Ortak Dersler Bölümü

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Citation - WoS: 3
Citation - Scopus: 2
Characterization of Linear and Nonlinear Optical Properties of Nabi(Wo4)2 Crystal by Spectroscopic Ellipsometry
(Elsevier, 2024) Guler, I.; Gasanly, N. M.; Isik, M.
NaBi(WO4)2 compound has been a material of considerable attention in optoelectronic applications. The present research, in which we examined the linear and nonlinear optical properties of NaBi(WO4)2 crystal using the spectroscopic ellipsometry method, elucidates the optical behavior of the crystal in detail. Our work provides a sensitive approach to determine the spectral characteristic of the crystal. The spectral dependence of various optical parameters such as refractive index, extinction coefficient, dielectric function and absorption coefficient was reported in the range of 1.2-5.0 eV. Optical values such as bandgap energy, critical point energy, single oscillator parameters were obtained as a result of the analyses. In addition to linear optical properties, we also investigated the nonlinear optical behavior of NaBi(WO4)2 and shed new light on the potential applications of the crystal. Absorbance and photoluminescence spectra of the crystal were also reported to characterize optical, electronic and emission behavior of the compound. Our findings may form the basis for a number of technological applications such as optoelectronic devices, frequency conversion, and optical sensors. This research contributes to a better understanding of the optical properties of NaBi(WO4)2 crystal, highlighting the material's role in future optical and electronic technologies.
Citation - WoS: 7
Citation - Scopus: 7
Exploring the Linear and Nonlinear Optical Behavior of (Tlins2)0.75 Insights From Ellipsometry Measurements
(Elsevier, 2023) Guler, I.; Gasanly, N.; Isik, M.
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: 53
Citation - Scopus: 56
Optical and Structural Characterization of Silicon Nitride Thin Films Deposited by Pecvd
(Elsevier, 2019) Guler, I
Plasma enhanced chemical vapor deposition (PECVD) technique was used to deposit silicon nitride (SiNx) thin films. The silane (SiH4) and ammonia (NH3) were used as reactant gases. Both the flow rates of the NH3 and SiH4 gases were changed but total flow rate kept constant to obtain the different ratio nitrogen (N) in the SiNx films. Fourier transform infrared spectroscopy (FTIR) was used to get information about absorption ratios of the films and the bond types in the films. The refractive index of the films was obtained from ellipsometry measurements. From FTIR measurements and ellipsometry measurements, refractive index for amorphous silicon (Si) and refractive index for stoichiometric SiNx were found as 3.27 and 1.91, respectively. The photoluminescence (PL) measurements were used to see the luminescent of the amorphous Si nanoparticles which were occurred spontaneously during deposition process. High resolution transmission electron microscopy (HRTEM) was used to analyze the Si nanoparticle size.
Citation - WoS: 6
Citation - Scopus: 6
A Phenomenological Study on Ferroelectric Pyridinium Tetrafluoroborate (C5nh6) Bf4
(Elsevier, 2019) Kiraci, A.
The temperature dependence of the specific heat C-V of (C5NH6)BF4 was analyzed according to a power law formula with a critical exponent alpha deduced from the compressible Ising model in the vicinity of the phase transition temperatures of T-C1 = 238 K and T-C2 = 204 K. The extracted values of the critical exponent alpha within the temperature intervals of vertical bar T - T-C1 vertical bar < 6 K and also T - T-C2 < 6 K were consistent with that predicted from the 3d-Ising model (alpha = 0.10) while obtained values of alpha within the temperature interval of T-C2 - T < 6 K were consistent with that predicted from 2-d potts model (alpha = 0.30). In addition, the thermodynamic quantities: the internal energy (U), the entropy (S) and the Helmholtz free energy (F) of this compound were calculated on the basis of the extracted values of the critical exponent a below and above the phase transition temperatures of T-C1 and T-C2.
Citation - WoS: 8
Citation - Scopus: 8
Study of Vibrational Modes in (Ga2s3)x - (ga2se3)1-X Mixed Crystals by Raman and Infrared Reflection Measurements
(Elsevier, 2019) Guler, I.; Gasanly, N. M.; Isik, 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.

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