12) cm(-3) and 873 cm(2) V-1 s(-1), respectively. The crystals were observed to have Schottky diode properties. The Ag/Tl4Se3S Schottky barrier device bias voltage was observed to depend on the crystal direction and on temperature. It was found that the calculated energy barrier height decreased and the diode ideality factor increased with temperature decreasing. The photosensitivity-light intensity dependence of this device was found to be linear reflecting the ability of using it in optoelectronics. (C) 2009 Elsevier B.V. All rights reserved.Conference Object Citation - WoS: 2Citation - Scopus: 2Temperature-Dependent Capacitance-Voltage Biasing of the Highly Tunable Tlgate2 Crystals(Elsevier Science Bv, 2012) Qasrawi, A. F.; Gasanly, N. M.The temperature effects on the capacitance-voltage characteristics as well as the room temperature capacitance-frequency characteristics of TlGaTe2 crystals are investigated. A very wide range of linearly varying tunable capacitance from 6.0 mu F to 60 pF was recorded. The capacitance-voltage characteristics, being recorded in the temperature range of 290-380 K, revealed a linear increase in the build in voltage associated with exponential decrease in the density of non-compensated ionized carriers with increasing temperature. The high temperature (up to 380 K) biasing ability, the linear tunability and the high dielectric constant values ( similar to 10(3)) make the TlGaTe2 crystals applicable in microelectronic components. (C) 2012 Elsevier B.V. All rights reserved.Article Citation - WoS: 3Citation - Scopus: 3Temperature and Excitation Intensity Tuned Photoluminescence in Ga0.75in0.25< Crystals(Elsevier Science Bv, 2013) Isik, M.; Guler, I.; Gasanly, N. M.Photoluminescence (PL) spectra of Ga0.75In0.25Se layered single crystals have been studied in the wavelength range of 580-670 nm and temperature range of 7-59 K. Two PL emission bands centered at 613 nm (2.02 eV, A-band) and 623 nm (1.99 eV, B-band) were revealed at T = 7K. The excitation laser intensity dependence of the emission bands have been studied in the 0.06-1.40 W cm(-2) range. Radiative transitions from shallow donor levels located at E-A = 0.11 and E-B = 0.15 eV below the bottom of conduction band to single shallow acceptor level located at 0.01 eV above the valence band are suggested to be responsible for the observed A- and B-bands. A simple model was proposed to interpret the recombination processes in Ga0.75In0.25Se single crystals. (c) 2012 Elsevier B.V. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 8Photo-Transferred Thermoluminescence of Shallow Traps in Β-Irradiated Beo Ceramics(Elsevier Science Bv, 2017) Isik, M.; Bulur, E.; Gasanly, N. M.Photo-transferred thermoluminescence signals from beryllium oxide (BeO) ceramics were measured in the low temperature range of 10-300 K. Samples irradiated at room temperature using a Sr-90/Y-19 beta source were cooled down to 10 K and trapped charges were photo-transferred at this low temperature using the light from a high power blue LED emitting at similar to 470 nm (2.6 eV). Thermoluminescence glow curve recorded at 0.2 K/s heating rate exhibited three peaks around 90, 160 and 185 K. The analyses of the TL peaks of the glow curve were accomplished using curve fitting, differential and peak shape methods. Results obtained from these techniques are in good agreement about the presence of three trapping centers in BeO ceramics with activation energies of 0.24, 0.48 and 0.56 eV. Moreover, the analyses indicated that first-order kinetics (slow retrapping) is the dominant mechanism in the luminescence process. Heating rate dependence of the glow curves was also investigated between 0.2 and 0.8 K/s rates. (C) 2017 Elsevier B.V. All rights reserved.Article Citation - WoS: 9Citation - Scopus: 8Multiphonon Absorption Processes in Layered Structured Tlgas2, Tlins2 and Tlgase2 Single Crystals(Elsevier Science Bv, 2013) Isik, M.; Gasanly, N. M.; Korkmaz, F.The infrared transmittance and Raman scattering spectra in TlGaS2, TlInS2 and TlGaSe2 layered single crystals grown by Bridgman method were studied in the frequency ranges of 400-1500 and 10-400 cm(-1), respectively. Three, three and five bands observed at room temperature in IR transmittance spectra of TlGaS2, TlInS2 and TlGaSe2, respectively, were interpreted in terms of multiphonon absorption processes. (C) 2013 Elsevier By. All rights reserved.
