Fizik Bilim Dalı Yayın Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/4363

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Growth and temperature tuned band gap characteristics of NaBi(MoO4)2 single crystal
(2023) Isik, M.; Güler, İ.; Gasanly, N.M.; 101531
Structural and optical properties of double sodium-bismuth molybdate NaBi(MoO4)2 semiconductor compound was investigated by x-ray diffraction, Raman and transmission experiments. From the x-ray diffraction experiments, the crystal that has tetragonal structure was obtained. Vibrational modes of the crystal were found from the Raman experiments. Transmission experiments were performed in the temperature range of 10-300 K. Derivative spectroscopy analysis and absorption spectrum analysis were performed to get information about the change in band gap energy of the crystal with temperature. It was observed that the band gap energies of the crystal at different temperatures obtained from these techniques are well consisted with each other. By the help of absorption spectrum which was obtained from transmission measurements performed at varying temperatures, absolute zero value of the band gap and average phonon energy as 3.03 ± 0.02 eV and E p h = 24 ± 0.2 meV, respectively. Moreover, based on absorption spectrum analysis the Urbach energy of the crystal was obtained as 0.10 eV.
Optical characterization of (TlInS2)0.5(TlInSe2)0.5 crystal by ellipsometry: linear and optical constants for optoelectronic devices
(2023) Guler, İ.; Isik, M.; Gasanly, N.; 101531
TlInSSe [(TlInS2)0.5(TlInSe2)0.5] crystals have garnered significant attention as promising candidates for optoelectronic applications due to their exceptional optoelectrical characteristics. This study focused on investigating the linear and nonlinear optical properties of TlInSSe layered single crystals through ellipsometry measurements. The X-ray diffraction analysis revealed the presence of four distinct peaks corresponding to a monoclinic crystalline structure. In-depth analysis was conducted to examine the variations of refractive index, extinction coefficient, and complex dielectric function within the energy range of 1.25–6.15 eV. By employing derivative analysis of the absorption coefficient and utilizing the Tauc relation, the indirect and direct bandgap energies of TlInSSe crystals were determined to be 2.09 and 2.26 eV, respectively. Furthermore, this research paper presents findings on oscillator energy, dispersion energy, Urbach energy, zero and high frequency dielectric constants, plasma frequency, carrier density to effective mass ratio, nonlinear refractive index, and first-order and third-order nonlinear susceptibilities of TlInSSe crystals.
Thermoluminescence in gallium sesquisulfide single crystals: usual and unusual heating rate dependencies
(2018) Guler, I.; Isik, M.; Gasanova, L.; Mahammadov, A.; Gasanly, N.
Thermoluminescence (TL) experiments were conducted for Ga2S3 crystals to obtain information about trapping parameters. TL measurements were performed from 10 to 300 K with varying heating rates in the range of 0.2–0.8 K/s. Two TL glow peaks centered at 44 K (peak A) and 91 K (peak B) were observed at heating rate of β = 0.5 K/s. For peak A, TL intensity decreased whereas that for peak B increased with elevating the heating rates that means anomalous heating rate occurred for peak B. TL glow curves were analyzed using initial rise method to find activation energies of traps. Distribution of trap centers was investigated using Tmax − Tstop method. Quasi-continuous distributions with increasing activation energies from 40 to 135 meV and 193 to 460 meV were attributed to trap centers A and B, respectively.

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Browsing Fizik Bilim Dalı Yayın Koleksiyonu by Author "Isik, M."