Browsing by Author "Gasanly, N. M."

Now showing 1 - 20 of 174

Citation Count: 5
Absorption Edge and Optical Constants of Tl₂ga_{2< Crystals From Reflection and Transmission, and Ellipsometric Measurements}
(Elsevier, 2012) Isik, M.; Işık, Mehmet; Gasanly, N. M.; Department of Electrical & Electronics Engineering
The optical properties of Tl2Ga2S3Se layered crystalline semiconductors were investigated from transmission, reflection and ellipsometric measurements. The experimental results of the room temperature transmission and reflection measurements performed in the wavelength range of 400-1100 nm showed the presence of both indirect and direct transitions in the band structure of the crystals with 2.38 and 2.62 eV band gap energies. Spectroscopic ellipsometry measurements on Tl2Ga2S3Se crystals were carried out on the layer-plane (0 0 1) surfaces with light polarization E perpendicular to c* in the 1.20-4.70 eV spectral range at room temperature. The real and imaginary parts of the dielectric function as well as refractive and absorption indices were found as a result of analysis of ellipsometric data. The Wemple-DiDomenico single-effective-oscillator model was used to study the dispersion of the refractive index in the below band gap energy range. The structures of critical points have been characterized from the second derivative spectra of the dielectric function. The analysis revealed four interband transition structures with 3.14, 3.40, 3.86 and 4.50 eV critical point energies. (C) 2012 Elsevier B.V. All rights reserved.
Citation Count: 5
Acoustic Phonons Scattering Mobility and Carrier Effective Mass in In₆s_{7< Crystals}
(Elsevier Science Sa, 2006) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Gasanly, N. M.; Department of Electrical & Electronics Engineering
Systematic dark electrical resistivity and Hall coefficient measurements have been carried out in the temperature range of 170-320 K on n-type In6S7 crystals. The analysis of the electrical resistivity and carrier concentration reveals the intrinsic type of conduction with an average energy band gap of similar to 0.75 eV The carrier effective masses of the conduction and valence bands were calculated from the intrinsic temperature-dependent carrier concentration data and were found to be 0.565m(0) and 2.020m(0), respectively. The temperature-dependent Hall mobility was observed to follow the mu alpha T-3/2 law and was analyzed assuming the domination of acoustic phonons scattering. The acoustic phonons scattering mobility was calculated from the crystal's structural data with no assumptions. The experimental Hall mobility data of In6S7 crystals coincides with the theoretical acoustic phonons scattering mobility data with acoustic deformation potential of 6.4 eV. (c) 2006 Elsevier B.V. All rights reserved.
Citation Count: 2
Analysis of Temperature-Dependent Transmittance Spectra of Zn_0.5in_{0.5< (zis) Thin Films}
(Springer, 2019) Isik, M.; Işık, Mehmet; Gullu, H. H.; Delice, S.; Güllü, Hasan Hüseyin; Gasanly, N. M.; Parlak, M.; Department of Electrical & Electronics Engineering
Temperature-dependent transmission experiments of ZnInSe thin films deposited by thermal evaporation method were performed in the spectral range of 550-950nm and in temperature range of 10-300K. Transmission spectra shifted towards higher wavelengths (lower energies) with increasing temperature. Transmission data were analyzed using Tauc relation and derivative spectroscopy. Analysis with Tauc relation was resulted in three different energy levels for the room temperature band gap values of material as 1.594, 1.735 and 1.830eV. The spectrum of first wavelength derivative of transmittance exhibited two maxima positions at 1.632 and 1.814eV and one minima around 1.741eV. The determined energies from both methods were in good agreement with each other. The presence of three band gap energy levels were associated to valence band splitting due to crystal-field and spin-orbit splitting. Temperature dependence of the band gap energies were also analyzed using Varshni relation and gap energy value at absolute zero and the rate of change of gap energy with temperature were determined.
Citation Count: 6
Analysis of the Hall Effect in Tlgate₂ Single Crystals
(Iop Publishing Ltd, 2009) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Gasanly, N. M.; Department of Electrical & Electronics Engineering
The electrical resistivity and Hall coefficient of p-type TlGaTe2 crystals were measured in the temperature range of 110-320 K. The electrical resistivity, charge carrier density and Hall mobility data for the crystals have been analyzed by means of existing theories and models to determine the extrinsic energy levels, the carrier effective mass, the donor and acceptor concentrations and the dominant scattering mechanism in the crystal as well. The analysis of the temperature-dependent electrical resistivity recorded parallel and perpendicular to the crystal's axis ( c-axis) reflected the existence of energy levels located at 0.26 and at 0.20 eV, respectively. The difference of these two energy levels is due to crystal anisotropy. The energy level at 0.26 eV was found to represent an acceptor level, as confirmed from Hall data analysis. The temperature dependence of the carrier density was analyzed by using the single-donor-single-acceptor model. The latter analysis revealed the carrier effective mass and the acceptor and donor concentrations as 0.73m(0), 4.10 x 10(17) cm(-3) and 1.20 x 10(17) cm(-3), respectively. The Hall mobility of TlGaTe2 is found to be limited by the scattering of hole-acoustic phonon interactions. The calculated theoretical mobility fits to the experimental one under the condition that the acoustic deformation potential is 11.0 eV, which is the energy position of the top of valence band maximum that is formed by the Te 5s states.
Citation Count: 0
Analysis of Thermoluminescence Glow Peaks in Β-Irradiated Tlgases Crystals
(Polish Acad Sciences inst Physics, 2016) Isik, M.; Işık, Mehmet; Yildirim, T.; Gasanly, N. M.; Department of Electrical & Electronics Engineering
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.
Citation Count: 2
Anisotropic Electrical and Dispersive Optical Parameters in Ins Layered Crystals
(Pergamon-elsevier Science Ltd, 2010) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Gasanly, N. M.; Department of Electrical & Electronics Engineering
The anisotropy effect on the current transport mechanism and on the dispersive optical parameters of indium monosulfide crystals has been studied by means of electrical conductivity and polarized reflectance measurements along the a-axis and the b-axis, respectively. The temperature-dependent electrical conductivity analysis in the range 10-350 K for the a-axis and in the range 30-350 K for the b-axis revealed the domination of the thermionic emission of charge carriers and the domination of variable range hopping above and below 100 K, respectively. At high temperatures (T > 100 K) the conductivity anisotropy, s, decreased sharply with decreasing temperature following the law s proportional to exp(-E(s)/kT). The anisotropy activation energy, E(s), was found to be 330 and 17 meV above and below 220 K, respectively. Below 100 K, the conductivity anisotropy is invariant with temperature. in that region, the calculated hopping parameters are altered significantly by the conductivity anisotropy. The optical reflectivity analysis in the wavelength range 250-650 nm revealed a clear anisotropy effect on the dispersive optical parameters. In particular, the static refractive index, static dielectric constant, lattice dielectric constant, dispersion energy and oscillator energy exhibited values of 2.89, 8.39, 19.7, 30.02 eV and 4.06 eV, and values of 2.76, 7.64, 25.9, 22.26 eV and 3.35 eV for light polarized along the a-axis and the b-axis, respectively. (C) 2009 Elsevier Ltd. All rights reserved.
Citation Count: 5
Annealing Effect on the Low Temperature Thermoluminescence Properties of Gase Single Crystals
(Elsevier Science Bv, 2014) Isik, M.; Işık, Mehmet; Hadibrata, W.; Gasanly, N. M.; Department of Electrical & Electronics Engineering
Trapping centers in as-grown GaSe single crystals have been investigated by thermoluminescence (TL) measurements in the temperature range of 30-300 K. The analysis of the observed peaks in TL glow curve to determine the activation energies of the associated centers were accomplished using curve fitting, initial rise and peak shape methods. Activation energies of the revealed four trapping centers obtained from various methods were in good agreement with each other on the energy values of 0.14, 0.18, 0.24 and 037 eV. The annealing effect on the TL properties of the GaSe single crystals was also studied for the annealing temperature of 500 degrees C. It was observed that annealing significantly decreased the U intensity and shifted the observed peaks to lower temperature resulting with smaller activation energy values. The distribution of the trapping centers with most intensive peak was also studied on both as-grown and annealed crystals. (C) 2014 Elsevier B.V. All rights reserved.
Citation Count: 3
Characterization of Ag/Tlinse_{2< Structure}
(Wiley-blackwell, 2011) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Gasanly, N. M.; Department of Electrical & Electronics Engineering
In this work, the current voltage characteristics of Ag/TlInSe2/Ag and In/TlInSe2/In structures, the incident light intensity and time dependencies of photocurrent as well as the response time-illumination intensity dependence of Ag/TlInSe2/Ag structures have been studied. For bias voltages larger than 1200. and 4.0 V, the current injection was found to be space charge limited and was assigned to the existing of deep and shallow hole traps being located at 210 and 16 meV for Ag and In-contacted samples, respectively. While indium-contacted samples show S-shaped I-V dependence above bias voltage of 10.0V, silver contacted samples does not show this behavior even at 200.0 V. For the Ag/TlInSe2/Ag structure, photocurrent was observed to exhibit stable values in a very short period of time. The device response time decreases with increasing illumination intensity, it exhibits a value of 0.13 s at incident light intensity of 53.6 mW cm(-2). The decrement in response time with increasing illumination intensity is associated with an increment in photocurrent at the same ratio. The ohmic behavior up to high voltages (120 V), the fast response time and the large spatial photocurrent make the Ag/TlInSe2/Ag structure promising IR detectors. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Citation Count: 0
Characterization of Bi₁₂sio_{20< Single Crystal: Understanding Structural and Thermal Properties}
(Springer Heidelberg, 2024) Altuntas, G.; Işık, Mehmet; Isik, M.; Gasanly, N. M.; Department of Electrical & Electronics Engineering
This study presents a thorough examination of the structural and thermal characteristics of Bi12SiO20 crystal. X-ray diffraction (XRD) analysis was employed to investigate the crystallographic structure, while scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were utilized to ascertain morphological features and elemental composition, respectively. The XRD spectrum exhibited numerous peaks corresponding to the cubic crystalline structure. Thermal behavior was investigated through thermal gravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Within the crystal, negligible weight loss was observed up to 750 degrees C, followed by weight loss processes occurring in the temperature ranges of 750-919 degrees C and above 919 degrees C. The 2% weight loss in the range of 750-919 degrees C was associated with the decomposition process, and the activation energy of this process was found to be 199 kJ/mol considering Coats-Redfern expression. A significant weight loss was observed in the region above 919 C-o and was associated with the decomposition of the Bi12SiO20 compound and/or the melting processes of the components of the Bi12SiO20 compound. Three endothermic peaks were observed in the DTA plot. Additionally, DSC measurements conducted under varied heating rates indicated endothermic crystallization process around 348 degrees C, with an activation energy of 522 kJ/mol determined through the Kissenger equation. These findings present valuable details regarding the crystal's structural configuration, morphological attributes, and decomposition/phase transitions, thereby illuminating its potential applications across various fields.
Citation Count: 0
Characterization of Linear and Nonlinear Optical Properties of Nabi(wo4)2 Crystal by Spectroscopic Ellipsometry
(Elsevier, 2024) Isik, M.; Işık, Mehmet; Guler, I.; Gasanly, N. M.; Işık, Mehmet; Işık, Mehmet; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics Engineering
NaBi(WO4)2 compound has been a material of considerable attention in optoelectronic applications. The present research, in which we examined the linear and nonlinear optical properties of NaBi(WO4)2 crystal using the spectroscopic ellipsometry method, elucidates the optical behavior of the crystal in detail. Our work provides a sensitive approach to determine the spectral characteristic of the crystal. The spectral dependence of various optical parameters such as refractive index, extinction coefficient, dielectric function and absorption coefficient was reported in the range of 1.2-5.0 eV. Optical values such as bandgap energy, critical point energy, single oscillator parameters were obtained as a result of the analyses. In addition to linear optical properties, we also investigated the nonlinear optical behavior of NaBi(WO4)2 and shed new light on the potential applications of the crystal. Absorbance and photoluminescence spectra of the crystal were also reported to characterize optical, electronic and emission behavior of the compound. Our findings may form the basis for a number of technological applications such as optoelectronic devices, frequency conversion, and optical sensors. This research contributes to a better understanding of the optical properties of NaBi(WO4)2 crystal, highlighting the material's role in future optical and electronic technologies.
Citation Count: 1
Characterization of T1ins1.8se0.2 as Advanced Functional Crystals
(Elsevier Sci Ltd, 2018) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Atatreh, Areen A. M.; Gasanly, N. M.; Department of Electrical & Electronics Engineering
In this work, selenium doped TlInS1.8Se0.2 crystals are used to fabricate multifunctional devices that can handle more than one duty at a time. After revealing the morphological, compositional, structural and optical properties of the doped crystal, it is sandwiched between Ag and carbon metals. The crystals are characterized by means of ultraviolet-visible light spectrophotometry, impedance spectroscopy and illumination dependent current-voltage characteristics techniques. While the optical spectroscopy allowed determining the energy band gap of the crystals as well as the optical conductivity in the terahertz frequency domain, the impedance spectroscopy allowed identifying the conductance and reflectance spectra in the gigahertz frequency domain. The two techniques reveal promising characteristics presented by optical switching at 2.20 eV and band pass filtering properties in mega/gigahertz frequency domains. On the other hand, the analysis of the current (I)- voltage (V) characteristics which are recorded in the dark and under photoexcitation of unfiltered tungsten light in the light power range of 25-130 mW, revealed light intensity dependent rectifying properties. Particularly, the modeling of the experimental I-V curves in accordance with the Richardson Schottky and Chueng's theoretical approaches have shown that the Schottky diode ideality factor, series resistance and barrier height decreases with increasing light power. Such behavior indicates wide tunability of the device when used as photosensors. With the features presented by small size, photosensitivity, gigahertz/terahertz spectral responses, the device can be promising element for use in visible light and microwave communications.
Citation Count: 2
Characterization of the Mgo/Gase_{0.5< Heterojunction Designed for Visible Light Communications}
(Elsevier Sci Ltd, 2015) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; AlGarni, S. E.; Gasanly, N. M.; Department of Electrical & Electronics Engineering
In this study an optoelectronic design is reported and characterized. The device is made of p-type MgO solved in sodium silicate binder and n-type GaSe0.5S0.5 heterojunction. It is described by means of X-ray diffraction, optical absorption and reflection in the incident light wavelength range of 190-1100 nm and by means of dark and 406 nm laser excited current (I)-voltage (V) characteristics. The optical reflectance was also measured as a function of angle of incidence of light in the range of 35-80. The structural analysis revealed no change in the existing phases of the device composers. In addition, it was observed that for pure sodium silicate and for a 67% content of MgO solved in sodium silicate binder (33%), the heterojunction exhibits a valence band shift of 0.40 and 0.70 eV, respectively. The painting of MgO improved the light absorbability significantly. On the other hand, the angle-dependent reflectance measurements on the crystal displayed a Brewster condition at 70. The MgO/ GaSe0.5S0.5 heterojunction exhibited no Brewster condition when irradiated from the MgO side. Moreover, for the crystal and the MgO/ GaSe0.5S0.5 heterojunction, the dielectric spectral analysis revealed a pronounced increase in the quality factor of the device. The I-V characteristics of the device revealed typical optoelectronic properties with high photo-response that could amplify the dark current 24 times when irradiated with 5 mW power laser light. The structural, optical, dielectric and electrical features of the MgO/GaSe0.5S0.5 heterojunction nominate it for use in visible light communication technology. (C) 2015 Elsevier Ltd. All rights reserved.
Citation Count: 8
Characterization of Trap Centers in Gd₂o_{3< Nanoparticles by Low Temperature Thermoluminescence Measurements}
(Elsevier Gmbh, 2018) Delice, S.; Işık, Mehmet; Isik, M.; Gasanly, N. M.; Department of Electrical & Electronics Engineering
Trapping centers in Gd2O3 nanoparticles were investigated using thermoluminescence (TL) measurements in the below room temperature region of 10-280 K. Seven peaks having peak maximum temperatures between 30 and 252 K were observed in the TL spectra measured at constant heating rate of 0.3 K/s. Activation energies, order of kinetics and frequency factors were reported using three different analysis techniques: curve fitting, initial rise and peak shape methods. Activation energies of the trapping centers were found between 0.012 eV and 0.79 eV. Most of the TL transitions associated with observed peaks were found as dominated by mixed order of kinetics. Structural characterization of used nanoparticles was achieved using x-ray diffraction and scanning electron microscopy experiments. (C) 2017 Elsevier GmbH. All rights reserved.
Citation Count: 0
Compositional Dependence of Optical Modes Frequencies in T1ga_x< Layered Mixed Crystals (0 ≤ x ≤ 1)
(Polish Acad Sciences inst Physics, 2014) Isik, M.; Işık, Mehmet; Gasanly, N. M.; Korkmaz, F.; Department of Electrical & Electronics Engineering
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.
Citation Count: 4
Crystal Data and Indirect Optical Transitions in Tl₂ingase_{4< Crystals}
(Pergamon-elsevier Science Ltd, 2008) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Gasanly, N. M.; Department of Electrical & Electronics Engineering
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.
Citation Count: 2
Crystal Data and Some Physical Properties of Tl₂ingate_{4< Crystals}
(Wiley-v C H verlag Gmbh, 2007) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Gasanly, N. M.; Department of Electrical & Electronics Engineering
The room temperature crystal data, Debye temperature, dark and photoelectrical properties of the Bridgman method grown Tl2InGaTe4 crystals are reported for the first time. The X-ray diffraction technique has revealed that Tl(2)lnGaTe(4) is a single phase crystal of tetragonal body-centered structure belonging to the D-4H(18) - I4mcm space group. A Debye temperature of 124 K is calculated from the results of the X-ray data. The current-voltage measurements have shown the existence of the switching property of the crystals at a critical voltage of 80 V. The dark electrical resistivity and Hall effect measurements indicated the n-type conduction with an electrical resistivity, electron density and Hall mobility of 2.49x 10(3) Omega cm, 4.76x 10(12) cm(-3) and 527 cm V-2(-1) s(-1), respectively. The photosensitivity measurements on the crystal revealed that, the variation of photocurrent with illumination intensity is linear, indicating the domination of monomolecular recombination at room temperature. Moreover, the spectral distribution of the photocurrent allowed the determination of the energy band gap of the crystal studied as 0.88 cV.
Citation Count: 1
Dark Electrical Conductivity and Photoconductivity of Ga₄se_{3< Layered Single Crystals}
(Pergamon-elsevier Science Ltd, 2008) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Gasanly, N. M.; Department of Electrical & Electronics Engineering
Ga(4)Se(3)S layered crystals were studied through the dark electrical conductivity, and illumination- and temperature-dependent photoconductivity in the temperature region of 100-350 K. The dark electrical conductivity reflected the existence of two energy states located at 3 10 and 60 meV being dominant above and below 170 K, respectively. The photoconductivity measurements revealed the existence of another two energy levels located at 209 and 91 meV above and below 230 K. The photoconductivity was observed to increase with increasing temperature. The illumination dependence of photoconductivity was found to exhibit linear and supralinear recombination above and below 280 K, respectively. The change in recombination mechanism was attributed to the exchange in the behavior of sensitizing and recombination centers. (C) 2008 Elsevier Ltd. All rights reserved.
Citation Count: 15
Deep Traps Distribution in Tlins₂ Layered Crystals
(Polish Acad Sciences inst Physics, 2009) Isik, M.; Işık, Mehmet; Gasanly, N. M.; Ozkan, H.; Department of Electrical & Electronics Engineering
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.
Citation Count: 7
Defect Characterization in Bi₁₂geo_{20< Single Crystals by Thermoluminescence}
(Elsevier, 2021) Delice, S.; Işık, Mehmet; Isik, M.; Sarigul, N.; Gasanly, N. M.; Department of Electrical & Electronics Engineering
Bi12GeO20 single crystal grown by Czochralski method was investigated in terms of thermoluminescence (TL) properties. TL experiments were performed for various heating rates between 1 and 6 K/s in the temperature region of 300-675 K. One TL peak with peak maximum temperature of 557 K was observed in the TL spectrum as constant heating rate of 1 K/s was employed. Curve fitting, initial rise and variable heating rate methods were applied to calculate the activation energy of trap level corresponding to this TL peak. Analyses resulted in a presence of one trap center having mean activation energy of 0.78 eV. Heating rate characteristics of revealed trap center was also explored and theoretically well-known behavior that TL intensity decreases and peak maximum temperature increases with heating rates was observed for the trap level. Distribution of trapping levels was studied by thermally cleaning process for different T-stop between 425 and 525 K. Quasi-continuously distributed trapping levels were revealed with mean activation energies ranging from 0.78 to 1.26 eV. Moreover, absorption analysis revealed an optical transition taking place between a defect level and conduction band with an energy difference of 2.51 eV. These results are in good agreement for the presence of intrinsic defects above valence band in Bi12GeO20 crystals.
Citation Count: 7
The Defect State of Yb-Doped Zno Nanoparticles Using Thermoluminescence Study
(Elsevier Sci Ltd, 2019) Isik, M.; Işık, Mehmet; Gasanly, N. M.; Department of Electrical & Electronics Engineering
Shallow trapping centers in Yb-doped ZnO nanoparticles were determined using thermoluminescence (TL) measurements applied in the 10-300 K temperature region. Undoped and Yb-doped ZnO nanoparticles were synthesized by sol-gel method. TL glow curve of undoped nano-particles presented three peaks around 56, 108 and 150 K whereas one additional peak around 83 K was observed in the TL curve of Yb-doped ZnO nano-particles. The increase of Yb concentration in the nanoparticles increased the TL intensity of this additional peak. Activation energies of interstitial defect centers were found as 20, 82 and 105 meV while energy of trapping center existing due to Yb-doping was obtained as 72 meV using curve fitting and initial rise methods.