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Article Citation - WoS: 22Citation - Scopus: 22Optical Properties of Tlins2 Layered Single Crystals Near the Absorption Edge(Springer, 2006) Qasrawi, A. F.; Gasanly, N. M.The sample thickness effect on the optical properties of TlInS2 layered crystals has been investigated at room temperature. The absorption coefficient of the samples calculated from the experimental transmittance and reflectance in the photon energy range of 1.10-3.10 eV has two absorption regions. The first is a long-wavelength region of 1.16-1.28 eV. The second region lies above 2.21 eV with a thickness-dependent indirect band gap. The energy gap decreases from 2.333 to 2.255 eV as the sample thickness increases from 27 to 66 mu m. The differential spectra of absorption coefficient demonstrates the existence of a thickness-dependent impurity level being lowered from 2.360 to 2.307 eV as sample thickness increases from 27 to 66 mu m. (c) 2006 Springer Science + Business Media, Inc.Article Citation - WoS: 10Citation - Scopus: 11Structural and Temperature-Tuned Bandgap Characteristics of Thermally Evaporated β-in2< Thin Films(Springer, 2021) Surucu, O.; Isik, M.; Terlemezoglu, M.; Gasanly, N. M.; Parlak, M.In2S3 is one of the attractive compounds taking remarkable interest in optoelectronic device applications. The present study reports the structural and optical characteristics of thermally evaporated beta-In2S3 thin films. The crystalline structure of the thin films was found as cubic taking into account the observed diffraction peaks in the X-ray diffraction pattern. The atomic compositional ratio of constituent elements was obtained as consistent with chemical formula of In2S3. Three peaks around 275, 309 and 369 cm(-1) were observed in the Raman spectrum. Temperature-tuned bandgap energy characteristics of the In2S3 thin films were revealed from the investigation of transmittance spectra obtained at various temperatures between 10 and 300 K. The analyses of the transmittance spectra indicated that direct bandgap energy of the In2S3 thin films decreases from 2.40 eV (at 10 K) to 2.37 eV (at 300 K) with the increase of measurement temperature. The bandgap energy vs. temperature relation was investigated by means of Varshni optical model. The fitting of the experimental data under the light of theoretical expression revealed the absolute zero bandgap energy, the rate of change of bandgap energy and Debye temperature.Article Citation - WoS: 5Citation - Scopus: 5The Effect of Zn Concentration on the Structural and Optical Properties of Cd1-xznx< Nanostructured Thin Films(Springer, 2021) Isik, M.; Terlemezoglu, M.; Isik, S.; Erturk, K.; Gasanly, N. M.The structural and optical properties of electrodeposited Cd1-xZnxS nanostructured thin films were investigated in the present paper for compositions of x = 0, 0.03, 0.06 and 0.09. X-ray diffraction patterns of the deposited thin films consisted of diffraction peaks related to cubic crystal lattice. The atomic compositional ratios were determined by performing energy dispersive spectroscopy measurements. Scanning electron microscopy images indicated that deposited thin films have nanostructured forms. Raman spectra of the Cd1-xZnxS thin films exhibited two vibrational modes associated with longitudinal optical mode and its first overtone. Transmission measurements were performed on the deposited thin films to get their band gap energies. It was seen from the analyses of absorption coefficient that band gap energy of Cd1-xZnxS thin films increases almost linearly from 2.40 to 2.51 eV as the composition was increased from x = 0 to x = 0.09.Article Citation - WoS: 42Citation - Scopus: 41Analysis of Forward and Reverse Biased Current-Voltage Characteristics of Al/Al2< Schottky Diode With Atomic Layer Deposited Al2o3< Thin Film Interlayer(Springer, 2019) Gullu, H. H.; Yildiz, D. E.The dark current-voltage (I-V) characteristics of Al/Al2O3/n-Si Schottky diode are investigated in a wide temperature range of 260-360 K. The diode shows four orders of magnitude rectification. In forward and reverse bias regions, the temperature-dependent I-Vcharacteristics are detailed in terms of diode parameters and dominant conduction mechanisms. Due to the existence of Al2O3 film layer and series resistance in the diode structure, current flow under the forward bias is observed in a deviation from pure exponential characteristics. The diode parameters are estimated from thermionic emission model with non-unity ideality factor, and this non-ideal behavior is resulted in the ideality factors greater than two. In addition to these values, zero-bias barrier height is found to be strongly temperature dependent, and this variation indicates a presence of inhomogeneties in the barrier according to Gaussian distribution (GD) approximation. This fact is investigated plotting characteristic plot of this model and by extracting mean barrier height with its standard deviation. In order to complete the work on the forward I-V region, the carrier transport characteristics of the diode are explained on the basis of thermionic emission mechanism with a GD of the harrier heights. In accordance with this approximation, the conventional Richardson plot exhibits non-linearity behavior and modified current relation based on GD model is used to calculate mean barrier height and Richardson constant. In addition, the values of parasitic resistances are determined using Ohm's law as a function of temperature for all bias voltage spectra. In the reverse bias region, Poole-Frenkel effect is found to be dominant on the conduction associated with the barrier lowering, and barrier height in the emission process from the trapped states, and high-frequency dielectric constant of Al2O3 film layer is calculated.Book Part Citation - Scopus: 2The Meaning of Innovation and Entrepreneurship in Developing Countries(Springer, 2009) Capoglu, GoekhanThe meaning of innovation and entrepreneurship and policies to promote innovation differ across groups of developing countries. On the one hand, there is a small group of countries such as China, South Korea, Brazil, and Mexico which has achieved a certain stage of capitalistic development that provides an institutional environment for encouraging innovation and entrepreneurship. On the other hand, there is a large group of countries in Africa and Asia as well as in Latin America which lacks the critical level of capital accumulation even for sustainable development let alone for the growth of innovation and entrepreneurship. There is also a group of countries such as India with a world-class high-technology clusters developing in the midst of increasing poverty. That is, a generalization of policy proposals will fail to address the specific needs of country groups with different institutional characteristics. Appropriate government policies need to be designed to address specific needs of different country groups.Editorial Special Issue: International Workshop in Applied Probability 2014(Springer, 2016) Eryilmaz, S.; Koutras, Markos V.[No Abstract Available]Article Citation - WoS: 26Citation - Scopus: 28Nature of the Ω (2012) Through Its Strong Decays(Springer, 2018) Aliev, T. M.; Azizi, K.; Sarac, Y.; Sundu, H.We extend our previous analysis on the mass of the recently discovered Omega (2012) state by investigation of its strong decays and calculation of its width employing the method of light cone QCD sum rule. Considering two possibilities for the quantum numbers of Omega (2012) state, namely 1P orbital excitation with J(P) = 3/2(-) and 2S radial excitation with J(P) = 3/2(+), we obtain the strong coupling constants defining the Omega (1P/2S) -> Xi K decays. The results of the coupling constants are then used to calculate the decay width corresponding to each possibility. Comparison of the obtained results on the total widths in this work with the experimental value and taking into account the results of our previous mass prediction on the Omega (2012) state, we conclude that this state is 1P orbital excitation of the ground state Omega baryon, whose quantum numbers are J(P) = 3/2(-).Article Citation - WoS: 5Citation - Scopus: 3Investigation of Λ (1405)as a molecular pentaquark state(Springer, 2024) Azizi, K.; Sarac, Y.; Sundu, H.Lambda ( 1405 ) is one of the interesting particles with its unclear structure and distinct properties. It has a light mass compared to its non-strange counterpart, despite the strange quark it carries. This situation puts the investigation of this resonance among the hot topics in hadron physics and collects attention to clarify its properties. In this study, we focus on the calculation of the mass and residue of the Lambda ( 1405 ) resonance within the framework of QCD sum rules. We assign a structure in the form of a molecular pentaquark composed from admixture of K - meson-neutron. Using an interpolating current in this form, the masses and the current coupling constant are attained as m = 1406 +/- 128 MeV and lambda = ( 3.35 +/- 0.35 ) x 10( - 5) GeV 6 for q and m = 1402 +/- 141 MeV and lambda = ( 4.08 +/- 1.08 ) x 10( - 5) GeV 6 for I Lorentz structures entering the calculations, respectively. The obtained mass values agree well with the experimental data supporting the plausibility of the considered structure.Article Citation - WoS: 3Citation - Scopus: 4Analysis of Temperature-Dependent Transmittance Spectra of Zn0.5in0.5< (zis) Thin Films(Springer, 2019) Isik, M.; Gullu, H. H.; Delice, S.; Gasanly, N. M.; Parlak, M.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.Article Citation - WoS: 1Citation - Scopus: 3Optical constants and critical point energies of (AgInSe2)0.75-(In2Se3)0.25 single crystals(Springer, 2020) Isik, M.; Nasser, H.; Guseinov, A.; Gasanly, N. M.AgInSe2 and In2Se3 are two attractive semiconducting materials for various technological applications especially for photovoltaic applications. In the present study, structural and optical properties of (AgInSe2)(x)-(In2Se3)(1-x) crystals for composition of x = 0.75 corresponding to chemical formula of Ag3In5Se9 were characterized by X-ray diffraction, energy-dispersive spectroscopy, room temperature transmission, and ellipsometry experiments. The transmittance spectrum was analyzed to reveal energy band gap. The derivative spectrophotometry analysis resulted in band gap energy of 1.22 eV. The spectra of complex dielectric function, refractive index and extinction coefficient were presented between 1.6 and 6.2 eV from the outcomes of ellipsometry analyses. Critical point energies have been determined using the derivative analyses of dielectric function. Five critical points at 2.70, 3.30, 4.05, 4.73, and 5.42 eV were revealed from the analyses. Crystal structure and atomic composition in semiconducting compound were also reported in the present work. The obtained results were compared with those reported for constituent compounds.
