Kıyılarda iklim değişikliğine karşı kumlanma modeli destekli kırılganlık analiz projesi-KIDEKA

TÜBİTAK MAG15.03.201

Karadeniz ve Akdeniz tsunamileri için model geliştirme ve risk analizi projesi

TÜBİTAK ÇAYDAG15.07.201

A computer simulation model for seaport planning

Ph.D. - Doctoral Progra

Raman scattering in TlInS2xSe2(1-x) layered mixed crystals (0.25 <= x <= 1): Compositional dependence of the mode frequencies and line widths

The Raman spectra of TlInS2xSe2(1-x) layered mixed crystals were studied for a wide composition range (0.25 <= x <= 1) in the frequency region 10-360 cm(-1) at room temperature. The shift of Raman-active phonon frequencies versus mixed crystals composition x were established. The effect of crystal disorder on the line width broadening of three high-frequency Raman-active modes is reported

Trapping center parameters in TlInSSe layered single crystals bit thermally stimulated currents measurements

Thermally stimulated current measurements have been carried out on TlInSSe layered single crystals in the temperature range of 10-180 K at a constant heating rate 0.8 K s(-1) The electronic traps distributions have been analyzed by the different light illumination temperature technique (T-0.1 = 30, 40, 45, 50, 52, 55 and 57 K). It was revealed that the obtained traps distribution can be described as an exponential distribution. The variation of one order of magnitude in the trap density for every 41 meV was estimated. Moreover. the mean activation energy, attempt-to-escape frequency. capture cross-section and concentration of the traps were determined. (C) 2009 Elsevier B V All rights reserved

Optical and photoelectrical properties of TlInSSe layered single crystals

Optical and electrical properties of TlInSSe layered single crystals have been studied by means of transmission, reflection and photoconductivity measurements. Transmission and reflection experiments have been carried out from 540 to 1000 nm at room temperature. Derivative analysis was applied to both transmission and reflection spectra and indirect band gap energy was found as 2.06 eV. Photoconductivity measurements have been performed in the temperature range from 245 to 300 K and in the voltage range from 10 to 80 V. From the temperature-dependent photoconductivity measurements, the observed single peak shifted to higher wavelengths with increase of temperature. The increase of photoconductivity with temperature is due to the increase in the mobility of photocarriers that can be explained by Bube model. From X112 method, room temperature indirect band gap of the crystal was also found as 2.06 eV. From voltage-dependent photoconductivity measurements, the peak maximum increased linearly with increase of voltage because of increase of the mobility of charge carriers. Dark current-voltage characteristic of TlInSSe crystal showed the ohmic behavior that means space charge limited current did not exist in the crystal. From the photocurrent with different illumination intensity analysis, the supralinear photoconductivity associated with the two center model was found. (C) 2017 Elsevier GmbH. All rights reserved

Optical properties of TlGaSeS layered single crystals

The optical properties of TlGaSeS layered single crystals have been investigated by measuring the transmissions and the reflections in the wavelength region between 400 and 1100 nm. The optical indirect transitions with a band gap energy of 2.27 eV and direct transitions with a band gap energy of 2.58 eV were found by means of the analysis of the absorption data at the room temperature. The rate of change of the indirect band gap with temperature, that is, gamma = -3.2 x 10(-4) eV/K, was determined from the transmission measurements in the temperature range of 10 - 300 K. The absolute zero value of the band gap energy was obtained as E-gi(0) = 2.34 eV. The dispersion of the refractive index is discussed in terms of the Wemple-DiDomenico single-effective-oscillator model. The oscillator energy, the dispersion energy, the oscillator strength, and the zero-frequency refractive index, which are all refractive-index dispersion parameters, were found to be 4.71 eV, 28.98 eV, 8.88 x 10(13) m(-2) and 2.67, respectively. The parameters of the monoclinic unit cell were found by studying the X-ray powder diffraction

Determination of trapping center parameters in Tl2In2S3Se layered single crystals by thermally stimulated current measurements

As-grown Tl2In2S3Se layered single crystals were studied by thermally stimulated current measurements in the temperature range of 10-170K with different heating rates. Experimental data were analyzed according to various methods such as curve fitting and initial rise. The analysis of thermally stimulated current spectra registered at light excitation temperature T-0 = 10K revealed the trap level located at 30 meV. Attempt-to-escape frequency, concentration and capture cross section of the traps were determined as 4.2 s(-1), 2.4 x 10(9) cm(-3) and 1.7 x 10(-24) cm(2), respectively. It was concluded that slow retrapping (monomolecular condition) occurs for the traps in Tl2In2S3Se crystals. By the analysis of thermally stimulated current data at different light excitation temperatures, the value of 39 meV/decade was obtained for traps distribution

Trapping centers and their distribution in Tl2In2Se3S layered single crystals

Thermally stimulated current (TSC) measurements have been carried out on Tl(2)ln(2)Se(3)S layered single crystals in the temperature range of 10-175 K. The TSC spectra reveal the presence of two peaks (A and B). The electronic traps' distributions have been analyzed by different light illumination temperature techniques. It was revealed that the obtained traps' distribution can be described as an exponential one. The variations of one order of magnitude in the traps' density for every 30 meV (A peak) and 59 meV (B peak) were estimated. Moreover, the mean activation energy, attempt-to-escape frequency, capture cross section and concentration of the traps were determined