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Article Citation - WoS: 25Citation - Scopus: 25Temperature-Tuned Band Gap Properties of Mos2 Thin Films(Elsevier, 2020) Surucu, O.; Isik, M.; Gasanly, N. M.; Terlemezoglu, M.; Parlak, M.MoS2 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.Article Citation - WoS: 5Citation - Scopus: 4Pressure and Spin Effect on the Stability, Electronic and Mechanic Properties of Three Equiatomic Quaternary Heusler (fevhfz, Z = Al, Si, and Ge) Compounds(Elsevier, 2021) Surucu, G.; Gencer, A.; Surucu, O.; Usanmaz, D.; Candan, A.In 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 - WoS: 22Citation - Scopus: 22Exploring Temperature-Dependent Bandgap and Urbach Energies in Cdte Thin Films for Optoelectronic Applications(Elsevier, 2024) Surucu, O.; Surucu, G.; Gasanly, N. M.; Parlak, M.; Isik, M.This 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 - 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: 45Citation - Scopus: 41Temperature-Dependent Optical Characteristics of Sputtered Nio Thin Films(Springer Heidelberg, 2022) Terlemezoglu, M.; Surucu, O.; Isik, M.; Gasanly, N. M.; Parlak, M.In 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 - WoS: 29Citation - Scopus: 29Frequency Effect on Electrical and Dielectric Characteristics of Hfo2-interlayered Si-Based Schottky Barrier Diode(Springer, 2020) Gullu, H. H.; Yildiz, D. E.; Surucu, O.; Parlak, M.This 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 Cu Doping of Sb2Se3 Thin Films Via Thermal Evaporation: Tailoring Structural and Optical Properties for Enhanced Photovoltaic Performance(Elsevier, 2025) Isik, M.; Surucu, O.; Bektas, T.; Parlak, M.In this study, Cu-doped Sb2Se3 thin films were successfully grown using the thermal evaporation method, and their structural and optical properties were systematically investigated. Three different samples with thickness of similar to 400 nm were analyzed: undoped, 1 %, and 2 % Cu-doped Sb2Se3. X-ray diffraction (XRD) analysis revealed well-defined peaks, confirming the orthorhombic crystalline nature of the films. Scanning electron microscopy (SEM) images showed a uniform surface morphology without any significant defects. The optical properties were examined through transmission measurements. The band gap energy determined by Tauc analysis decreased from 1.27 to 1.21 eV as the Cu doping increased from 0 % to 2 %, indicating that Cu incorporation modifies the electronic structure of Sb2Se3. Similarly, Urbach energy increased from 0.148 to 0.168 eV depending on Cu content, suggesting a rise in localized states due to increased structural disorder. These findings demonstrate that Cu doping influences the electronic structure and defect states of Sb2Se3, which is crucial for optimizing its performance in photovoltaic and optoelectronic applications.Article Citation - WoS: 1Citation - Scopus: 1Temperature-Dependent Current-Voltage Characteristics of p-gase0.75< Heterojunction(Springer Heidelberg, 2023) Isik, M.; Surucu, O.; Gasanly, N. M.GaSe0.75S0.25 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.
