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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: 9Citation - Scopus: 9Temperature Effects on Optical Characteristics of Thermally Evaporated Cusbse2 Thin Films for Solar Cell Applications(Elsevier, 2022) Surucu, O.; Isik, M.; Terlemezoglu, M.; Bektas, T.; Gasanly, N. M.; Parlak, M.CuSbSe2 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 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.
