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Citation - WoS: 1
Citation - Scopus: 1
Hole-Polar Phonon Interaction Scattering Mobility in Chain Structured Tlse_0.75s_{0.25< Crystals}
(Wiley-blackwell, 2009) Qasrawi, A. F.; Gasanly, N. M.
In this study, the electrical resistivity, charge carriers density and Hall mobility of chain structured TlSe0.75S0.25 crystal have been measured and analyzed to establish the dominant scattering mechanism in crystal. The data analyses have shown that this crystal exhibits an extrinsic p-type conduction. The temperature-dependent dark electrical resistivity analysis reflected the existence of three energy levels located at 280 meV, 68 meV and 48 meV. The temperature dependence of carrier density was analyzed by using the single donor-single acceptor model. The carrier concentration data were best reproduced assuming the existence of an acceptor impurity level being located at 68 meV consistent with that observed from resistivity measurement, The model allowed the determination of the hole effective mass and the acceptor-donor concentration difference as 0.44m(0) and 2.2 x 10(12) cm(-3), respectively. The Hall mobility of the TlSe0.75S0.25 crystal is found to be limited by the scattering of charged carriers over the (chain) boundaries and the scattering of hole-polar phonon interactions above and below 300 K, respectively. The value of the energy barrier height at the chain boundaries was found to be 261 meV. The polar phonon scattering mobility revealed the high-frequency and static dielectric constants of 13.6 and 15.0, respectively. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Citation - WoS: 5
Citation - Scopus: 5
Dispersive Optical Constants of Tl₂ingase_{4< Single Crystals}
(Iop Publishing Ltd, 2007) Qasrawi, A. F.; Gasanly, N. M.
The structural and optical properties of Bridgman method grown Tl2InGaSe4 crystals have been investigated by means of room temperature x-ray diffraction, and transmittance and reflectance spectral analysis, respectively. The x-ray diffraction technique has shown that Tl2InGaSe4 is a single phase crystal of a monoclinic unit cell that exhibits the lattice parameters of a = 0.77244 nm, b = 0.64945 nm, c = 0.92205 nm and beta = 95.03 degrees . The optical data have revealed an indirect allowed transition band gap of 1.86 eV. The room temperature refractive index, which was calculated from the reflectance and transmittance data, allowed the identification of the dispersion and oscillator energies, static dielectric constant and static refractive index as 28.51 and 3.45 eV, 9.26 and 3.04, respectively.
Citation - WoS: 2
Citation - Scopus: 2
Space-charge-limited currents and photoconductive properties of Tl₂InGaSe₄ layered crystals
(Taylor & Francis Ltd, 2008) Qasrawi, A. F.; Gasanly, N. M.
The extrinsic electronic parameters of Tl2InGaSe4 layered crystals were investigated through measurement of the temperature-dependent dark conductivity, space-charge-limited currents and photoconductivity. Analysis of the dark conductivity reveals the existence of two extrinsic energy levels at 0.40 and 0.51 eV below the conduction band edge, which are dominant above and below 260 K, respectively. Current-voltage characteristics show that the one at 0.51 eV is a trapping energy level with a concentration of (4.8-7.7) x 10(10) cm(3). Photoconductivity measurements reveal the existence of another energy level located at 0.16 eV. In the studied temperature range, the photocurrent increases with increasing temperature. The dependence of the photoconductivity on the incident light intensity exhibits a linear recombination character near room temperature and a supralinear character as the temperature decreases. The change in recombination mechanism is attributed to an exchange in the behavior of sensitizing and recombination centres.
Citation - WoS: 8
Citation - Scopus: 8
Thermoluminescence Properties of Zno Nanoparticles in the Temperature Range 10-300 K
(Springer, 2016) Isik, M.; Yildirim, T.; Gasanly, N. M.
Low-temperature thermoluminescence (TL) properties of ZnO nanoparticles grown by sol-gel method were investigated in the 10-300 K temperature range. TL glow curve obtained at 0.2 K/s constant heating rate exhibited one broad peak around 83 K. The observed peak was analyzed using curve fitting method to determine the activation energies of trapping center(s) responsible for glow curve. Analyses resulted in the presence of three peaks at 55, 85 and 118 K temperatures with activation energies of 12, 30 and 45 meV, respectively. Thermal cleaning process was applied to separate overlapped peaks and get an opportunity to increase the reliability of results obtained from curve fitting method. Heating rate dependence of glow curve was also studied for rates between 0.2 and 0.7 K/s. The shift of the peak maximum temperatures to higher values and decrease in peak height with heating rate were observed. Moreover, X-ray diffraction and scanning electron microscopy were used for structural characterization.
Citation - WoS: 5
Citation - Scopus: 5
Optical Properties of Tlga_xin_{1-x< Mixed Crystals (0.5 ≤ x ≤ 1) by Spectroscopic Ellipsometry, Transmission, and Reflection}
(Taylor & Francis Ltd, 2014) Isik, M.; Delice, S.; Gasanly, N. M.
The layered semiconducting TlGaxIn1-xSe2-mixed crystals (0.5 <= x <= 1) were studied for the first time by spectroscopic ellipsometry measurements in the 1.2-6.2 eV spectral range at room temperature. The spectral dependence of the components of the complex dielectric function, refractive index, and extinction coefficient were revealed using an optical model. The interband transition energies in the studied samples were found from the analysis of the second-energy derivative spectra of the complex dielectric function. The effect of the isomorphic cation substitution (indium for gallium) on critical point energies in TlGaxIn1-xSe2 crystals was established. Moreover, the absorption edge of TlGaxIn1-xSe2 crystals have been studied through the transmission and reflection measurements in the wavelength range of 500-1100 nm. The analysis of absorption data revealed the presence of both optical indirect and direct transitions. It was found that the energy band gaps decrease with the increase of indium content in the studied crystals.
Citation - WoS: 3
Citation - Scopus: 3
Optoelectronic Properties of Ga₄se_{3< Single Crystals}
(Iop Publishing Ltd, 2008) Qasrawi, A. F.; Gasanly, N. M.; Ilaiwi, K. F.
The optoelectronic properties of Bridgman method-grown Ga(4)Se(3)S single crystals have been investigated by means of room temperature electrical resistivity, temperature-dependent photosensitivity and temperature-dependent optical absorption. The photosensitivity was observed to increase with decreasing temperature, the illumination dependence of which was found to exhibit monomolecular recombination in the bulk at 300 K. The absorption coefficient, which was calculated in the incident photon energy range of 2.01-2.35 eV, increased with increasing temperature. Consistently, the absorption edge shifts to lower energy values. The fundamental absorption edge corresponds to an indirect allowed transitions energy gap (2.08 eV at 300 K) that exhibits a temperature coefficient of -95 x 10(-4) eVK(-1).
Citation - WoS: 5
Citation - Scopus: 5
Growth and Temperature Tuned Band Gap Characteristics of Nabi(moo₄)_{2< Single Crystal}
(Iop Publishing Ltd, 2023) Isik, M.; Guler, I; Gasanly, N. M.
Structural and optical properties of double sodium-bismuth molybdate NaBi(MoO4)(2) semiconductor compound was investigated by x-ray diffraction, Raman and transmission experiments. From the x-ray diffraction experiments, the crystal that has tetragonal structure was obtained. Vibrational modes of the crystal were found from the Raman experiments. Transmission experiments were performed in the temperature range of 10-300 K. Derivative spectroscopy analysis and absorption spectrum analysis were performed to get information about the change in band gap energy of the crystal with temperature. It was observed that the band gap energies of the crystal at different temperatures obtained from these techniques are well consisted with each other. By the help of absorption spectrum which was obtained from transmission measurements performed at varying temperatures, absolute zero value of the band gap and average phonon energy as 3.03 +/- 0.02 eV and Eph = 24 +/- 0.2 meV, respectively. Moreover, based on absorption spectrum analysis the Urbach energy of the crystal was obtained as 0.10 eV.
Citation - WoS: 7
Citation - Scopus: 7
Dynamical and Passive Characteristics of the Ag/Tlgases Rf Resonators
(Wiley-v C H verlag Gmbh, 2012) Qasrawi, A. F.; Elayyat, S. M. S.; Gasanly, N. M.
Ag contacts on the surface of the TlGaSeS single crystals are observed to exhibit Schottky characteristics. The ideality factor of the Ag/ TlGaSeS/Ag device decreased from 5.2 to 1.3 by the reduction of series resistance effect on the I-V characteristics. Cheung's model analysis revealed a series resistance and barrier height of 40.6 KO and 0.32 V, respectively. The device was run on the passive mode by injection with an alternating ac signal of variable frequency in the frequency range of 0-120 MHz and recoding the device capacitance. Several resonance-antiresonance positions in the range of 27-350 KHz were observed. The tangent loss factor of the passive device was observed to decrease with increasing frequency. It exhibited a very low loss value of the order of 10-5 at 120 MHz. Such property is a characteristic of high performance tunable device being suitable as processor clock controller.
Citation - WoS: 15
Citation - Scopus: 15
Refractive Index, Static Dielectric Constant, Energy Band Gap and Oscillator Parameters of Ga₂ses Single Crystals
(Wiley-v C H verlag Gmbh, 2007) Qasrawi, A. F.; Gasanly, N. M.
The optical properties of Bridgman method grown Ga2SeS crystals have been investigated by means of room-temperature transmittance and reflectance spectral analysis. The optical data have revealed direct and indirect allowed transition band gaps of 2.49 and 2.10 eV, respectively. The room-temperature refractive index, which was calculated from the reflectance and transmittance data, allowed the identification of the dispersion and oscillator energies, static dielectric constant and static refractive index as 20.93 eV and 4.01 eV, 6.21 and 2.49, respectively.
Influence of Photonic Excitations on the Electrical Parameters of Tlins₂ Crystals
(Wiley-v C H verlag Gmbh, 2010) Qasrawi, A. F.; Gasanly, N. M.
The photo-excitation effect on the current transport mechanism in TlInS2 crystals has been studied by means of dark and illuminated conductivity measurements. The temperature-dependent electrical conductivity analysis in the temperature region of 110-340 K revealed the domination of the thermionic emission and the thermally assisted variable range hopping (VRH) of charge carriers above and below 160 K, respectively. Above 160 K, the conductivity activation energies in the dark are found to be 0.28 and 0.15 eV in the temperature regions of 340-240 K and 230-160 K, respectively. In the temperature region of 110-150 K, the dark variable range hopping analysis revealed a density of localized states of 1.99x 10(22) cm(-3)eV(-1), an average hopping distance of 0.53 nm and an average hopping energy of 79.65 meV. When the sample was photo-excited, the values of the conductivity activation energies, the density of localized states near the Fermi level and the average hopping energy were observed to decrease sharply with increasing illumination intensity. On the other hand, the average hopping distance increased with rising illumination intensity. Such behaviours were attributed to the Fermi level shift and/or trap density reduction by electron-hole recombination. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

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