WoS
Permanent URI for this collectionhttps://hdl.handle.net/20.500.14411/18
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Article Citation - WoS: 3Citation - Scopus: 3Cu Doping of Sb2Se3 Thin Films Via Thermal Evaporation: Tailoring Structural and Optical Properties for Enhanced Photovoltaic Performance(Elsevier, 2025-10) 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: 7Citation - Scopus: 7Characterization of Bi<sub>12</Sub>sio<sub>20< Single Crystal: Understanding Structural and Thermal Properties(Springer Heidelberg, 2024-09-17) Altuntas, G.; Isik, M.; Gasanly, N. M.This study presents a thorough examination of the structural and thermal characteristics of Bi12SiO20 crystal. X-ray diffraction (XRD) analysis was employed to investigate the crystallographic structure, while scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were utilized to ascertain morphological features and elemental composition, respectively. The XRD spectrum exhibited numerous peaks corresponding to the cubic crystalline structure. Thermal behavior was investigated through thermal gravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Within the crystal, negligible weight loss was observed up to 750 degrees C, followed by weight loss processes occurring in the temperature ranges of 750-919 degrees C and above 919 degrees C. The 2% weight loss in the range of 750-919 degrees C was associated with the decomposition process, and the activation energy of this process was found to be 199 kJ/mol considering Coats-Redfern expression. A significant weight loss was observed in the region above 919 C-o and was associated with the decomposition of the Bi12SiO20 compound and/or the melting processes of the components of the Bi12SiO20 compound. Three endothermic peaks were observed in the DTA plot. Additionally, DSC measurements conducted under varied heating rates indicated endothermic crystallization process around 348 degrees C, with an activation energy of 522 kJ/mol determined through the Kissenger equation. These findings present valuable details regarding the crystal's structural configuration, morphological attributes, and decomposition/phase transitions, thereby illuminating its potential applications across various fields.Article Citation - WoS: 14Citation - Scopus: 18Unveiling the Application Potential of Pbmo<sub>0.75</Sub>w<sub>0.25< Crystal: Linear and Nonlinear Optical Properties Through Ellipsometry(Elsevier, 2024-12) Isik, M.; Gasanly, N. M.PbMo0.75W0.25O4 compound is formed by replacing one quarter of the Mo atoms in the PbMoO4 with W atoms and has significant potential for optoelectronic applications. Optical properties of PbMo0.75W0.25O4 single crystal have been systematically investigated using ellipsometry measurements in the spectral range of 2.4-5.4 eV. The linear optical parameters, including refractive index, extinction coefficient, and absorption coefficient, were extracted from the obtained ellipsometry data. By analyzing spectral dependence of these parameters, band gap energy, critical point energy, and single effective oscillator parameters were determined. The refractive index spectrum was analyzed in the below band gap energy region by considering Cauchy and Sellmeier models. Additionally, nonlinear optical values were calculated, providing a comprehensive understanding of the optical properties of the PbMo0.75W0.25O4 single crystal. This study not only contributes to the fundamental understanding of the crystal's optical properties but also has potential implications for applications in optoelectronic devices and photovoltaics.Article Citation - WoS: 6Citation - Scopus: 6Identification of Shallow Trap Centers in Inse Single Crystals and Investigation of Their Distribution: a Thermally Stimulated Current Spectroscopy(Elsevier, 2024-10) Isik, M.; Gasanly, N. M.Identification of trap centers in semiconductors takes great importance for improving the performance of electronic and optoelectronic devices. In the present study, we employed the thermally stimulated current (TSC) method within a temperature range of 10-280 K to explore trap centers in InSe crystal-a material with promising applications in next-generation devices. Our findings revealed the existence of two distinct hole trap centers within the InSe crystal lattice located at 0.06 and 0.14 eV. Through the leveraging the T-stop method, we offered trap distribution parameters of revealed centers. The results obtained from the experimental methodology employed to investigate the distribution of trap centers indicated that one of the peaks extended between 0.06 and 0.13 eV, while the other spanned from 0.14 to 0.31 eV. Notably, our research uncovers a remarkable variation in trap density, spanning one order of magnitude, for every 10 and 88 meV of energy variation. The results of our research present the characteristics of shallow trap centers in InSe, providing important information for the design and optimization of InSe-based optoelectronic devices.Article Citation - WoS: 3Citation - Scopus: 3Optical Characterization of Nabi(moo<sub>4</Sub>)<sub>2< Crystal by Spectroscopic Ellipsometry(Springer Heidelberg, 2024-08-12) Guler, I.; Isik, M.; Gasanly, N. M.The compound NaBi(MoO4)(2) has garnered significant interest in optoelectronic fields. This study employs spectroscopic ellipsometry to thoroughly examine the linear and nonlinear optical characteristics of NaBi(MoO4)(2) crystals, offering detailed insights into their optical behavior. Our investigation presents a precise method for discerning the crystal's spectral features, revealing the spectral variations of key optical parameters such as refractive index, extinction coefficient, dielectric function, and absorption coefficient within the 1.2-5.0 eV range. Through analysis, we determined optical attributes including bandgap energy, critical point energy, and single oscillator parameters. Additionally, we explored the nonlinear optical properties of NaBi(MoO4)(2), unveiling potential applications such as optoelectronic devices, frequency conversion, and optical sensors. This study enhances comprehension of optical properties of NaBi(MoO4)(2), underscoring its significance in future optical and electronic advancements.Article Citation - WoS: 28Citation - Scopus: 30Exploring Temperature-Dependent Bandgap and Urbach Energies in Cdte Thin Films for Optoelectronic Applications(Elsevier, 2024-10) 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: 25Citation - Scopus: 26Temperature-Tuned Band Gap Properties of Mos<sub>2</Sub> Thin Films(Elsevier, 2020-09) 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: 17Citation - Scopus: 18Investigation of Band Gap Energy Versus Temperature for Sns 2 Thin Films Grown by Rf-Magnetron Sputtering(Elsevier, 2020-08) Isik, M.; Gullu, H. H.; Terlemezoglu, M.; Surucu, O. Bayrakli; Parlak, M.; Gasanly, N. M.[No Abstract Available]Article Citation - WoS: 4Citation - Scopus: 4TL and OSL studies on gallium sulfide (GaS) single crystals(Elsevier, 2020-09) Isik, M.; Yuksel, M.; Topaksu, M.; Gasanly, N. M.[No Abstract Available]Article Citation - WoS: 9Citation - Scopus: 10Investigation of Structural and Optical Characteristics of Thermally Evaporated Ga<sub>2</Sub>se<sub>3< Thin Films(Pergamon-elsevier Science Ltd, 2020-09) Isik, M.; Gasanly, N. M.Ga2Se3 thin films were prepared by thermal evaporation technique and structural, optical characteristics of the deposited thin films were investigated in the present study. X-ray diffraction pattern of the thin film exhibited one intensive and sharp peak associated with (111) plane of cubic crystalline structure of the compound. Energy dispersive spectroscopic analyses pointed out the atomic compositional ratio of the constituent elements as consistent with chemical formula of Ga2Se3. The optical characteristics of thin film were studied by means of temperature-dependent transmission experiments carried out in between 10 and 300 K. The analyses to get band gap energies at applied temperatures were accomplished using absorption coefficient according to Tauc relation and derivative transmittance spectra. Absorption coefficient analyses end up with band gap energies increasing from 2.60 eV (room temperature) to 2.67 eV (10 K). The derivatives of transmittance spectra were also utilized for purpose and band gap energies were found very closer (max. +/- 0.02 eV deviation) to those of absorption coefficient analyses. Varshni and Fan models were applied to band gap energy vs. temperature plot and various optical parameters of Ga2Se3 thin film were determined.