Browsing by Subject "A. Semiconductors"
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Item Open Access Low temperature photoluminescence spectra of InS single crystals(Elsevier, 1997-03) Gasanly, N. M.; Aydınlı, AtillaPhotoluminescence (PL) spectra of InS were investigated in the wavelength region 477.5–860 nm and in the temperature range 8.5–293 K. We observed three PL bands centered at 605 nm (A-band), 626 nm (B-band) and 820 nm (C-band). The A- and B-bands are due to radiative transitions from the donor level at 0.01 eV below the bottom of the conduction band to the valence band and from the donor level at 0.06 eV below the bottom of the conduction band to the acceptor level 0.12 eV above the top of the valence band, respectively. The proposed energy-level scheme allows us to interpret the recombination processes in InS single crystals. Copyright © 1997 Published by Elsevier Ltd.Item Open Access Low-temperature photoluminescence spectra of layered semiconductor TlGaS2(Pergamon Press, 1998) Gasanly, N. M.; Aydınlı, Atilla; Bek, A.; Yilmaz, I.Photoluminescence (PL) spectra of TlGaS2 layered single crystals were studied in the wavelength region 500-860 nm and in the temperature range 9.5-293 K. We observed a total of three PL bands centered at 568 nm (2.183 eV, A-band), 718 nm (1.727 eV, B-band) and 780 nm (1.590 eV, C-band) at various temperatures. We have also studied the variations of the A- and B-band intensities vs excitation laser density in the range from 7 × 10-2 to 9 W cm-2. The A- and B-bands were found to be due to radiative transitions from the deep donor levels located at 0.362 and 0.738 eV below the bottom of the conduction band to the shallow acceptor levels at 0.005 and 0.085 eV located above the top of the valence band, respectively. The proposed energy-level diagram permits us to interpret the recombination processes in TlGaS2 layered single crystals. © 1997 Elsevier Science Ltd.Item Open Access Low-temperature photoluminescence study of GaS0.5Se0.5 layered crystals(Elsevier Science, 2001) Aydnl, A.; Gasanly, N. M.; Gökşen, K.Photoluminescence (PL) spectra of GaS0.5Se0.5 layered single crystals have been studied in the wavelength range of 565-860 nm and in the temperature range of 15-170 K. Two PL bands centered at 585 nm (2.120 eV) and 640 nm (1.938 eV) were observed at T = 15 K. Variations of both bands were studied as a function of excitation laser intensity in the range from 10-3 to 15.9 W cm-2. These bands are attributed to recombination of charge carriers through donor-acceptor pairs located in the band gap. Radiative transitions from shallow donor levels located at 0.029 and 0.040 eV below the bottom of the conduction band to deep acceptor levels located 0.185 and 0.356 eV above the top of the valence band are suggested to be responsible for the observed A- and B-bands in the PL spectra, respectively. A simple energy level diagram explaining the recombination process is proposed.Item Open Access Trap levels in layered semiconductor Ga2SeS(Elsevier, 2004) Aydınlı, Atilla; Gasanly, N. M.; Aytekin, S.Trap levels in nominally undoped Ga2SeS layered crystals have been characterized by thermally stimulated current (TSC) measurements. During the measurements, current was allowed to flow along the c-axis of the crystals in the temperature range of 10-300 K. Two distinct TSC peaks were observed in the spectra, deconvolution of which yielded three peaks. The results are analyzed by curve fitting, peak shape and initial rise methods. They all seem to be in good agreement with each other. The activation energies of three trapping centers in Ga2SeS are found to be 72, 100 and 150 meV. The capture cross section of these traps are 6.7×10-23, 1.8×10-23 and 2.8×10-22cm2 with concentrations of 1.3×1012, 5.4×1012 and 4.2×1012cm-3, respectively.