Browsing by Author "Gasanly, N.M."

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    Donor - acceptor pair recombination in Tl2InGaS4 layered crystals
    (2005) Goksen, K.; Gasanly, N.M.; Ozkan H.; Aydınlı, Atilla
    Photoluminescence (PL) spectra of Tl2InGaS4 layered single crystals were studied in the temperature range 15-150 K and wide laser excitation intensity range 0.01-110.34 Wcm-2. We observed a total of three PL bands, one centered at 542 nm (2.286 eV, A-band), one at 607 nm (2.041 eV, B-band), and one at 707 nm (1.754 eV, C-band), at various excitation intensities. The A- and the B-bands were determined to be due to radiative transitions from moderately deep donor levels located at 0.189 and 0.443 eV below the bottom of the conduction band to the shallow acceptor levels at 0.025 and 0.016 eV above the top of the valence band, respectively. The blue shift of the C-band peak energy and the quenching of the PL with increasing temperature are explained within the configuration coordinate model. The observation in the PL spectra of different emission bands in the sequence of B-, C- and A-bands at low, moderate, and high excitation laser intensities, respectively, are attributed to the shift of the quasi-Fermi level with increasing excitation intensity.
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    Thermally stimulated currents in layered Ga4SeS3 semiconductor
    (2004) Aytekin, S.; Yuksek, N.S.; Goktepe, M.; Gasanly, N.M.; Aydınlı, Atilla
    Thermally stimulated current (TSC) measurements are carried out on nominally undoped Ga4SeS3 layered semiconductor samples with the current flowing along the c-axis in the temperature range of 10 to 150 K. The results are analyzed according to various methods, such as curve fitting, initial rise and Chcn's methods, which seem to be in good agreement with each other. Experimental evidence is found for the presence of three trapping centers in Ga4SeS3 with activation energies of 70, 210 and 357 meV. The calculation yielded 7.9 × 10-21,7.0 × 10 -19 and 1.5 × 10-13 cm2 for the capture cross section, and 1.6 × 1010, 6.5 × 1010 and 1.2 × 1011 cm-3 for the concentration of the traps studied. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinlteim.