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Article Citation - WoS: 10Citation - Scopus: 11Low Temperature Thermoluminescence of Gd2o3< Nanoparticles Using Various Heating Rate and tmax< - texc< Methods(Elsevier, 2019) Delice, Serdar; Isik, Mehmet; Gasanly, Nizami M.Thermoluminescence (FL) measurements for Gd2O3 nanoparticles were carried out for various heating rates between 0.3 and 0.8 K/s at low temperatures (10-280 K). TL spectrum exhibited two observable and one faint peaks in the temperature region of 10-100 K, and four peaks in the temperature region of 160-280 K. Heating rate analysis was achieved to understand the behaviors of trap levels. It was seen that the peak maximum temperatures and TL intensities of all peaks increase with increasing heating rate. This behavior was ascribed to anomalous heating rate effect. T-max - T(exc )analysis was accomplished for TL, peaks at relatively higher temperature region to reveal the related traps depths. T-max - T-exc plot presented a staircase structure indicating that the TL glow curve is composed of well separated glow peaks. Mean activation energies of trapping centers corresponding to these separated peaks were found as 0.43, 0.50, 0.58 and 0.80 eV.Article Citation - WoS: 5Citation - Scopus: 5Identification of Shallow Trap Centers in Inse Single Crystals and Investigation of Their Distribution: a Thermally Stimulated Current Spectroscopy(Elsevier, 2024) Isik, M.; Gasanly, N. M.Identification of trap centers in semiconductors takes great importance for improving the performance of electronic and optoelectronic devices. In the present study, we employed the thermally stimulated current (TSC) method within a temperature range of 10-280 K to explore trap centers in InSe crystal-a material with promising applications in next-generation devices. Our findings revealed the existence of two distinct hole trap centers within the InSe crystal lattice located at 0.06 and 0.14 eV. Through the leveraging the T-stop method, we offered trap distribution parameters of revealed centers. The results obtained from the experimental methodology employed to investigate the distribution of trap centers indicated that one of the peaks extended between 0.06 and 0.13 eV, while the other spanned from 0.14 to 0.31 eV. Notably, our research uncovers a remarkable variation in trap density, spanning one order of magnitude, for every 10 and 88 meV of energy variation. The results of our research present the characteristics of shallow trap centers in InSe, providing important information for the design and optimization of InSe-based optoelectronic devices.Article Citation - WoS: 14Citation - Scopus: 14Low Temperature Thermoluminescence Behaviour of Y2o3< Nanoparticles(Elsevier, 2019) Delice, S.; Isik, M.; Gasanly, N. M.Y2O3 nanoparticles were investigated using low temperature thermoluminescence (TL) experiments. TL glow curve recorded at constant heating rate of 0.4 K/s exhibits seven peaks around 19, 62, 91, 115, 162, 196 and 215 K. Activation energies and characteristics of traps responsible for observed curves were revealed under the light of results of initial rise analyses and T-max-T-stop experimental methods. Analyses of TL curves obtained at different stopping temperatures resulted in presence of one quasi-continuously distributed trap with activation energies increasing from 18 to 24 meV and six single trapping centers at 49, 117, 315, 409, 651 and 740 meV. Activation energies of all revealed centers were reported in the present paper. Structural characterization of Y2O3 nanoparticles was accomplished using X-ray diffraction and scanning electron microscopy measurements. (C) 2019 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 5Thermoluminescence characteristics of GaSe and Ga2Se3 single crystals(Elsevier, 2022) Isik, M.; Sarigul, N.; Gasanly, N. M.GaSe and Ga2Se3 are semiconducting compounds formed from same constituent elements. These compounds have been attractive due to their optoelectronic and photovoltaic applications. Defects take remarkable attention since they affect quality of semiconductor devices. In the present paper, deep defect centers in GaSe and Ga2Se3 single crystals grown by Bridgman method were reported from the analyses of thermoluminescence measurements performed in the 350-675 K range. Experimental TL curves of GaSe and Ga2Se3 single crystals presented one and two overlapped peaks, respectively. The applied curve fitting and initial rise techniques were in good agreement about trap activation energies of 0.83 eV for GaSe, 0.96 and 1.24 eV for Ga2Se3 crystals. Crystalline structural properties of the grown single crystals were also investigated by x-ray diffraction measurements. The peaks observed in XRD patterns of the GaSe and Ga2Se3 crystals were well-consistent with hexagonal and zinc blende structures, respectively.Article Citation - WoS: 5Citation - Scopus: 6Thermoluminescence Properties and Trapping Parameters of Tlgas2 Single Crystals(Elsevier, 2022) Delice, S.; Isik, M.; Gasanly, N. M.TlGaS2 layered single crystals have been an attractive research interest due to their convertible characteristics into 2D structure. In the present paper, structural, optical and thermoluminescence properties of TlGaS2 single crystals were investigated. XRD pattern of the crystal presented five well-defined peaks associated with monoclinic unit cell. Band gap and Urbach energies were found to be 2.57 and 0.25 eV, respectively, from the analyses of transmittance spectrum. Thermoluminescence measurements were carried out above room temperature up to 660 K at various heating rates. One TL peak with peak maximum temperature of 573 K was obtained in the TL spectrum at 1.0 K/s. Curve fitting, initial rise and variable heating rate methods were used for analyses. All of those resulted in presence of a deep trapping level with activation energy around 0.92 eV. Heating rate dependence of the TL peak was also studied and it was indicated that peak maximum temperature shifted to higher temperatures besides decreasing TL intensity as the higher heating rates were employed.Article Citation - WoS: 9Citation - Scopus: 9TL and TSC studies on TlGaSe2 layered single crystals(Elsevier, 2013) Isik, M.; Bulur, E.; Gasanly, N. M.Defects in - as grown - TlGaSe2 layered single crystals were investigated using Thermoluminescence (TL) and Thermally Stimulated Currents (TSC) techniques in the temperature range 10-300 K. TL and TSC curves of samples illuminated using a light with energy greater than the band gap of the material, i.e. blue light (similar to 470 nm) at 10 K, exhibited peaks around 27 and 28 K, respectively, when measured by heating up the samples at a rate of 1 K/s. TL and TSC curves were analyzed to characterize the defects responsible for the peaks. Both TL and TSC peaks were observed to be obeying first order kinetics. Thermal activation energies of the peaks were determined using various methods: curve fitting, initial rise, peak shape and different heating rates. For both TL and TSC peaks, thermal activation energy was determined as around 8 meV, implying that they may originate from similar kinds of trapping centers. A distribution of traps (in terms of energy) was experimentally verified by illuminating the sample at different temperatures and measuring the TL curves. As a result of this, the apparent thermal energies were observed to be shifted from similar to 8 to similar to 17 meV by increasing the illumination temperature from 10 to 16 K. (C) 2013 Elsevier B.V. All rights reserved.Article Citation - WoS: 10Citation - Scopus: 11Effect of Heating Rate on Thermoluminescence Characteristics of Y2o3< Nanoparticles(Elsevier, 2019) Delice, S.; Isik, M.; Gasanly, N. M.The present paper reports the results of heating rate dependencies of thermoluminescence (TL) peaks observed for Y2O3 nanoparticles in the below room temperature region. TL glow curve presented six peaks around 62.5, 91.3, 114.5, 162.7, 196.0 and 214.9 K for heating rate of 0.4 K/s. The increase of heating rate resulted in increase in peak maximum temperature and decrease in peak maximum intensity as expected according to theoretical information. Peak maximum temperature-heating rate dependencies of observed peaks were analysed according to exponential dependency relation. Curve fit and initial rise methods were applied on thermally cleaned individual peaks and activation energies of associated trap centers, frequency factors and order of kinetics were obtained from the analyses. Activation energy values of the revealed trapping centers found from both methods were in good agreement with each other. Moreover, lattice parameters, crystalline size and micro-strain of nanoparticles were investigated by means of x-ray diffraction measurements.Article Citation - WoS: 12Citation - Scopus: 13Low-Temperature Thermoluminescence in Tlgas2 Layered Single Crystals(Elsevier, 2013) Isik, M.; Bulur, E.; Gasanly, N. M.Thermoluminescence (TL) measurements have been carried out on TlGaS2 layered single crystals in the temperature range of 10-300 K. After illuminating with blue light (similar to 470 nm) at 10 K, TL glow curves exhibited peaks around 23, 36, 58, 75 and 120 K when measured with a heating rate of 0.8 K/s. The observed peaks were analyzed using curve fitting, initial rise, and peak shape methods to determine the activation energies of the associated defect centers. Analyses have revealed the presence of five defect centers with activation energies of 13, 27, 87, 94 and 291 meV. The results of all methods were found to be in good agreement with each other. The consistency between the theoretical predictions for slow retrapping and experimental results showed that the retrapping process for the observed centers was negligible. The independence of peak position from concentration of carriers trapped in defect levels was also another indication of negligible retrapping. The dependence of TL glow curves on heating rate and distribution of traps was also studied. (C) 2012 Elsevier B.V. All rights reserved.Article Citation - WoS: 12Citation - Scopus: 13Trap Characterization by Photo-Transferred Thermoluminescence in Mgo Nanoparticles(Elsevier, 2018) Isik, M.; Gasanly, N. M.Shallow trapping centers in MgO nanoparticles were characterized using photo-transferred thermoluminescence (TL) measurements. Experiments were carried out in low temperature range of 10-280 K with constant heating rate. Shallow traps were filled with charge carriers firstly by irradiating the sample at room temperature using S-90/Y-90 source and then illuminating at 10 K using blue LED. TL glow curve exhibited one peak around 150 K. Curve fitting analyses showed that this peak is composed of two individual peaks with maximum temperatures of 149.0 and 155.3 K. The activation energies of corresponding trapping centers were revealed as 0.70 and 0.91 eV. The dominant mechanism for TL process was found as second order kinetics which represent that fast retrapping is effective transitions taking place within the band gap. Structural characterization of MgO nanoparticles were investigated using x-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy measurements. Analyses of experimental observations indicated that MgO nanoparticles show good crystallinity with particle size in nanometer scale.
