126 results
Search Results
Now showing 1 - 10 of 126
Article Citation - Scopus: 3Complete Characterization of a Class of Permutation Trinomials in Characteristic Five(Springer, 2024) Grassl,M.; Özbudak,F.; Özkaya,B.; Temür,B.G.In this paper, we address an open problem posed by Bai and Xia in [2]. We study polynomials of the form f(x)=x4q+1+λ1x5q+λ2xq+4 over the finite field F5k, which are not quasi-multiplicative equivalent to any of the known permutation polynomials in the literature. We find necessary and sufficient conditions on λ1,λ2∈F5k so that f(x) is a permutation monomial, binomial, or trinomial of F52k. © The Author(s) 2024.Article Evaluating Anterior Segment Stability and Corneal Endothelium After Prolene Gonioscopy Assisted Transluminal Trabeculotomy (gatt) in Open-Angle Glaucoma(Springer, 2024) Aribas, Yavuz Kemal; Aktas, Zeynep; Ertop, MestanIntroduction This study investigates the short-term effects of prolene gonioscopy-assisted transluminal trabeculotomy (GATT) on anterior segment parameters and corneal endothelium in patients with open-angle glaucoma. Methods This retrospective study included 30 eyes from 30 patients who underwent GATT surgery. Demographic data, ophthalmological examination findings, and intraocular pressure (IOP) measurements using a Goldman applanation tonometer were recorded. Scheimpflug images were acquired at the pre-operative stage, as well as on the 1st day, 1st week, and 1st month postoperatively. Corneal endothelial cell counts were obtained via specular microscopy. Results The mean age of patients was 60.3 +/- 15.5 years. Anterior chamber depth and central corneal thickness increased on the 1st postoperative day (p:0.002, p < 0.001, respectively). Changes in anterior chamber depth values at the postoperative 1st week and 1st month compared to baseline were not statistically significant. Central corneal thickness decreased significantly at the 1st postoperative month compared to baseline (p:0.007). Corneal endothelial cell counts at the 1st month were comparable to baseline values (p:0.936). Conclusion Our findings reveal that prolene gonioscopy-assisted transluminal trabeculotomy induces temporary changes in anterior segment parameters but preserves corneal endothelial cell count within the first month, suggesting a promising profile for GATT in glaucoma management.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: 7Citation - Scopus: 7Physical Design and Dynamical Analysis of Resonant-Antiresonant Ag/MgO/GaSe/Al Optoelectronic Microwave Devices(Springer, 2015) Kmail, Renal R. N.; Qasrawi, A. F.In this work, the design and optical and electrical properties of MgO/GaSe heterojunction devices are reported and discussed. The device was designed using 0.4-mu m-thick n-type GaSe as substrate for a 1.6-mu m-thick p-type MgO optoelectronic window. The device was characterized by means of ultraviolet-visible optical spectrophotometry in the wavelength region from 200 nm to 1100 nm, current-voltage (I-V) characteristics, impedance spectroscopy in the range from 1.0 MHz to 1.8 GHz, and microwave amplitude spectroscopy in the frequency range from 1.0 MHz to 3.0 GHz. Optical analysis of the MgO/GaSe heterojunction revealed enhanced absorbing ability of the GaSe below 2.90 eV with an energy bandgap shift from 2.10 eV for the GaSe substrate to 1.90 eV for the heterojunction design. On the other hand, analysis of I-V characteristics revealed a tunneling-type device conducting current by electric field-assisted tunneling of charged particles through a barrier with height of 0.81 eV and depletion region width of 670 nm and 116 nm when forward and reverse biased, respectively. Very interesting features of the device are observed when subjected to alternating current (ac) signal analysis. In particular, the device exhibited resonance-antiresonance behavior and negative capacitance characteristics near 1.0 GHz. The device quality factor was similar to 10(2). In addition, when a small ac signal of Bluetooth amplitude (0.0 dBm) was imposed between the device terminals, the power spectra of the device displayed tunable band-stop filter characteristics with maximum notch frequency of 1.6 GHz. The energy bandgap discontinuity, the resonance-antiresonance behavior, the negative capacitance features, and the tunability of the electromagnetic power spectra at microwave frequencies nominate the Ag/MgO/GaSe/Al device as a promising optoelectronic device for use in multipurpose operations at microwave frequencies.Article Citation - WoS: 14Citation - Scopus: 15Structural and Optical Properties of Ga2se3< Crystals by Spectroscopic Ellipsometry(Springer, 2019) Guler, I.; Isik, M.; Gasanly, N. M.; Gasanova, L. G.; Babayeva, R. F.Optical and crystalline structure properties of Ga2Se3 crystals were analyzed utilizing ellipsometry and x-ray diffraction (XRD) experiments, respectively. Components of the complex dielectric function (epsilon=epsilon(1)+i epsilon(2)) and refractive index (N=n+ik) of Ga2Se3 crystals were spectrally plotted from ellipsometric measurements conducted from 1.2eV to 6.2eV at 300K. From the analyses of second-energy derivatives of epsilon(1) and epsilon(2), interband transition energies (critical points) were determined. Absorption coefficient-photon energy dependency allowed us to achieve a band gap energy of 2.02eV. Wemple and DiDomenico single effective oscillator and Spitzer-Fan models were accomplished and various optical parameters of the crystal were reported in the present work.Conference Object Citation - WoS: 3Citation - Scopus: 4Production of Ultra-High Molecular Weight Polyethylene-Granite Composite Films by Gelation/Crystallization(Springer, 2016) Efe, Gozde Celebi; Ozaydin, Fevzi; Ucisik, Hikmet; Bindal, Cuma; Liang, HongThe present study reports on film of ultra-high molecular weight polyethylene (UHMWPE) containing 1 mass% granite composite produced by gelation/crystallization technique at 150 A degrees C from decalin solution. The morphology of UHMWPE-granite composite film was determined by using optical and scanning electron microscope, differential scanning calorimetry and Raman. Uniform dispersion of granite particles within ultra-high molecular weight polyethylene solution was the first step to achieve ultra-high molecular weight polyethylene-granite sheet samples with excellent properties. In differential scanning calorimetry analysis 50.1 % crystallinity of ultra-high molecular weight polyethylene-1 mass% granite composite was calculated from the endothermic peak area occurred around 142 A degrees C which correspond to melting point of composite. Mechanical property of ultra-high molecular weight polyethylene-1 mass% granite composite was tested with tensile test and shown to possess unique properties, in particular an increase of over 2.5 times in Young's modulus in comparison with pure ultra-high molecular weight polyethylene.Article Citation - WoS: 11Citation - Scopus: 12Analysis of the Structural and Optical Characteristics of Znse Thin Films as Interface Layer(Springer, 2025) Emir, C.; Tataroglu, A.; Gökmen, U.; Ocak, S.B.This research reveals the results of a comprehensive analysis of the optical and structural features of zinc selenide (ZnSe) thin film. The studied film was synthesized using the thermal evaporation method after preparation on the glass substrate. The film’s structural characteristics, which have been determined by using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD), confirm the polycrystalline nature of the films with a predominant cubic zinc-blende structure. The surface morphology investigated through SEM reveals a uniform grain distribution with minimal surface defects, indicating high-quality film formation. In order to examine the optical characteristics, the ultraviolet–visible spectroscopy method is used in a spectral range between 300 and 900 nm. In this way, the ultraviolet–visible spectroscopy data are utilized to obtain optical features such as extinction coefficient (k), optical band gap (Eg), refractive index (n), absorption coefficient (α), and optical conductivity (σopt). These optical properties are assessed using ultraviolet–visible spectroscopy, revealing a direct band gap of approximately 2.88 eV, which is consistent with the bulk properties of ZnSe and suitable for optoelectronic applications. The results of this study clearly show that the studied ZnSe film can be used for optoelectronic device applications. © The Author(s) 2025.Article Citation - WoS: 2Citation - Scopus: 2Performance of Ge-Sandwiched Gase Layers(Springer, 2018) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Abdallah, Maisam M. A.; Qasrawı, Atef Fayez Hasan; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics EngineeringIn the current work, we report the effect of sandwiching Ge between two stacked layers of GaSe. The GaSe and Ge-sandwiched GaSe were subjected to x-ray diffraction, optical spectrophotometry and impedance spectroscopy measurement and analysis. The presence of a Ge layer between two layers of GaSe was observed to cause uniform deformation and increase the absorption of light by GaSe. The response of the dielectric constant to incident light was also significantly enhanced by Ge sandwiching. In addition, Drude-Lorentz modeling of the imaginary part of the dielectric constant revealed that the layer of Ge layer between GaSe layers increased the drift mobility from 30.76 cm(2)/Vs to 52.49 cm(2)/Vs. It also enhanced the plasmon frequency without altering the free carrier density. Moreover, Ge improved the band filtering features of GaSe. In particular, it enhanced the sensitivity of the impedance response to the incident signal and increased the return loss factor of GaSe when it was used as a high band pass filter.Article Citation - WoS: 2Citation - Scopus: 3Electrical Characterization of Zninse2 Thin-Film Heterojunction(Springer, 2019) Gullu, H. H.; Parlak, M.ZnInSe2/Cu0.5Ag0.5InSe2 diode structures have been fabricated by thermal evaporation of stacked layers on indium tin oxide-coated glass substrates. Temperature-dependent dark current-voltage measurements were carried out to extract the diode parameters and to determine the dominant conduction mechanisms in the forward- and reverse-bias regions. The heterostructure showed three order of magnitude rectifying behavior with a barrier height of 0.72 eV and ideality factor of 2.16 at room temperature. In the high forward-bias region, the series and shunt resistances were calculated with the help of parasitic resistance relations, yielding room-temperature values of 9.54 x 10(2) Omega cm(2) and 1.23 x 10(3) Omega cm(2), respectively. According to the analysis of the current flow in the forward-bias region, abnormal thermionic emission due to the variation of the ideality factor with temperature and space-charge-limited current processes were determined to be the dominant conduction mechanisms in this heterostructure. In the reverse-bias region, the tunneling mechanism was found to be effective in the leakage current flow with trap density of 10(6) cm(-3). Spectral photocurrent measurements were carried out to investigate the spectral working range of the device structure. The main photocurrent peaks observed in the spectrum corresponded to the band-edge values of the active thin-film layers.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.
