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Article Citation - WoS: 2Citation - Scopus: 2Optical Characterization of Nabi(moo4)2< Crystal by Spectroscopic Ellipsometry(Springer Heidelberg, 2024) 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: 1Citation - Scopus: 2Spectroscopic Ellipsometry Studies of Optical Properties of Tlin(s0.25se0.75< Crystal(Springer Heidelberg, 2023) Guler, I.; Isik, M.; Gasanly, N.The optical properties of TlIn(S0.25Se0.75)(2) crystals were studied by ellipsometry measurements. X-ray diffraction pattern presented well-defined peaks associated with monoclinic structure. Energy dependent graphs of various linear optical parameters of the crystal were presented in the 1.25-4.50 eV range. The band gap and Urbach energies of the compound were found as 1.96 and 0.68 eV, respectively, from the analyses of the absorption coefficient. Refractive index spectrum was analyzed considering the single-effective-oscillator model to get oscillator and dispersion energies, zero and high frequency dielectric constants, plasma frequency. Moreover, the nonlinear refractive index, first-order and third-order nonlinear susceptibilities of TlIn(S0.25Se0.75)(2) crystal were revealed in the present paper.Article Citation - WoS: 7Citation - Scopus: 7Characterization of Bi12sio20< Single Crystal: Understanding Structural and Thermal Properties(Springer Heidelberg, 2024) 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: 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: 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.
