Browsing by Author "Surucu, O."
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Article Citation Count: 25Equiatomic quaternary Heusler compounds TiVFeZ (Z=Al, Si, Ge): Half-metallic ferromagnetic materials(Elsevier Science Sa, 2021) Sürücü, Özge; Surucu, O.; Usanmaz, D.; Khenata, R.; Candan, A.; Surucu, G.; Electrical-Electronics EngineeringEquiatomic quaternary Heusler compounds (EQHCs) are very promising materials for spintronic applications due to their excellent electronic and magnetic properties. In this study, structural, electronic, magnetic, mechanic, and dynamic properties of TiVFeZ (Z=Al, Si, Ge) EQHCs are investigated. Three nonequivalent structural configurations of alpha, beta, and gamma type structures are considered. The gamma is defined as the most stable phase for all these compounds and has a half-metallic character. The predicted Curie temperatures of TiVFeAl, TiVFeSi, and TiVFeGe compounds are about 488 K, 256 K, and 306 K, respectively. We also show that TiVFeZ (Z=Al, Si, Ge) have thermodynamic, dynamic, and mechanical stabilities. The presented results reveal that these compounds are potential materials for spintronics applications. (C) 2021 Elsevier B.V. All rights reserved.Article Citation Count: 0Exploring Temperature-Dependent bandgap and Urbach energies in CdTe thin films for optoelectronic applications(Elsevier, 2024) Sürücü, Özge; Surucu, G.; Işık, Mehmet; Parlak, M.; Isik, M.; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringThis study examines CdTe thin films deposited via RF magnetron sputtering, focusing on structural and optical properties. X-ray diffraction, Raman spectroscopy, and SEM assessed structural characteristics. Optical properties were analyzed through transmittance measurements from 10 to 300 K. Tauc plots and Varshni modeling revealed a temperature-dependent bandgap, increasing from 1.49 eV at room temperature to 1.57 eV at 10 K. Urbach energy rose from 82.7 to 93.7 meV with temperature. These results are essential for applications where temperature affects CdTe-based device performance.Article Citation Count: 22Frequency effect on electrical and dielectric characteristics of HfO2-interlayered Si-based Schottky barrier diode(Springer, 2020) Sürücü, Özge; Yildiz, D. E.; Güllü, Hasan Hüseyin; Parlak, M.; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringThis study reveals the electrical properties of In/HfO2/n-Si structure with atomic layer-deposited interfacial oxide layer, HfO2 thin film between In top metal contact and monocrystalline Si wafer substrate. From the dark current-voltage measurements, the diode structure showed good rectifying behavior and low saturation current of about two order of magnitude and 1.2 x 10(- 9) A, respectively. According to the conventional thermionic emission model, zero-bias barrier height and ideality factor were calculated from the forward bias current-voltage curve at room temperature under dark conditions as 0.79 eV and 4.22 eV, respectively. In order to get detailed information about density of interface states and series resistance of this structure, capacitance-voltage and conductance-voltage measurements in the frequency range of 10-1000 kHz were performed. As a result, a decreasing capacitance profile with increasing frequency was obtained. In addition, peak-like behavior in the capacitance profiles was observed and these were found to be the indication of density of states. Further analysis was performed on the evaluation of density of interface states values and these values were calculated by using two different methods: Hill-Coleman and high-low frequency capacitance. These profiles were also analyzed by eliminating the effect of series resistance values on the measured capacitance and conductance; then the values of corrected capacitance and conductance as a function of applied voltage were discussed. Based on these analyses on the capacitive characteristics of the diode, dielectric constant, dielectric loss, loss tangent, electrical conductivity, and the real and imaginary part of electric modulus were investigated for complete understanding on the diode characteristics.Article Citation Count: 4Growth and optical characterization of Sn0.6Sb0.4Se layer single crystals for optoelectronic applications(Elsevier Sci Ltd, 2022) Sürücü, Özge; Terlemezoglu, M.; Işık, Mehmet; Isik, M.; Parlak, M.; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringSnSe compound is an attractive semiconductor material due to its usage in photovoltaic applications. The sub-stitution of Sb in the SnSe compound presents a remarkable advantage especially in point of tuning optical characteristics. The present paper reports the structural and optical properties of Sn1-xSbxSe (x = 0.4) layered single crystals grown by the vertical Bridgman method. To the best of our knowledge, this work is the first investigation of the Sn0.6Sb0.4Se crystal grown with the vertical Bridgman technique. X-ray diffraction (XRD) pattern of the grown crystal indicated the well crystalline structure of the grown crystals. Lattice strain and interplanar spacing of the crystal structure were determined using the XRD pattern. Scanning electron micro-scope images allowed to the observation of the layer crystal structure. The layer crystalline structure shows 2D material properties and provides 2D applications. Optical properties were revealed by carrying out Raman, ellipsometry and transmission measurements. Raman modes, refractive index, extinction coefficient, and dielectric spectra, band gap energy of the crystal were presented throughout the paper. The obtained results indicated that Sn1-xSbxSe (x = 0.4) layer single crystals may be an alternative potential for photovoltaic and optoelectronic applications.Article Citation Count: 0Innovative 2D materials for efficient photocatalysis: A comparative study for WSi2N4, WGe2N4, and their janus counterpart WSiGeN4 monolayers(Pergamon-elsevier Science Ltd, 2024) Sürücü, Özge; Surucu, G.; Lisesivdin, S. B.; Surucu, O.; Altuntas, G.; Bostan, B.; Gencer, A.; Electrical-Electronics EngineeringIn pursuit of environmentally friendly and effective photocatalytic materials for water splitting, this research paper presents a thorough evaluation of WSi2N4, WGe2N4, and their Janus counterpart WSiGeN4 monolayers through the application of Density Functional Theory. The study elucidates the optical, electronic, and structural characteristics of these monolayers, thereby demonstrating their potential as highly favorable contenders for applications involving photocatalytic water splitting. By means of comprehensive optimization and analysis, it is shown that these monolayers possess advantageous characteristics, such as favorable band gaps, stable work functions, and stability over a broad pH range. These attributes are of utmost importance in ensuring the effectiveness of hydrogen evolution reaction (HER). The inclusion of Janus WSiGeN4, which possesses an intrinsic mirror asymmetry, significantly improves the photocatalytic efficacy of the material. This is achieved by meeting the demands of optimal redox reaction levels in both the conduction and valence bands. In conjunction with machine learning force fields, ab initio molecular dynamics (AIMD) simulations validate the thermal stability of these monolayers at 300 K. In addition, our analysis of the optical properties reveals substantial absorption in the visible spectrum - vital for photocatalytic applications powered by solar energy. In summary, the research highlights the potential of Janus WSiGeN4, WGe2N4, and WSi2N4 monolayers as multifunctional and effective substances for forthcoming photocatalytic water -splitting systems. This advancement indicates of a significant stride in the direction of sustainable energy solution development.Article Citation Count: 0Performance enhancement of silicon photodiodes through the integration of green synthesized reduced graphene oxide variants(Iop Publishing Ltd, 2024) Sürücü, Özge; Surucu, O.; Balaban, H. Mert; Bilici, I; Yildirim, M.; Electrical-Electronics EngineeringThis study examines the potential of enhancing the optoelectronic properties of silicon photodiodes by producing and analyzing heterostructures that incorporate reduced graphene oxide (rGO) synthesized with silicon using different reduction methods. Graphene oxide (GO) was manufactured utilizing an enhanced Hummers' method. Subsequently, reduced graphene oxides (rGOs) were made by chemical and thermal reduction processes, which are considered ecologically friendly. The use of ascorbic acid to produce ascorbic acid-reduced graphene oxide (ArGO) and thermal processing to produce thermally reduced graphene oxide (TrGO) have significantly contributed to the development of high-performance photodiode technology. The electrical properties were carefully assessed under different levels of light, revealing the substantial impact of integrating reduced graphene oxides (rGOs) on the performance of the diodes. Comparing ArGO/Si, TrGO/Si, and GO/Si heterostructures shows that customized rGO has the potential to greatly influence the responsivity and efficiency of Si-based optoelectronic devices, making a significant contribution to photodiode technology.Article Citation Count: 3Pressure and spin effect on the stability, electronic and mechanic properties of three equiatomic quaternary Heusler (FeVHfZ, Z = Al, Si, and Ge) compounds(Elsevier, 2021) Sürücü, Özge; Gencer, A.; Surucu, O.; Usanmaz, D.; Candan, A.; Electrical-Electronics EngineeringIn this paper, three equiatomic quaternary Heusler compounds -FeVHfZ (Z = Al, Si, and Ge) - are investigated for their structural, magnetic, electronic, mechanic, and lattice dynamic properties under pressure effect. These compounds are optimized for under three structural types and three magnetic phases: beta is the most stable structure with ferromagnetic phase. The electronic properties reveal that FeVHfAl is a half-metal, and that FeVHfSi and FeVHfGe are spin gapless semiconductors. In addition to electronic band structure, possible hybridization and partial density of states are presented. Furthermore, the mechanical properties are studied, and the three-dimensional direction-dependent mechanical properties are visualized under varying pressure effects. Our results reveal the half-metal and spin gapless semiconductor nature of the ferromagnetic FeVHfZ com-pounds, making them promising materials for spintronics applications.Article Citation Count: 6Structural and temperature-tuned bandgap characteristics of thermally evaporated β-In2S3 thin films(Springer, 2021) Sürücü, Özge; Isik, M.; Işık, Mehmet; Gasanly, N. M.; Parlak, M.; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringIn2S3 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 Count: 6Temperature effects on optical characteristics of CdSe thin films(Elsevier Sci Ltd, 2021) Sürücü, Özge; Isik, M.; Işık, Mehmet; Gasanly, N. M.; Güllü, Hasan Hüseyin; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringCdSe is one of the significant members of II-VI type semiconducting family and it has a wide range of technological applications in which optoelectronic devices take a special position. The present paper reports the structural and optical characteristics of thermally evaporated CdSe thin films. XRD pattern exhibited preferential orientation along (111) plane while atomic composition analyses resulted in the ratio of Cd/Se as closer to 1.0. Temperature-dependent band gap characteristics of CdSe thin films were investigated for the first time by carrying out transmission experiments in the 10-300 K range. The analyses showed that direct band gap energy of the compound decreases from 1.750 (at 10 K) to 1.705 eV (at 300 K). Varshni model was successfully applied to the temperature-band gap energy dependency and various optical constants were determined. Raman spectrum of CdSe thin films was also presented to understand the vibrational characteristics of the compound. The present paper would provide worthwhile data to researchers especially studying on optoelectronic device applications of CdSe thin films.Article Citation Count: 5Temperature effects on optical characteristics of thermally evaporated CuSbSe2 thin films for solar cell applications(Elsevier, 2022) Sürücü, Özge; Isik, M.; Işık, Mehmet; Bektas, T.; Gasanly, N. M.; Parlak, M.; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringCuSbSe2 thin film was deposited by co-evaporation of binary CuSe and Sb2Se3 sources. The structural and morphological properties of the deposited thin film were investigated with X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis measurements. XRD pattern indicated that deposited thin film has an orthorhombic crystalline structure with the preferential orientation of (013) direction. SEM image presented that the thin film surface is almost uniform. The optical characteristics of the deposited CuSbSe2 thin film were investigated in detail by performing room temperature Raman, temperature-dependent transmittance spectroscopy, and photoluminescence techniques. Raman spectrum exhibited one mode at around 210 cm(-1) associated with A(g) vibrational mode. The derivative spectroscopy technique was used to obtain the band gap energy of the films. Temperature dependence of band gap energy was investigated by considering the Varshni model. The rate of change of band gap energy, absolute zero value of gap energy, and Debye temperature were determined as 1.3 x 10(-4) eV/K, 1.21 eV, and 297 +/- 51 K, respectively. The photoluminescence spectrum indicated the room temperature direct band gap energy as 1.30 eV.Article Citation Count: 0Temperature-dependent current-voltage characteristics of p-GaSe0.75S0.25/n-Si heterojunction(Springer Heidelberg, 2023) Sürücü, Özge; Surucu, O.; Işık, Mehmet; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringGaSe0.75S0.25 having layered structure is a potential semiconductor compound for optoelectronics and two-dimensional materials technologies. Optical and structural measurements of the GaSe0.75S0.25 thin film grown on the glass substrate showed that the compound has hexagonal structure and band energy of 2.34 eV. GaSe0.75S0.25 thin film was also grown on the silicon wafer and p-GaSe0.75S0.25/n-Si heterojunction was obtained. To make the electrical characterization of this diode, temperature-dependent current-voltage (I-V) measurements were carried out between 240 and 360 K. Room temperature ideality factor and barrier height of the device were determined from the analyses of I-V plot as 1.90 and 0.87 eV, respectively. Temperature-dependent plots of these electrical parameters showed that the ideality factor decreases from 2.19 to 1.77, while barrier height increases to 0.94 from 0.71 eV when the temperature was increased from 240 to 360 K. The conduction mechanism in the heterojunction was studied considering the Gaussian distribution due to presence of inhomogeneity in barrier height. The analyses presented the mean zero-bias barrier height, zero-bias standard deviation, and Richardson constant.Conference Object Citation Count: 4Temperature-dependent material characterization of CuZnSe2 thin films(Elsevier Science Sa, 2020) Sürücü, Özge; Surucu, O.; Işık, Mehmet; Isik, M.; Güllü, Hasan Hüseyin; Gasanly, N. M.; Parlak, M.; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringIn the present work, CuZnSe2 (CZSe) thin films were co-deposited by magnetron sputtering of ZnSe and Cu targets. The structural analyses resulted in the stoichiometric elemental composition and polycrystalline nature without secondary phase contribution in the film structure. Optical and electrical properties of CZSe thin films were investigated using temperature-dependent optical transmission and electrical conductivity measurements. The band gap energy values were obtained using transmittance spectra under the light of expression relating absorption coefficient to incident photon energy. Band gap energy values were found in decreasing behavior from 2.31 to 2.27 eV with increase in temperature from 10 to 300 K. Temperature-band gap dependency was evaluated by Varshni and O'Donnell models to detail the optical parameters of the thin films. The experimental dark and photoconductivity values were investigated by thermionic emission model over the grain boundary potential. Room temperature conductivity values were obtained in between 0.91 and 4.65 ( x 10(-4) Omega(-1)cm(-1)) under various illumination intensities. Three different linear conductivity regions were observed in the temperature dependent profile. These linear regions were analyzed to extract the activation energy values.Article Citation Count: 14Temperature-dependent optical characteristics of sputtered NiO thin films(Springer Heidelberg, 2022) Sürücü, Özge; Surucu, O.; Işık, Mehmet; Gasanly, N. M.; Parlak, M.; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringIn this work, nickel oxide thin films were deposited by radio frequency magnetron sputtering technique. X-ray diffraction (XRD), scanning electron microscopy and energy-dispersive X-ray analysis methods were applied to reveal the structural and morphological properties of sputtered thin films. The XRD pattern of films confirmed the presence of the cubic phase of nickel oxide with the preferential orientation of (200) direction. The surface morphology of thin films was observed as almost uniform and smooth. Optical aspects of sputtered film were studied by employing the room temperature Raman and temperature-dependent transmittance spectroscopy techniques in the range of 10-300 K. Tauc relation and derivative spectroscopy techniques were applied to obtain the band gap energy of the films. In addition, the relation between the band gap energy and the temperature was investigated in detail considering the Varshni optical model. The absolute zero band gap energy, rate of change of band gap energy, and Debye temperature were obtained as 3.57 eV, - 2.77 x 10(-4) eV/K and 393 K, respectively.Article Citation Count: 19Temperature-tuned band gap properties of MoS2 thin films(Elsevier, 2020) Sürücü, Özge; Isik, M.; Işık, Mehmet; Terlemezoglu, M.; Parlak, M.; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringMoS2 is one of the fascinating members of transition metal dichalcogenides and has attracted great attention due to its various optoelectronic device applications and its characteristic as two-dimensional material. The present paper reports the structural and temperature tuned optical properties of MoS2 thin films grown by RF magnetron sputtering technique. It was observed that the atomic composition ratio of Mo:S was nearly equal to 1:2 and the deposited thin films have hexagonal crystalline structure exhibiting Raman peaks around 376 and 410 cm(-1). The band gap energies were determined as 1.66 and 1.71 eV at 300 and 10 K, respectively and temperature dependency of band gap energy was analyzed by means of Varshni and O'Donnell-Chen models. (C) 2020 Elsevier B.V. All rights reserved.