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Citation - WoS: 3
Citation - Scopus: 4
Optical Properties of Cu₃in_{5< Single Crystals by Spectroscopic Ellipsometry}
(Elsevier Gmbh, 2018) Isik, M.; Nasser, H.; Ahmedova, F.; Guseinov, A.; Gasanly, N. M.
Cu3In5S9 single crystals were investigated by structural methods of x-ray diffraction and energy dispersive spectroscopy and optical techniques of ellipsometry and reflection carried out at room temperature. The spectral dependencies of optical constants; dielectric function, refractive index and extinction coefficient, were plotted in the range of 1.2-6.2 eV from ellipsometric data. The spectra of optical constants obtained from ellipsometry analyses and reflectance spectra presented a sharp change around 1.55 and 1.50 eV, respectively, which are associated with band gap energy of the crystal. The critical point (interband transition) energies were also found from the analyses of second-energy derivative of real and imaginary components of dielectric function. The analyses indicated the presence of four critical points at 2.73, 135, 4.04 and 4.98 eV.
Citation - WoS: 10
Citation - Scopus: 11
Spectroscopic Ellipsometry Investigation of Optical Properties of Β-ga₂s_{3< Single Crystals}
(Elsevier Science Bv, 2018) Isik, M.; Gasanly, N. M.; Gasanova, L.
Ga2S3 single crystals were studied by x-ray diffraction (XRD), energy dispersive spectroscopy and spectroscopic ellipsometry measurements. XRD pattern of the sample is well-matched with reported hexagonal structure of beta-Ga2S3 . The spectra of real and imaginary parts of complex dielectric function (epsilon = epsilon(1) + epsilon(2)) and refractive index (N = n + ik) were plotted in the 1.2-6.2 eV range according to results of ellipsometric data. The e 2 -spectrum and analyses of absorption coefficient pointed out that studied sample has band gap energy of 2.48 eV which is consistent with that of beta-Ga(2)S(3)2. Critical point energies of beta-Ga2S3 were also reported in the present study.
Citation - WoS: 12
Citation - Scopus: 12
Interband Transitions in Gallium Sulfide Layered Single Crystals by Ellipsometry Measurements
(Elsevier, 2013) Isik, M.; Gasanly, N. M.; Turan, R.
Spectroscopic ellipsometry measurements on the GaS single crystals are presented in the energy range of 1.2 - 6.2 eV at room temperature. Optical constants; pseudorefractive index, pseudoextinction coefficient, real and imaginary parts of the pseudodielectric function were determined. Analysis of the second derivative of real and imaginary parts of the pseudodielectric constant revealed five transitions with critical point energies of 3.95, 4.22, 4.51, 4.75 and 5.50 eV. These energies were assigned to interband transitions according to theoretical study of GaS band structure available in literature. (C) 2012 Elsevier B.V. All rights reserved.
Citation - WoS: 7
Citation - Scopus: 7
Exploring the Linear and Nonlinear Optical Behavior of (tlins2)0.75(tlinse2)0.25: Insights From Ellipsometry Measurements
(Elsevier, 2023) Isik, M.; Guler, I.; Gasanly, N.
The search for layered structured new semiconductor materials with remarkable optical properties has become a driving force, especially for materials science. Tl2In2S3Se [(TlInS2)0.75(TlInSe2)0.25], a fascinating compound, holds great promise for advanced photonic and optoelectronic applications. In the present study, the linear and nonlinear optical properties of Tl2In2S3Se layered single crystals were studied by ellipsometry measurements. The variation of refractive index, extinction coefficient, absorption coefficient and skin depth with energy were investigated. Applying the derivative analysis technique to the absorption spectrum, indirect bandgap was found as 2.19 eV. The refractive index data was analyzed considering single-effective-oscillator model. The lattice dielectric constant, plasma frequency, carrier density to the effective mass ratio and zero-frequency refractive index were found. Moreover, the change in optical conductivity with energy yielded to determine the direct bandgap as 2.40 eV. The optical parameters of nonlinear refractive index, first-and third-order nonlinear susceptibilities were also reported.
Citation - WoS: 19
Citation - Scopus: 20
Optical characteristics of Bi₁₂SiO₂₀ single crystals by spectroscopic ellipsometry
(Elsevier Sci Ltd, 2020) 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: 11
Citation - Scopus: 11
Ellipsometry Study of Interband Transitions in Tlgas_{2x< Mixed Crystals (0 ≤ x ≤ 1)}
(Elsevier, 2012) Isik, M.; Gasanly, N. M.
In this paper, the spectroscopic ellipsometry measurements on TlGaS2xSe2(1 - x) mixed crystals (0 <= x <= 1) were carried out on the layer-plane (001) surfaces with light polarization E perpendicular to c* in the 1.2-6.2 eV spectral range at room temperature. The real and imaginary parts of the dielectric function, refractive index and extinction coefficient were calculated from ellipsometric data using the ambient-substrate optical model. The critical point energies in the above-band gap energy range have been obtained from the second derivative spectra of the dielectric function. Particularly for TlGaSe2 crystals, the determined critical point energies were assigned tentatively to interband transitions using the available electronic energy band structure. The effect of the isomorphic anion substitution (sulfur for selenium) on critical point energies in TlGaS2xSe2(1 - x) mixed crystals was established. (C) 2012 Elsevier B.V. All rights reserved.
Citation - WoS: 11
Citation - Scopus: 12
Characterization of Au/As_{2< Hybrid Devices Designed for Dual Optoelectronic Applications}
(Elsevier, 2020) Kayed, T. S.; Qasrawi, A. F.
In this work, hybrid devices composed of n-As2Se3/p-MoO3 encapsulated between two Schottky shoulders (Au/n-As2Se3, Ag/MoO3) are prepared and characterized. While the structural analyses proofed the preferred growth of monoclinic MoO3 onto amorphous layers of As2Se3, the spectroscopic ellipsometry analysis revealed the high frequency dielectric constants, the effective mass and the negative pseudodielectric constant values. Electrically, the hybrid device displayed both tunneling and standard diode characteristics. As passive mode devices, the capacitance-voltage characteristics displayed the accumulation-depletion -inversion modes in the device. Furthermore, the conductivity spectral analysis has shown that the current conduction is dominated by the quantum mechanical tunneling and correlated barriers hoping mechanisms. The amplitude of the reflection coefficient and the return loss spectral analyses indicated that the hybrid devices are band stop filters in addition to it is usability as nonlinear optical interfaces, CMOS device and tunneling diodes.
Citation - WoS: 10
Citation - Scopus: 10
Ellipsometric Study of Optical Properties of Gas_xse_{1-x< Layered Mixed Crystals}
(Elsevier Science Bv, 2016) Isik, Mehmet; Gasanly, Nizami
Spectroscopic ellipsometry measurements were performed on GaSxSe1-x mixed crystals (0 <= x <= 1) in the 1.2-6.2 eV range. Spectral dependence of optical parameters; real and imaginary components of pseudodielectric function, pseudorefractive index and pseudoextinction coefficient were reported in the present work. Critical point (CP) analyses on second-energy derivative spectra of the pseudodielectric function were accomplished to find the interband transition energies. The revealed energy values were associated with each other taking into account the fact that band gap energy of mixed crystals rises with increase in sulfur content. The variation of CP energies with composition (x) was also plotted. Peaks in the spectra of studied optical parameters and CP energy values were observed to be shifted to higher energy values as sulfur concentration is increased in the mixed crystals. (C) 2016 Elsevier B.V. All rights reserved.
Citation - WoS: 10
Citation - Scopus: 11
Optical Constants of Layered Structured Ga_0.75in_{0.25< Crystals From the Ellipsometric Measurements}
(Pergamon-elsevier Science Ltd, 2012) Isik, M.; Cetin, S. S.; Gasanly, N. M.; Ozcelik, S.
We have carried out the spectroscopic ellipsometry measurements on Ga0.75In0.25Se single crystals in the 1.2-6.0 eV spectral range at room temperature. The optical constants, real and imaginary parts of the dielectric function, refractive index and extinction coefficient, were found as a result of analysis of ellipsometric data. The critical point analysis of the second derivative spectra of the dielectric function revealed four interband transition structures with critical point energy values of 3.19, 3.53, 4.10 and 4.98 eV. The results of the analysis were compared with those of the ellipsometric studies performed on GaSe which is the main constituent of the Ga0.75In0.25Se crystal. The obtained critical point energies are in good agreement with the energies of the GaSe crystal reported in the literature. (C) 2012 Elsevier Ltd. All rights reserved.
Citation - WoS: 13
Citation - Scopus: 17
Unveiling the Application Potential of Pbmo_0.75w_{0.25< Crystal: Linear and Nonlinear Optical Properties Through Ellipsometry}
(Elsevier, 2024) 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.

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