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Article Citation - WoS: 9Citation - Scopus: 9Determination of optical parameters of Ga0.75In0.25Se layered crystals(Wiley-v C H verlag Gmbh, 2012) Isik, M.; Gasanly, N. M.The optical properties of the Ga0.75In0.25Se crystals have been investigated by means of transmission and reflection measurements in the wavelength range of 380-1100 nm. The analysis of the results performed at room temperature revealed the presence of optical indirect transtions with band gap energy of 1.89 eV. The variation of the band gap energy as a function of temperature was also studied in the temperature range of 10-300 K. The rate of change of band gap energy (? = 6.2 x 10(4) eV/K) and absolute zero value of the band gap (Egi(0) = 2.01 eV) were reported. The wavelength dependence of the refractive index was analyzed using Wemple and DiDomenico, Sellmeier and Cauchy models to find the oscillator energy, dispersion energy, oscillator strength and zero-frequency refractive index values. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)Article Influence of Photonic Excitations on the Electrical Parameters of Tlins2 Crystals(Wiley-v C H verlag Gmbh, 2010) Qasrawi, A. F.; Gasanly, N. M.The photo-excitation effect on the current transport mechanism in TlInS2 crystals has been studied by means of dark and illuminated conductivity measurements. The temperature-dependent electrical conductivity analysis in the temperature region of 110-340 K revealed the domination of the thermionic emission and the thermally assisted variable range hopping (VRH) of charge carriers above and below 160 K, respectively. Above 160 K, the conductivity activation energies in the dark are found to be 0.28 and 0.15 eV in the temperature regions of 340-240 K and 230-160 K, respectively. In the temperature region of 110-150 K, the dark variable range hopping analysis revealed a density of localized states of 1.99x 10(22) cm(-3)eV(-1), an average hopping distance of 0.53 nm and an average hopping energy of 79.65 meV. When the sample was photo-excited, the values of the conductivity activation energies, the density of localized states near the Fermi level and the average hopping energy were observed to decrease sharply with increasing illumination intensity. On the other hand, the average hopping distance increased with rising illumination intensity. Such behaviours were attributed to the Fermi level shift and/or trap density reduction by electron-hole recombination. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
