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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14411/18

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Citation - WoS: 14
Citation - Scopus: 18
Unveiling the Application Potential of Pbmo0.75w0.25< 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.
Citation - WoS: 3
Citation - Scopus: 3
Optical Characterization of Nabi(moo4)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.
Citation - WoS: 42
Citation - Scopus: 47
Structural and Temperature-Dependent Optical Properties of Thermally Evaporated Cds Thin Films
(Elsevier Sci Ltd, 2019-04) Isik, M.; Gullu, H. H.; Delice, S.; Parlak, M.; Gasanly, N. M.
In this work, structural and temperature dependent optical properties of thermally evaporated CdS thin films were investigated. X-ray diffraction, energy dispersive spectroscopy and Raman spectroscopy experiments were carried out to characterize the thin films and obtain information about the crystal structure, atomic composition, surface morphology and vibrational modes. Temperature-dependent transmission measurements were performed in between 10 and 300 K and in the spectral range of 400-1050 nm. The analyses of transmittance spectra were accomplished by two different methods called as the absorption coefficient and the derivative spectrophotometry analyses. All evaluated band gap energy values at each studied temperature were in good agreement with each other depending on the applied analyses techniques. Room temperature gap energy values were found around 2.39 eV and 2.40 eV from absorption coefficient and derivative spectrophotometry analyses, respectively. Band gap energy depending on the sample temperature was studied under the light of two different models to investigate average phonon energy, electron phonon coupling parameter and the rate of change of band gap energy with temperature.
Citation - WoS: 5
Citation - Scopus: 5
Optical properties of (Ga2Se3)0.75 - (Ga2S3)0.25 single crystals by spectroscopic ellipsometry
(Elsevier Science Bv, 2019-05) Isik, M.; Gasanly, N. M.; Gasanova, L.
Structural and optical properties of 75 mol % Ga2Se3 - 25 mol % Ga2S3 system of single crystals were investigated by experimental techniques of x-ray diffraction (XRD), energy dispersive spectroscopy, Raman spectroscopy and ellipsometry. XRD pattern indicated that the studied compound has crystalline nature with cubic structure. Vibrational modes in the crystal were revealed using Raman spectroscopy experiments in the 90-450 cm(-1) frequency range and nine modes were observed in the spectrum. Ellipsometry measurements were utilized in the 1.2-6.2 eV range to get spectral dependencies of optical constants; complex dielectric function, refractive index and extinction coefficient. Under the light of fundamental expressions and models, refractive index and extinction coefficient spectra were analyzed to get various optical parameters of the single crystal.
Citation - WoS: 8
Citation - Scopus: 8
Study of Vibrational Modes in (ga2s3< - (ga2se3< Mixed Crystals by Raman and Infrared Reflection Measurements
(Elsevier, 2019-09) Isik, M.; Guler, I.; Gasanly, N. M.
Raman and infrared (IR) reflection characteristics were investigated in the frequency region of 100-450 cm(-1) for (Ga2S3)(x) - (Ga2Se3)(1-x) mixed crystals for compositions of x increasing from 0.0 to 1.0 by intervals of 0.25 obtained by Bridgman crystal growth technique. In the Raman spectra of these crystals four dominant peak features were observed while two bands were detected in the IR spectra of interest samples. Kramers-Kronig dispersion relations applied to IR spectra presented the frequencies of transverse optical modes. The compositional dependencies of revealed Raman- and IR-active mode frequencies on (Ga2S3)(x) - (Ga2Se3)(1-x) crystals were established. One-mode behavior was displayed from indicated dependencies.
Citation - WoS: 22
Citation - Scopus: 27
Temperature Dependence of Band Gaps in Sputtered Snse Thin Films
(Pergamon-elsevier Science Ltd, 2019-08) Delice, S.; Isik, M.; Gullu, H. H.; Terlemezoglu, M.; Surucu, O. Bayrakli; Parlak, M.; Gasanly, N. M.; Bayrakli Surucu, O.
Temperature-dependent transmission experiments were performed for tin selenide (SnSe) thin films deposited by rf magnetron sputtering method in between 10 and 300 K and in the wavelength region of 400-1000 nm. Transmission spectra exhibited sharp decrease near the absorption edge around 900 nm. The transmittance spectra were analyzed using Tauc relation and first derivative spectroscopy techniques to get band gap energy of the SnSe thin films. Both of the applied methods resulted in existence of two band gaps with energies around 1.34 and 1.56 eV. The origin of these band gaps was investigated and it was assigned to the splitting of valence band into two bands due to spin-orbit interaction. Alteration of these band gap values due to varying sample temperature of the thin films were also explored in the study. It was seen that the gap energy values increased almost linearly with decreasing temperature as expected according to theoretical knowledge.
Citation - WoS: 25
Citation - Scopus: 26
Temperature-Tuned Band Gap Properties of Mos2 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.
Citation - WoS: 9
Citation - Scopus: 10
Investigation of Structural and Optical Characteristics of Thermally Evaporated Ga2se3< 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.
Citation - WoS: 19
Citation - Scopus: 20
Optical characteristics of Bi12SiO20 single crystals by spectroscopic ellipsometry
(Elsevier Sci Ltd, 2020-12) Isik, M.; Delice, S.; Nasser, H.; Gasanly, N. M.; Darvishov, N. H.; Bagiev, V. E.
Structural and optical characteristics of Bi12SiO20 single crystal grown by the Czochralski method were investigated by virtue of X-ray diffraction (XRD) and spectroscopic ellipsometry measurements. XRD analysis indicated that the studied crystal possesses cubic structure with lattice parameters of a = 1.0107 nm. Spectral dependencies of several optical parameters like complex dielectric constant, refractive index, extinction and absorption coefficients were determined using ellipsometry experiments performed in the energy region of 1.2-6.2 eV. The energy band gap of Bi12SiO20 crystals was found to be 3.25 eV by utilizing absorption coefficient analysis. Moreover, critical point energies were calculated as 3.54, 4.02, 4.82 and 5.58 eV from analyses of the second energy derivative spectra of the complex dielectric constant.
Citation - WoS: 12
Citation - Scopus: 12
Structural and Temperature-Tuned Optical Characteristics of Bi12geo20< Sillenite Crystals
(Elsevier, 2020-08) Delice, S.; Isik, M.; Gasanly, N. M.; Darvishov, N. H.; Bagiev, V. E.
Sillenite compounds exhibit unique photorefractive and electro-optic characteristics providing attractiveness to these materials in various optoelectronic applications. The present paper aims at investigating one of the members of this family. Structural and optical characteristics of Bi12GeO20 (BGO) were studied by means of x-ray diffraction, Raman spectroscopy and temperature-dependent transmittance measurements. Obtained transmission curves in the wavelength range of 350-1100 nm and at different applied temperatures between 10 and 300 K were employed to find out the absorption coefficient dependence on the photon energy. Tauc relation revealed the presence of an energy gap of 2.49 eV at room temperature. Extension of energy gap up to 2.57 eV due to decreased temperature down to 10 K was deduced by the analysis. In order to have reliable results, the energy gap value was corroborated by utilizing derivative spectral method and well consistency between both methods was indicated. Energy gap change with temperature was also discussed in the study using an empirical formula developed by Varshni. Energy gap at absolute zero and rate of band gap alteration with temperature were determined as 2.57 eV and -2.4 x 10(-4) eV K (- 1), respectively. Taking into account the previously reported studies on investigation of band gap characteristics of BGO, intrinsic Bi-Ge(3+) + V-O(+) defect could be responsible for the revealed energy value of 2.49 eV which is much lower than reported band gap energy of similar to 3.2 eV.

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